Methods and compositions for treating concrete reclaimed water

Abstract

Provided herein are compositions and methods for carbonating wash water (reclaimed water) produced during the production and use of concrete, and subsequent uses of the carbonated reclaimed water, including its use in the manufacture and use of additional batches of concrete.

Description

[Technical Field]

[0001] cross reference This application is a continuation of PCT Application No. PCT / CA2018 / 050750, filed June 20, 2018; PCT Application No. PCT / CA2017 / 050445, filed April 11, 2017; U.S. Provisional Patent Application No. 62 / 321,013, filed April 11, 2016; U.S. Provisional Patent Application No. 62 / 522,510, filed June 20, 2017; U.S. Provisional Patent Application No. 62 / 554,830, filed September 6, 2017; U.S. Provisional Patent Application No. 62 / 558,173, filed September 13, 2017; This application is related to U.S. Provisional Patent Application No. 62 / 559,771, filed September 19, 2017, U.S. Provisional Patent Application No. 62 / 560,311, filed September 19, 2017, U.S. Provisional Patent Application No. 62 / 570,452, filed October 10, 2017, U.S. Provisional Patent Application No. 62 / 675,615, filed May 23, 2018, U.S. Provisional Patent Application No. 62 / 652,385, filed April 4, 2018, and U.S. Provisional Patent Application No. 62 / 573,109, filed October 16, 2017, all of which are incorporated by reference in their entirety. This application also claims priority to U.S. Provisional Patent Application No. 62 / 911,871, filed October 7, 2019, which is incorporated by reference in its entirety. [Background technology]

[0002] Wash water generated during the preparation of concrete poses significant problems regarding use and / or disposal. Methods and compositions are needed to better manage concrete wash water. Summary of the Invention

[0003] In one aspect, provided herein is a composition.

[0004] In certain embodiments, provided herein is an apparatus for introducing gas into concrete regeneration water, the apparatus including: (i) a first conduit operably connected at a proximal end thereof to a source of concrete regeneration water, the first conduit allowing the regeneration water to flow from its proximal end through it and out its distal end; and (ii) a second conduit located inside the first conduit, the second conduit operably connected to a source of gas and configured to allow the gas to flow into and out of the regeneration water in the first conduit. In certain embodiments, the gas includes carbon dioxide. In certain embodiments, the first conduit has a diameter of 0.5 to 5 inches, and the second conduit has a diameter of 0.3 to 3 inches. In certain embodiments, the first conduit is operably connected at its proximal end to the source of concrete regeneration water by a third conduit, the diameter of the first conduit being larger than the diameter of the third conduit. In certain embodiments, the first conduit is operably connected at its distal end to the regenerator by a fourth conduit, the diameter of the first conduit being larger than the diameter of the fourth conduit. In certain embodiments, the apparatus further includes a control system including: (iii) a sensor that senses the specific gravity of the regenerated water and transmits information regarding the specific gravity to a controller; and (iv) the controller that processes information from the sensor. The control system may further include (v) an actuator that receives a signal from the controller based at least in part on the processed information from the sensor. In certain embodiments, the actuator includes a valve that can regulate the flow of gas into the second conduit. In certain embodiments, the second conduit includes perforations configured to allow gas to pass from the second conduit to the regenerated water in the first conduit when the gas exceeds a threshold pressure in the second conduit, but not allow the regenerated water to enter the second conduit from the first conduit.In certain embodiments, the apparatus further includes at least one of a sensor for sensing the level of reclaimed water in the reclaimed water holding tank, a sensor for sensing the temperature of the reclaimed water, a sensor for sensing the flow rate of gas into the second conduit, a sensor for sensing whether and / or how much admixture has been added to the reclaimed water, a device indicating whether a pump pumping the reclaimed water through the first conduit is operating, or a timer, wherein the sensor, device, or timer is configured to send information to a controller that processes the information. In certain embodiments, the apparatus further includes at least two of a sensor for sensing the level of reclaimed water in the reclaimed water holding tank, a sensor for sensing the temperature of the reclaimed water, a sensor for sensing the flow rate of gas into the second conduit, a sensor for sensing whether and / or how much admixture has been added to the reclaimed water, a device indicating whether a pump pumping the reclaimed water through the first conduit is operating, or a timer, wherein the sensors, devices, or timers are configured to send information to a controller that processes the information. In certain embodiments, the apparatus further includes at least three of a sensor for sensing the level of reclaimed water in the reclaimed water holding tank, a sensor for sensing the temperature of the reclaimed water, a sensor for sensing the flow rate of gas into the second conduit, a sensor for sensing whether and / or how much admixture has been added to the reclaimed water, a device indicating whether a pump pumping the reclaimed water through the first conduit is operating, or a timer, wherein the sensors, devices, or timers are configured to send information to a controller that processes the information. In certain embodiments, the apparatus further includes at least four of a sensor for sensing the level of reclaimed water in the reclaimed water holding tank, a sensor for sensing the temperature of the reclaimed water, a sensor for sensing the flow rate of gas into the second conduit, a sensor for sensing whether and / or how much admixture has been added to the reclaimed water, a device indicating whether a pump pumping the reclaimed water through the first conduit is operating, or a timer, wherein the sensors, devices, or timers are configured to send information to a controller that processes the information.In certain embodiments, the controller further receives information regarding the composition of the reclaimed water, including the percentage of the reclaimed water that is cementitious material.

[0005] In another aspect, provided herein is a method.

[0006] In certain embodiments, provided herein are methods for treating concrete reclaimed water with a gas, the method including: (i) flowing reclaimed water from a source of reclaimed water into a first conduit at a proximal end of the first conduit and exiting the first conduit at a distal end of the first conduit; (ii) flowing gas from a source of gas into a second conduit located inside the first conduit; and (iii) flowing the gas out of the second conduit and into the reclaimed water in the first conduit. In certain embodiments, the gas comprises carbon dioxide. In certain embodiments, the first conduit has a diameter of 0.5 to 5 inches, and the second conduit has a diameter of 0.3 to 3 inches. In certain embodiments, the reclaimed water flows from the source of concrete reclaimed water into the first conduit through a third conduit operably connected to the source of concrete reclaimed water and connected to the first conduit at the proximal end of the first conduit, the diameter of the first conduit being larger than the diameter of the third conduit. In certain embodiments, the reclaimed water flows out of the first conduit and into a fourth conduit operably connected at a distal end of the first conduit, the first conduit having a diameter greater than the diameter of the fourth conduit. In certain embodiments, the method further includes determining a specific gravity of the reclaimed water and transmitting information regarding the specific gravity to a controller that processes the information. In certain embodiments, the method further includes transmitting a signal from the controller to an actuator, the signal based at least in part on the processed information. In certain embodiments, the actuator includes a valve that regulates the flow of gas into the second conduit based at least in part on the signal received from the controller. In certain embodiments, the gas travels from the second conduit to the reclaimed water in the first conduit through perforations configured to allow gas to pass from the second conduit to the reclaimed water in the first conduit when the gas exceeds a threshold pressure in the second conduit, but not allow the reclaimed water to enter the second conduit from the first conduit.In certain embodiments, the method further includes transmitting information to the controller from at least one of a sensor sensing the level of reclaimed water in the reclaimed water holding tank, a sensor sensing the temperature of the reclaimed water, a sensor sensing the flow rate of gas into the second conduit, a sensor sensing whether and / or how much admixture has been added to the reclaimed water, a device indicating whether a pump pumping the reclaimed water through the first conduit is operating, or a timer, and processing the information in the controller. In certain embodiments, the method further includes transmitting information to the controller from at least two of a sensor sensing the level of reclaimed water in the reclaimed water holding tank, a sensor sensing the temperature of the reclaimed water, a sensor sensing the flow rate of gas into the second conduit, a sensor sensing whether and / or how much admixture has been added to the reclaimed water, a device indicating whether a pump pumping the reclaimed water through the first conduit is operating, or a timer, and processing the information in the controller. In certain embodiments, the method further includes transmitting information to the controller from at least three of: a sensor that senses the level of the reclaimed water in the reclaimed water holding tank, a sensor that senses the temperature of the reclaimed water, a sensor that senses the flow rate of gas into the second conduit, a sensor that senses whether and / or how much admixture has been added to the reclaimed water, a device that indicates whether a pump that pumps the reclaimed water through the first conduit is operating, or a timer; and processing the information in the controller. In certain embodiments, the method further includes transmitting information to the controller from at least four of: a sensor that senses the level of the reclaimed water in the reclaimed water holding tank, a sensor that senses the temperature of the reclaimed water, a sensor that senses the flow rate of gas into the second conduit, a sensor that senses whether and / or how much admixture has been added to the reclaimed water, a device that indicates whether a pump that pumps the reclaimed water through the first conduit is operating, or a timer; and processing the information in the controller. In certain embodiments, the controller further receives information regarding the composition of the reclaimed water, including the percentage of the reclaimed water that is cementitious material.

[0007] Incorporation by Reference All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.

[0008] The novel features of this specification are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which: [Brief explanation of the drawings]

[0009] [Figure 1] 1 shows the slump of concrete mixes made with 10% w / w dry carbonated wash water solids, 20% w / w dry carbonated wash water solids, or a control (no dry carbonated wash water solids). [Figure 2] 1 shows the compressive strength at 1, 7, and 28 days of concrete mixes made with 10% w / w dry carbonated wash water solids, 20% w / w dry carbonated wash water solids, or a control (no dry carbonated wash water solids). [Figure 3] Calorimetry as power versus time is shown for concrete mixes made with 10% w / w dry carbonated wash water solids, 20% w / w dry carbonated wash water solids, or a control (no dry carbonated wash water solids). [Figure 4] 1 shows the composition of various concrete mixes made with 10% w / w dry carbonated wash water solids, 20% w / w dry carbonated wash water solids, or a control (no dry carbonated wash water solids). [Figure 5] FIG. 1 shows the slump compared to a control for concrete mixes made with wash water exposed to carbon dioxide by exposure to simulated exhaust gas and varying levels of cement, or made with reduced cement and water. [Figure 6]Figure 1 shows the compressive strength at 1, 7, and 28 days compared to a control for concrete mixes made with wash water exposed to carbon dioxide by exposure to simulated exhaust gas and varying levels of cement, or made with reduced cement and water. [Figure 7] 1 shows calorimetry as power versus time of concrete mixes made with wash water exposed to carbon dioxide by exposure to simulated exhaust gas and varying levels of cement, or made with reduced cement and water, compared to a control. [Figure 8] 1 shows the composition of various concrete mixes made with wash water exposed to carbon dioxide by exposure to simulated exhaust gas and various levels of cement, or made with reduced cement and water, compared to a control. [Figure 9] The slump of a control concrete made without wash water; a concrete batch made with wash water substituted entirely with wash water and treated with 1.5% sodium gluconate at a specific gravity of 1.10; a concrete batch made with wash water substituted entirely with wash water and treated with 1.5% sodium gluconate at a specific gravity of 1.075; and a concrete batch made with wash water substituted entirely with wash water and treated with 1.5% sodium gluconate at a specific gravity of 1.05. [Figure 10] Figure 1 shows compressive strengths at 1, 7, and 28 days for a control concrete made without wash water; a concrete batch made with wash water substituted entirely with wash water and treated with 1.5% sodium gluconate at a specific gravity of 1.10; a concrete batch made with wash water substituted entirely with wash water and treated with 1.5% sodium gluconate at a specific gravity of 1.075; and a concrete batch made with wash water substituted entirely with wash water and treated with 1.5% sodium gluconate at a specific gravity of 1.05. [Figure 11]Calorimetry as power versus time is shown for a control concrete made without wash water; a concrete batch made with wash water substituted entirely with wash water and treated with 1.5% sodium gluconate at a specific gravity of 1.10; a concrete batch made with wash water substituted entirely with wash water and treated with 1.5% sodium gluconate at a specific gravity of 1.075; and a wash water batch substituted entirely with wash water and treated with 1.5% sodium gluconate at a specific gravity of 1.05. [Figure 12] The compositions of various concrete mixes are shown, which were produced as a control concrete made without wash water; a concrete batch made with wash water substituted entirely with wash water and treated with 1.5% sodium gluconate at a specific gravity of 1.10; a concrete batch made with wash water substituted entirely with wash water and treated with 1.5% sodium gluconate at a specific gravity of 1.075; and a concrete batch made with wash water substituted entirely with wash water and treated with 1.5% sodium gluconate at a specific gravity of 1.05. [Figure 13] Figure 1 shows the slump of various concrete mixes, including mixes made with a control mix (no wash water); and untreated wash water without gluconate; untreated wash water with gluconate added after 3 hours of hydration; untreated wash water with gluconate added after 24 hours of hydration and just before concrete batching; treated wash water without gluconate; treated wash water with gluconate added before treatment and after 3 hours of hydration; and treated wash water with gluconate added after 24 hours and just before concrete batching. [Figure 14]Figure 1 shows the compressive strength at 7 and 28 days of various concrete mixes, including mixes made with a control mix (no wash water); and untreated wash water without gluconate; untreated wash water with gluconate added after 3 hours of hydration; untreated wash water with gluconate added after 24 hours of hydration and just before concrete batching; treated wash water without gluconate; treated wash water with gluconate added before treatment and after 3 hours of hydration; and treated wash water with gluconate added after 24 hours and just before concrete batching. [Figure 15] 1 shows calorimetry as power versus time for various concrete mixes, including mixes made with a control mix (no wash water); and untreated wash water without gluconate; untreated wash water with gluconate added after 3 hours of hydration; untreated wash water with gluconate added after 24 hours of hydration and just before concrete batching; treated wash water without gluconate; treated wash water with gluconate added before treatment and after 3 hours of hydration; and treated wash water with gluconate added after 24 hours and just before concrete batching. [Figure 16] 1 shows the compositions of various concrete mixes, including mixes made with a control mix (no wash water); untreated wash water without gluconate; untreated wash water with gluconate added after 3 hours of hydration; untreated wash water with gluconate added after 24 hours of hydration and just before concrete batching; treated wash water without gluconate; treated wash water with gluconate added before treatment and after 3 hours of hydration; and treated wash water with gluconate added after 24 hours and just before concrete batching. [Figure 17]Figure 1 shows the slump of a control concrete batch made without wash water; a concrete batch made with untreated wash water containing 0.6% sodium gluconate replaced entirely with wash water; a concrete batch made with untreated wash water containing 1.2% sodium gluconate replaced entirely with wash water; a concrete batch made with treated wash water batch containing 3% sodium gluconate, 5% reduction in cement, and replaced entirely with wash water; and a concrete batch made with treated wash water containing 3% sodium gluconate, 10% reduction in cement, and replaced entirely with wash water. [Figure 18] 1 shows the compressive strength of a control concrete batch made without wash water; a concrete batch made with untreated wash water containing 0.6% sodium gluconate replaced entirely with wash water; a concrete batch made with untreated wash water containing 1.2% sodium gluconate replaced entirely with wash water; a concrete batch made with treated wash water batch containing 3% sodium gluconate, 5% reduction in cement, and replaced entirely with wash water; and a concrete batch made with treated wash water containing 3% sodium gluconate, 10% reduction in cement, and replaced entirely with wash water. [Figure 19] Calorimetry as power versus time is shown for a control concrete batch made without wash water; a concrete batch made with untreated wash water containing 0.6% sodium gluconate replaced entirely with wash water; a concrete batch made with untreated wash water containing 1.2% sodium gluconate replaced entirely with wash water; a concrete batch made with treated wash water batch containing 3% sodium gluconate, 5% reduction in cement, and replaced entirely with wash water; and a concrete batch made with treated wash water containing 3% sodium gluconate, 10% reduction in cement, and replaced entirely with wash water. [Figure 20]The compositions shown are for a control concrete batch made without wash water; a concrete batch made with untreated wash water containing 0.6% sodium gluconate, replaced entirely with wash water; a concrete batch made with untreated wash water containing 1.2% sodium gluconate, replaced entirely with wash water; a concrete batch made with treated wash water batch containing 3% sodium gluconate, 5% reduction in cement, and replaced entirely with wash water; and a concrete batch made with treated wash water containing 3% sodium gluconate, 10% reduction in cement, and replaced entirely with wash water. [Figure 21] Figure 1 shows the slump of a control concrete batch made without wash water; a concrete batch made with aged treated wash water containing no sodium gluconate and substituted entirely with wash water; a concrete batch made with aged treated wash water containing 2.4% sodium gluconate and substituted entirely with wash water; and a concrete batch made with aged treated wash water containing 4.8% sodium gluconate and substituted entirely with wash water. [Figure 22] Figure 1 shows compressive strengths at 1, 7, and 28 days for a control concrete batch made without wash water; a concrete batch made with aged treated wash water containing no sodium gluconate and substituted entirely with wash water; a concrete batch made with aged treated wash water containing 2.4% sodium gluconate and substituted entirely with wash water; and a concrete batch made with aged treated wash water containing 4.8% sodium gluconate and substituted entirely with wash water. [Figure 23] 1 shows the compositions of a control concrete batch made without wash water; a concrete batch made with aged treated wash water containing no sodium gluconate and substituted entirely with wash water; a concrete batch made with aged treated wash water containing 2.4% sodium gluconate and substituted entirely with wash water; and a concrete batch made with aged treated wash water containing 4.8% sodium gluconate and substituted entirely with wash water. [Figure 24]Shown is the slump for concrete batches made as follows: control (no wash water); untreated wash water control (2.7% gluconate just before batching); treated wash water (no gluconate); treated wash water (2.7% gluconate added just before batching); treated wash water control (8.1% lignosulfonate added just before batching). [Figure 25] Shown are compressive strengths at 3, 7, and 28 days for concrete batches made as follows: control (no wash water); untreated wash water control (2.7% gluconate added just before batching); treated wash water (no gluconate); treated wash water (2.7% gluconate added just before batching); treated wash water control (8.1% lignosulfonate added just before batching). [Figure 26] Calorimetry as power versus time is shown for concrete batches made as follows: control (no wash water); untreated wash water control (2.7% gluconate just before batching); treated wash water (no gluconate); treated wash water (2.7% gluconate added just before batching); treated wash water control (8.1% lignosulfonate added just before batching). [Figure 27] The compositions of concrete batches made as follows are shown: control (no wash water); untreated wash water control (2.7% gluconate just before batching); treated wash water (no gluconate); treated wash water (2.7% gluconate added just before batching); treated wash water control (8.1% lignosulfonate added just before batching). [Figure 28] Slumps are shown for concrete batches made as follows: control (no wash water); treated wash water batch, all wash water replacement, 1.4% sodium gluconate; treated wash water batch, all wash water replacement, 1.4% sodium gluconate before carbonation and 0.7% sodium gluconate after carbonation; treated wash water batch, 5% cement reduction, all wash water replacement, 1.4% sodium gluconate. [Figure 29]The compressive strengths at 1, 7, and 28 days are shown for concrete batches made as follows: control (no wash water); treated wash water batch, all wash water replacement, 1.4% sodium gluconate; treated wash water batch, all wash water replacement, 1.4% sodium gluconate before carbonation and 0.7% sodium gluconate after carbonation; and treated wash water batch, 5% cement reduction, all wash water replacement, 1.4% sodium gluconate. [Figure 30] Calorimetry as power versus time is shown for concrete batches made as follows: control (no wash water); treated wash water batch, all wash water replacement, 1.4% sodium gluconate; treated wash water batch, all wash water replacement, 1.4% sodium gluconate before carbonation and 0.7% sodium gluconate after carbonation; treated wash water batch, 5% cement reduction, all wash water replacement, 1.4% sodium gluconate. [Figure 31] The compositions shown are for concrete batches made as follows: control (no wash water); treated wash water batch, all wash water replacement, 1.4% sodium gluconate; treated wash water batch, all wash water replacement, 1.4% sodium gluconate before carbonation and 0.7% sodium gluconate after carbonation; treated wash water batch, 5% cement reduction, all wash water replacement, 1.4% sodium gluconate. [Figure 32] Figure 1 shows the slump (min) over time for concrete batches made as follows: control (no wash water); treated wash water, all substitutes, 1.4% gluconate by weight of wash water solids; treated wash water, all substitutes, 2% gluconate by weight of wash water solids. [Figure 33] Figure 1 shows the compressive strength of concrete batches made as follows: control (no wash water); treated wash water, all substitutes, 1.4% gluconate by weight of wash water solids; treated wash water, all substitutes, 2% gluconate by weight of wash water solids. [Figure 34]Calorimetry as power versus time is shown for concrete batches made as follows: control (no wash water); treated wash water, all substitutes, 1.4% gluconate by weight of wash water solids; treated wash water, all substitutes, 2% gluconate by weight of wash water solids. [Figure 35] The compositions of concrete batches made as follows are shown: control (no wash water); treated wash water, all substitutes, 1.4% gluconate by weight of wash water solids; treated wash water, all substitutes, 2% gluconate by weight of wash water solids. [Figure 36] The slump of concrete batches made as follows is shown: control (no wash water); treated wash water, all substitutes, no gluconate; treated wash water, all substitutes, 1.6% gluconate by weight of wash water solids. [Figure 37] Figure 1 shows the compressive strength at 1, 7, and 28 days for concrete batches made as follows: control (no wash water); treated wash water, all substitutes, no gluconate; treated wash water, all substitutes, 1.6% gluconate by weight of wash water solids. [Figure 38] Calorimetry as power versus time is shown for concrete batches made as follows: control (no wash water); treated wash water, all substitutes, no gluconate; treated wash water, all substitutes, 1.6% gluconate by weight of wash water solids. [Figure 39] The compositions of concrete batches made as follows are shown: control (no wash water); treated wash water, all substitutes, no gluconate; treated wash water, all substitutes, 1.6% gluconate by weight of wash water solids. [Figure 40] Shown are the slumps of concrete batches made as follows: control (no wash water); treated wash water, all substitutes, 1.7% gluconate by weight of wash water solids; treated wash water, all substitutes, 1.7% gluconate by weight of wash water solids, 5% cement reduction. [Figure 41]Figure 1 shows compressive strengths at 1 day and 28 days for concrete batches made as follows: control (no wash water); treated wash water, all substitutes, 1.7% gluconate by weight of wash water solids; treated wash water, all substitutes, 1.7% gluconate by weight of wash water solids, 5% cement reduction. [Figure 42] Calorimetry as power versus time is shown for concrete batches made as follows: control (no wash water); treated wash water, all substitutes, 1.7% gluconate by weight of wash water solids; treated wash water, all substitutes, 1.7% gluconate by weight of wash water solids, 5% cement reduction. [Figure 43] The compositions of concrete batches made as follows are shown: control (no wash water); treated wash water, all substitutes, 1.7% gluconate by weight of wash water solids; treated wash water, all substitutes, 1.7% gluconate by weight of wash water solids, 5% cement reduction. [Figure 44] Shown are the slumps of concrete batches made as follows: control (no wash water); treated wash water, half replaced, 2% gluconate by weight of wash water solids, wash water mixed with tap water added first; treated wash water, half replaced, 2% gluconate by weight of wash water solids, wash water added first and tap water added later; treated wash water, half replaced, 2% gluconate by weight of wash water solids, tap water added first and wash water added later. [Figure 45] Figure 1 shows the compressive strength of concrete batches made as follows: control (no wash water); treated wash water, half substituted, 2% gluconate by weight of wash water solids, wash water mixed with tap water added first; treated wash water, half substituted, 2% gluconate by weight of wash water solids, wash water added first and tap water added later; treated wash water, half substituted, 2% gluconate by weight of wash water solids, tap water added first and wash water added later. [Figure 46]Calorimetry as power versus time is shown for concrete batches made as follows: control (no wash water); treated wash water, half substituted, 2% gluconate by weight of wash water solids, wash water mixed with clean water added first; treated wash water, half substituted, 2% gluconate by weight of wash water solids, wash water added first and clean water added later; treated wash water, half substituted, 2% gluconate by weight of wash water solids, clean water added first and wash water added later. [Figure 47] The compositions shown are for concrete batches made as follows: control (no wash water); treated wash water, half substituted, 2% gluconate by weight of wash water solids, wash water mixed with clean water added first; treated wash water, half substituted, 2% gluconate by weight of wash water solids, wash water added first and clean water added later; treated wash water, half substituted, 2% gluconate by weight of wash water solids, clean water added first and wash water added later. [Figure 48] Shown are the slumps of concrete batches made as follows: control (no wash water); treated wash water, all substitute, 2.5% gluconate by weight of wash water solids; treated wash water, 75% substitute, 2.5% gluconate by weight of wash water solids; and treated wash water, 50% substitute, 2.5% gluconate by weight of wash water solids. [Figure 49] Figure 7 shows compressive strengths at 7 and 28 days for concrete batches made as follows: control (no wash water); treated wash water, all substitutes, 2.5% gluconate by weight of wash water solids; treated wash water, 75% substitute, 2.5% gluconate by weight of wash water solids; and treated wash water, 50% substitute, 2.5% gluconate by weight of wash water solids. [Figure 50] Calorimetry as power versus time is shown for concrete batches made as follows: control (no wash water); treated wash water, all substitutes, 2.5% gluconate by weight of wash water solids; treated wash water, 75% substitute, 2.5% gluconate by weight of wash water solids; treated wash water, 50% substitute, 2.5% gluconate by weight of wash water solids. [Figure 51]The compositions of concrete batches made as follows are shown: control (no wash water); treated wash water, all substitute, 2.5% gluconate by weight of wash water solids; treated wash water, 75% substitute, 2.5% gluconate by weight of wash water solids; treated wash water, 50% substitute, 2.5% gluconate by weight of wash water solids. [Figure 52] The slump of concrete batches made as follows is shown: control (no wash water); untreated wash water, all substitute, 2% gluconate by weight of wash water solids; treated wash water, all substitute, 2% gluconate by weight of wash water solids; untreated wash water, 50% substitute, 2% gluconate by weight of wash water solids; treated wash water, 50% substitute, 2% gluconate by weight of wash water solids. [Figure 53] Figure 1 shows the compressive strength of concrete batches made as follows: control (no wash water); untreated wash water, all substitutes, 2% gluconate by weight of wash water solids; treated wash water, all substitutes, 2% gluconate by weight of wash water solids; untreated wash water, 50% substitute, 2% gluconate by weight of wash water solids; treated wash water, 50% substitute, 2% gluconate by weight of wash water solids. [Figure 54] Calorimetry as power versus time is shown for concrete batches made as follows: control (no wash water); untreated wash water, all substitutes, 2% gluconate by weight of wash water solids; treated wash water, all substitutes, 2% gluconate by weight of wash water solids; untreated wash water, 50% substitute, 2% gluconate by weight of wash water solids; treated wash water, 50% substitute, 2% gluconate by weight of wash water solids. [Figure 55] The compositions of concrete batches made as follows are shown: control (no wash water); untreated wash water, all substitutes, 2% gluconate by weight of wash water solids; treated wash water, all substitutes, 2% gluconate by weight of wash water solids; untreated wash water, 50% substitute, 2% gluconate by weight of wash water solids; treated wash water, 50% substitute, 2% gluconate by weight of wash water solids. [Figure 56] 1 shows the carbon dioxide uptake of wash water treated with low, medium, and high carbon dioxide flow rates. [Figure 57] The 7-day compressive strength (tests were repeated for each flow rate) is shown for the following mortar batches compared to the control: control, untreated wash water, all substituted, no CO2; treated wash water, all substituted, 7-8% CO2; treated wash water, all substituted, 10-13% CO2; treated wash water, all substituted, 14-15% CO2; treated wash water, all substituted, 16-17% CO2; and treated wash water, all substituted, 19-21% CO2. [Figure 58] Slump (tests were repeated for each flow rate) compared to the control is shown for mortar batches made as follows: control, untreated wash water, all substituted, no CO2; treated wash water, all substituted, 7-8% CO2; treated wash water, all substituted, 10-13% CO2; treated wash water, all substituted, 14-15% CO2; treated wash water, all substituted, 16-17% CO2; treated wash water, all substituted, 19-21% CO2. [Figure 59] Calorimeter setting times (tests were repeated for each flow rate) compared to the control for the following mortar batches: control, untreated wash water, all substituted, no CO2; treated wash water, all substituted, 7-8% CO2; treated wash water, all substituted, 10-13% CO2; treated wash water, all substituted, 14-15% CO2; treated wash water, all substituted, 16-17% CO2; treated wash water, all substituted, 19-21% CO2. [Figure 60] Calorimeter peak energy output (tests were repeated for each flow rate) compared to the control for the following mortar batches: control, untreated wash water, all substituted, no CO2; treated wash water, all substituted, 7-8% CO2; treated wash water, all substituted, 10-13% CO2; treated wash water, all substituted, 14-15% CO2; treated wash water, all substituted, 16-17% CO2; treated wash water, all substituted, 19-21% CO2. [Figure 61]Mortar batches were made as follows: control, untreated wash water, all substituted, no CO2; treated wash water, all substituted, 7-8% CO2; treated wash water, all substituted, 10-13% CO2; treated wash water, all substituted, 14-15% CO2; treated wash water, all substituted, 16-17% CO2; treated wash water, all substituted, 19-21% CO2, wash water temperature (tests were repeated for each flow rate) is shown. [Figure 62] Mortar batches were prepared as follows: control, untreated wash water, all substituted, no CO2; treated wash water, all substituted, 7-8% CO2; treated wash water, all substituted, 10-13% CO2; treated wash water, all substituted, 14-15% CO2; treated wash water, all substituted, 16-17% CO2; treated wash water, all substituted, 19-21% CO2. Wash water pH (tests were repeated for each flow rate) is shown. [Figure 63] 1 shows the carbon dioxide uptake over time for wash water of various specific gravities treated with carbon dioxide. [Figure 64] 1 shows the temperature versus time of wash water of various specific gravities treated with carbon dioxide. [Figure 65] Figure 1 shows the compressive strength of mortars containing blends of 70% cement and 30% Class C fly ash. All Class C fly ash was contained in prepared wash water treated with 1.2, 2.2, 2.4, 3.2, or 3.5% carbon dioxide. [Figure 66] Calorimetry as power versus time for mortars containing blends of 70% cement and 30% Class C fly ash is shown. All Class C fly ash was contained in prepared wash water treated with 1.2, 2.2, 2.4, 3.2, or 3.5% carbon dioxide. [Figure 67] The compositions of mortars made with mortars containing a blend of 70% cement and 30% Class C fly ash are shown. All Class C fly ash was contained in prepared wash water treated with 1.2, 2.2, 2.4, 3.2, or 3.5% carbon dioxide. [Figure 68]The slump of concrete mixes made as follows is shown: control, no wash water; untreated wash water, all substitutes; treated wash water, 20 minutes of CO2 injection; treated wash water, 40 minutes of CO2 injection. [Figure 69] The compressive strength of concrete mixes made as follows: control, no wash water; untreated wash water, all substitutes; treated wash water, 20 minutes of CO2 injection; and treated wash water, 40 minutes of CO2 injection are shown. [Figure 70] Calorimetry as power versus time is shown for concrete mixes made as follows: control, no wash water; untreated wash water, all substitutes; treated wash water, 20 min CO injection; treated wash water, 40 min CO injection. [Figure 71] The compositions of the concrete mixes prepared as follows are shown: control, no wash water; untreated wash water, all substitutes; treated wash water, 20 minutes of CO2 injection; treated wash water, 40 minutes of CO2 injection. [Figure 72] Shown is the slump of concrete mixes made as follows: control, no wash water, 15g air-entraining admixture; treated wash water, all substitutes, 15g air-entraining admixture; treated wash water, all substitutes, 15g air-entraining admixture, with sodium gluconate added at 2% by weight of wash water solids. [Figure 73] Shown is the entrained air in concrete mixes made as follows: control, no wash water, 15g air-entraining admixture; treated wash water, all substitutes, 15g air-entraining admixture; treated wash water, all substitutes, 15g air-entraining admixture, with the addition of 2% sodium gluconate by weight of wash water solids. [Figure 74] Figure 1 shows the compressive strength at 1, 7, and 28 days for concrete mixes made as follows: control, no wash water, 15g air-entraining admixture; treated wash water, all substitutes, 15g air-entraining admixture; treated wash water, all substitutes, 15g air-entraining admixture, with the addition of 2% sodium gluconate by weight of wash water solids. [Figure 75]Calorimetry as power versus time is shown for concrete mixes made as follows: control, no wash water, 15g air entraining admixture; treated wash water, all substitutes, 15g air entraining admixture; treated wash water, all substitutes, 15g air entraining admixture, with sodium gluconate added at 2% by weight of wash water solids. [Figure 76] The compositions shown are for concrete mixes made as follows: control, no wash water, 15g air-entraining admixture; treated wash water, all substitutes, 15g air-entraining admixture; treated wash water, all substitutes, 15g air-entraining admixture, with sodium gluconate added at 2% by weight of wash water solids. [Figure 77] The slump is shown for concrete mixes made as follows: control, no wash water; treated wash water, all replacement, adding 12% of the wash water assuming it is unavailable for concrete hydration; treated wash water, all replacement, adding 17% of the wash water assuming it is unavailable for concrete hydration. [Figure 78] The compressive strengths at 1, 7, and 28 days are shown for concrete mixes made as follows: control, no wash water; treated wash water, all substitutes, with 12% of the wash water added assuming it is unavailable for concrete hydration; and treated wash water, all substitutes, with 17% of the wash water added assuming it is unavailable for concrete hydration. [Figure 79] Calorimetry as power versus time is shown for concrete mixes made as follows: control, no wash water; treated wash water, all substitutes, adding 12% of the wash water assuming it is unavailable for concrete hydration; treated wash water, all substitutes, adding 17% of the wash water assuming it is unavailable for concrete hydration. [Figure 80] The compositions shown are for concrete mixes made as follows: control, no wash water; treated wash water, all replacements, 12% of the wash water added assuming it is unavailable for concrete hydration; treated wash water, all replacements, 17% of the wash water added assuming it is unavailable for concrete hydration. [Figure 81]The slump of concrete mixes made as follows is shown: control, no wash water; treated wash water, all substitutes, with sodium gluconate added at 1% by weight of wash water solids; treated wash water, all substitutes, with Daratard 17 added at 5% by weight of wash water solids; treated wash water, all substitutes, with Recover added at 5% by weight of wash water solids. [Figure 82] Shown are compressive strengths at 1, 7, and 28 days for concrete mixes made as follows: control, no wash water; treated wash water, all substitutes, sodium gluconate added at 1% by weight of wash water solids; treated wash water, all substitutes, Daratard 17 added at 5% by weight of wash water solids; treated wash water, all substitutes, Recover added at 5% by weight of wash water solids. [Figure 83] Calorimetry as power versus time is shown for concrete mixes made as follows: control, no wash water; treated wash water, all substitutes, sodium gluconate added at 1% by weight of wash water solids; treated wash water, all substitutes, Daratard 17 added at 5% by weight of wash water solids; treated wash water, all substitutes, Recover added at 5% by weight of wash water solids. [Figure 84] The compositions shown are for concrete mixes made as follows: control, no wash water; treated wash water, all substitutes, with sodium gluconate added at 1% by weight of wash water solids; treated wash water, all substitutes, with Daratard 17 added at 5% by weight of wash water solids; and treated wash water, all substitutes, with Recover added at 5% by weight of wash water solids. [Figure 85] The slump of concrete mixes made as follows is shown: control, no wash water; treated wash water, all substitutes, wash water from a pumping system; treated wash water, all substitutes, wash water from a drilling system. [Figure 86] 1 shows the compressive strength of concrete mixes made as follows: control, no wash water; treated wash water, all substitutes, wash water from a pumping system; treated wash water, all substitutes, wash water from a drilling system. [Figure 87]Calorimetry as power versus time is shown for concrete mixes made as follows: control, no wash water; treated wash water, all substitutes, wash water from pump system; treated wash water, all substitutes, wash water from drill system. [Figure 88] The compositions of the concrete mixes made as follows: control, no wash water; treated wash water, all substitutes, wash water from the pump system; treated wash water, all substitutes, wash water from the drill system are shown. [Figure 89] 1 shows the carbon dioxide uptake and uptake efficiency for different flow rates and total carbon dioxide added to the slurry. [Figure 90] 1 shows the in-line carbon dioxide uptake and uptake efficiency when carbon dioxide is added relative to no in-line mixing. [Figure 91] 1 shows the carbon dioxide uptake and uptake efficiency of one carbon dioxide injection point versus two carbon dioxide injection points. [Figure 92] 1 shows an apparatus for adding carbon dioxide to the wash water slurry. [Figure 93] The workability (slump) of concrete prepared with high specific gravity (1.15) and low substitution levels of wash water (10, 20, and 30%) is shown. [Figure 94] Calorimetry (power versus time) of concrete prepared with high specific gravity (1.15) and low substitution levels of wash water (10, 20, and 30%) is shown. [Figure 95] The compressive strengths at 1, 7, and 28 days of concrete prepared with high specific gravity (1.15) and low substitution levels of wash water (10, 20, and 30%) are shown. [Figure 96] The mix designs for concrete prepared with high specific gravity (1.15) and low substitution levels of wash water (10, 20, and 30%) are presented. [Figure 97] The workability (slump) of concrete prepared with two different batches of wash water, with specific gravities of 1.10 and 1.05, respectively, is shown. [Figure 98]Calorimetry (power versus time) of concrete prepared with two different batches of wash water, with specific gravities of 1.10 and 1.05, respectively, is shown. [Figure 99] Figure 1 shows the compressive strength at 1, 7, and 28 days of concrete prepared with two different batches of wash water at specific gravities of 1.10 and 1.05, respectively. [Figure 100] The mix designs for concrete prepared with two different batches of wash water, with specific gravities of 1.10 and 1.05, respectively, are shown. [Figure 101] 1 shows X-ray diffraction analysis of wash water with a specific gravity of 1.10 treated with CO2 to 0, 5, 10, 15, 20, and 25% by weight of cement at time 0. [Figure 102] 1 shows X-ray diffraction analysis of wash water with a specific gravity of 1.10 treated with CO2 to 0, 5, 10, 15, 20, and 25% by weight of cement at 3 hours. [Figure 103] 1 shows X-ray diffraction analysis of wash water with a specific gravity of 1.10 treated with CO2 to 0, 5, 10, 15, 20, and 25% by weight of cement at 6 hours. [Figure 104] 2 shows X-ray diffraction analysis of wash water with a specific gravity of 1.10 treated with CO2 to 0, 5, 10, 15, 20, and 25% by weight of cement at 24 hours. [Figure 105] 1 shows X-ray diffraction analysis of wash water with a specific gravity of 1.10 treated with CO2 to 0, 5, 10, 15, 20, and 25% by weight of cement at 72 hours. [Figure 106] Figure 1 shows the slump of concrete made using wash water treated at two different treatment levels (5%, 25%) compared to a clean water reference and an untreated wash water reference. All conditions were made with and without a 3% cement reduction. [Figure 107] Calorimetry (power versus time) of concrete prepared using wash water treated at two different treatment levels (5%, 25%) and compared to a clean water reference and an untreated wash water reference is shown. All conditions were made with and without a 3% reduction in cement. [Figure 108]Figure 1 shows the compressive strength at 1, 7, and 28 days of concrete prepared using wash water treated at two different treatment levels (5%, 25%) compared to a clean water reference and an untreated wash water reference. All conditions were made with and without a 3% cement reduction. [Figure 109] The concrete mix designs were prepared using wash water treated at two different treatment levels (5% and 25%) and compared to a clean water reference and an untreated wash water reference. All conditions were made with and without a 3% reduction in cement. [Figure 110] Figure 1 shows the slump of concrete made with wash water treated with CO2 at 0, 3, 6, and 9% by weight of solids. Wash water was produced on a large scale (1000 L) and treated in a manner that simulates the process used in the regenerator; that is, the wash water was transferred from one tank to another while CO2 was injected into the transfer line. The wash water was transferred / treated every 30 minutes. [Figure 111] Calorimetry (power vs. time) of concrete prepared with wash water treated with CO2 at 0, 3, 6, and 9% by weight of solids is shown. Wash water was produced on a large scale (1000 L) and treated in a manner that simulates the process used in the regenerator; that is, the wash water was transferred from one tank to another while CO2 was injected into the transfer line. The wash water was transferred / treated every 30 minutes. [Figure 112] The compressive strengths of concrete prepared with wash water treated with CO2 at 0, 3, 6, and 9% by weight of solids are shown at 1, 7, and 28 days. The wash water was produced on a large scale (1000 L) and treated in a manner that simulates the process used in the regenerator; that is, the wash water was transferred from one tank to another while CO2 was injected into the transfer line. The wash water was transferred / treated every 30 minutes. [Figure 113]The mix designs for concrete prepared with CO2-treated wash water at 0, 3, 6, and 9% by weight of solids are shown. Wash water was generated on a large scale (1000 L) and treated in a manner that simulates the process used in the regenerator. That is, the wash water was transferred from one tank to another while CO2 was injected into the transfer line. The wash water was transferred / treated every 30 minutes. [Figure 114] Figure 1 shows the slump of concrete made with wash water treated with CO2 at 0, 3, 6, and 9% by weight of solids. Wash water was produced on a large scale (1000 L) and treated in a manner that simulates the process used in the regenerator; that is, the wash water was transferred from one tank to another while CO2 was injected into the transfer line. The wash water was transferred / treated every 30 minutes and then allowed to sit for 24 hours after treatment. [Figure 115] Calorimetry (power vs. time) of concrete prepared with wash water treated with CO2 at 0, 3, 6, and 9% by weight of solids is shown. Wash water was generated on a large scale (1000 L) and treated in a manner that simulates the process used in the regenerator; that is, the wash water was transferred from one tank to another while CO2 was injected into the transfer line. The wash water was transferred / treated every 30 minutes, and then allowed to sit for 24 hours after treatment. [Figure 116] The compressive strengths of concrete prepared with wash water treated with CO2 at 0, 3, 6, and 9% by weight of solids are shown at 1, 7, and 28 days. The wash water was generated on a large scale (1000 L) and treated in a manner that simulates the process used in the regenerator; that is, the wash water was transferred from one tank to another while CO2 was injected into the transfer line. The wash water was transferred / treated every 30 minutes and then allowed to age for 24 hours after treatment. [Figure 117] This shows the mix design for concrete prepared with wash water treated with CO2 at 0, 3, 6, and 9% by weight of solids. The wash water was generated on a large scale (1000 L) and treated in a manner that simulates the process used in the regenerator. That is, the wash water was transferred from one tank to another while CO2 was injected into the transfer line. The wash water was transferred / treated every 30 minutes and then allowed to sit for 24 hours after treatment. [Figure 118] Figure 1 shows the slump of mortars made with 100% replacement of water with wash water treated with CO2 up to 8% CO2 uptake by weight of wash water solids, either neat or treated with two different concentrations of a commercial set retarding admixture. [Figure 119] Calorimetry (power versus time) of mortars made with 100% replacement of water with wash water treated with CO2 up to 8% CO2 uptake by weight of wash water solids, either as is or treated with two different concentrations of a commercial set retarding admixture, is shown. [Figure 120] Figure 1 shows compressive strengths at 1, 7, and 28 days for mortars made with 100% replacement of water with wash water treated with CO2 up to 8% CO2 uptake by weight of wash water solids, either as is or treated with two different concentrations of a commercial set retarding admixture. [Figure 121] Mixture designs for mortars made with 100% replacement of water with wash water treated with CO2 up to 8% CO2 uptake by weight of wash water solids, either neat or treated with two different concentrations of a commercial set retarding admixture, are shown. [Figure 122] 1 shows the X-ray diffraction at time 0 for wash water prepared with 100% cement treated with 0, 5, 10, 15, 20, and 25% CO by weight of cement. [Figure 123] 1 shows X-ray diffraction at 24 hours for wash water prepared with 100% cement treated with 0, 5, 10, 15, 20, and 25% CO by weight of cement. [Figure 124] 1 shows the X-ray diffraction at time 0 for wash water prepared with 75% cement and 25% slag treated with 0, 5, 10, 15, 20, and 25% CO by weight of cement. [Figure 125] 1 shows the X-ray diffraction at 24 hours for wash water prepared with 75% cement and 25% slag treated with 0, 5, 10, 15, 20, and 25% CO by weight of cement. [Figure 126]1 shows the X-ray diffraction at time 0 for wash water prepared with 100% cement and treated with CO at 0, 5, 10, 15, 20, and 25% CO by weight of cement solids at a flow rate of 5 LPM. [Figure 127] 24 hour X-ray diffraction of wash water prepared with 100% cement and treated with CO at 0, 5, 10, 15, 20, and 25% CO by weight of cement solids at a flow rate of 5 LPM. [Figure 128] 1 shows the X-ray diffraction at time 0 of wash water prepared with 100% cement and treated with CO at 0, 5, 10, 15, 20, and 25% CO by weight of cement solids at a flow rate of 10 LPM. [Figure 129] 24 hour X-ray diffraction of wash water prepared with 100% cement and treated with CO at 0, 5, 10, 15, 20, and 25% CO by weight of cement solids at a flow rate of 10 LPM. [Figure 130] 1 shows the X-ray diffraction at time 0 for wash water prepared with 100% cement at a specific gravity of 1.05 and treated with CO2 at 0, 5, 10, 15, 20, 25 and 30% CO2 by weight of cement solids. [Figure 131] 24 hour X-ray diffraction of wash water prepared with 100% cement at a specific gravity of 1.05 and treated with CO2 at 0, 5, 10, 15, 20, 25 and 30% CO2 by weight of cement solids. [Figure 132] 48 hours of X-ray diffraction of wash water prepared with 100% cement at a specific gravity of 1.05 and treated with CO2 at 0, 5, 10, 15, 20, 25, and 30% CO2 by weight of cement solids. [Figure 133] 1 shows the X-ray diffraction at time 0 for wash water prepared with 100% cement at a specific gravity of 1.15 and treated with CO2 at 0, 5, 10, 15, 20, 25 and 30% CO2 by weight of cement solids. [Figure 134] 24 hour X-ray diffraction of wash water prepared with 100% cement at a specific gravity of 1.15 and treated with CO2 at 0, 5, 10, 15, 20, 25 and 30% CO2 by weight of cement solids. [Figure 135] 48 hours of X-ray diffraction of wash water prepared with 100% cement at a specific gravity of 1.15 and treated with CO2 at 0, 5, 10, 15, 20, 25, and 30% CO2 by weight of cement solids. DETAILED DESCRIPTION OF THE INVENTION

[0010] Wash water (also referred to herein as grey water or reclaimed water) is generated as a by-product of the concrete industry. This water may contain suspended solids in the form of sand, aggregate, and / or cementitious materials and is generated throughout various stages in the production cycle of concrete structures. Typically, large amounts of concrete wash water (reclaimed water) are generated by washing concrete mixer trucks after concrete delivery. This water is alkaline in nature and requires special treatment, handling, and disposal. As used herein, "wash water" includes water primarily composed of concrete drum wash water, which may include water from other parts of the concrete manufacturing process, stormwater runoff, and the like, as known in the art. As the context makes clear, "wash water" includes water used to wash ready-mix trucks and / or other mixer drums containing cement and aggregate, as well as water that has had the aggregate removed (e.g., in a reclaimer) but still contains solids, such as cementitious solids. Typically, at least a portion of such solids is retained in the wash water for reuse in subsequent concrete batches.

[0011] While this water may be suitable for reuse in concrete production, it has been demonstrated that wash water can have adverse effects on concrete properties, such as accelerated setting and reduced workability. Wash water is primarily a mixture of cement and, often, supplementary cementitious materials (SCMs) in water. This is problematic as mixing water because cement changes the chemistry of the water as it hydrates. When water is used as mixing water, these changes in chemistry, along with hydration products, cause many problems, including acceleration, increased water demand, and reduced 7-day strength. These problems generally worsen as the amount of cement in the water increases and / or the water ages.

[0012] The methods and compositions of the present invention utilize the application of CO to concrete wash water to improve its properties for reuse in concrete production. Thus, wash water that has a cement content (e.g., specific gravity) and / or aged to a degree that would normally not allow for use as mixing water can be so used after the application of carbon dioxide.

[0013] Without wishing to be bound by theory, it is believed that carbonating the wash water can have several beneficial effects on using the water as part or all of the mixing water for a subsequent concrete batch.

[0014] 1) Maintain a pH of about 7: This allows the acidity of CO2 to effectively dissolve the cement. This helps deliver a uniform washout chemistry and eliminates the "aging effect." In certain embodiments, a pH below or above 7 may be maintained, as described elsewhere herein.

[0015] 2) Precipitate any insoluble carbonates: CO2 actively forms carbonation reaction products with many ions. This removes certain species, such as calcium, aluminum, and magnesium, from solution. This is another step that helps provide a washout with uniform chemistry.

[0016] 3) Altering the solubility of cement ions: The solubility of many ions is pH dependent. Maintaining a pH of about 7 with CO2 can favorably alter the water chemistry. In certain embodiments, a pH below or above 7 may be maintained, as described elsewhere herein.

[0017] 4) Stopping the pozzolanic reaction: By maintaining a pH of about 7, no Ca(OH)2 is available to react with the slag and / or fly ash in the washwater. This can mean that these SCMs remain unchanged throughout the treatment and reuse of the washwater, thus substantially reducing the impact of the washwater. In certain embodiments, a pH below or above 7 may be maintained, as described elsewhere herein.

[0018] 5) Reduces the amount of remaining anions: Forming carbonate precipitates using CO2 is advantageous over other common acids such as HCl or H2SO4, which can adversely affect the chemistry of wash wastewater for concrete batching if anions remain soluble in the treated water.

[0019] 6) Delay: Wash wastewater with CO2 / HCO3 - By saturating with HCl, a delay can be achieved when used as batch water.

[0020] 7) Precipitate Properties: The process may be modified to produce precipitates that have less impact on the water demand of concrete prepared with the washout. Carbonation conditions may be used that produce nanocrystalline carbonates, such as nanocrystalline calcium carbonate, which are known to be particularly beneficial for use in concrete products.

[0021] In certain embodiments, the present invention provides a method of providing mixing water for a batch of concrete, wherein the mixing water comprises wash water from one or more previous concrete batches that has been exposed to carbon dioxide in an amount greater than the atmospheric concentration of carbon dioxide to carbonate the wash water ("carbonated wash water"). The mixing water may contain wash water that is at least 10, 20, 30, 40, 50, 60, 70, 80, 90, 95, 99, or 99.5% carbonated. Alternatively, or in addition, the mixing water may contain wash water that is within 20, 30, 40, 50, 60, 70, 80, 90, 95, 99, 99.5, or 100% carbonated. In certain embodiments, the mixing water is 100% carbonated wash water. In certain embodiments, the mixing water is 1 to 100% carbonated wash water. In certain embodiments, the mixing water is 1 to 80% carbonated wash water. In certain embodiments, the kneading water is wash water that is 1 to 50% carbonated. In certain embodiments, the kneading water is wash water that is 1 to 30% carbonated. In certain embodiments, the kneading water is wash water that is 10 to 100% carbonated. In certain embodiments, the kneading water is wash water that is 20 to 100% carbonated. In certain embodiments, the kneading water is wash water that is 50 to 100% carbonated. In certain embodiments, the kneading water is wash water that is 70 to 100% carbonated. In certain embodiments, the kneading water is wash water that is 90 to 100% carbonated.

[0022] In certain embodiments, a first portion of mixing water that is plain water (e.g., plain water typically used in concrete mixes, but not carbonated wash water or other water) is mixed with concrete materials such as cement, aggregate, etc., and then a second portion of mixing water that includes carbonated plain water or carbonated water, which may be, for example, carbonated wash water, is added. The first portion of water may be such that an acceptable level of mixing is achieved, e.g., a mix that is free of lumps or that is free of a substantial amount of lumps. For example, the first portion of the mix water, which is ordinary water, can be more than 1, 2, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90% and / or less than 2, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 95%, e.g., 1-90%, or 1-80%, or 1-75%, or 1-70%, or 1-65%, or 1-60%, or 1-55%, or 1-50%, or 1-45%, or 1-40%, or 1-30%, or 1-20%, or 1-10%, of the total mix water used in the concrete mix, while the remainder of the mix water used in the concrete mix is ​​the second portion, i.e., carbonated mix water. The first portion of water can be added at one location and the second portion can be added at a second location. For example, in a pre-mixing operation, a first portion of water can be added to the concrete material to be mixed, and then the mixed material is transferred to a drum of a ready-mix truck, where a second portion of water is added to the concrete in the drum of the ready-mix truck. However, it is also possible for both the first and second locations to be the same location, e.g., a mixer prior to loading into the ready-mix truck or the drum of the ready-mix truck. The second portion of water may be added at any suitable time after adding the first portion. Generally, the second portion of water is added at least after the first portion and after the concrete material has been sufficiently mixed to achieve a lump-free mix or a substantial amount of lump-free mix.In certain embodiments, the second portion of water is added at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 20, 25, 30, 40, 50, or 60 minutes after the first portion of water, and / or within 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 20, 25, 30, 40, 50, or 60 minutes, or within 1, 2, 3, 4, 5, or 6 hours after the first portion of water.

[0023] The wash water can be carbonated at any suitable time, for example, immediately after production, some time thereafter, or immediately before use in concrete, or any combination thereof. Without being bound by theory, it is believed that at time 0 (immediately after the wash water is produced), the added carbon dioxide reacts with unhydrated cement phases (C3S, C2S, C3A, etc.), while at more recent times, the added carbon dioxide reacts with hydrated cement phases (CSH, ettringite, etc.). Providing a later dosage can result in different properties than earlier application of the dosage, potentially resulting in different properties when the wash water is reused in the production of concrete. Furthermore, the phases that react in older wash water are generally more thermodynamically stable and therefore may have a lower heat of reaction when reacting with carbon dioxide. The inventors have observed that treating fresh wash water with carbon dioxide can result in a greater exothermic heat rise (e.g., as measured by temperature) than treating aged wash water. Because the elevated temperature of the treated water may need to be cooled before it can be used as mixing water, a lower heat rise may be advantageous. Accordingly, certain embodiments provide methods and apparatus for cooling wash water by generating gaseous carbon dioxide from liquid carbon dioxide to treat the wash water, e.g., piping or conduits that contact the wash water and absorb the heat required to convert the liquid to gaseous carbon dioxide, thereby cooling the wash water. These are described in more detail elsewhere herein. Furthermore, when treating aged wash water with carbon dioxide, it may be possible that less carbon dioxide may be required to produce stable wash water than using fresh wash water. The amount of carbon dioxide required to produce stable wash water (e.g., relatively unchanged properties after further aging) may depend on the relative contributions of Ca(OH), ettringite, CSH, and / or unreacted cement (e.g., unreacted ordinary Portland cement, OPC) to the undesirable properties of the wash water. Furthermore, different phases may have different carbon dioxide reaction rates, which in turn may affect the selection of carbon dioxide delivery settings, approaches (e.g., type of delivery system, or adjustments to the delivery system), etc.

[0024] Thus, for example, in certain embodiments, the carbonation of the wash water is performed within 1, 2, 5, 10, 20, 30, 40, 60, 80, 100, 120, 150, 180, 240, 300, 360, 420, or 480 minutes, or within 7, 8, 9, 10, 11, 12, 14, 16, 18, or 24 hours, or within 1.5, 2, 3, 4, or 5 days after the generation of the wash water. and / or can begin as soon as 0, 0.5, 1, 2, 5, 10, 20, 30, 40, 60, 80, 100, 120, 150, 180, 240, 300, 360, 420, 480, or 540 minutes, or 8, 9, 10, 11, 12, 14, 16, 18, or 24 hours, or 1.5, 2, 3, 4, 5, or 6 days after generation of the wash water. Carbonation can continue for any suitable period of time, for example, in certain embodiments, the wash water is continuously exposed to carbon dioxide for a period of time after carbonation begins. Alternatively, or in addition, the wash water can be carbonated immediately prior to use as mix water, e.g., within 1, 2, 5, 10, 20, 30, 40, 60, 80, 100, 120, 150, 180, 240, 300, 360, 420, or 480 minutes before use as mix water (e.g., before contacting with a concrete mix), and / or immediately after 0, 0.5, 1, 2, 5, 10, 20, 30, 40, 60, 80, 100, 120, 150, 180, 240, 300, 360, 420, 480, or 540 minutes before use as mix water.Additionally or alternatively, the wash water may be allowed to sit for some time after the addition of carbon dioxide before use as wash water, for example, carbonated wash water may be added within 1, 2, 5, 10, 20, 30, 40, 60, 80, 100, 120, 150, 180, 240, 300, 360, 420, or 480 minutes, or 7, 8, 9, 10, 12, 18, or 24 hours, or 1.5, 2, 3, 4, 5, or 6 days after carbonation of the wash water, and / or within 0, 0.5, or 10 minutes after carbonation of the wash water. , 1, 2, 5, 10, 20, 30, 40, 60, 80, 100, 120, 150, 180, 240, 300, 360, 420, 480, or 540 minutes, or 8, 10, 12, 18, or 24 hours, or 1.5, 2, 3, 4, 5, 6, 7, 8, 10, 12, or 14 days after the washing water is carbonated, for example, at least 3 hours, at least 6 hours, at least 12 hours, at least 1 day, at least 3 days, or at least 5 days after the washing water is carbonated.

[0025] The water used for washing can be clean water or recycled wash water. In certain embodiments, the water used to wash the truck can be carbonated before and / or during the washing process, i.e., before the wash water enters the reclamation tank. Concrete trucks typically undergo a 10-15 minute mixing period when washed. Carbon dioxide can be injected, for example, into the water pump line on the way to the truck (fresh water input) or from the settling pond / reclamation system pump (reclaimed water input).

[0026] Additionally or alternatively, carbon dioxide can be added to the truck after it is emptied and water is added to it for rinsing. The carbon dioxide reacts with the slurry, and the carbon dioxide can "sleep the cement" (e.g., stop or slow most or all adverse reactions and react with most or all harmful substances as outlined herein). In certain embodiments, the slurry can be reused with a new batch. In certain embodiments, the slurry does not even need to be removed from the truck. The carbon dioxide can be added as a solid, liquid, or gas, or a combination thereof. For example, the carbon dioxide may be added as a solid. In certain embodiments, the carbon dioxide is added as a mixture of solids and gas produced when liquid carbon dioxide is released to atmospheric pressure. The liquid carbon dioxide is conveyed by a conduit from a container to an injector configured to effect the desired conversion to gas and solid. The mixture of gaseous and solid carbon dioxide is directed into the drum of the ready-mix truck. The amount of carbon dioxide added can be a predetermined amount based, for example, on a typical remaining amount of concrete left in the truck. The amount of carbon dioxide added may also be adjusted depending on the condition of the wash water, for example, the pH at which the carbon dioxide mixes and reacts with the wash water components. Using this method, it is possible to eliminate the need to drain the wash water from the mixer. This allows the wash water to be used as mixing water for the next batch of concrete produced and prevents residual plastic concrete from hardening. In certain embodiments, the treatment can stabilize the wash water so that it can be used as mixing water for the next batch after at least 0.5, 1, 2, 3, 4, 5, 6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, 72, 78, 86, or 92 hours, and / or within 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, 72, 78, 86, 92, or 104 hours.The carbon dioxide treatment may be used alone or in conjunction with other treatments designed to stabilize wash water and allow it to be reused, such as Recover from GCP Applied Technologies, Inc., Cambridge, Mass., or similar admixtures.

[0027] In certain embodiments, the wash water is recycled before use as kneading water. For example, some or all of the carbonated wash water may be recycled (e.g., through one or more loops to aid in kneading and / or reaction, or to provide agitation or stirring, etc.). This circulation may occur continuously or intermittently while the water is held before use. In certain embodiments, the wash water is recycled for at least 5, 10, 20, 50, 70, 80, 90, 95, or 99%, and / or within 10, 20, 50, 70, 80, 90, 95, 99, or 100% of the time it is held before use as kneading water.

[0028] It will be appreciated that many different wash waters are typically combined and held, for example, in a holding tank, until use or disposal. Carbonation of the wash water may occur before, during, or after the wash water enters the holding tank, or any combination thereof. Some or all of the wash water from a given operation may be carbonated. Also, the wash water from one batch of concrete may be carbonated and then used directly in a subsequent batch without storage. Typically, the tank is equipped or modified to circulate the water without settling and to allow reuse of the material in the wash water when carbonated.

[0029] The wash water can be carbonated using any suitable method or combination of methods. For example, the wash water can be held in a container and exposed to a carbon dioxide atmosphere during kneading. Carbon dioxide can be bubbled through the kneading water by any suitable method, such as using a bubbling mat, or alternatively or additionally, by introducing carbon dioxide through one or more conduits with one or more openings below the surface of the wash water. The conduits are positioned so as to be above the settling sludge in the tank and, in certain embodiments, can be adjusted so as not to significantly interfere with settling. A catalyst can also be used to promote one or more reactions in the carbonated wash water. In certain embodiments, liquid carbon dioxide injection is used. A vaporizer can be installed in the tank, which draws heat from the water to convert the liquid carbon dioxide to gas, thereby cooling the water. For example, a set of metal tubes can be submerged in water, configured to ensure the gas rises to the surface and is forced out through a nozzle. The pipes are laid vertically, but because the heat capacity and transfer velocity in water are much higher than in air, the fins typically present in low-temperature carbon dioxide heat exchangers operating in air may not be required.

[0030] Impeller Blade In certain embodiments, carbon dioxide is added to the slurry tank by injection through specially designed agitator blades. As is known in the water treatment industry, rapid mixing blades designed to create turbulence, vortices, vacuum pockets, and high shear forces behind the mixer blades can be used to promote rapid mixing. See, for example, the P4 Pitch Impeller Blade supplied by Dynamix Inc., 14480 River Road, Unit 150, Richmond, British Columbia, Canada V6V 1L4. This is merely an example, and one skilled in the art will understand that various types, such as pitched blade impellers or airfoil impellers, can be used.

[0031] Injecting carbon dioxide at specific locations along the blade edge increases the mixing action and contact time. The blade action promotes mixing rather than forcing the carbon dioxide bubbles to the surface in a suspended state. Selecting the appropriate hole size ensures fine, dispersed bubbles. It is important to ensure that the holes are not blocked. If the slurry is not stirred, solids will settle onto the perforated hose at the bottom of the tank, but the holes in the agitator blade are not at the bottom of the tank and will not be covered by the settling solids. Furthermore, holes can be located on the sides or bottom of the agitator element to avoid vertical accumulation of sediment.

[0032] Auger In ponds using augers for mixing, injection can be through the central axis of the auger shaft. In certain embodiments, to ensure serviceability and potentially reduce the occurrence of buildup, a telescopic injection pipe with a gas distribution nozzle at the end can be routed through the central axis of the kneading auger shaft. Carbon dioxide can be injected, for example, when a control system requests it, and then the injector can be retracted out of the water when the system determines that the amount of carbon dioxide is sufficient. Alternatively, a telescopic injector is not routed through the shaft, but the shaft is simply hollow. Carbon dioxide can be injected down the center of the kneading auger shaft. An opening at the injection point can promote the formation of fine, dispersed bubbles. In any case, the position, direction, and injection rate of the injector nozzle are such that they do not interfere with normal mixing and therefore do not cause settling.

[0033] Submersible pump A suitably efficient or powerful pump can circulate the slurry and, in some cases, send it to the concrete batching process. Carbon dioxide can be pumped in via injection into the impeller housing, for example, at a location selected to maximize mixing, or, for example, just below the intake so that suction draws the gas into the housing. The impeller blades mix and pressurize the carbon dioxide / wastewater mixture, resulting in better carbon dioxide uptake, and pump the slurry through a long hose. The transfer through the hose allows additional time for increased uptake. The slurry can be returned to the tank or pumped directly to the batch process.

[0034] The CO injection rate can be related to the flow rate / density of the slurry. If one cycle of the loop is insufficient to provide the desired degree of carbon dioxide uptake, the cycle can be recirculated through the same loop or through another loop, e.g., via a secondary, smaller pump, until the desired amount of CO is absorbed.

[0035] Carbon dioxide injection can occur near the impeller. Carbon dioxide injection can also occur in the discharge pipeline, near the pump itself, or at any point in the pipeline. Carbon dioxide injection can be achieved at single or multiple injection points, and the carbon dioxide can be injected at 90 degrees or any suitable angle to the direction of flow. Because the buoyancy of the carbon dioxide causes the wash water to move upward, orienting the carbon dioxide outlet parallel to the rising liquid flow will increase the liquid flow.

[0036] Eductor Nozzle In certain embodiments, one or more eductor nozzles are used. Eductor nozzles are well known in the art. Eductor nozzles knead, agitate, and increase the overall water flow rate, allowing a relatively small pump to move enough water and ensuring sufficient kneading to prevent settling. The nozzle applies high pressure to the first-stage nozzle to increase velocity, and the eductor then creates low pressure, creating a Venturi effect of high flow, drawing the added liquid into the flow and allowing a larger volume to exit at a lower velocity. Such nozzles are supplied, for example, by Bete Ltd., PO Box 2748, Lewes, East Sussex, United Kingdom. Such nozzles can incorporate carbon dioxide injection into their operation. When carbon dioxide is injected as nanobubbles into the solution (supersaturated carbon dioxide water, see elsewhere in this application, for example, the system supplied by Gaia USA Inc., Scottsdale, Arizona), the buoyancy forces acting on coarse bubbles can be avoided. Pumps can be used for kneading only if they are strategically placed and provide sufficient flow rate.

[0037] In certain embodiments, a combination of kneading blades and a discharge pump with an eductor can be used, as long as the pump(s) are located out of the way and do not interfere with the necessary kneading action. The water and carbon dioxide discharge (educator) is located so as not to interfere with the blade kneading action. Because most regenerator blades force material downward, it is preferable to pump water / carbon dioxide discharge near the blade axis to help promote kneading. In certain embodiments, an integrated kneading and injection process is used: strategically placed eductor nozzles can be used to carbonate the water and maintain sufficient fluid flow. The eductor is fed by pump(s), which can introduce carbon dioxide in several ways, as described herein. For retrofitting existing washwater settling ponds, a complete eductor can be configured to knead the pond. It is important that the eductor configuration ensures that the water flow throughout the tank exceeds the settling velocity of the suspended solids.

[0038] Headspace Integration If the processing vessel is a sealed vessel, efficiency can be increased by recycling gas from the headspace back to the injection hardware. As gas bubbles rise through the liquid and enter the headspace, such an approach provides additional opportunity for carbon dioxide molecules to dissolve and react. This process can monitor the carbon dioxide and pressure of the headspace gas. For a given amount of injected carbon dioxide, the carbon dioxide content and pressure will initially increase. As the reaction progresses, the carbon dioxide concentration and pressure will decrease. This can be a signal to trigger another carbon dioxide injection. The efficiency of the dosage is directly responsive to absorption.

[0039] Supersaturated carbon dioxide In certain cases, the mixing water, e.g., wash water, can be treated with carbon dioxide so that the carbon dioxide content of the water exceeds normal saturation, for example, by at least 10, 20, 30, 40, 50, 70, 100, 150, 200, or 300% or less than 10, 20, 30, 40, 50, 70, 100, 150, 200, 300, 400, or 500% compared to the same water under the same conditions that is normally saturated with carbon dioxide. Normal saturation is achieved, for example, by bubbling carbon dioxide through water, e.g., wash water, until saturation is achieved, without manipulating the water other than contacting it with carbon dioxide gas. For methods of treating water to increase the carbon dioxide concentration above normal saturation levels, see, for example, U.S. Patent Application Publication No. 2015 / 0202579.

[0040] In certain embodiments, the wash water is exposed to carbon dioxide in a conduit, where the wash water is drawn from a wash water source, such as a slurry pond, by input into the conduit and travels through the conduit to a discharge. In certain embodiments, the treated wash water is directed from the discharge to a concrete mixing operation. That is, the exposure to carbon dioxide occurs outside the wash water source, and the system can act as an on-demand wash water carbonation system. The carbonated water can be used in concrete mixes, disposed of, or used in any other suitable manner. This type of system can be easily retrofitted to virtually any existing wash water system, since most or all of the injection system is independent of the wash water source, e.g., a slurry pond. The conduit is operably connected to a carbon dioxide source with one or more carbon dioxide injection points, e.g., at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, or 20 injection points, and / or no more than 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 20, or 30 injection points. Carbon dioxide is injected into the wash water slurry stream at each injection point. If multiple injection points are used, the injection points are spaced sufficiently apart to accommodate appropriate slurry flow rates and carbon dioxide injection rates, as well as the diameter of the conduit and cement content of the wash water. The carbon dioxide is injected as bubbles at the injection points, with the bubbles separated from each other (or at least 50, 60, 70, 80, or 90% of the bubbles separated from each other), so that by the end of the conduit section, at least 20, 30, 40, 50, 60, 70, 80, 90, 95, or 99% of the carbon dioxide from the injection has been absorbed and / or reacted with the slurry, and / or up to 30, 40, 50, 60, 70, 80, 90, 95, 99, or 100% has been absorbed and / or reacted with the slurry. See Figure 92 for a diagram of one section of the injector system. The conduit, as described, can include any suitable number of injection points so that carbon dioxide can be added to each section to achieve the desired carbon dioxide uptake.Thus, by way of example only, a single section may be capable of capturing, for example, 2% carbon dioxide, while the desired carbon dioxide capture may be 10%, resulting in a conduit having five sections / injection points. In certain embodiments, the sections are adjacent, although it is also possible to separate one or more sections from the others and operably connect non-adjacent sections with conduits. This may help utilize available space, for example, allowing multiple sections to be used with minimal height requirements compared to adjacent systems. Additionally or alternatively, to increase carbon dioxide capture, wash water can be recirculated through the system, resulting in more carbon dioxide being captured with each pass through the wash water. Thus, in certain embodiments, the wash water is recirculated at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 times, and / or no more than 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, or 20 times. Any suitable orientation of the system may be used. In certain embodiments, the conduit (or conduit sections, if the sections are not adjacent) are positioned vertically, e.g., within 1, 2, 5, 10, 15, 20, 30, 40, or 50% of the vertical. In certain embodiments, one or more of the sections are configured to knead the wash water as it travels through it. Example calculations of system parameters and additional explanations are provided in Example 27.

[0041] In certain embodiments, the present invention allows for the use of wash water substantially "as is," i.e., without settling to remove solids. Carbonation of the wash water allows for its use as mixing water, even at high specific gravity.

[0042] This technology can enable the use of wash water (rinse water) as mixing water, and the specific gravity of the wash water (rinse water) can be at least 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.20, 1.22, 1.25, 1.30, 1.35, 1.40, or 1.50, and / or 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.20, 1.22, 1.25, 1.30, 1.35, 1.40, or 1.50. 2, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.20, 1.22, 1.25, 1.30, 1.35, 1.40, 1.50 or 1.60 or less, for example, 1.0 to 1.2, or 1.0 to 1.3, or 1.0 to 1.18, or 1.0 to 1.16, or 1.0 to 1.15, or 1.0 to 1.14, or 1.0 to 1.13, or 1.0 to 1.12, or 1.0 to 1.10, or 1.0 to 1.09, or 1.0 to 1.08, or 1.0 to 1.07, or 1.0 to 1.06, or 1.0 to 1.05, or or 1.0 to 1.04, or 1.0 to 1.03, or 1.0 to 1.02, 1.01 to 1.2, or 1.01 to 1.3, or 1.01 to 1.18, or 1.01 to 1.16, or 1.01 to 1.15, or 1.01 to 1.14, or 1.01 to 1.13, or 1.01 to 1.12, or 1.01 to 1.10, or 1.01 to 1.09, or 1.01 to 1.08, or 1.01 to 1.07, or 1.01 to 1.06, or 1.01 to 1.05, or 1.01 to 1.04, or 1.01 to 1.03, or 1.01 to 1.0 2, or 1.02 to 1.2, or 1.02 to 1.3, or 1.02 to 1.18, or 1.02 to 1.16, or 1.02 to 1.15, or 1.02 to 1.14, or 1.02 to 1.13, or 1.02 to 1.12, or 1.02 to 1.10, or 1.02 to 1.09, or 1.02 to 1.08, or 1.02 to 1.07, or 1.02 to 1.06, or 1.02 to 1.05, or 1.02 to 1.04, or 1.02 to 1.03, or 1.03 to 1.2, or 1.03 to 1.3, or 1.03 to 1.18, or 1.03~1.16, or 1.03~1.15, or 1.03~1.14, or 1.03~1.13, or 1.03~1.12, or 1.03~1.10, or 1.03~1.09, or 1.03~1.08, or 1.03~1.07, or 1.03~1.06, or 1.03~1.05, or 1.03~1.04, or 1.05~1 .2, or 1.05-1.3, or 1.05-1.18, or 1.05-1.16, or 1.05-1.15, or 1.05-1.14, or 1.05-1.13, or 1.05-1.12, or 1.05-1.10, or 1.05-1.09, or 1.05-1.08, or 1.05-1.07, or 1.05-1.06. In certain embodiments, the methods and compositions of the present invention enable the use of wash water as mixing water, where the wash water has a specific gravity of at least 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, or 1.20. The methods and compositions of the present invention can reduce or eliminate the need for further treatment of the wash water, other than carbonation, to make it suitable for use as mixing water in subsequent batches. In certain embodiments, the wash water is carbonated and then used in subsequent batches of concrete with no more than 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, or 95% of the residual solids removed. In certain embodiments, no residual solids are removed at all. The carbonated wash water can be combined with non-wash water, e.g., regular mix water, before or during use in a subsequent concrete batch to provide the total amount of water used in the batch; in certain embodiments, the carbonated wash water comprises at least 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 95, or 99% of the total amount of water used in the batch; and in certain embodiments, 100% of the total amount of water used in the batch is carbonated wash water (excluding water used to wash equipment and, in some cases, excluding water added on-site before or during the pouring of the concrete mix).

[0043] The use of wash water, particularly carbonated wash water, in concrete mixes often results in increased strength of the resulting concrete composition at one or more time points after pouring, for example, at least a 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 22, or 25% increase in compressive strength at 1 day, 7 days, and / or 28 days compared to the same concrete mix without the carbonated wash water. This increase in early strength, and the presence of cementitious material in the carbonated wash water, which can also or alternatively replace a portion of the cementitious material in subsequent mixes, often allows for the use of less cement in mixes with carbonated wash water than would be used in the same mix without the carbonated wash water, e.g., at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 20, 22, 25, 30, 35, or 40% less cement in the mix, which retains a compressive strength after pouring, e.g., at 1, 7, and / or 28 days, that is within 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 20, 30, 40, or 50%, e.g., within 5%, or within 7%, or within 10%, of the compressive strength of a mix without the carbonated wash water.

[0044] Additionally, carbonation of the wash water may allow for the use of aged wash water that would otherwise be unfeasible, for example, wash water that is at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, or 15 days old. The carbonated wash water can be used on aged concrete that would otherwise result in a concrete mix that is not workable enough to be used.

[0045] The CO2 treatment produces a carbonation reaction product that may contain some nanostructured material. At least 1, 2, 5, 7, 10, 12, 15, 20, 25, 30, 25, 40, 45, 50, 60, 70, 80, or 90% of the carbonation product, e.g., calcium carbonate, in the wash water may be present as nanostructured material, and / or up to 5, 7, 10, 12, 15, 20, 25, 30, 25, 40, 45, 50, 60, 70, 80, 90, 95, or 100% may be present as nanostructured material. As used herein, the term "nanostructured material" includes solid products of the reaction of wash water components with carbon dioxide that have a longest dimension of 500 nm or less, in certain embodiments 400 nm or less, in certain embodiments 300 nm or less, and in certain embodiments 100 nm or less.

[0046] Carbon dioxide treatment of wash water may result in a solid material that differs from untreated wash water with respect to the coordination environment of the aluminum and silicon bridges, as measured, for example, by NMR. Without being bound by theory, it is believed that carbon dioxide treatment of wash water may form a carbonate shell around the particles, which may have an inhibitory effect on the phases contained therein, possibly physically inhibiting dissolution.

[0047] CO2 treatment has the added benefit of sequestering carbon dioxide, since the carbon dioxide not only reacts with components of the wash water (typically cement or auxiliary cementitious materials), but also exists as dissolved carbon dioxide / carbonates / bicarbonates that, when the wash water is added to a new concrete mix, further react with the cement in the mix to produce additional carbon dioxide sequestration products. In certain embodiments, the carbon dioxide added to the wash water results in products in the wash water equivalent to at least 1, 2, 5, 7, 10, 12, 15, 20, 25, 30, 25, 40, 45, 50, 60, 70, 80, or 90% carbon dioxide by weight (bwc) of the cement in the wash water, and / or up to 2, 5, 7, 10, 12, 15, 20, 25, 30, 25, 40, 45, 50, 60, 70, 80, 90, 95, or 100% carbon dioxide by weight (bwc) of the cement in the wash water.

[0048] Embodiments include applying CO2 immediately after the wash water is produced in the tank and / or when the wash water is being loaded for batching.

[0049] Alternatively, or in addition, carbonation of the wash water may allow for the use of aged wash water as kneading water, for example wash water that is at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 days old.

[0050] The carbon dioxide source can be any suitable source. In certain embodiments, some or all of the carbon dioxide is recovered from a cement kiln operation, such as one or more cement kiln operations proximate to a concrete manufacturing facility, e.g., one or more cement kiln operations that produce cement for use in the concrete manufacturing facility. In certain embodiments, wash water is transported from a concrete washing station or similar facility where the concrete wash water is generated to a cement kiln or power plant, and flue gas from the cement kiln or power plant is used to carbonate the wash water. The carbon dioxide concentration in the cement kiln flue gas or power plant flue gas may be sufficient such that no additional carbon dioxide is needed to carbonate the wash water, and it may not be necessary to completely treat the flue gas before exposing it to the wash water. That is, it will be understood that, in addition to containing carbon dioxide, cement kiln and power plant flue gases may also contain SOx, NOx, mercury, volatile organics, and other substances that must be removed or reduced to acceptable levels before the flue gas is released to the atmosphere. In certain embodiments, the flue gas is treated to remove one or more of these substances or reduce them to acceptable levels before exposing it to the wash water. In certain embodiments, one or more of these substances remain in the exhaust gas upon contact with the wash water, and the amount of the substance in the exhaust gas after contact with the wash water is reduced, thereby reducing or eliminating the need for further treatment of that substance. For example, in certain embodiments, the exhaust gas contains SOx, and treating the wash water with the exhaust gas reduces the amount of SOx in the exhaust gas (e.g., by forming insoluble sulfates), such that the exhaust gas after wash water treatment requires less or no treatment to remove SOx. Additionally or alternatively, one or more of NOx, volatile organics, acids, and / or mercury can be reduced in the exhaust gas by contact with the wash water, thereby reducing or eliminating the need for treatment of the exhaust gas for that substance.After treatment with the exhaust gas, the carbonated wash water can be transported to a concrete manufacturing facility, either the same facility where it was produced and / or a different facility, and used, for example, as an admixture in the production of concrete at the facility, e.g., to reduce the amount of cement required in the concrete due to the presence of cement in the wash water.

[0051] The wash water can be monitored, for example, during its carbonation. Any suitable characteristic described herein can be used to determine whether to change the carbon dioxide delivery to the wash water. One convenient measure is pH. For example, in certain embodiments, carbonated wash water with a pH of 8.0, 7.9, 7.8, 7.7, 7.6, 7.5, 7.4, 7.3, 7.2, 7.1, or less than 7.0 is desirable for use, for example, as kneading water. The pH can be monitored and adjusted to an appropriate pH or within an appropriate range before use, for example, as kneading water. For example, the pH may be at least 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, or 8.5, and / or 6.1, 6.2, 6.3, 6.4, 6.5 , 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.7, 9.0, 9.3, 9.5, 9.7, 10, 10.3, 10.5, 10.7, 11.0, 12.0, or 13.0 or less.

[0052] Furthermore, it is desirable that the gas flow rate within the wash water, e.g., in the holding tank, does not increase to a level high enough that the supply rate exceeds the absorption / reaction rate; if this occurs, bubbles are typically observed at the surface of the wash water. If the supply rate is equal to or less than the absorption / reaction rate, bubbles are not observed at the surface of the wash water. The rate of absorption and reaction may change over time, e.g., slowing as more particles react with or become coated with the reaction products. Therefore, the appearance of bubbles can be used as an indicator for adjusting the carbon dioxide flow rate, and appropriate sensor(s) can be used to determine whether bubbles are appearing. Alternatively, or in addition, the carbon dioxide content of the air above the wash water surface can be monitored using appropriate sensor(s) and used as a signal to adjust, e.g., slow or stop, the delivery of carbon dioxide to the wash water when the carbon dioxide in the air above the surface reaches a certain threshold concentration. The rate of concentration change can also be used as an indicator for adjusting the carbon dioxide flow rate.

[0053] In tanks where water is agitated to prevent solids from settling, it is desirable to use a minimum amount of energy to move the water in a sufficient motion pattern to keep the solids suspended. Therefore, air bubble formation, in particular, should be minimized or avoided; air bubbles that naturally rise to the surface can disrupt flow and require more energy for adequate agitation, regardless of their location in the tank's overall flow pattern. For example, in holding tanks that use augers for agitation, the system of the present invention can draw water from the tank into a recirculation loop that introduces carbon dioxide. The rate of introduction, loop length, and other related factors can be manipulated to allow the carbon dioxide to be absorbed by the water and / or react with water components before being returned to the tank. Carbon dioxide can be injected into the loop near or at the beginning of the loop to maximize the distance for the carbon dioxide to absorb and / or react. It can also be advantageous to inject carbonated water at a lower location within the tank.

[0054] Additional properties that may be useful to monitor include the temperature of the wash water (the reaction of carbon dioxide with the cement product is usually exothermic), the ionic concentration of the wash water, the electrical conductivity of the wash water, and / or the optical properties of the wash water (e.g., it has been observed that carbon dioxide can change the color of the wash water). Suitable sensors for one or more of these properties may be included in the apparatus of the present invention. Other properties and sensors are also suitable, as described herein.

[0055] The arrangement includes an apparatus for carbonating concrete wash water in a wash water operation, the apparatus including a carbon dioxide source operably connected to a conduit extending to a wash water container containing wash water from a concrete production site, the conduit having one or more openings arranged to deliver carbon dioxide to the surface of, below, or both the wash water in the container, and a system for transporting the carbonated wash water to a concrete mixing operation where the carbonated wash water is used as mixing water in a concrete mix (e.g., a second conduit that may be arranged to remove the carbonated wash water from the wash water container and transport it to the concrete mixing operation), the system using the carbonated wash water as some or all of the mixing water for the concrete batch. Typically, the carbon dioxide is delivered directly to the wash water tank as described elsewhere herein, although in some embodiments, carbonation may occur outside the tank and the carbonated water may be returned to the tank. The apparatus may further include a controller that determines whether to modify the carbon dioxide delivery based at least in part on one or more characteristics of the wash water or the wash water operation. The characteristics may include one or more of the following: pH of the wash water, rate of delivery of carbon dioxide to the wash water, total volume of wash water in the wash water container, temperature of the wash water, specific gravity of the wash water, concentration of one or more ions in the wash water, age of the wash water, rate of circulation of the wash water, timing of circulation of the wash water, air bubbles on the surface, carbon dioxide concentration of the air above the surface, optical properties, electrical properties such as conductivity, or any combination thereof. One or more sensors may be used to monitor one or more properties of the wash water, and manual measurements, such as specific gravity, pH, etc., may be taken periodically. The device may further include one or more actuators operably connected to the controller for altering the delivery of carbon dioxide to the wash water, or another property of the wash water, or both. The device may include a system for moving the wash water, such as by circulating or agitating the wash water continuously or intermittently.The composition can further include a delivery system for delivering carbon dioxide to a carbon dioxide source, where some or all of the carbon dioxide is from a cement kiln operation proximate to the concrete production site, for example, a cement kiln operation that produces some or all of the cement used at the concrete production site.

[0056] In certain embodiments, solids are removed from the carbonated wash water, for example, by filtration. These solids, which primarily comprise carbonated cement particles, can be further processed (e.g., dried). The dried solids can then be reused, for example, in a new concrete batch.

[0057] Ready-mix truck, regenerator, and / or in-line wash water carbonation In certain embodiments, the concrete wash water is carbonated directly in the drum of the ready-mix truck and / or prior to reaching the holding tank, for example, during circulation in the regenerator or in the line between the regenerator and the holding tank.

[0058] In normal operation, ready-mix trucks are loaded at the batching facility and the load may be partially loaded or fully loaded. A full load may contain several cubic metres, e.g., 8 m², depending on the size of the truck. 3Regardless of the size of the load, however, most (and in some cases substantially all) of the drum and its internal components (e.g., fins, etc.) will come into contact with the wet cement. The load is then unloaded at the site, and the truck is returned to a wash station (usually at the batching facility) where it is washed before further batching. After unloading at the site, a certain amount of water carried in containers (commonly called saddlebags) on the truck can be released into the truck at the site and during the return trip to the wash station and mixed in the truck to prevent the wet concrete from hardening in the time before the truck is washed at the wash station. Additional water is then introduced into the drum at the wash station, with spraying and mixing, to thoroughly wash the interior of the drum, followed by the resulting wash water being discarded or, more commonly, sent to one or more tanks for disposal and / or treatment before reuse.

[0059] Usually, 1m of concrete 3 Approximately 100-160 (e.g., 120) L of wash water is used per truck, but as mentioned above, partial loads coat a larger portion of the truck than the full load, and in some cases completely coat the empty truck drum. In some cases with partial loads, a more realistic estimate of the amount of water required is approximately 100-160 (e.g., 120) L of wash water per m of concrete. 3 For example, if the total volume of a truck is 8m 3 and 4m 3 For a load of 120 L, the amount of wash water may be greater than 4 x 120 L, perhaps as much as that used for a full load, e.g., 8 x 120 L, or 960 L. For any particular operation, the amount of water required for a particular size load and type of mix is ​​generally known and can be used for any calculations required.

[0060] In some facilities, regenerators are used to separate aggregates (e.g., sand and gravel) from the wash water, typically for reuse in further concrete batches. The remainder of the wash water is typically sent to a settling pond to allow additional solids to settle, or alternatively is pumped to a slurry tank where the remainder of the wash water is kept suspended with paddles, diluted to a certain specific gravity, or otherwise treated so that at least some of the water can be reused in concrete production. In conventional regenerator processes, not all of the treated wash water produced can be reused, for example, in concrete; the excess is sent to a holding pond where it is disposed of in a conventional manner.

[0061] In certain embodiments, methods and compositions are provided herein for carbonating wash water in a system that includes a regenerator, i.e., a system that includes a mechanism for removing aggregate from the wash water. The methods and compositions can be used to create new systems, but are also advantageously used in retrofitting existing systems. Generally, in a regenerator system, wash water is passed through a device to remove a portion of the aggregate and other solids in the wash water. An exemplary system is a rotating perforated drum, from which treated wash water with a relatively low percentage of solids is sent to a holding tank. When washing a new truck, for example, some or all of the water from the holding tank can be used to provide water for washing the truck drum and / or other components. Once the drum and / or other components are washed, the wash water travels through the system to remove a portion of the solids and is then sent back to the tank. In many systems, a recirculation loop returns from the tank to the system to remove solids, allowing the water to pass through the solids removal system multiple times. In certain embodiments, a portion of this recirculation line is used to carbonate the wash water. For example, one section of the line can be replaced with a system including two conduits. The first conduit is for wash water, and the second is a conduit within the first conduit for supplying carbon dioxide to the wash water. To avoid flow obstruction, the first conduit may be of a larger diameter than the conduits leading to and from the carbonation section, i.e., the conduits used in the system prior to carbonation. For example, if the system uses 2-inch diameter conduits, the first conduit in the carbonation section may be greater than 2 inches in diameter, e.g., 3 inches. This is merely exemplary; the diameter of the first conduit for the portion of the conduit not in the carbonation section may be any suitable multiple of the non-carbonating conduit, as long as flow through the first conduit is unobstructed or substantially unobstructed, e.g., as long as flow through the first conduit is sufficient for the purposes of the system. Generally, unless otherwise indicated, diameters are outside diameters.For example, the diameter of the first conduit in the carbonation section may be at least 1.01, 1.02, 1.05, 1.07, 1.1, 1.12, 1.15, 1.17, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.2, 2.5, 3.0, 3.5, 4, 5, 6, 7, 8, or 9 times the diameter of the non-carbonated portion of the conduit, e.g., the diameter of the recirculation conduit leading to the carbonation section, and / or The diameter of the non-carbonated portion of the carbonation conduit may be, for example, 1.02, 1.05, 1.07, 1.1, 1.12, 1.15, 1.17, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.2, 2.5, 3.0, 3.5, 4, 5, 6, 7, 8, 9, or 10 times or less, e.g., 1.1 to 3 times, or 1.2 to 2 times, or 1.3 to 2 times, the diameter of the recirculation conduit leading to the carbonation section. In certain embodiments, the first conduit is 0.5 to 10 inches, or 1 to 8 inches, or 1.5 to 7 inches, or 1.5 to 5 inches, or 2 to 5 inches, or 2 to 4 inches in diameter. The first conduit may be connected to the non-carbonating section of the recirculation loop by any suitable fastener; in some embodiments, the first conduit is fitted at its proximal and / or distal ends to the non-carbonating conduit so that the low point (bottom) of the first conduit is flush with or substantially not offset from the low point (bottom) of the non-carbonating conduit. Without being bound by theory, this arrangement, where the conduits are offset but the low points are flush or substantially flush, is believed to prevent settling or accumulation of solids as the non-carbonating conduit extends into the first conduit. However, any suitable configuration that prevents or limits the accumulation of solids in the first conduit may be used.

[0062] The second conduit of the carbonation section is located inside the first conduit and supplies carbon dioxide gas to carbonate the wash water flowing through the first conduit. The second conduit is configured to allow carbon dioxide gas supplied into the second conduit to flow into the first conduit but not allow wash water from the first conduit to flow into the second conduit. For example, the second conduit may be made of a flexible material that includes perforations that essentially function as a one-way valve, closing to prevent water from entering the second conduit but allowing gas to pass from the second conduit to the first conduit when gas is supplied to the second conduit. Perforations of an appropriate number, diameter, and density can be used to carbonate the wash water. The diameter of the second conduit is smaller than that of the first conduit, and any suitable diameter for the first conduit can be used, as long as it is sufficient to allow carbon dioxide to transfer to the wash water flowing through the first conduit. Thus, in certain embodiments, the diameter of the second conduit is less than 0.99, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, or 0.1 times the diameter of the first conduit, and / or The second conduit may be greater than 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, or 0.05 times the diameter of the first conduit, e.g., 0.1 to 0.9, or 0.2 to 0.8, or 0.3 to 0.7 times the diameter of the first conduit. In certain embodiments, the second conduit has a diameter of 0.2 to 5 inches, or 0.5 to 2 inches, or 0.5 to 1.5 inches. Using appropriate fittings, the second conduit can be connected to the first conduit and to an additional conduit leading to a carbon dioxide gas source. In some cases, the conduit leading from the second conduit leads to waste, and in some cases, the conduit leads back to a carbon dioxide gas source to recycle any gas not captured on the first pass.

[0063] In embodiments retrofitting a regenerator system, a section of the recirculation line of an existing system is removed and replaced with first and second conduits as described, appropriate fittings, a carbon dioxide source, appropriate sensors, generally as described below, and a control system that receives information from the sensors and / or sensors already present in the system and adjusts the carbon dioxide delivery according to the received information. In a retrofit or new system, the length of the carbonation conduit section can be any suitable length, for example, at least 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 15, 20, 25, 30, 40, or 50 feet, and / or no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 15, 20, 25, 30, 40, 50, or 100 feet, for example, 0.5 to 50 feet, or 1 to 20 feet, or 2 to 15 feet, or 5 to 15 feet.

[0064] Thus, the carbonation section of the recirculation loop between the regenerator and the holding tank allows for the carbonation of wash water without a large amount of additional equipment (simply by replacing a section of conduit with the carbonation section and installing appropriate sensors, control systems, and a carbon dioxide source).

[0065] In general, the system is configured to provide information regarding relevant parameters. Such information may be determined by sensors, human input, or any other suitable method. In certain embodiments, the information may include at least one, two, three, four, five, six, or all of the following: 1) operation of the pump for the recirculation loop (e.g., on / off and / or circulation rate); 2) level of wash water in the holding tank; 3) temperature; 4) specific gravity, e.g., of the wash water in the holding tank or other relevant area; 5) composition of solids in the holding tank (e.g., cement vs. aggregate); 6) volume of new wash water received from an incoming truck or other source; 7) carbon dioxide content of the wash water in the carbonation section or other area (which may be monitored directly and / or indirectly); 8) flow rate of carbon dioxide sent to the second conduit; 9) duration of carbon dioxide flow; 10) type, amount, and / or timing of admixture addition, and other suitable characteristics. Some or all of this information may be sent to a controller, which may process the information, compare it to predetermined parameters, and send outputs to appropriate actuators to regulate the process. The actuators may include one, two, three, or more of the following: 1) one or more valves for regulating carbon dioxide flow, 2) one or more pumps for regulating the flow of wash water through the recirculation section, 3) one or more systems for adding admixtures to the system, and any other suitable actuators. The control system may be linked to the overall regenerator control system.

[0066] During operation, the system monitors the appropriate characteristics of the wash water and adjusts the carbon dioxide delivery accordingly to carbonate the wash water to a desired level. Generally, the desired level is one that allows treated wash water with a higher specific gravity to be used in concrete manufacturing operations than would otherwise be possible. In certain embodiments, batches made with carbonated wash water can have higher compressive strengths than batches made without carbonated wash water, which also reduces the use of fresh cement in subsequent concrete batches, as less cement is required to produce the same compressive strength. Thus, a typical regenerator system produces wash water that can be diluted with tap water to a specific gravity of, for example, 1.03 or less and used in concrete. The methods and compositions of the present invention allow for less dilution of wash water to be required before use in concrete production, e.g., at least 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, or 1.2, and / or ...4, 1.05, 1.06, 1.07, 1.08, 1.19, or 1.2, and / or 1.09, 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, or 1.2, and / or 1.09, 1.10, 1.11,

[0044] It is possible to produce wash water that can be used in concrete production with a specific gravity of 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.2, 1.25, 1.3, 1.4, or 1.5 or less, for example, 1.03 to 1.25, or 1.04 to 1.2, or 1.05 to 1.15.Additionally, or alternatively, the methods and compositions of the present invention may produce wash water that, when used on a subsequent batch of cement, enables the production of concrete of the same or substantially the same compressive strength at, for example, 1, 2, 7, 14, or 28 days, or other suitable time, using at least 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 20, 25, 30, 35, or 40%, and / or no more than 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 20, 25, 30, 35, 40, or 50% less cement than would be used without the use of carbonated wash water. Additionally, the use of carbonated wash water produced by the system may also allow for the use of less and / or different admixtures than would be required if non-carbonated wash water were used in the concrete batch.

[0067] Carbon dioxide can be introduced into the carbonation section at appropriate time intervals, at appropriate flow rates, and for appropriate periods of time, depending on the state of the system. While the carbon dioxide flow rate is preferably such that little or no carbon dioxide is wasted, any appropriate flow rate and / or time interval can be used to achieve the desired carbonation. In systems where the carbonation section is new or has not been used for a long time, carbon dioxide can be added to carbonate the currently existing wash water to the desired level. Typically, unless new wash water is added, the wash water in the system retains its carbonated state and requires little or no "touch-up" carbon dioxide. In certain cases, admixtures such as one or more set retarders, e.g., carbohydrate set retarders such as sodium gluconate, are added to the wash water. In these cases, not only is the amount of set retarder monitored, but the time interval since the last addition can also be monitored. Unlike carbonation, set retarders may require additional additions over time. When additional new wash water is added, the appropriate amounts of carbon dioxide and admixtures, if used, are added. The amount of carbon dioxide added may depend, for example, on the specific gravity of the new wash water (measured and / or calculated directly from the change in SG of the wash water in the system, e.g., in a holding tank, or determined by any other suitable method), the amount of wash water added (measured directly and / or calculated from the change in the level of the wash water in the system, e.g., in a holding tank, or determined by any other suitable method), and in some cases the composition of the wash water (e.g., the percentage of solids as cementitious material relative to inert materials such as aggregate), and any other parameters. Carbon dioxide addition is initiated and stopped at the appropriate time, for example, when a predetermined amount of carbon dioxide has been added, when one or more properties of the wash water indicate that a desired level of carbonation has been achieved, and / or by any other suitable method. The amount of admixture added may be determined by similar properties and may also vary based on the time since the last admixture was added.In some cases, additional admixture is added even if no new wash water has been added, based on the time since the previous addition.

[0068] A further advantage of the carbonation system is that it allows for the use of smaller holding tanks, and in some cases, the elimination of holding tanks altogether. In the latter case, current setups require trucks to arrive at the end of the day and the water to be held until the next day for treatment and release, and / or reuse in additional batches. With carbonation, the wash water can be treated with carbon dioxide and / or admixtures, making it ready to be batched and stored, for example, in drums on the truck itself. Additionally or instead, smaller holding tanks can be used, and in some retrofit embodiments, the retrofit can include replacing current holding tanks with smaller ones.

[0069] An exemplary wash water control system is as follows. Amount of cementitious solids The CO2 treatment target depends on the amount of cementitious solids contained in the regenerator tank, which is a function of the tank volume; the tank's specific gravity (SG), or solids content; and the properties of the solids (cement fraction, fly ash fraction, non-cementitious fraction such as sand). An exemplary control protocol for determining the amount of cementitious solids contained in the regenerator tank is as follows: 1. Continuous measurement of regenerator tank volume; 2. Semi-continuous measurement of the regenerator tank SG, and / or 3. Monitoring of inflow and outflow of all tanks (current sensors on all pumps providing supply / withdrawal from regenerator tanks).

[0070] Option 1 assumes that monitoring and measurement of all material inflows is possible. Option 2 assumes that this is not possible due to equipment limitations. Both options assume continuous monitoring of tank levels.

[0071] Option 1: Measure the total volume of all inflows and SG 4. In case of tank spill: SG(n) of tank = SG(n-1) of tank

[0072] where n is the SG of the tank after the tank spill, and SG(n-1) is the SG of the tank before the tank spill. The previous SG set point is maintained by the control logic. 5. For tank inflow: SG of tank(n) = volume of tank(n-1) x SG of tank(n-1) / [volume of tank(n-1) x inflow volume] + inflow volume x SG of inflow / [volume of tank(n-1) x inflow volume]

[0073] The SG of the inflow can be a set point or a measured value, for example, if the inflow is tap water, the SG set point is 1, if the inflow is a washout inflow, the SG can be measured or set as a set point.

[0074] The new SG set point is set based on the total volume of inflow and the SG. 6. For both inflow and outflow: Amount of solids (n) = SG of tank (n) x volume of tank (n) Amount of cementitious solids (n) = Amount of solids (n) x % of cementitious solids

[0075] where % cementitious solids is a set value or a set value continuously corrected based on past batch records or quantitative wash water solids data. This can be further characterized as % cement, % fly ash, and % slag depending on the characterization requirements. % CACO3 is described below.

[0076] Option 2: Do not measure inflow volume and SG In some systems, it is not possible to measure all material inflows (gravity drainage or overflow from a preceding unit operation is used to manage material flow). 7. In case of tank spill: Same as (4) above. 8. For tank inflow: Measure the tank SG semi-continuously. 9. For both inflow and outflow: Same as (6) above.

[0077] CO2 Treatment The amount of cementitious solids in the regenerator tank is known and the amount of CO2 to inject is determined based on a setpoint, described as the mass of CAO in CACO3 / mass of CAO in cement in the regenerator system, as explained below.

[0078] Starting Scenario: Consider that for a given regenerator tank system, there are known properties of the tank solids. For example, Tank SG=1.1 Tank volume = 100,000 L 10. If a solid is characterized (as a pre-defined set point) as follows: · Mass % of cement (in the solid fraction) = 80% → SG of cement = 3.15 · Mass % of fly ash (in the solid fraction) = 10% → SG of fly ash = 2.2 · Mass % of slag (in the solid fraction) = 5% → SG of slag = 2.9 · Mass % of sand (in the solid fraction) = 5% → SG of sand = 1.6 Mass % of CACO3 (in the solid fraction) = 0% → SG of CACO3 = 2.6 11.To convert the tank's SG to solids content, you need to convert it to % by volume: · Volume % cement (in solid fraction) = [0.8 / 3.15] / [0.8 / 3.15 + 0.1 / 2.2 + 0.05 / 2.9 + 0.05 / 1.6 + 0 / 2.6] = 72.6% · Volume % of fly ash (in solid fraction) = [0.1 / 2.2] / [0.8 / 3.15 + 0.1 / 2.2 + 0.05 / 2.9 + 0.05 / 1.6 + 0 / 2.6] = 13% Slag volume % (in solid fraction) = 5% Sand volume % (in solid fraction) = 9% Volume % of CACO3 (in solid fraction) = 0% 12. Determine the solids fraction of the slurry in the regenerator tank using the SG of the tank and the volume % of the components: SG of solids = [volume % cement × SG of cement + volume % fly ash × SG of fly ash + volume % slag × SG of slag + volume % sand × SG of sand + volume % CACO3 × SG of CACO3] ·SG of solids = [0.73×3.15+2.2×0.13+2.9×0.05+1.6×0.05+0×0] = 2.87 13.Therefore, Mass % of tank solids = [SG of solids × [SG of tank - 1] / [SG of solids - 1]] / SG of tank Tank solids mass % = [2.87 x [1.1 - 1] / [2.87 - 1]] / 1.1 = 0.1395 = 13.95% 14.Therefore, Cement mass% = 0.8 x 0.1395 = 11.2% Slurry kg = Tank SG x Tank volume = 1.1 x 100,000 = 110,000 kg Cement kg = 0.112 x 110,000 = 12,320 kg Other components: Fly ash kg = 1,534.5 kg Slag KG=767.25kg Sand kg = 767.25 kg Water kg = 94,611

[0079] If the amount of cement in the system is known, the required CO2 injection rate can be determined based on the stoichiometric reaction of CaO with CaCO3.

[0080] Using the above example, consider a known amount of cement having a known percentage of CaO.

[0081] The treatment system then sets a target treatment level based on the system's target mass of CAO in CACO3 / mass of CAO in cement set point.

[0082] Using the example above, The set value for mass of CAO in CACO3 / mass of CAO in cement is considered to be 0.4. 16.So, using the above example, KG of CAO = KG of CAO in cement + KG of CAO in CACO3 8,008 = kg of CAO in cement + 0.4 x kg of CAO in cement KG of CAO in cement = 8,008 / 1.4 = 5,720 KG KG of CAO in CACO3 = 0.4 x 5,720 = 2,288 KG KMOL of CAO in CACO3 = 2,288 / 56.08 = 40.8 KMOL 17. Therefore, using the stoichiometry of the reaction CO2 + CaO = CaCO3 and the molar mass of CO2 (44.01), · Where KMOL of CO2 = KMOL of CAO. KG of CO2 = KMOL of CO2 x 44.01 = 40.8 x 44.01 = 1,795.6 KG

[0083] In this example, 1,795.6 CO2 would be required to process to the desired level. 18. Characterization of the obtained solid: Characterization of the resulting solids in this example is as follows, where (n) is after treatment and n-1 is before treatment with CO2: KG(n) of cement = KG(n-1) of cement - KG(n) of CAO in CACO3 = 12,320 - 2,288 = 10,032 KG KG of fly ash(n) = KG of fly ash(n-1) = 1,534.5 KG KG of slag(n) = KG of slag(n-1) = 767.25 KG KG of sand(n) = KG of sand(n-1) = 767.25 KG KG of CACO3(n) = KG of CACO3(n-1) + KG of CO2 + KG of CAO in CACO3(n) = 0 + 1795.6 + 2,288 = 4,083 KG 19. Determine the mass % (in the solid fraction) of XX obtained: Cement mass% (n) = 58.4% Fly ash mass% (n) = 9% Slag mass% (n) = 4.4% Sand mass% (n) = 4.4% Mass% of CACO3 (n) = 23.8% and % of solids = % of Tank Solids = (10,032 + 1534.5 + 767.25 + 767.25 + 4,083) / [(10,032 + 1534.5 + 767.25 + 767.25 + 4,083) + 94,611] = 15.4%

[0084] Steady state scenario: Considering the example above, where the solids fraction is included as CaCO3, the characterization of known influent materials from truck wash water is as follows: · Mass % of cement (in the solid fraction) = 80% → SG of cement = 3.15 · Mass % of fly ash (in the solid fraction) = 10% → SG of fly ash = 2.2 · Slag mass% (in solid fraction) = 5% → SG of slag = 2.9 · Mass % of sand (in the solid fraction) = 5% → SG of sand = 1.6 Mass % of CACO3 (in the solid fraction) = 0% → SG of CACO3 = 2.6 Additionally, consider a scenario where the following daily operating parameters are known / measured: Tank's SG (end of day) = 1.12 Tank volume = 98,000L Volume of outflow slurry = 20,000 L (measured and monitored by concrete batching) Influent volume = 10,000L (monitoring tap water / fresh water inflow to the regenerator tank) As set out in the previous example, assume a steady-state material balance in the regenerator tank at the beginning of the operating day: Mass % of cement (n) (in the solid fraction) = 58.4% Mass % of fly ash (n) (in the solid fraction) = 9% Mass % of slag (n) (in the solid fraction) = 4.4% Mass % of sand (n) (in the solid fraction) = 4.4% Mass % of CACO3 (n) (in the solid fraction) = 23.8% 20. Therefore, using the calculation of SG for solids as above: · SG(n-1) of tank solids = 2.85 where n-1 is the SG of the tank solids at the beginning of the operating day 21. Therefore, using the volume balance and calculation of SG of solids as above: Influent slurry volume = Tank volume (n) - [Tank volume (n-1) + Influent water volume - Outflow slurry volume] =98,000-[100,000+10,000-20,000]=8,000L 22.From steps (10) to (12) above, ·SG of influent slurry solids=2.87 · SG(n-1) of tank solids = 2.85 Influent SG=1 Therefore, the initial slurry volume from the start of the day in SG1.1 is: · Slurry volume (n-1) = 100,000 - 20,000 = 80,000 L → SG1.1 Including inflows, Influent volume = 10,000 L → SG1 Inflow slurry volume = 8,000 L → SG unknown 23.If the SG measurement is 1.12, then: · SG of tank (n) = [Volume of slurry (n-1) × SG of slurry (n-1) + Volume of influent water × SG of water + Volume of influent slurry × [SG of influent slurry] / [Volume of tank (n)] · 1.12 = [80,000 × 1.1 + 10,000 × 1 + 8,000 × SG of inlet slurry] / 98,000 ·SG of inflowing slurry=1.47 24. If the SG of the influent slurry is calculated to be 1.47, then from (13) above, we get: Influent slurry solids mass% = [2.87 × [1.47 - 1] / [2.87 - 1]] / 1.47 = 0.49 = 49% 25. Therefore, from (14) above, Cement mass% = 0.8 x 0.49 = 39.2% KG of slurry = SG of inflowing slurry x volume of inflowing slurry = 1.47 x 8,000 = 11,760 KG Cement kg = 0.392 x 11,760 = 4,609.9 kg Other components: Fly ash KG=576.24kg Slag kg = 288.1 kg Sand kg = 288.1 kg 26.From 15 above, the influx of CAO in cement is determined as follows: KG of CAO in cement = KG of cement x 0.65 = 4,609.9 x 0.65 = 2,996.4 KG 27. Next, determine a new mass balance at the end of the operating day using the inflow and outflow balances before treating the regenerator tank with CO2. In this example, the resulting balance is: -Leakage Cement kg = 10,032 - (20,000 L) x (1.1 KG / L) x 0.154 x 0.584 = 8,053 KG Fly ash kg = 1,534.5 - (20,000 L) x (1.1 KG / L) x 0.154 x 0.09 = 1,229.6 KG Slag kg=614.8KG Sand kg = 614.8 kg CACO3 KG = 4,083 KG - 806.34 = 3,276.7 KG Water kg = 94,611 - (20,000 L) x (1.1 KG / L) x (1 - 0.154) = 75,999 KG +Inflow Cement kg = 8,053 + 4,609.9 = 12,692.9 kg Fly ash kg = 1,229.6 + 576.24 = 1,805.84 kg Slag KG = 614.8KG + 288.1KG = 902.9KG Sand kg = 614.8 kg + 288.1 kg = 902.9 kg CACO3 KG = 3,276.7 + 0 KG = 3,276.7 KG Water kg = 75,999 + 10,000 + (8,000 L) x (1.47 KG / L) x (1 - 0.49) = 91,996 KG 28. Mass of CAO in CACO3 / Mass of CAO in cement: Using the molar masses of CaO (56.08) and CaCO3 (100.9), we get: Mass of CAO in CACO3 = 3,276.7 kg x (56.08 / 100.9) = 1,821.2 kg Using the CAO fraction (cement) relative to cement as a constant = 65% (as in (15) above): Mass of CAO in cement = 12,692.9 kg x 0.65 = 8,250.4 kg Therefore, the ratio is: Mass of CAO in CACO3 / Mass of CAO in cement = 1821.2 / 8250.4 = 0.22 ·Total CAO=1821.2+8250.4=10,071.6 29. If the desired ratio is 0.4, then from (16) above, the amount of KG of CAO in CACO₃ is 2,877.4. If 1,821.2 KG of CAO is already present as CAO in CACO₃, then the net amount of CAO needed for the reaction is 2,877.4 - 1,821.2 = 1,056.2 KG = 18.83 KMOL. 30. Using the stoichiometry as in (17) and (18) above, the amount of CO2 needed to react to the desired set point is: Where KMOL of CO2 = KMOL of CAO KG of CO2 = KMOL of CO2 x 44.01 = 18.83 x 44.01 = 828.7 KG In this example, 828.7 KG of CO2 is required to process to the desired level. 31. Characterization of the obtained solid: The characterization of the resulting solids in this example is as follows, where (n) is after treatment and n-1 is before treatment with CO2: KG of cement(n) = KG of cement(n-1) - Net KG of CAO in CACO3(n) = 12,692.9 - 1,056.2 = 11,636.7 KG KG of fly ash(n) = KG of fly ash(n-1) = 1,805.84 KG of slag(n) = KG of slag(n-1) = 902.9 KG KG of sand(n) = KG of sand(n-1) = 902.9 KG KG of CACO3(n) = KG of CACO3(n-1) + KG of CO2 + KG of CAO in CACO3(n) = 3,276.7 + 828.7 + 1056.2 = 5,161.6 KG 32. Determine the mass % (in the solid fraction) of XX obtained: Cement mass% (n) = 57.0% Fly ash mass% (n) = 8.8% Slag mass% (n) = 4.4% Sand mass% (n) = 4.4% Mass% of CACO3 (n) = 25.3% and % of solids = · % of tank solids = (11,636.7 + 1805.84 + 902.9 + 902.9 + 5161.6) / [(11,636.7 + 1805.84 + 902.9 + 902.9 + 5161.6) + 91,966] = 18.2%

[0085] The properties of this tank solids now become the new start-of-day mass balance for the next day's operations at the concrete plant.

[0086] Additional or alternative scenarios are as follows: An exemplary method for monitoring and controlling the reaction mechanism of CO with concrete wash water slurry is as follows: Concrete wash water slurry containing cement fractions of known specific gravity / solids content and solids content can be treated with carbon dioxide to produce nano-calcium carbonate. Without being bound by theory, the reaction mechanism depends on many factors, including: 1) the ionic calcium concentration, or amount of free calcium in solution; 2) the carbon dioxide injection rate; and 3) the reaction residence time.

[0087] The relative influence of each factor and mechanistic control strategies are discussed below. 1) Ionic calcium: Hydrating and hydrated Portland cement is known to contain calcium hydroxide (Ca(OH)2), which dissociates in water to form Ca in solution. 2+ ions (and OH - ), resulting in a caustic solution. The solubility of Ca(OH)2 decreases with increasing temperature. Data are expressed as saturated solubility in grams per 100 grams of water. [Table 1]

[0088] Carbon dioxide reacts with the calcium oxide portion of the cement / calcium hydroxide to produce calcium carbonate. Without being bound by theory, it is believed that two CO2 mineralization mechanisms occur in the slurry: a) Pathway 1: Carbon dioxide reacts with the free calcium ions and OH in solution. -a) Pathway 1: Carbon dioxide reacts with the cement solids to form individual nano-calcium carbonate in solution (solution mechanism); b) Pathway 2: Carbon dioxide reacts with the cement solids to form calcite crystals on the surface of the cement particles (surface reaction mechanism). The reaction pathways can be controlled by predicting the ionic calcium concentration in the wash water slurry and subsequently controlling the carbon dioxide injection rate for a given reaction residence time. 2) Carbon Dioxide Injection Rate: The carbon dioxide injection rate can be managed and controlled to ensure (1) maximum reaction efficiency and (2) targeted control of the reaction between carbon dioxide and calcium.

[0089] The reaction rate of Pathway 1 above is hypothesized to be faster than Pathway 2. Furthermore, the reaction of Pathway 1 is hypothesized to be more predictable than Pathway 2 and to produce a more predictable product in the form of "free" nano calcium carbonate. This can improve reaction efficiency, enhance control and consistency in the application of the produced nano calcium carbonate, and increase the predictability of the hydration characteristics and reaction rate of the remaining cementitious fines. As a result, methods for controlling the carbon dioxide injection rate, as well as reaction methods based on predicted ionic calcium concentration, carbon dioxide bubble size, and reaction length, can be created.

[0090] As previously mentioned, the injection device used in this application consists of a section of pipe length (the "injection length," the aforementioned first conduit) installed as a subsection of a longer conduit with an internal diameter suitable for the insertion of a single perforated, stretched microcellular foam hose (the aforementioned second conduit), in this example used to generate nanobubbles, such as for water oxygenation in fish / aquaculture applications. This method ensures a uniform distribution of nanobubbles throughout the injection length. Increasing the internal diameter of the pipe section would result in a decrease in volume due to the insertion of the foam hose and the addition of CO2 via injection. Alternatively, the diameter can be sized to slow the fluid velocity and therefore increase the residence time the slurry is in direct contact with the bubbled CO2. The pressure drop (high to low pressure) at the inlet of the injection length can facilitate disruption of the laminar flow in the previous pipe section, creating turbulence, which promotes effective mixing of the slurry with the injected CO2.

[0091] Example scenario Consider a slurry with the following properties flowing through an 11 meter length of 2 inch internal diameter pipe at 160 gallons per minute or GPM (equivalent to 607 liters per minute or LPM). CO2 injection begins at a 3 inch section of pipe at 0 meter injection length and ends at 1 meter injection length. The aerated foam hose has a 1 inch outer diameter. CO2 is injected uniformly throughout the injection length using the injection mechanism described above. This is followed by a 10 meter contained reaction length of flow before being released to the atmosphere and entering recirculation. Slurry SG: 1.1 Slurry temperature: 20 degrees Celsius Cement SG: 3.15 Fly ash SG: 2.2 Cement fraction of solids (volume %): 85% Solid fly ash fraction: (volume %): 15% Determination of the solids content of the slurry: % solids = [(SG of cement × cement fraction + SG of fly ash × fly ash fraction)] × [(SG of slurry - 1) / ((SG of cement × cement fraction + SG of fly ash × fly ash fraction) - 1)] / (SG of slurry) % solids=13.6% Water %=86.4% Volume of slurry and CO2 at injection length: Slurry flow rate = [(160 gal / min) x (3.7854 L / gal) x (1 min / 60 sec)] = 6.3 L / s CO2 flow rate = (100 L / min) x (1 min / 60 sec) = 1.6 L / s Volumetric Flow Ratio スラリー / CO2 = volume of slurry / volume of CO2 Volumetric Flow Ratio スラリー / CO2 =6.3L / s / 1.6L / s Volumetric Flow Ratio スラリー / CO2 =3.9375 Volumetric Flow Ratio CO2 / スラリー =0.2540 Cross-sectional area of ​​2-inch pipe = π × (d / 2) 2 Cross-sectional area of ​​2-inch pipe = π × [(2 inches × 0.0254 m / inch) / 2] 2 Cross-sectional area of ​​2-inch pipe = 0.002027 m 2 Cross-sectional area of ​​3-inch pipe = π × (d / 2) 2 Cross-sectional area of ​​3-inch pipe = π × [(3 inches × 0.0254 m / inch) / 2] 2 Cross-sectional area of ​​3 inch pipe = 0.00456 m 2 Volume of a 3-inch pipe = pipe cross-sectional area x pipe length Volume of a 3-inch pipe = π x [(3 inches x 0.0254 m / inch) / 2] 2 ×(1m) Volume of a 3 inch pipe = 0.00456 m 3 =4.56L Volume of foamed hose = hose cross section x hose length Volume of foam hose = π x [(1 inch x 0.0254 m / inch) / 2] 2 ×(1m) Volume of foam hose = 0.000507m 3 =0.507L Available injection length volume = Pipe volume - Hose volume Available injection length volume = 4.56 L - 0.507 = 4.05 L Available injection length volume = Volume of slurry + Volume of CO2 Here, volume of CO2 = 0.2540 x volume of slurry Available pour length volume = volume of slurry + 0.254 x volume of slurry Available pour length volume = Volume of slurry × (1 + 0.2540) Volume of slurry = Volume of available pour length / (1 + 0.2540) Volume of slurry = (4.05 L) / (1 + 0.2540) Slurry volume = 3.23 L CO2 volume = slurry volume x volumetric flow rate CO2 / スラリー CO2 volume = (3.23 L) x 0.2540 Volume of CO2 = 0.820L Slurry mass = slurry volume x slurry specific gravity Slurry mass = 3.23 L x 1.1 kg / L Mass of slurry = 3.55 kg Water fraction = slurry mass x water fraction of slurry Water fraction = 3.55 kg x 0.864 Water fraction = 3.07 kg = 3.07 L Velocity change of slurry in a pipe: For a 2-inch diameter section before injection: Slurry flow rate = 6.3 L / s = 0.0063 m 3 / s Cross-sectional area of ​​pipe = 0.002027 m 2 Slurry velocity in a 2-inch pipe = slurry flow rate / cross-sectional area of ​​the pipe Slurry velocity in 2-inch pipe = 0.0063 m3 / s / 0.002027m 2 Slurry velocity in 2-inch pipe = 3.11 m / s For a 3-inch diameter section where injections will be made: Slurry flow rate = [(160 gal / min) x (3.7854 L / gal) x (1 min / 60 sec)] Slurry flow rate = 6.3 L / s = 0.0063 m 3 / s Volume of slurry = 3.23 L = 0.00323 m 3 Effective cross-sectional area of ​​slurry = volume of slurry / injection length Effective cross-sectional area of ​​the slurry = 0.00323 m 3 / 1m=0.00323m 2 Slurry velocity in a 3-inch pipe = slurry flow rate / effective cross-sectional area of ​​the slurry Slurry velocity in 3 inch pipe = 0.0063 m 3 / s / 0.00323m 2 Slurry velocity in 3 inch pipe = 1.95 m / s

[0092] The slurry slows down within the injection length, resulting in a drop in pressure and promoting turbulence / disrupting laminar or plug flow. In another embodiment of the present invention, a Pitot tube sight glass assembly can be used to measure / monitor the pressure drop across each pipe diameter change.

[0093] Velocity of the slurry / CO2 mixture in the 2-inch pipe following the injection length: Assumes negligible CO2 conversion within the injection length (i.e., the majority of the reaction occurs in the 10-meter 2-inch pipe section following the injection length). Volumetric flow rate of kneaded material = Volumetric flow rate of slurry + Volumetric flow rate of CO2 Volumetric flow rate of kneaded material = 6.3 L / s + 1.6 L / s Volumetric flow rate of the kneaded material = 7.9 L / s = 0.0079 m 3 / s Cross-sectional area of ​​2-inch pipe = 0.002027 m 2 Slurry velocity in 2-inch pipe = volumetric flow rate of kneaded material / cross-sectional area of ​​2-inch pipe Slurry velocity in 2-inch pipe = 0.0079 m 3 / s / 0.002027m 2 Slurry velocity in 2-inch pipe = 3.9 m / s

[0094] As the velocity increases, there is a pressure drop in the direction of flow (high to low pressure) as the flow leaves the 3 inch diameter injection length and enters the 2 inch diameter reaction length. In another embodiment, additional venturi tubes are installed along the reaction length to disrupt laminar / plug flow and promote turbulence, thereby increasing mixing and potentially increasing reaction efficiency.

[0095] Stoichiometric equilibrium of Cao and CO2: CaO: At 20 degrees Celsius, the saturated solubility of Ca(OH)2 in 100 grams of water is 0.165 grams.

[0096] Therefore, the following is predicted: Mass of Ca(OH)2 = Saturated solubility of Ca(OH)2 × Volume of solution Mass of Ca(OH)2 = (0.165 grams of Ca(OH)2 / 100 grams) x 3070 grams of solution Mass of Ca(OH)2 = 5.065 grams of Ca(OH)2 available in solution Moles of Ca(OH)2 = 5.065g of Ca(OH)2 / molar mass of Ca(OH)2 Moles of Ca(OH)2 = 5.064 grams / 74.093 g / mol Moles of Ca(OH)2 = 0.0684 moles Mass of Ca = 0.0343 moles x 40.08 g / mol of Ca = 2.74 grams of Ca CO2: Mass of CO2 = Mass of CO2 within injection length Mass of CO2 = Volume of CO2 within injection length x Gas Density Mass of CO2 = 0.820 L x (1.98 g / L) = 1.624 g Moles of CO2 = mass of CO2 / molar mass of CO2 Moles of CO2 = 1.624 g / (44.01 g / mol) = 0.0369 moles

[0097] The simplified stoichiometric reaction between CO2 and CaO is: CaO + CO2 = CaCO3

[0098] The molar stoichiometry (CaO:CO2) is 1:1. In this example, this means that the stoichiometric excess of CaO in solution is: Stoichiometric excess = (moles of Ca(OH)₂ / moles of CO₂) Stoichiometric excess = (0.0684 moles / 0.0369 moles)-1 Stoichiometric excess = +85.4%

[0099] In this example, the reaction is expected to be controlled via Pathway 1 because CO2 is expected to react more readily / have a higher affinity for free calcium ions in solution compared to surface reactions with cement solids to form calcite crystals. For the purposes of this discussion, the reaction length (10 meters) following the injection length is assumed to provide sufficient residence time to allow for 100% reaction efficiency based on the slurry flow rate; i.e., there is no unreacted CO2 released to the atmosphere at the end of the reaction length.

[0100] It is assumed that the replenishment rate of free calcium ions is sufficiently low that it can be considered negligible within the reaction length (residence time = approximately 3-3.5 seconds in this example). Free calcium replenishment occurs as a result of free calcium consumption / reaction with CO2 during injection and subsequent reactions in the injection and reaction pipes, reducing the CaO content below the saturated solubility point.

[0101] Free calcium can be predicted using solubility and flow properties, or alternatively, can be measured using a calcium ion sensor.

[0102] To further clarify the proposed method for monitoring and controlling the rate of occurrence of the Pathway 1 reaction relative to the Pathway 2 reaction, consider a flow rate of CO equal to the stoichiometric equivalent of CaO in the reaction to produce CaCO. Stoichiometric CO2 = 0.0684 moles Mass of CO2 = 0.0684 moles × (44.01 g / mol of CO2) = 3.01 grams of CO2 Volume of CO2 = 3.01 grams / (1.98 g / L) = 1.52 L Slurry volume = 4.05 L - 1.52 L = 2.53 L Volumetric flow ratio (slurry volume / CO2 volume) = 2.53 L of slurry / 1.52 L of CO2 = 1.664 Stoichiometric equivalent of CO2 flow rate = slurry flow rate / volume flow rate ratio スラリー / CO2 Stoichiometric equivalent of CO2 flow rate = 6.3 L / s of slurry / L of slurry / L of CO2 = 1.664 Stoichiometric equivalent of CO2 flow=3.79L CO2 / s=227SLPM

[0103] This indicates that the maximum CO flow rate allowed for a stoichiometric reaction of free calcium ions in solution, based on a particular input, is 227 SLPM. This does not correspond to the residence time required after injection to achieve 100% reaction efficiency, which, as noted, depends on the reaction rate and residence time over the reaction length.

[0104] In practice, the goal is a stoichiometric excess that maximizes the rate of occurrence of the Pathway 1 reaction relative to Pathway 2. A method for determining the extent of reaction (in terms of CO2 consumed / CaCO3 produced per pass) is described.

[0105] g / s of CaCO3 produced per reaction pass: Assuming 100% reaction efficiency within the reaction length and only Path 1 reaction, the amount of CaCO produced during each pass can be calculated using a CO flow rate of 100 SLPM. Path 1 reaction is ensured by maintaining a target stoichiometric excess of CaO in solution (85.4% excess in this example). CO2 flow rate = 100SLPM CO2 flow rate = (100 L / min) x (1 min / 60 sec) CO2 flow rate = 1.6 L / s CO2 flow rate = 1.6 L / s × (1.98 g / L) = CO2 3.168 g / s Molar rate of CaCO3 produced = CO2 flow rate × molar mass of CO2 Molar rate of CaCO3 produced = 3.168 g / s / (44.01 g / mol) Molar rate of CaCO3 produced = 0.0720 mol CO2 / s moles of CaCO3 produced = moles of CO2 consumed Rate of CaCO3 produced = moles of CaCO3 produced x molar mass of CaCO3 Rate of CaCO3 produced = 0.0720 moles of CaCO3 × (0.0869 g / mol of CaCO3) Rate of CaCO3 produced = 7.21 g CaCO3 / s

[0106] The amount of nano-CaCO3 produced "in situ" in the wash water tank over a period of time can then be predicted.

[0107] For example, for an overnight 10 hour treatment period in an 80,000 L tank containing a slurry with a specific gravity of 1.1, the mass of CaCO3 produced / concentration of CaCO3 is: CaCO3 produced = 7.21 g CaCO3 / s x 3600 sec / hr x 10 hr Produced CaCO3 = 259,560 grams Produced CaCO3 = 260 kg Mass of slurry (before treatment) = Volume of slurry (before treatment) x Specific gravity of slurry Slurry mass (before treatment) = 80,000 L x 1.1 kg / L Mass of slurry (before treatment) = 88,000 kg Mass of slurry (after treatment) = Mass of slurry (before treatment) + Produced CaCO3 Mass of slurry (after treatment) = 88,000 kg of untreated slurry + 260 kg of CaCO3 Mass of slurry (after treatment) = 88,260 kg of treated slurry Assuming the specific gravity of the slurry does not change, Volume of slurry (after treatment) = Mass of slurry (after treatment) / Specific gravity of slurry Slurry volume (after treatment) = 88,259 kg / 1.1 kg / L Slurry volume (after treatment) = 80,236 L Nano-CaCO3 concentration = produced CaCO3 / volume of slurry (after treatment) Nano CaCO3 concentration = 260 kg of CaCO3 / 80,236 L of treated slurry Nano CaCO3 concentration = 3.23 g / L slurry Nano CaCO3 concentration = approx. 323 ppm

[0108] The incidence of the Pathway 1 reaction relative to the Pathway 2 reaction can be determined by monitoring the free calcium concentration in solution via a calcium probe and by assessing the particle size of experimental slurries after controlled treatment.

[0109] Consider a test in which the slurry is circulated through an injection system at a flow rate of 50 gallons per minute (GPM). For a 55-gallon mixing vessel, the tank turnover rate is 55 gallons / 50GPM = 1.1 minutes. Because of the high potential for short-circuiting in this system, it is difficult to control the reactions of Path 1 and Path 2. Furthermore, the replenishment rate of free calcium ions in solution can exceed 1.1 minutes, especially at high treatment levels (CO2 injection causes an exothermic reaction, and the solubility of Ca(OH)2 decreases with increasing temperature).

[0110] On a commercial scale, after release to the atmosphere and recirculation conduit, the slurry returns to the wash water slurry tank. With proper management of the tank feed points for recirculation and the tank discharge points for CO injection and reaction, it is assumed that short-circuiting of the slurry will be negligible.

[0111] 3) Pipe reaction length / reaction residence time Using the scenario provided in this example, consider a system monitoring the energy input resulting from the exothermic formation of CaCO3 (either Path 1 or Path 2). It is assumed that the Path 1 reaction occurs much faster than Path 2 and therefore occurs at a higher efficiency for a given length of pipe. Consequently, if CO2 injection is controlled to maintain Path 1, the occurrence of an over-injection of CO2 (or alternatively, a reduction in the required stoichiometric excess of free calcium ions in solution) can be observed by a decrease in efficiency. This decrease in efficiency can be observed by a reduction in the exothermic reaction in a given pipe section, which is observed from the operational / control level using temperature probes before and after injection and reaction. To observe this, it is assumed that the reaction residence time (3-3.5 seconds in the example shown) is short enough that any ambient / environmental influence on the slurry temperature is negligible and that the only discernible / measurable temperature change results from the exothermic reaction.

[0112] A predictive model is provided that allows for the modification of the measured DEL-T based on a theoretical calculation of 100% reaction efficiency, and shows the effect of varying the DEL-T on actual efficiency. See Example 38.

[0113] Maintaining / controlling the Pathway 1 reaction results in a more predictable slurry in the concrete production environment. Predictability of cementitious solids in recycled wash water management systems is a key issue affecting reuse rates in concrete production. This typically leads to significant dilution of the wash water to reduce the impact of variability in cementitious solids hydration on the fresh properties of the produced concrete. This, in turn, requires holding larger volumes in the recycled wash water tanks, which in turn leads to a higher sustained solids load and greater variability in the age of the cementitious solids contained in the regenerator tank. The more predictable cementitious solids hydration effect, complemented by the “in situ” generation of nano-calcium carbonate, allows the CO2-treated wash water slurry to be used at higher replacement levels and for a greater portion of concrete production with little or no dilution, thereby reducing the sustained load in the regenerator tank and therefore the variability in the age of the cementitious solids contained in the regenerator tank.

[0114] Any reaction in the form of Pathway 2 is difficult to measure, and the corresponding impact on the reactivity / kinetics of the solids produced in Pathway 2 creates even more challenges in terms of predictability. Conversely, if the reaction is maintained as Pathway 1, the remaining (unreacted) cementitious solids will behave predictably as typical cementitious solids in water, and the hydration reaction kinetics can be managed using industry-proven hydration stabilization / set retardation techniques. Furthermore, the production of nano-CaCO3 results in a unique "in situ" product with added value that improves intrinsic performance and is now accepted as such by the industry.

[0115] Introducing Carbon Dioxide into the Truck Drum. In certain embodiments of the present invention, carbon dioxide is introduced into the water in the drum of the ready-mix truck before the water leaves the drum. The carbon dioxide can be in any form and can be introduced in any suitable manner.

[0116] 1) Introducing carbon dioxide after the concrete load is poured and before the truck arrives at the wash station. For example, carbonated water can be used as the saddlebag water and / or wash water at the wash station. As described elsewhere, supersaturated carbonated water can be used (see, e.g., U.S. Patent Application Publication No. 2015 / 0202579). Additionally or alternatively, solid carbon dioxide can be introduced into the water. For example, a quantity of dry ice can be added on-site before, during, or after the addition of saddlebag water and mixed with the saddlebag water and remaining concrete in the drum of the ready-mix truck during the return to the wash station. The dry ice sublimes in the water and reacts with the cement in the remaining concrete to produce reaction products, e.g., carbonates, providing a stable source of carbon dioxide. The dry ice can be added in a single dose or in multiple doses, e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, or more than 10 doses, or continuously or semi-continuously. Additionally or alternatively, gaseous carbon dioxide can be introduced into the drum either in a single addition, or multiple additions, or as a carbon dioxide stream injected into the drum, for example, during part or all of the transportation time from the site. For example, carbon dioxide gas can be added in a single dose or in multiple doses, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more than 10 doses, or continuously or semi-continuously. Carbon dioxide can also be introduced as a mixture of gaseous carbon dioxide and solid carbon dioxide, for example, by using a snow horn, which can also be added in one or more additions or continuously. For example, carbon dioxide as a mixture of gas and solid can be added in a single dose or in multiple doses, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more than 10 doses, or continuously or semi-continuously. In embodiments using dry ice, there can be an additional effect of cooling the wash water as the cementitious material reacts. It will be appreciated that one or more of the above options may be used for any given load.

[0117] For example, carbon dioxide can be added to the drum after the saddlebag water is added while the truck is traveling from the site to the washing station. In one option, a certain amount of dry ice can be carried by the truck and introduced into the drum at the time the saddlebag water is introduced, which is an easy and convenient way to introduce a relatively large amount of carbon dioxide into the drum. The dry ice can be used in pieces of a certain size, or within a certain range of sizes, determined by, for example, one or more of the following: the volume of the saddlebag water, the amount of cement in the mix, the expected amount of concrete coating the inside of the truck, the estimated transport time back to the washing station, the desired level of carbon dioxide uptake, the efficiency of the uptake, temperatures the truck is likely to encounter, etc., so that the dry ice sublimes at a rate that matches the expected rate of reaction with the concrete residue, particularly cement. This tends to retain more carbon dioxide in the truck drum, since the carbon dioxide reacts at a rate close to the rate at which it sublimes into a gas. In a second option, the saddlebag water is carbonated or supersaturated with carbon dioxide before being loaded into its container, typically at a batching facility. The container may be modified as needed to maintain the carbonation of the water for the required period of time prior to use. Supersaturated solutions have been found to retain a high percentage of the introduced carbon dioxide for a relatively long period of time; therefore, little or no modification of the saddlebags may be necessary when using supersaturated solutions. See, for example, U.S. Patent Application Publication No. 2015 / 0202579. In a third option, gaseous carbon dioxide is added to the ready-mix truck drum before, after, or during the addition of saddlebag water. As noted above, addition can be in a single dose, multiple doses, continuous, or a combination. The total amount of carbon dioxide added can be metered and adjusted based on the same criteria as for dry ice. In a fourth option, a mixture of solid and gaseous carbon dioxide is added to the drum, for example, using liquid carbon dioxide passed through a snow horn. Dosage and adjustment are similar to those for gaseous carbon dioxide. Any combination of these options can be used as needed, as appropriate for a particular load, truck, or operation.

[0118] Because the truck is empty, the drum provides a significant headspace for the gaseous carbon dioxide to hold. In certain embodiments, the opening of the drum may be partially or completely closed to retain the carbon dioxide within the drum during transport back to the washing station, or at the washing station, or both.

[0119] 2) Addition of Carbon Dioxide at a Washing Facility. Additionally or alternatively, carbon dioxide can be added to the drum of the ready-mix truck during the washing process at the washing station. Any or all of the above options for adding carbon dioxide after the load is poured and before the truck returns to the washing facility, i.e., carbonated or supercarbonated wash water, dry ice, gaseous carbon dioxide, or a mixture of gaseous and solid carbon dioxide, can also be used during washing at the washing station. If carbon dioxide has already been added to the drum before the truck arrives at the washing station, one or more properties of the water can be useful in determining the extent of the carbon dioxide reaction. As described elsewhere herein, measurements of pH, temperature, etc. can be useful. The amount of additional carbon dioxide to be added can then be calculated from the measurement(s).

[0120] A wash can be performed as a single wash or can be split into two or more washes, one or more of which can include carbonation. Thus, a wash may be performed as one, two, three, or more than three washes. One or more of these may include carbonation. Splitting the washes in combination with carbonation may potentially require less water than using a single wash. If the addition of saddlebag water counts as one wash, typically a minimum of two washes will be used (one with saddlebag water and one at the wash station). If multiple washes are used at the wash station, that would be three, four, etc. washes. Of these total washes, one or more may include a carbonation step; for example, one wash may include a carbonation step (e.g., the addition of saddlebag water on-site or a wash step at the wash station), or there may be two washes total (saddlebag and wash station) where both washes include a carbonation step. As another example, there may be one wash (e.g., one of two washes at the saddlebags or wash station on-site) that includes a carbonation step, or two washes (e.g., one of two washes at the saddlebags and wash station on-site, or both washes at the wash station) that include a carbonation step, or three washes (two separate washes at the saddlebags and wash station) where all three washes include a carbonation step.

[0121] Carbon dioxide can be added manually, automatically, or a combination of the two. When carbon dioxide is added as carbonated wash water, normal wash routines can typically be used, with some or all of the wash water being carbonated or overcarbonated. If the concrete in the truck is already partially carbonated, e.g., carbonated during transport to the washing facility, the desired amount of carbon dioxide to be added can be calculated, in some cases, based on one or more of the properties described above, e.g., pH, and the amounts of carbonated wash water and regular (non-carbonated) wash water, adjusted accordingly. If the concrete in the truck is not carbonated, the amount of carbon dioxide can be calculated as described below, and the amounts of carbonated wash water and regular (non-carbonated) wash water can be adjusted accordingly. Alternatively, the wash water can be used normally without any specific calculations or adjustments.

[0122] Optionally, carbon dioxide can also or alternatively be added as solid carbon dioxide. Thus, the dry ice can be adjusted to a particular size or size range and added to the drum in the desired amount. Addition can be as simple as manual addition by a truck driver or other personnel.

[0123] Additionally or alternatively, carbon dioxide can be added as gaseous carbon dioxide or as a mixture of gaseous and solid carbon dioxide. In this case, an injection system is used. In these cases, the delivery system for carbon dioxide generally includes a carbon dioxide source (e.g., a tank of liquid carbon dioxide), a conduit from the carbon dioxide source to an injector for placing the carbon dioxide in the truck drum, and a system for positioning the injector to inject carbon dioxide and direct it into the truck drum (typically at a desired location within the drum), although in some cases little more than directing the injector into the drum is required. The system can include multiple injectors to serve multiple trucks, e.g., at least 2, 3, 4, 5, 6, 7, 8, 9, 10, or more than 10 injectors simultaneously. All of the injectors can utilize the same carbon dioxide source with appropriate piping and valving. Typically, the system also includes a controller.

[0124] The injector is positioned so that delivery of carbon dioxide into the drum occurs into the drum opening at the desired location on the drum. This can be as simple as a truck driver backing the truck into a designated position, where the delivery system is properly aligned and positioned to inject carbon dioxide into the drum with little or no additional adjustments (e.g., the injector may be positioned near the drum opening as the truck backs in, and the truck driver may then need to manually move the injector into its final position). In certain embodiments, an automated system can be used to assist in positioning the injector, or even position the injector completely without human intervention. The system further includes an actuator, e.g., a valve, for starting and stopping carbon dioxide delivery to the drum, and a connection between the valve and a controller that controls the start and stop of delivery. Typically, the system also includes a system for measuring the carbon dioxide flow rate. In systems using liquid-to-gas and solids, this can be, for example, a system such as that described in U.S. Pat. No. 9,376,345.

[0125] The controller can be as simple as a button or switch that the truck driver flips after backing the truck into the bay. It will be understood that such a “switch” can be any suitable switch, such as a wireless device, e.g., the touchscreen of a smartphone. The flow can last for a specified time and then stop. Again, the simplest way to do this is for the truck driver to press the switch again. However, to avoid human error and more precisely regulate delivery, it is preferable to have an automatic controller, whereby the flow of carbon dioxide automatically stops upon a signal from the controller. This may be after a certain amount of time or after a certain amount of carbon dioxide has been delivered (derived from flow rate and time) and / or based on one or more characteristics of the wash water, measurable by sensors, such as pH, specific gravity, temperature, etc., communicated to the controller, which then stops or adjusts the flow based on a predetermined algorithm. The automatic controller can also automatically initiate the flow when the truck and injector are properly aligned, using appropriate positioning sensors to determine this point. The controller can also alert the truck driver when the truck is properly aligned with the injector or if the truck or injector is misaligned.

[0126] An exemplary control system that may be used in any suitable system for treating wash water with carbon dioxide, particularly a system that reuses carbonated wash water as mixing water, utilizes inputs regarding one or more conditions of the wash water holder and / or its environment, e.g., at least two, three, four, five, or six conditions, processes the inputs, and then signals at least two, three, four, five, or six actuators, e.g., one or more actuators such as valves that adjust the carbon dioxide flow based on the processing. The inputs may include, but are not limited to, one or more of the pH of the wash water, the temperature of the wash water, the carbon dioxide content of the air in contact with the wash water (e.g., the air in the headspace above the tank), and / or a calculated amount of carbon dioxide to add. In the latter case, the calculation may be based, for example, on the volume of the wash water, the known or estimated amount of concrete in the wash water, the known or estimated percentage of cement in the concrete, the known or estimated amount of carbon dioxide uptake required to reach an acceptable endpoint, e.g., an acceptable pH and / or an acceptable amount of carbon dioxide uptake. Thus, one exemplary control system utilizes inputs including, for example, the pH, temperature, and / or carbon dioxide concentration of the wash water in the holding tank or regenerator. Certain embodiments use all three of the pH, temperature, and carbon dioxide concentration; certain embodiments use two of the pH, temperature, and carbon dioxide concentration; and certain embodiments use only one of the pH, temperature, and carbon dioxide concentration, e.g., the carbon dioxide concentration above the wash water. Additional sensors and / or information that can be input to the controller can include a flow meter that determines the carbon dioxide flow rate, a sensor that determines the water level in the holding tank (which can vary depending on various conditions), and / or information from pump(s), such as a pump that pumps fresh wash water into the holding tank, e.g., from the regenerator, and / or a pump that pumps water into the recirculation loop.In the case of pumps from a regenerator, the pump(s) typically have a fixed flow rate, so information about the time the pump is on may be sufficient for the controller to determine the amount of new wash water added to the system, and taking into account the typical amount of cement in the load, the controller can, for example, adjust the carbon dioxide flow rate to the wash water to take into account the expected amount of material to carbonate and anticipate carbonation demands. Alternatively, or in addition, the controller can send signals to other sensors, e.g., pH, temperature, and / or carbon dioxide, to take more frequent readings so that the system can adjust more quickly to the added load.

[0127] Additional sensors may also include a sensor to assist the carbon dioxide control valve in monitoring pressure (typically used to send an alarm signal if the pressure is outside of acceptable limits), and a sensor for the temperature of the incoming gas, which indicates whether the carbon dioxide source, e.g., a tank, can keep up with demand. Such a sensor can indicate whether demand exceeds the source, as droplets of liquid carbon dioxide may form in such a case.

[0128] For convenience, the system is described using all three sensors, but it will be understood that fewer or more sensors may be used. Thus, in the exemplary embodiment, the sensors include a pH sensor / meter, a temperature sensor such as a thermocouple, and a CO2 sensor / meter. The sensors are operably connected to a control system, e.g., by wired connection, wireless connection, or a combination. The control system is also connected to the wash water carbon dioxide addition equipment and, optionally, the pump(s). Any suitable control system, such as a programmable logic controller (PLC), may be used. The control system may be stand-alone, integrated with the overall wash water facility control system, or a combination thereof. Additional equipment may include first and second pneumatic cylinders, one or both of which are extendable and retractable, a mass flow meter for measuring and controlling the CO2 gas flow rate, and a water line solenoid in the clean water line to control the flow rate of clean water for rinsing the pH probe. The system may include a pump; an exemplary pump serves to agitate the water in the holding tank to prevent solids from settling. Alternatively, or in addition, the pump may include a regenerator pump.

[0129] The wash water temperature sensor, e.g., a thermocouple, can be placed anywhere in the system that comes into contact with the wash water, but is typically submerged to ensure that the mass of the sensor does not affect the reading. A single wash water temperature sensor may be used, or multiple temperature sensors may be used, such as at least 2, 3, 4, 5, or 6 wash water temperature sensors.

[0130] The CO2 sensor is positioned above the wash water surface, for example, at the location of the upward-flowing wash water. The distance of the CO2 sensor from the water surface can be any suitable distance, as long as the sensor can detect carbon dioxide released from the wash water, i.e., carbon dioxide that has been in contact with the wash water but has not been absorbed or reacted with it and therefore escapes to the atmosphere above the wash water (headspace). For example, the sensor can be 0.1 to 100 cm, or 1 to 100 cm, or 1 to 50 cm, or 5 to 100 cm, or 5 to 50 cm, or any other suitable distance above the wash water surface. If the CO2 sensor is in a fixed location, the distance from the water surface can vary as the water level fluctuates, for example, with additional cargo, water use, etc. Therefore, the system can also include a sensor that senses the level of the wash water in the tank. The controller can adjust the weighting given to the carbon dioxide value depending on the distance from the surface—e.g., the farther the sensor is from the surface, the more carbon dioxide must accumulate before the sensor takes a reading—and the controller can adjust the flow rate to a different extent, e.g., reduce the flow rate more or at a different rate (e.g., faster) than when the sensor is closer to the water surface. Additionally or alternatively, the CO2 sensor can be configured to remain a fixed distance or within a fixed distance range from the surface of the wash water. For example, the CO2 sensor may include a gas-sensing portion on a float that is a fixed distance above the float's water level line, or may include a mechanism that moves the sensor based on, for example, a reading of the wash water level. Any other suitable method and device for maintaining a fixed distance from the surface of the wash water may be used. The system can use a single CO2 sensor or multiple CO2 sensors, e.g., at least 2, 3, 4, 5, or 6.

[0131] Alternatively, or in addition, input from a sensor signaling the water level in the tank may be used to adjust one or more aspects of the system. For example, if the water level is low, changes will tend to be more rapid and the interval between samplings may be shortened and / or the carbon dioxide flow rate may be reduced.

[0132] The pH sensor(s) can be used in any suitable location that allows for an accurate reading of the pH of the wash water. Any suitable sensor that can withstand conditions typical of concrete wash water may be used. To obtain an accurate reading and prevent sensor fouling, the sensor is typically exposed to wash water in which solids have settled sufficiently to obtain an accurate reading and not foul the sensor. This can be done in any suitable manner. For example, a portion of the wash water may be removed from the tank for pH measurement and allowed to settle before taking the measurement. In another example, a pneumatic cylinder can be extended into the wash water at a location where the wash water flows downward, e.g., about 12 inches into the wash water, or any other suitable distance. The water inside the cylinder is not exposed to the movement of the entire wash water, and solids can settle. After an appropriate interval to allow sufficient solids to settle, e.g., at least 5, 10, 15, 20, 30, 40, 50, or 60 seconds, a second pneumatic cylinder containing a pH sensor is extended into the first cylinder, and the pH of the water inside the first cylinder is read. After the reading is completed, the probe is withdrawn from the first cylinder and subjected to appropriate treatment to prepare it for the next reading, which may be, for example, rinsing the probe with clean water released from the clean water line by the action of a solenoid in the line. The first cylinder is also withdrawn from the rinse water at some point between samples to provide a fresh sample for the next reading. A single pH sensor may be used, or multiple pH sensors, such as at least 2, 3, 4, 5, or 6, may be used.

[0133] The sensor(s) send a signal to the control system. Readings from the various sensors can be reviewed to ensure proper sampling occurred; for example, validation logic checks that the readings are within an expected range based on the reading time and that the change in value between readings is reasonable, i.e., not too high or too low. If an anomaly is detected, an error signal can be sent, and standby logic ensures continued safe operation (e.g., with respect to temperature, pH). If a CO2 sensor is malfunctioning, an alarm may sound and / or the system may be shut down to ensure safety. If the readings are determined to be appropriate, the control system can determine whether any adjustments to the CO2 flow rate should be made based on one or more readings.

[0134] Generally, the variable(s) are determined to be within an appropriate range, and if so, the point within that range is determined. This can be any suitable form of interpolation. The values ​​of each variable can be combined either as is or as weighted variables. The appropriate range for each value can be determined by routine testing in the field. The pH range can be any suitable range, for example, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11.0, 11.2, 11.4, 11.6, 11.8, 12.0, 12.2, 12.4, 12.6, 12.8, 13.0, 13.2, 13.4, 13.6, 13.8, 14.0, or 15. 4.5 to 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9. 8, 9.9, 10, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11.0, 11.2, 11.4, 11.6, 11.8, 12.0, 12.2, 12.4, 12.6, 12.8, 13.0, 13.2, 13.4, 13.6, 13.8, 14.0, 14.5, or up to 15.0.The temperature range may be any suitable range, for example, from 5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30°C to 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, The temperature may be up to 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 50, 52, or 55°C. Generally, the tank operates in an open state, and the lower limit can be adjusted depending on the air temperature, while the upper limit can be determined by the concrete manufacturing facility, and the facility must not use mixing water that is above a certain temperature.The carbon dioxide range may be any suitable range, for example, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 520, 540, 560, 580, 600, 620, 640, 660, 680, 700, 720, 740, 760, 780, 800, 825, 850, 875, 900, 925 , 950, 975, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2400, 2600, 2800, 3000, 3200, 3400, 3600, 3800, 4000, 4200, 4400, 4600, or 48 00ppm to 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 520, 540, 560, 580, 600, 620, 640, 660, 680, 700, 720, 740, 760, 780, 800, 825, 850, 875, 900, 925, 950, 975, 1000, 1050, The maximum limit may be up to 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2400, 2600, 2800, 3000, 3200, 3400, 3600, 3800, 4000, 4200, 4400, 4600, 4800, or 5000 ppm. Because tanks are generally open to the atmosphere, the lower limit is typically determined on-site or on the day, as it will not fall below the atmospheric level of elevated carbon dioxide. The maximum limit may be constrained by regulations regarding worker safety, which may vary and may be as low as 1000 ppm or, for example, 5000 ppm. However, the upper limit is generally lower than the personnel safety limit to more efficiently control carbon dioxide use within the system and limit waste. Another carbon dioxide sensor may be installed on-site within the personnel area and set to sound an alarm at a certain level or even shut off the supply of carbon dioxide into the system.This sensor does not necessarily need to be in communication with the entire system, but may for example be a stand-alone alarm.

[0135] Samples may be taken at any suitable interval, which may be constant or may vary depending on conditions; for example, the sampling rate may be increased, for example, upon sensing loading from the regenerator, as described elsewhere. Exemplary sampling intervals are from 1, 2, 3, 4, 5, 7, 10, 20, 30, 40, or 50 seconds, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, or 20 minutes to 2, 3, 4, 5, 7, 10, 20, 30, 40, or 50 seconds, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 20, 22, or 25 minutes. To obtain an accurate reading at each sampling time, several readings may be taken from one or more sensors, for example, at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 17, or 20 readings. Such readings may be averaged, or the control system may include logic that enables selection of the reading from the group that is most likely to be accurate.

[0136] An exemplary control logic for controlling CO2 flow rate based on all three of pH, temperature, and CO2 above the surface (e.g., headspace), using upper and lower limits (any suitable ranges may be used) that are merely exemplary, and using linear interpolation (suitable interpolation may be used), is as follows:

[0137] Adjustable Variables Sensor interval (min) = 5 pH (lower limit, LL)=7 pH (upper limit)=13 CO2PPM(LL)=400 CO2 PPM (UL) = 1000 Temperature C(LL)=20℃ Temperature C(UL)=40℃ Maximum flow rate = The maximum flow rate determined on-site for the configuration used to ensure 100% uptake in the new wash water. It may be adjusted according to factors affecting uptake, such as the water volume in the tank (e.g., the water level in the tank).

[0138] The following is part of the logic that can be incorporated into the logic for controlling the flow rate based on the state of the wash water. For simplicity, this logic uses a linear interpolation of 100% to 0% of the maximum uptake flow rate between the expected minimum / maximum sensor readings, but it is relatively straightforward to change the equations for the CO2 factor, pH factor, and temperature factor, for example, in the case of data supporting the change. Equal weighting is given to all variables, but this can also be adjusted as appropriate.

[0139] Conditions: - If pH < pH(LL), then pH factor = 0 - If pH > pH(UL), then pH factor = 1 - If pH(LL) < pH < pH(UL), then pH factor = (pH - pH(LL)) / (pH(UL) - pH(LL)) - If CO2 < CO2(LL), then CO factor = 1 - If CO2 > CO2(UL), then CO factor = 0 - If CO2(LL) < CO2 < CO2(UL), then CO factor = (CO2(UL) - CO2) / (Co2(UL) - Co2(LL)) - If temperature < temperatureC(LL), then temperature factor = 1 - If temperature > temperatureC(UL), then temperature factor = 0 - If temperatureC(LL) < temperature < temperatureC(UL), then temperature factor = (temperature(UL) - temperature) / (temperature(UL) - temperature(LL)) Flow rate = Maximum flow rate × ((pH factor × CO2 factor × temperature factor) / 3). It will be understood that this flow rate formula is merely exemplary, and any suitable weighting of the factors may be used. In the example formula, due to the multiplication of values, a value of 0 for any factor will stop the inflow of carbon dioxide, but any suitable numerical manipulation may be used to produce the desired result. In general, the combination of factors should not exceed 1.0, i.e., the maximum flow rate. Also, as in the example, it may be desirable for any one of the factors exceeding an upper or lower limit to be able to stop the inflow of carbon dioxide, depending on the factor.

[0140] Thus, in certain embodiments, the present invention provides a method for treating waste concrete in a concrete mixer, the method comprising adding water to the mixer to wash the mixer and adding carbon dioxide to the mixer to produce carbonated wash water in the mixer. At least a portion of the carbon dioxide added to the mixer is added as dissolved carbon dioxide in the mixer's wash water. The concentration of carbon dioxide in the wash water can be any concentration described herein, e.g., at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 g / L of water. In certain embodiments, such as when using supersaturated wash water, the concentration of carbon dioxide in the wash water can be greater than 10 g / L, e.g., at least 12, 13, 14, 15, 16, 17, 18, 19, or 20 g / L. Additionally or alternatively, at least a portion of the carbon dioxide added to the mixer can be added as solid and / or gaseous carbon dioxide. The mixer can be any suitable mixer. In certain embodiments, the mixer is a portable mixer, such as the drum of a ready-mix truck. The method can include transferring at least a portion of the carbonated wash water to a wash water treatment system. The wash water treatment system can, for example, treat the wash water, including the carbonated wash water, to remove aggregate. The wash water treatment system can also, or instead, add additional carbon dioxide to the wash water, including the carbonated wash water. Any suitable method for adding carbon dioxide can be used to add the carbon dioxide, such as the methods described herein.

[0141] Regardless of the form of carbon dioxide, the total amount of carbon dioxide used in the truck on the way back to the washing station and / or at the station can be determined by the cement content of the concrete mix in the truck, the expected amount of concrete to be coated on the inside of the truck, the expected or desired level of carbon dioxide uptake by the cement, and the expected uptake efficiency (e.g., carbon dioxide loss due to leakage from the truck drum). For example, for an 8m capacity truck, 3It is known or estimated that a truck can carry concrete with a 15% cement content, and that after unloading, approximately 500 pounds of concrete remain in the truck, regardless of the size of the load. With this cement type, a maximum carbon dioxide uptake of 50% by weight of cement is expected, resulting in an estimated uptake efficiency of 80%. The calculated carbon dioxide input for maximum carbonation is 500 x 0.15 / 0.50 x 0.80 = approximately 188 lbs of carbon dioxide. Generally, the amount of concrete in an empty truck is not precisely known; a proxy is the specific gravity of the wash water immediately after adding enough water to form a slurry. From the specific gravity and volume, the mass of the solids can be calculated, and from that mass and the percentage of cement in the concrete mix held in the truck, the amount of cement in the wash water can be calculated. Thus, in certain embodiments, the carbon dioxide dosage used in the wash water (in a single track or combination of tracks) can be expressed as an amount by weight of solids, where the percentage of cement and other carbon dioxide reactive or carbon dioxide absorbent materials is known or estimated, and / or the carbonation efficiency is known or estimated, for example, at least 1, 2, 5, 7, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, or 95% carbon dioxide by weight of the solids, and / or no more than 2, 5, 7, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100% carbon dioxide by weight of the solids. Higher dosages, eg, greater than 100% by weight of solids, may be used depending on the cement content of the wash water, the expected efficiency of carbonation, etc.

[0142] In any embodiment of the present invention, less than a full (total) dosage can be used. This can be for any reason, for example, the desired or available system for carbon dioxide delivery does not deliver enough carbon dioxide, or it is desirable to maintain a constant level of carbon dioxide reaction during a period such as between the unloading of a concrete load and final washing at a batching facility, or between washing and further processing. As noted elsewhere herein, aged wash water may require less than a full dosage (e.g., a dosage calculated based on fresh concrete in a truck) to produce the desired level of reaction. As described elsewhere herein, a total or complete dosage may be calculated for a given truck, load, and mixer design, but less than a total or complete dosage of carbon dioxide may be provided, for example, less than 95, 90, 80, 70, 60, 50, 40, 30, 20, or 10% of the full dosage, and / or more than 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, or 90% of the total dosage. In certain embodiments of the invention, the dosage of carbon dioxide used to treat the wash water is such that the total amount of carbon dioxide delivered to the subsequent concrete mix using the carbonated mix water (and calculated only from the carbon dioxide in the mix water and ignoring other carbon dioxide added to the subsequent concrete mix) is less than 2.0, 1.5, 1.3, 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1% by weight of the cement in the subsequent mix, such as less than 1.0%, or less than 0.8%, or less than 0.5%, or less than 0.3%, or less than 0.1%, such as less than 0.5%. Relative to the weight of solids in the wash water, the carbon dioxide dosage may be at least 0.1, 0.2, 0.4, 0.6, 0.8, 1.0, 2.0, 5.0, 10.0, 15.0, 20.0, 25, 30, 35, or 40% by weight of the solids in the wash water, and / or no more than 0.2, 0.4, 0.6, 0.8, 1.0, 2.0, 5.0, 10.0, 15.0, 20.0, 25, 30, 35, 40, or 50% by weight of the solids in the wash water.The amount of carbon dioxide in the wash water may be determined, for example, by multiplying the total amount of carbon dioxide delivered to the wash water by the efficiency of carbon dioxide absorption by the wash water (measured or calculated) and dividing by the volume of the wash water. In typical cases where a holding tank contains wash water from multiple trucks and can be used continuously to provide mixing water, appropriate adjustments may be made based on the truck contents and water usage, as well as other appropriate measures. In certain embodiments, the carbon dioxide content (e.g., carbonate, bicarbonate, carbonic acid, and / or dissolved carbon dioxide) in the wash water may be determined by chemical or other appropriate measurement. It may be assumed that substantially all of the carbon dioxide content of the carbonated wash water is due to carbonation of the wash water, either dissolved or as a reaction product with the cementitious material.

[0143] In certain embodiments, the full dosage, or a dosage calculated to be the full dosage, can be delivered on-site and / or during transport to the washing station, and in some cases, less than the full dosage is desired. In some cases, testing at the batching facility can indicate whether carbon dioxide uptake is complete, and if not, additional carbon dioxide can be added at the batching facility, for example, during washing of the drum or at a later step, to achieve the desired full dosage or less than the full dosage. In certain embodiments, there is no carbon dioxide until the truck returns to the batching facility. In certain embodiments, a partial dosage is used on-site and / or during the return to the batching facility, and one or more additional partial dosages are delivered at the batching facility, as described above, for example, during or after washing.

[0144] In certain embodiments of the invention, the carbon dioxide dosage is determined primarily or exclusively by the methods described above, e.g., no further preliminary testing (other than specific gravity, as the case may be) is required. In some cases, without the need to test the wash water at all, and particularly without the need to test the initial carbon dioxide dosage, the dosage is simply calculated from the known or assumed amount of concrete left in the truck and the truck mix design (including the amount of cement in the concrete, and, as the case may be, the type of cement in the concrete, and the known or assumed efficiency of carbonation).

[0145] Carbon dioxide added to the wash water first dissolves in the water and then reacts to form various products, such as bicarbonate and carbonate (e.g., calcium carbonate). The carbon dioxide in the wash water is transferred to the cement for which the wash water is used as mixing water in the form of dissolved carbon dioxide, carbonic acid, bicarbonate, and carbonate. Thus, the cement mix will contain a certain amount of carbon dioxide (including dissolved carbon dioxide, carbonic acid, bicarbonate, and carbonate) provided by the carbonated wash water, which can be expressed as a weight percent of the cement in the mix. For example, the wash water may have a solids content of 150,000 ppm, or 15%, which gives a specific gravity of approximately 1.10. If carbon dioxide is added to the wash water and the uptake by the wash water is 30%, 4.5% of the water will be carbon dioxide, primarily as a carbonation product. Next, if a concrete mix is ​​made using carbonated wash water at a water / cement ratio of 0.5, the amount of carbon dioxide (as dissolved carbon dioxide, carbonic acid, bicarbonate, and carbonate) in the concrete mix is ​​2.25% bwc. These figures are merely exemplary. The solids content of the wash water, the entrapment efficiency, the w / c ratio, the amount of mix water that is wash water, etc. can vary. Therefore, the amount of carbon dioxide provided by the carbonated wash water in a concrete mix containing carbonated wash water is at least 0.01, 0.05, 0.1, 0.2, 0.5, 0.7, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.2, 4.4, 4.6, 4.8, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12, or 12.5% ​​bwc and / or 0.05, 0.1, 0.2, 0.5, 0.7, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.2, 4.4, 4.6, 4.8, 5.0, 5.5, 6.The carbon dioxide concentration can be 0, 6.5, 7.0, 8.0, 9.0, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 14, 15, 16, 17, 18, 19, 20, 22, 25, or 30% bwc or less. For example, the present invention provides a method for preparing a concrete mix, comprising: (i) adding concrete ingredients, including cement, to a mixer; and adding mixing water to the mixer, wherein the mixing water is carbonated concrete wash water such that the total carbon dioxide or carbon dioxide reaction products (expressed as carbon dioxide) supplied to the concrete mix by the carbonated mixing water is at least 0.01, 0.05, 0.1, 0.2, 0.5, 0.7, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 3.10, 3.11, 3.12, 3.13, 3.14, 3.15, 3.16, 3.17, 3.18, 3.19, 3.20, 3.21, 3.22, 3.23, 3.24, 3.25, 3.26, 3.27, 3.28, 3.29, 3.30, 3 8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.2, 4.4, 4.6, 4.8, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12, or 12.5% ​​bwc and / or 0.05, 0.1, 0.2, 0.5, 0.7, 1.0, 1.1, 1.2, 1.3 , 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.2, 4.4, 4.6, 4.8, 5.0, 5.5, 6.0, 6.5, 7.0, 8.0, 9.0, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, or 13.0% bwc or less, e.g., at least 0.5, 1.0, 1.5, or 2 0.0%, and / or 2.5, 2.0, 1.5, or 1.0% or less, or such as 2% or less, or 2.5% or less, or 3.0% or less, or 3.5% or less, or 4.0% or less, or such as at least 0.01% bwc, or at least 0.05% bwc, or at least 0.1% bwc, or at least 0.5% bwc, or at least 1.0% bwc, or at least 2.0% bwc, or at least 3.0% bwc, or at least 4.0% bwc, or at least 5.0% bwc, or for example in the range of 0.01 to 13.0% bwc, or in the range of 0.01 to 12.0% bwc, or in the range of 0.01 to 11.0% bwc, or in the range of 0.01 to 10.0% bwc, or in the range of 0.01 to 8.0% bwc, or in the range of 0.01 to 6.0% bwc, or in the range of 0.01 to 4.0% bwc, or in the range of 0.1 to 13.0% bwc, or in the range of 0.1 to 12.0% bwc, or in the range of 0.1 to 11.0% bwc, or in the range of 0.1 to 10.0% bwc, or in the range of 0.1 and (iii) mixing water and concrete ingredients to produce a concrete mix. It is understood that the amount of carbonated wash water in the total mixing water can be any suitable amount, such as those described herein.

[0146] Carbon dioxide delivery within the regenerator and piping from the regenerator to a pond or slurry tank. Some facilities utilize regenerators to reclaim aggregates, such as sand and gravel, from wash water. The water may then be further used, typically through further processing, either as part of the mixing water or as wash water, with any remaining water being disposed of in the usual manner. In a typical regenerator, the water containing the coarse particles and solid components is pumped through the process, and the sand and gravel are separated, for example, by sieving. The water is then sent to a settling pond and / or tank for reuse. In the case of water sent to a settling pond, the water can be transferred to a tank where carbon dioxide is added to the water, for example, via a recirculation line, and then sent back to the tank; if a tank already exists, a carbonation device, for example, a recirculation line, can be added. This water can also, or alternatively, be carbonated or supercarbonated with carbon dioxide added to the water during the pumping process, resulting in more carbon dioxide being supplied to the water as it is consumed in the carbonation reaction. Carbon dioxide can also or alternatively be supplied to the piping as the water is pumped to the settling basin or slurry tank. In optimal situations, the sand and gravel are separated as usual, but the water in, for example, the slurry tank, can be reused without further dilution or with less dilution than would normally be required. For example, this process can produce water from the regenerator, e.g., slurry tank water, having a specific gravity greater than, for example, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, or 1.20, suitable for use as mixing water. This differs from existing regenerators, where the water, e.g., slurry tank water, typically requires dilution to reduce its specific gravity to an acceptable level.In the process of the present invention, the carbonation process stops or significantly slows adverse reactions of the cementitious material while leaving it available for reaction in the second concrete batch and further adjusts the pH of the water to a more acceptable level, so little or no additional processing may be required (although carbonation in the slurry tank may be required in addition or instead, if necessary or desired). For example, filtration and / or settling of solids is generally not required in this process. Indeed, an advantage of the methods and compositions of the present invention is that material from one batch can be reused in another batch(es), potentially allowing for the use of less material, e.g., cement, and reducing or even eliminating costs associated with disposing of wash water materials.

[0147] Retrofitting Existing Facilities to Provide Reclamation: Most concrete facilities do not include reclaimers but can benefit from the ability to reuse wash water, and in some cases, aggregate from the wash water. Currently, most solid materials are simply allowed to settle in one or more settling ponds and periodically disposed of with little or no reuse, while the water from the settling ponds must be further treated to meet environmental standards before disposal. If the wash water were instead carbonated before entering the ponds, or while in the ponds, or both, some or all of the water could be used as mixing water, reducing or eliminating the costs and equipment required to treat the water for disposal. Additionally, some or all of the aggregate could be reused instead of hardening and being wasted.

[0148] As an example, in some operations, wash water from trucks is unloaded into a first bay, where solids settle, harden, and are typically disposed of. The surface water from the first bay passes over a weir into a second bay, where solids typically settle further, and the surface water is removed and often sent to a third bay, where the water, now largely solid-free but still containing high pH, ​​silicates, calcium, etc., is treated for disposal or, in some cases, at least partial reuse. In currently available systems, treatment in the solid-free third bay can be with carbon dioxide. The present invention allows for the conversion of the first or second bay, where solids still exist, so that instead of being a settling pond, the bay is a slurry pond where carbonation occurs, and the carbonated wash water is suitable for use as mixing water rather than simply being disposed of. This can be done by using an agitator, a recirculation pump, or a combination thereof, where carbon dioxide is added directly to the pond (e.g., via a bubble mat as described elsewhere herein), in the line of the recirculation pump, or both. Other methods of adding carbon dioxide, such as with an impeller or eductor, are described herein. Other means of adding carbon dioxide, such as solid carbon dioxide or a mixture of gas and solids, can also be used as described herein.

[0149] In certain embodiments, a wall, e.g., a wall having a notch, is added to the first bay, which directs water through the notch (e.g., a weir) and over the wall into a region of the first tank. The wall can be positioned to provide a partition within the first tank, allowing solids such as aggregate to settle but allowing the remaining water with suspended solids to flow over the notch into a second portion of the first bay. Optionally, a second wall can be added opposite the first wall to reduce the volume of the region where water flows over the notch. The water can be pumped from that region, e.g., by a discharge pump or similar pump, to a holding tank, where it can be carbonated, e.g., using a recirculation loop, pumping the water from the tank into a pipe, adding carbon dioxide to the water in the pipe, and then returning the carbonated water to the tank. The carbonated water in the holding tank can then be returned to the batching plant for use in subsequent concrete batches. The addition of carbon dioxide to the water can be controlled as described elsewhere herein. In these embodiments, a second or third bay may not be necessary, or their volumes may be reduced.

[0150] Prior to the conversion, little or none of the water from the ponds was reused as mix water, but instead was disposed of. This conversion allows some or all of the water from the first or second ponds to be used as mix water, often at a higher specific gravity than would otherwise be achievable, e.g., greater than 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, or 1.20. The conversion also allows cementitious material from a previous batch to be used in subsequent batches (see calculations below). Appropriate sensors and control systems can be used to monitor the addition of carbon dioxide, as well as to monitor appropriate water properties, as described herein, to modify carbon dioxide delivery and further control the redirection of water back into the batching system for use as mix water. In this way, up to 100% of the wash water can be reused as mixing water, for example, at least 10, 20, 30, 40, 50, 60, 70, 80, 90, or 95% of the wash water can be reused as mixing water. 3 A typical truck uses approximately 120 litres of wash water per m of concrete. 3 For a typical mix using about 130 L of water per mix, it is possible to reuse practically 100% of the wash water in subsequent concrete batches.

[0151] The modifications may also or alternatively include modifications at the wash station, or at the truck, or both, to carbonate the wash water before it reaches the pond. At the truck level, this includes the addition of a carbon dioxide source, which can be solid, gaseous (in solution or free), or a system for delivering both solid and gaseous carbon dioxide, as described elsewhere herein. For example, if desired, a truck may be modified so that its saddlebags can hold carbonated water. A batching location may be modified to include a system for carbonated water and supplying it to the truck's saddlebags, including a carbon dioxide source, appropriate piping and injection systems, optionally a system for supersaturating the water with carbon dioxide, and a delivery system for delivering the carbonated water to the saddlebags, and appropriate control systems. Alternatively, or in addition, a truck may be modified to provide a system for transporting dry ice for delivery to drums after delivering its load, which may be as simple as an insulated container. The batching facility may also include a storage system for dry ice and, optionally, a system for producing dry ice. As described elsewhere herein, if it is desired to produce dry ice in a size range appropriate for a particular mix or load, the batch facility or the truck itself may further include a system for producing dry ice of the desired size. Additionally, or alternatively, the truck may be retrofitted with a system for delivering gaseous carbon dioxide to the truck's drum, which includes a carbon dioxide source, a conduit for delivering carbon dioxide from the source to the drum, and typically a metering and control system for regulating the addition of carbon dioxide to the drum. All of these modifications may further include an appropriate control system, such as sensors (e.g., pH and other sensors described elsewhere herein, or in the simplest case, a timer and a sensor for determining the flow rate of carbon dioxide), a processor, and one or more actuators (e.g., valves) for controlling the flow rate of carbon dioxide according to the desired dosage / rate or other parameters.If it is desired to provide a mixture of solid and gaseous carbon dioxide to a truck drum, the same basic setup is used as for gas, except that the piping must be such that it can withstand the temperatures of the liquid carbon dioxide, and the injector must be a snow horn of appropriate design to produce the desired mixture of solid and gaseous carbon dioxide.

[0152] At the wash station level, this includes the equipment described elsewhere herein for supplying carbon dioxide at the wash station, including suitable carbon dioxide source(s), suitable conduits, injectors, positioning systems if carbon dioxide is injected into a drum, metering systems, and control systems, if that method is used, for carbonated or supercarbonated water and delivering carbonated water to the wash line.

[0153] If the plant is modified to carbonate the wash water on-site / during transport, or at the washing station, or both, sufficient carbonation of the wash water may occur such that further carbonation in the ponds is not necessary; however, it will be understood that additional carbonation in the ponds may be necessary in some cases. Furthermore, carbonation in the truck after pouring and during transport and / or washing may allow the aggregate in the concrete in the truck to be reused. Using the example of a two-pond settling system, if the washing station and / or truck are equipped to carbonate the remaining concrete, the aggregate material in the first pond will remain as separate particles that can be appropriately recovered and sieved for use as aggregate in subsequent batches. At this point, the water may be ready for use as mixing water, or it may require further processing, such as further carbonation, to be used in this manner.

[0154] For example, further possibilities for modification are as follows:

[0155] Agitation of the wash water can be considered in at least three general approaches.

[0156] Customer has existing wash water tank and agitation system: The retrofit CO2 treatment system may include a pump to move water to / through the treatment steps (either in-line or in a separate tank). The pump is not the primary source of agitation and therefore only needs to be started when CO2 treatment begins and is controlled based on one or all of the sensors (temperature, pH, headspace CO2 level).

[0157] Non-agitated storage tank: A pump is used to keep the material suspended in the tank. The pump moves the water to / through the processing step (either in-line, in the same tank, or in a separate tank). The pump is always on when injecting CO2 and starts / stops based on sensor logic.

[0158] Customer has an unstirred pond: CO2 treatment is retrofitted to the pond. A pump is used to move water to / through the treatment step (either in-line or in a separate tank). The pump must be on at all times while CO2 is being injected. Pump and CO2 start / stop is determined by sensor logic checking the wash water supply.

[0159] Additionally, there are various possibilities for the location of addition of carbon dioxide and / or admixtures (described elsewhere herein) to the wash water. In an exemplary pre-mix operation, after the truck is unloaded, wash water is first added to the truck to prevent the remaining concrete from hardening. At this point, admixtures, such as set-retarding admixtures, may be added to the wash water in the truck's drum. Alternatively, or in addition, carbon dioxide may be added to the wash water in the truck's drum. The truck then proceeds to a washing station, where additional water may be added to the drum. At this point, admixtures, such as set-retarding admixtures, may be added to the wash water in the truck's drum. Alternatively, or in addition, carbon dioxide may be added to the wash water in the truck's drum. The wash water is then typically pumped to a holding tank, where admixtures and / or carbon dioxide may be added to the wash water in the line from the truck to the tank. In operations using a regenerator, admixtures and / or carbon dioxide may be added as described elsewhere herein. In some operations, additional holding tanks may be used, any one or more of which may contain admixtures and / or carbon dioxide. As described herein, addition may occur in the tank itself, or in a recirculation line where wash water is removed from the tank and circulated in a loop; see, e.g., Example 14. At some point, the wash water is returned, for example, from the holding tank to the drum (or in the central mixer) of the ready-mix truck to be used as part or all of the mixing water for a new batch of concrete. Carbon dioxide and / or admixtures may also be added in the line from the tank to the mixer (truck drum or central mixer).

[0160] The present invention also provides kits suitable for the various types and combinations of modifications described herein that can be packaged and shipped to an operating facility, typically with all the necessary parts and fittings, at a central facility that selects the appropriate components and sizes for the operation being modified, for easy and efficient installation at the facility.

[0161] Those skilled in the art will appreciate that the above considerations regarding modifications apply equally to the construction of new facilities, but will understand that some modifications may not be necessary when building a facility from scratch, while other modifications may be necessary.

[0162] Benefits of Wash Water Carbonation: The benefits of wash water carbonation include a reduced carbon footprint for concrete operations, reduced water usage, reduced waste generation, and increased use of recycled content.

[0163] Using the methods and compositions of the present invention, it is possible to restore a certain percentage of the cement's cement quality, e.g., at least 10, 20, 30, 40, 50, 60, 70, 80, 90, or 95%. The manufacturer can then reduce the amount of cement in the next batch by a corresponding amount. For example, if a truck with 500 lb of residual concrete and 15% cement is treated with the process and composition of the present invention, the resulting slurry contains cement that retains 80% of its cementitious properties. If all of the wash water can be transferred to the next mix as mixing water, the next batch would need to use 500 x 0.15 x 0.80 lb, or 60 lb less cement. If the remaining 90% of the concrete is recoverable aggregate through the carbonation process, an additional 450 lb of aggregate could be reduced in subsequent loads. These improvements contribute to a lower carbon footprint, reduced waste emissions, and increased use of recycled content.

[0164] Furthermore, as shown in the examples and described herein, concrete made using wash water treated as described herein exhibits higher strength, particularly higher early strength, than concrete made using untreated water. The higher strength can, in some cases, exceed 40% of the strength of concrete made using the same mix design and procedure, except that regular mix water is used instead of carbonated mix water. Therefore, mixes using carbonated wash water can use less fresh cement than the same mixes using regular mix water, further reducing the carbon footprint. For example, to achieve the same compressive strength, at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 20, 25, 30, 35, or 40% less cement, and / or 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 20, 25, 30, 35, 40, or 50% less cement.

[0165] Furthermore, carbonating a cement mix, even one made with regular water, increases the strength of the resulting poured material, correspondingly reducing the cement required in the batch. See, e.g., U.S. Patent No. 9,388,072. When used with carbonated wash water, the results can be additive or even synergistic; thus, using both methods, operators can reduce their carbon footprint and simultaneously save money on concrete's most expensive component, cement. For example, combining the two methods (carbonation of the wash water and further carbonation of the concrete mix) can result in the use of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 20, 25, 30, 35, 40, 50, or 60% less cement, and / or up to 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 20, 25, 30, 35, 40, 50, 60, or 70% less cement to achieve the same compressive strength, for example.

[0166] Also, as described herein, the reuse of water in facilities using the methods and compositions of the present invention can be dramatically increased, sometimes up to 100% (for example, at least 10, 20, 30, 40, 50, 60, 70, 80, 90, or 95% of the wash water is reused in the subsequent kneading), and correspondingly, waste generation can also be reduced by 100% or nearly 100% in some cases (for example, compared to using non-carbonated wash water, at least 10, 20, 30, 40, 50, 60, 70, 80, 90, or 95% of the wastewater from the wash water is reduced).This reduces the energy used for the treatment and disposal of wash water, resulting in significant cost savings and further reduction of carbon footprint.

[0167] By using the methods and compositions described herein, disposal and control costs, as well as cement costs, can be reduced. For example, admixtures that may normally be required for workability when wash water is used as the mixing water can often be reduced or eliminated when carbonated wash water is used.

[0168] In many cases, the carbonated wash water can be reused as wash water as well as used as kneading water.

[0169] Mechanism of wash water carbonation. Without being bound by theory, it is believed that when carbon dioxide is introduced into the wash water, it is rapidly converted to carbonate anions due to the high alkalinity of the wash water, and the carbonate anions react with calcium, forming a coating on the suspended cement particles, reducing their reactivity in the wash water. In this way, they are "put to sleep" by the carbon dioxide, thereby reducing / eliminating acceleration but contributing to subsequent strength. Variability is also reduced when using carbonated wash water.

[0170] Sulfate: The inventors have found that the methods and compositions of the present invention can also be useful for successfully modifying the sulfate content in concrete batches made with mix water containing carbonated wash water. Carbon dioxide-treated wash water can be a tool for addressing undersulfated binders. Generally, concrete mixes containing a high ratio of aluminate to sulfate may not be usable mixes when used directly. For example, the use of aluminate-providing supplemental cementitious materials (SCMs) can mean that a cement with the appropriate aluminate-sulfate balance is now present in the low-sulfated cement blend. Carbonated wash water can contain significant concentrations of sulfate in solution. If the sulfate content of the carbonated wash water is known, an appropriate amount of carbonated wash water mix can be added to compensate. In this case, the wash water may have a low solids content because the sulfate is in solution.

[0171] composition. Further provided herein are compositions such as carbonated wash water compositions. In certain embodiments, the present invention provides a carbonated concrete wash water composition comprising (i) wash water from concrete, (ii) carbon dioxide, and a reaction product of the carbon dioxide with the wash water. The wash water can consist primarily of water used to rinse the drum of a concrete mixer, e.g., a ready-mix truck, or a combination of wash waters from multiple mixers, e.g., multiple ready-mix trucks. The amount of carbon dioxide and carbon dioxide reaction products in the carbonated concrete wash water can be at least 0.1, 0.2, 0.5, 0.7, 1.0, 1.2, 1.5, 1.7, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 17.0, 20.0, or 25% by weight of the solids in the wash water composition, e.g., at least 0.5% by weight of the solids in the wash water composition, in some cases at least 2% by weight of the solids in the wash water composition, e.g., at least 5% by weight of the solids in the wash water composition, or at least 10% by weight of the solids in the wash water composition. The specific gravity of the carbonated wash water can be at least 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.17, 1.20, or any other specific gravity described herein, e.g., at least 1.03, e.g., at least 1.05, or at least 1.10.The pH of the carbonated cleaning water composition can be any pH or pH range described herein, e.g., at least 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, or 8.5, and / or 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, The pH of the carbonated wash water may be 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.7, 9.0, 9.3, 9.5, 9.7, 10, 10.3, 10.5, 10.7, 11.0, 12.0, or 13.0 or less, e.g., the pH of the carbonated wash water may be less than 9.0, e.g., less than 8.5, or less than 8.0. The composition may further include (iii) an additional cement other than the cement in the wash water, e.g., a cement mix made from dry cement and carbonated wash water. Such a mix may further include aggregate, admixture, etc.

[0172] Carbon dioxide sequestration and economic benefits Concrete production facilities utilizing the methods and compositions described herein can realize significant annual savings through reuse of solids in the wash water (thereby avoiding the use of a certain amount of new cement), avoided landfill costs, and other economic benefits, e.g., reduced or no additional water treatment costs because some or all of the wash water is reused. In addition, there will be significant carbon dioxide sequestration / offset. Thus, in certain embodiments, the present invention provides a method for sequestering and / or offsetting carbon dioxide by treating wash water, concrete by-products (such as returned concrete), or a combination thereof, with carbon dioxide, and optionally reusing some or all of the solids in the wash water as cementitious material in subsequent concrete batches. See Example 9. In certain embodiments, at least 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 11, 12, 13, 14, or 15% of the carbon dioxide generated in producing cement for use in a concrete facility, transportation emissions, other emissions associated with concrete manufacture and use, or a combination thereof, is offset by the process. As used herein, the term "offset" includes avoided carbon dioxide emissions (e.g., through reduced cement use) as well as the amount of carbon dioxide actually sequestered, for example, as part of carbonation wash solids, etc. In certain embodiments, the process results in savings of at least 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, or 10% in annual production costs for a concrete facility (e.g., compared to the pre-carbonation period, adjusting appropriately for variations in loading, costs, etc.). Further cost benefits can be realized in areas where there is a price on carbon, e.g., cap-and-trade or a carbon tax, where the offset carbon dioxide can be an additional source of revenue.Additional or alternative carbon dioxide offsetting can be achieved by treating the in-house produced concrete with carbon dioxide during mixing, for example, by applying gaseous carbon dioxide, or solid carbon dioxide, or a mixture of gaseous and solid carbon dioxide, to the concrete mix during mixing, for example, at a dosage of less than 3, 2, 1.5, 1.2, 1.0, 0.8, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 bwc. See, e.g., U.S. Patent Nos. 9,108,883 and 9,738,562. In addition to the carbon dioxide sequestered directly in the concrete, because carbonated concrete products have higher strength after setting and hardening than non-carbonated concrete products of the same mix design, this process can result in concrete products that require less cement than non-carbonated products, resulting in concrete products that require at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 25, or 30% less cement than non-carbonated products. In such cases, the carbon dioxide offset by simply carbonating the concrete mix can be at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 25, or 30%. When treating concrete wash water with carbon dioxide and, for example, reusing some or all of the solids in the wash water in a subsequent concrete batch, is combined with carbonation of the concrete batch at the concrete facility, the total carbon dioxide offset can be at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 32, 35, 37, 40, 42, or 45%.

[0173] admixture material One or more admixtures can be added to the concrete wash water and / or concrete made with the wash water. This addition can occur at one or more points during the process, as described elsewhere herein. Whether an admixture is used, the type of admixture, the point in the process at which the admixture is added, and / or the amount of admixture added can depend, for example, on the type and amount of cement in the wash water. In some cases, the addition of carbon dioxide to the wash water from a concrete batch can change the properties of a subsequent batch made using the carbonated wash water as part or all of the mixing water.

[0174] Reduction of powder particle size in a binder system can reduce workability (addition of silica fume is an illustrative example). Particle size distribution may not be important, as the impact on workability can be observed for both CO2-treated and untreated wash water. Admixtures that effectively agglomerate fine particles, increasing median particle size and reducing effective specific surface area, etc., can mitigate the adverse effects associated with CO2-induced particle size reduction.

[0175] The use of chemicals in the flocculation of precipitated calcium carbonate (PCC) may work well for CO2-treated solids, given that its outer surface can effectively behave as calcium carbonate. Highly charged polyelectrolytes, along with PCC, are known to produce powerful, large flocculants and faster flocculation rates. Both cross-linking and charge neutralization occur in polyelectrolyte-induced flocculation of PCC. See, for example, R. Gaudreault, N.D. Cesare, D. Weitz, T.G.M. van de Ven; "Flocculation kinetics of precipitated calcium carbonate"; Colloids and Surfaces A: Physicochem Eng. Aspects 340, p56-65, 2009 https: / / doi.org / 10.1016 / j.colsurfa.2009.03.008.

[0176] Without being bound by theory, the aggregation of PCC by positively charged polyelectrolytes suggests two mechanisms. Low-molar-mass polymers with high charge density, such as polyethyleneimine, can induce aggregation of PCC by neutralizing the charge, thereby eliminating electrostatic repulsion. On the other hand, high-molecular-weight polymers with low charge density, such as polyacrylamide, interact with PCC through a combination of electrostatic and cross-linking forces. See, for example, A. Vanerek, B. Alince, and T.G.M. van de Ven, "Interaction of calcium carbonate fillers with pulp fibers: effects of surface charge and cationic polyelectrolytes," J. Pulp Pap. Sci., 26(9), pp. 317-322, 2000. Natural carbohydrates, such as starch (potato starch, corn starch, and / or tapioca starch), dextran, and lignin can also be used. The starch derivative glycidyl tetradecyldimethylammonium chloride (GTDAC) can also be used. See, for example, Y. Wei, F. Cheng, H. Zheng, "Synthesis and flocculating properties of cationic starch derivatives", Carbohydr. Polym., 74(3), pp. 673-679, 2008. Another possible admixture is pectin (a biopolymer of D-galacturonic acid), and Al 3+ and Fe 3+The addition of cationic ions significantly increased the flocculation efficiency of pectin. The cationic ions neutralized and stabilized the negatively charged pectin, binding the particles together through electrostatic attraction. See, for example, H. Yokoi, T. Obita, J. Hirose, S. Hayashi, and Y. Takasaki, "Flocculation properties of pectin in various suspensions," Bioresource. Technol., 84(3), pp. 287-290, 2002. https: / / doi.org / 10.1016 / S0960-8524(02)00023-8.

[0177] Another potential admixture is cellulose or a cellulose derivative, such as electrosterically stabilized nanocrystalline cellulose (ENCC), dissolved carboxylated cellulose (DCC), rod-shaped dialdehyde cellulose (DAC) nanofibers, also known as sterically stabilized nanocrystalline cellulose (SNCC), or dissolved DAC as dialdehyde-modified cellulose (DAMC). ENCC / DCC showed high aggregation efficiency with PCC particles, inducing PCC aggregation through a combination of electrostatic and crosslinking forces. ENCC / DCC induced maximum PCC aggregation when the PCC particles reached their isoelectric point. SNCC: SNCC particle-induced PCC aggregation can be induced at low dosages (>1 mg / g) by crosslinking PCC. Because SNCC particles become unstable after deposition on PCC, SNCC induced maximum aggregation when its partial coverage was greater than half. Adsorption isotherms were measured for three types of SNCC and dialdehyde-modified cellulose (DAMC) on PCC particles. DAMC had a higher affinity for PCC than three types of SNCC with different aldehyde contents, and the affinity of SNCC increased with reaction time. This indicates that DAMC chains adsorb more strongly onto PCC than the nanocrystalline portions of SNCC. See, for example, Dezhi Chen and Theo GM van de Ven, "Flocculation kinetics of precipitated calcium carbonate induced by electrosterically stabilized nanocrystalline cellulose," Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 504, 2016, Pages 11–17, ISSN 0927-7757, https: / / doi.org / 10.1016 / j.colsurfa.2016.05.023; Chen, Dezhi. "Flocculation Kinetics of Precipitated Calcium Carbonate Induced by Functionalized Nanocellulose." (2015). PhD Thesis.

[0178] Another useful admixture is a cationic polysaccharide with N-alkyl-N,N-dimethyl-N-(2-hydroxypropyl)ammonium chloride pendant groups attached to the dextran backbone. The flocculation performance of hydrophobically modified cationic dextrans was strongly dependent on their hydrophobicity and charge density, and less dependent on their molar mass. See, for example, L. Ghimici and M. Nichifor, "Novel biodegradable flocculant agents based on cationic amphiphilic polysaccharides," Bioresource. Technol., 101(22), pp. 8549-8554, 2000. Doi:10.1016 / j.biortech.2010.06.049.

[0179] Another useful admixture is a cationic derivative of dialdehyde cellulose (CDAC). While CDAC has shown very good flocculation performance in neutral and acidic suspensions, low flocculation activity has been observed in alkaline suspensions because CDAC breaks down into small fragments at alkaline pH. See, for example, Liimatainen, H, Sirvio, J, Sundman, O, Visanko, M, Hormi, O & Niinimaki, J 2011, "Flocculation performance of a cationic biopolymer derived from a cellulosic source in mild aqueous solution," BIORESOURCE TECHNOLOGY, vol. 102, no. 20, pp. 9626-9632. DOI: 10.1016 / j.biortech.2011.07.099.

[0180] Another useful admixture is a graft copolymer of carboxymethyl cellulose (CMC) and polyacrylamide. Copolymers with fewer and longer PAM chains have shown better flocculation performance. See, for example, D.R. Biswal and R.P. Singh, "Flocculation studies based on water-soluble polymers of grafted carboxymethyl cellulose and polyacrylamide," J. Appl. Polym. Sci., 102(2), pp. 1000-1007, 2006. doi:10.1002 / app.24016.

[0181] The flocculation kinetics of PCC has been studied in relation to cationic potato starch (C-starch), anionic potato carboxymethyl starch (A-starch), cationic polyacrylamide (C-PAM), anionic polyacrylamide (A-PAM), poly(ethylene oxide) (PEO), PEO cofactor, PVFA / NaAA, glyoxalated PAM (PAM-glyoxal), cationic polyacrylamide (C-PAM), and polyamine (PAM) polyethyleneimine (PEI). See, for example, Gaudreault, R., Di Cesare, N., Weitz, D., & van de Ven, TG (2009). Flocculation kinetics of precipitated calcium carbonate. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 340(1-3), 56-65. doi:10.1016 / j.colsurfa.2009.03.008. During polymer-induced flocculation, particle size increases from its initial value to a plateau value. PEO / cofactor, A-PAM, and C-PAM retention aid systems are very cost-effective for inducing PCC flocculation, producing very large aggregates at high polymer dosages. C-PAM, glyoxalated PAM, and polyamine coagulants (PAMs) do not significantly induce filler flocculation. PEO / cofactor and C-PAM both produce faster flocculation rates and larger flocculation sizes, making them useful for clarification of treated water. Neither PEO nor cofactors alone, without salt, induce PCC aggregation. PCC aggregates induced by PVFA / NaAA and C-starch have floc size that is less sensitive to dosage in Region I. PEO / cofactors, which are known to cluster, resulted in faster aggregation rates and larger flocs because the polymer clusters increase the effective polymer size, resulting in larger flocs. A-PAM is highly charged and produces strong flocs due to its strong binding to PCC.PAM-glyoxal, C-PAM (dry strength), and polyamines act as dispersants similar to PEI, resulting in little or no flocculation.

[0182] The effect of cationic polyacrylamide on precipitated calcium carbonate flocculation: Kinetics, charge density, and ionic strength has also been studied. See, for example, Peng, P. and Garnier, G., 2012. Effect of cationic polyacrylamide on precipitated calcium carbonate flocculation: Kinetics, charge density, and ionic strength. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 408, pp. 32-39. doi:10.1016 / j.colsurfa.2012.05.002. Cationic polyacrylamide (CPAM). The adsorption kinetics of CPAM onto PCC can be explained by a balance of electrostatic and van der Waals interactions, hydrogen bonding, and steric hindrance between the adsorbed and dissolved CPAM molecules and the PCC. Increasing the ionic strength of the PCC suspension consistently shielded the charges on the CPAM molecules, resulting in a shift from the initially dominant electrostatic attraction between CPAM and PCC in the absence of salt to a hydrogen-bond-dominated attraction at high ionic strength (I = 0.1). At low ionic strength (I = 0.01), both electrostatic attraction and hydrogen bonding were important in controlling the interaction between CPAM and PCC.

[0183] An admixture used to keep solids in suspension. In certain embodiments, the carbonated wash water is treated with one or more admixtures to produce a mix in which the solids remain suspended with little or no agitation. These may include viscosity modifying admixtures (VMAs). VMAs can be composed of a wide range of different chemicals. Some VMAs are based on finely divided inorganic materials such as colloidal silica, while others are composed of more complex synthetic polymers such as styrene-maleic anhydride terpolymers and hydrophobically modified ethoxylated urethanes (HEURs). More common VMAs are based on cellulose ethers and biopolymers (xanthan, welan, and diutan gum). VMAs further include biopolymer polysaccharides such as S-657, welan gum, xanthan, rhamsan, gellan, dextran, pullulan, curdlan, and derivatives thereof; (b) marine gums such as algin, agar, carrageenan, and derivatives thereof; (c) plant exudates such as carob, gum arabic, karaya, tragacanth, ghatti, and derivatives thereof; (d) seed gums such as guar, carob, okra, psyllium, mesquite, or derivatives thereof; and (e) starch-based gums such as ethers, esters, and derivatives thereof; and (f) associative thickeners such as hydrophobically modified alkali-swellable acrylic copolymers, hydrophobically modified urethane copolymers, associative thickeners (polyurethane, cellulose, polyacrylate, or polyether-based). In another classification scheme (Khayat, KH, 1998. Viscosity-enhancing admixtures for cement-based materials - An overview. Cement and Concrete Composites 20, 171-188. https: / / doi.org / 10.1016 / S0958-9465(98)80006-1), VMAs are divided into various classes: Class A is a water-soluble synthetic and natural organic polymer that increases the viscosity of the mixing water. Class A materials include cellulose ethers, polyethylene oxide, polyacrylamide, polyvinyl alcohol, etc.Class B is an organic, water-soluble flocculant that adsorbs to cement particles and increases viscosity by increasing the interparticle attractive forces between them. Class B materials include styrene copolymers with carboxyl groups, synthetic polyelectrolytes, and natural rubber. Class C is an emulsion of various organic materials that enhance interparticle attractive forces and provide additional ultrafine particles in the cement paste. Among the materials in Class C are acrylic emulsions and aqueous clay dispersions. Class D is a water-swellable inorganic material with a high surface area, such as bentonite, silica fume, and ground asbestos, which increases the water-holding capacity of the paste. Class E is a high-surface-area inorganic material that increases the fine particle content in the paste, thereby increasing thixotropy. These materials include fly ash, hydrated lime, kaolin, various rock powders, and diatomaceous earth. In another classification scheme, Kawai classified water-soluble polymers as natural, semi-synthetic, and synthetic polymers. Natural polymers include starch, guar gum, locust bean gum, alginate, agar, gum arabic, welan gum, xanthan gum, rhamsan gum, and gellan gum, as well as vegetable proteins. Semi-synthetic polymers include degraded starch and its derivatives; cellulose ether derivatives, such as hydroxypropyl methylcellulose (HPMC), hydroxyethyl cellulose (HEC), and carboxymethyl cellulose (CMC); and electrolytes, such as sodium alginate and propylene glycol alginate. Finally, synthetic polymers include ethylene-based polymers such as polyethylene oxide, polyacrylamide, and polyacrylate, and vinyl-based polymers such as polyvinyl alcohol. In some cases, viscosity modifiers can be used in conjunction with superplasticizers, such as hydrocolloids, e.g., welan gum or hydroxypropyl methylcellulose, as well as sulfonated naphthalene, sulfonated melamine, modified lignosulfates, their derivatives, and mixtures thereof. Thus, the wash water may comprise a stable hydrocolloid composition in which the hydrocolloid is uniformly dispersed in a superplasticizer such as sulfonated naphthalene, sulfonated melamine, modified lignosulfates, derivatives thereof, and mixtures thereof.Suitable hydrocolloids include welan gum, methylcellulose, hydroxypropyl methylcellulose (HPMC), hydroxyethyl cellulose (HEC), polyvinyl alcohol (PVA), starch, etc. The mix is ​​then stabilized with a rheology modifier consisting of reticulated cellulose fibers. This composition is rapidly hydratable and useful as a stabilizing additive in many cement and drilling fluid applications. Further useful admixtures are described in Naik, HK, Mishra, MK, Rao Karanam, UM, 2009, The Effect of Drag-Reducing Additives on the Rheological Properties of Fly Ash-Water Suspensions at Varying Temperature Environment. Coal Combustion and Gasification Products 1, 25-31, doi:10.4177 / CCGP-D-09-00005.1, https: / / www.researchgate.net / publication / 209640967_The_Effect_of_Drag-Reducing_Additives_on_the_Rheological_Properties_of_Fly_Ash-Water_Suspensions_at_Varying_Temperature_Environment.

[0184] In this case, the cationic surfactant cetyltrimethylammonium bromide (CTAB) was chosen for its ecologically friendly properties. It is known to be resistant to mechanical degradation and to have a significant effect on turbulence in very small amounts. It is also largely unaffected by the presence of calcium and sodium ions in tap water. The chemical formula for CTAB is CHBrN. The surfactant can be procured, for example, from LOBA Chemie Pvt. Ltd., Mumbai, India. The molecular weight of this surfactant is 364.46.

[0185] In the case of surfactant drag-reducing additives, the rod-like micellar structure is believed to be key to imparting complex rheological fluid properties, including viscoelasticity. The counterion acts as a reagent to reduce the ionic radius of the surfactant and transform the micellar shape from spherical to rod-like micelles. These rod-like micelles entangle together to create a specific network structure. The counterion acts as a catalyst for the disassembly and reorganization of the entanglement points. The counterion selected for this study could be, for example, sodium salicylate (NaSal) (HOC6H4COONa) with a molecular weight of 160.10, obtained from LOBA Chemie Pvt. Ltd., Mumbai, India.

[0186] Set retarder In certain embodiments, the set retarder is added to the wash water before carbonating it, e.g., while the wash water is still in the truck, or by any suitable method for introducing the set retarder before carbonating the wash water. Set Retarder: Set retarders are generally substances that can delay the time it takes for cement to hydrate, for example, in a concrete mix. Set retarders are well known in the concrete industry, and any suitable set retarder can be used. Set retarders include carbohydrates, i.e., sugars such as fructose, glucose, and sucrose, as well as sugar acids / bases and their salts, e.g., sodium gluconate and sodium glucoheptonate; phosphonates, e.g., nitrilotri(methylphosphonic acid), 2-phosphonobutane-1,2,4-tricarboxylic acid; and chelating agents, e.g., EDTA, citric acid, and nitrilotriacetic acid. Other sugars and sugar-containing admixtures include molasses and corn syrup. An exemplary set retarder is sodium gluconate. Other exemplary admixtures that can be used as set retarders include sodium sulfate, citric acid, BASF Pozzolith XR, fumed silica, colloidal silica, hydroxyethyl cellulose, hydroxypropyl cellulose, fly ash (as defined in ASTM C618), mineral oil (such as light naphthenic), hectorite clay, polyoxyalkylene, natural rubber, or mixtures thereof, polycarboxylate superplasticizers, naphthalene HRWR (high performance water reducer). Additional set retarders that can be used include, but are not limited to, oxyboron compounds, lignin, polyphosphonic acids, carboxylic acids, hydroxycarboxylic acids, polycarboxylic acids, hydroxylated carboxylic acids such as fumaric acid, itaconic acid, malonic acid, borax, gluconic acid, and tartaric acid, lignosulfonic acid, ascorbic acid, isoascorbic acid, sulfonic acid-acrylic acid copolymers and their corresponding salts, polyhydroxysilanes, and polyacrylamides. Illustrative examples of retarders are described in US Pat. Nos. 5,427,617 and 5,203,919, which are incorporated herein by reference.

[0187] The set retarder is added to the concrete or concrete wash water in any suitable amount. Generally, dosage amounts are well established for specific set retarders and desired effects. Exemplary percentages of sodium gluconate can be, for example, at least 0.1, 0.2, 0.5, 1.0, 2.0, 3.0, 4.0, or 5% by weight of the solids in the wash water, and / or up to 0.2, 0.5, 1.0, 2.0, 3.0, 4.0, 5, or 10% by weight of the solids in the wash water. It is understood that the dosage must be fairly accurate for some applications, for example, when used with concrete coated on the inside of a ready-mix drum, and operators often add excess set retarder to ensure that setting and hardening do not occur. This excess amount can be taken into account when carbonating the concrete or concrete wash water, and, if necessary, additional carbonation of new concrete added to old concrete can be used to offset the excess set retarder.

[0188] Thus, in certain embodiments, the present invention provides methods and compositions for treating concrete wash water treated with set retarders with carbon dioxide. This can be used when trucks are returned to a batch location and washed, but the wash water is not removed from the truck; typically, such trucks are left overnight at the batching facility, and then a new load of concrete is introduced into the truck the next day. The wash water containing set retarders contains the components of the load that was in the truck, including cement. The wash water containing set retarders can be treated with carbon dioxide after the addition of the set retarders, before and / or during the addition of the new load of concrete to the truck. For example, the concrete wash water can be exposed to a set retarder and then allowed to stand, e.g., in a truck drum, for at least 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 24, 28, 32 hours, and / or up to 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 24, 28, 32, or 36 hours, and then carbon dioxide is added to the wash water. This may be done before the new load is added to the truck, for example at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 30, 40, 50, or 60 minutes before the new load, or at least 1, 1.5, 2, 2.5, 3, 4, 5, 6, or 8 hours before the new load, and / or within 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 30, 40, 50, or 60 minutes before the new load, or within 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, or 10 hours before the new load. Additionally or alternatively, carbon dioxide may be added when the new load is added, or carbon dioxide addition may occur both before and during the addition of the new load.Carbon dioxide may be added in an amount sufficient to reverse some or all of the effects of the set retarder on the cement in the wash water containing the set retarder. The carbon dioxide dosage may be any appropriate dosage calculated relative to the weight of cement in the wash water. It is understood that such calculations often must be based on an estimate of the amount of concrete adhering to the truck drum, and typically, the mix design of the load(s) in the truck before washing is also used to estimate the cement content. Alternatively, a fixed amount of carbon dioxide may be used, such as an amount known to provide excess carbon dioxide so that all the cement reacts. The carbon dioxide dosage may also be adjusted depending on the amount of set retarder in the wash water, which may be, for example, recorded by the operator, specified by a protocol, or estimated. It is understood that if excess set retarder is used in the wash water, additional carbon dioxide may be required to prevent its impact on the next load added to the wash water. In such cases, it may be useful to add carbon dioxide when or just before adding the next load, so that carbon dioxide does not escape from the treated wash water to the atmosphere. Exemplary dosage amounts are described elsewhere herein, e.g., dosage amounts of 0.001 to 5.0% bwc. Additionally or alternatively, carbon dioxide may be added to a fresh batch of concrete, typically at a dosage of less than 2% bwc by weight of cement, e.g., less than 1.5% bwc by weight of cement, or less than 1% bwc by weight of cement, or in some cases less than 0.5% bwc by weight of cement.

[0189] In certain embodiments, concrete wash water can be transferred to a holding tank and treated with one or more set retarders at some point, either in the truck or in the tank, or a combination thereof, and then carbon dioxide can be introduced at a later point, such as when it is desired to reuse the wash water in a new batch of concrete. For example, the set retarder-treated wash water can be exposed to carbon dioxide before and / or during its use as mix water. Thus, without being bound by theory, it is believed that the use of set retarders keeps the cement in a "resting" state, which is then reversed by the carbonation reaction from the addition of carbon dioxide.

[0190] In certain embodiments, the wash water is treated with a first dosage of a first set retarder, and then at a later time with a second dosage of a second set retarder, where the first and second set retarders may be the same or different. Additional dosages may be used as appropriate. The time of the first dosage may be within several hours of the generation of the wash water, and the time of the second dosage may be, for example, immediately before, after, and / or during exposure of the wash water to carbon dioxide.

[0191] In certain embodiments, the present invention provides methods and compositions for treating concrete that has been treated with one or more set retarders with carbon dioxide. This can be done, for example, when a truck returns to a batching facility after only a portion of its load has been used on-site. In this case, the concrete may be treated with the set retarder on-site or at a later time, and the concrete may be batched accordingly, and the set retarder may then be added a certain time after batching, for example, at least 0.1, 0.2, 0.5, 0.7, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, or 8 hours after batching, and / or within 0.2, 0.5, 0.7, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 8, or 10 hours after batching. The truck generally returns to the batching facility, and it may be desirable to load additional concrete onto the truck in addition to the returned concrete. Carbon dioxide can be added to returned concrete that has been treated with one or more set retarders at any suitable dosage as described elsewhere herein, for example, at a dosage of 0.001 to 5.0% bwc, and the carbon dioxide may be added at any suitable time after the addition of the set retarders, which may depend on several factors such as return time to the batching facility, storage time at the batching facility, etc. Thus, in certain embodiments, the carbon dioxide may be added to the returned concrete that has been treated with one or more set retarders. The retarder may be added at least 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 20, 25, 30, 35, or 40 hours after the retarder is added to the concrete, and / or within 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 20, 25, 30, 35, or 40 hours after the retarder is added to the concrete.The concrete may then be used with additional concrete in a new batch of concrete, which may occur simultaneously or nearly simultaneously with the addition of carbon dioxide, or at any suitable time after the addition of carbon dioxide, e.g., at least 1, 2, 5, 7, 10, 15, 20, 25, 30, 40, or 50 minutes after the addition of carbon dioxide, or at least 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, or 6 hours after the addition of carbon dioxide, and / or within 2, 5, 7, 10, 15, 20, 25, 30, 40, or 50 minutes after the addition of carbon dioxide, or within 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, or y hours after the addition of carbon dioxide. The new concrete may be further treated with carbon dioxide, such that in some embodiments, both the old and new concrete are treated with carbon dioxide. As noted, this may occur simultaneously, or the old concrete may be treated with carbon dioxide, and then the new concrete is treated, e.g., as it is being mixed with the old concrete. The carbon dioxide dosage to the new concrete may be any suitable dosage described herein.

[0192] In some cases, set retarders are added to the concrete batch at a batching facility or in the truck en route to the site because expected traffic, temperature, and other factors on the way to the site prevent the batch from beginning to set too quickly. In this case, it may be desirable to reverse the effect of the set retarder before pouring at the site; i.e., in this case and others described herein, the set retarder acts as an “off switch” and the carbon dioxide acts as an “on switch” for the cement in the concrete. In these embodiments, the carbon dioxide would be added to the concrete at some other location besides the batching facility, for example, en route to the site or in the truck at the site. The truck may be equipped with a portable carbon dioxide delivery system, such as a carbon dioxide source and a conduit for transporting the carbon dioxide to the truck's drum. Additionally or alternatively, the carbon dioxide delivery system may be installed at or near the site, the truck may arrive at a carbon dioxide delivery location, and the concrete contained therein may then be treated with carbon dioxide at an appropriate time before use at the site. In this way, trucks have a larger time frame for transporting and using the concrete, factors such as traffic, job site delays, etc. become less of an issue, and the concrete is "dormant" with the set retarder and then activated using carbon dioxide. The carbon dioxide dosage may be any suitable dosage described herein, such as a dosage of 0.001-5.0% bwc, and as described elsewhere, the dosage may depend on the type of cement in the concrete, the type and amount of set retarder, the expected use time of the concrete after the carbon dioxide addition, the temperature, etc. The carbon dioxide can be added at any suitable time before the expected use time of the concrete, for example, at least 1, 2, 3, 4, 5, 7, 10, 15, 20, 30, 40, or 50 minutes before the expected use time, or at least 1, 1.5, 2, 2.5, or 3 hours before the expected use time, and / or within 2, 3, 4, 5, 7, 10, 15, 20, 30, 40, or 50 minutes before the expected use time, or within 1, 1.5, 2, 2.5, 3, or 3.5 hours before the expected use time.Thus, in certain embodiments, the present invention provides a method of treating concrete, the method comprising treating the concrete with a set retarder and then treating the concrete with carbon dioxide. The set retarder is typically added at the batching facility, but may also be added in the drum of the truck after leaving the batching facility, for example, if traffic and / or on-site delays are known. Carbon dioxide is added en route to and / or at the site; typically, carbon dioxide is added in the drum of the ready-mix truck, but may also be added during transfer of the concrete from the drum, for example, to forms on the site.

[0193] In certain embodiments, set retarders and carbon dioxide are added to a concrete mix to provide the desired combination of improved workability and acceptable set time. One or more set retarders may be added to a concrete mix to improve workability, but this often comes at the cost of slowing the set time. To shorten the set time (but still maintain workability), set accelerator admixtures can be used. However, while set retarders are generally relatively inexpensive, set accelerators are often expensive and often contain undesirable species, such as chlorides. Therefore, it is desirable to use a less expensive substance that can accelerate set within the desired time frame, and carbon dioxide is one such substance. In these cases, the carbon dioxide and set retarder may be added in any suitable order, for example, sequentially, with the set retarder added first and then the carbon dioxide, or the carbon dioxide added first and then the set retarder, or simultaneously or near simultaneously, for example, such that the timing of the addition of the set retarder and carbon dioxide is such that they are both added to the concrete mix during at least a portion of their respective addition times. Thus, in certain embodiments, carbon dioxide is added to the concrete mix and then the set retarder is added after the carbon dioxide addition (i.e., after the carbon dioxide addition has begun; depending on the length of time of the carbon dioxide addition, the set retarder addition may begin before the carbon dioxide addition has ended, although this is not typical), and the set retarder can be added, for example, at least 0.1, 0.5, 1, 2, 3, 4, 5, 7, 10, 15, 20, 30, 40, or 50 minutes after the carbon dioxide addition, or at least 1, 1.5, 2, 2.5, 3, 3.5, or 4 hours after the carbon dioxide addition, and / or within 0.5, 1, 2, 3, 4, 5, 7, 10, 15, 20, 30, 40, or 50 minutes after the carbon dioxide addition, or within 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, or 6 hours after the carbon dioxide addition. In another particular embodiment, a set retarder is added to the concrete mix, and then carbon dioxide is added after the set retarder addition (i.e., after the set retarder addition has begun).Depending on the length of time for the set retarder addition, the carbon dioxide addition may begin before the set retarder addition is complete (although this is not typical), and the carbon dioxide can be added, for example, at least 0.1, 0.5, 1, 2, 3, 4, 5, 7, 10, 15, 20, 30, 40, or 50 minutes after the set retarder addition, or at least 1, 1.5, 2, 2.5, 3, 3.5, or 4 hours after the set retarder addition, and / or within 0.5, 1, 2, 3, 4, 5, 7, 10, 15, 20, 30, 40, or 50 minutes after the set retarder addition, or within 1, 1.5, 2, 2.5, 3, 3.5, 4, or 4.5 hours after the set retarder addition. The set retarder, carbon dioxide, or both can also be added in divided doses, and the timing of each dose can be relative to the other dose in any suitable manner. For example, a certain amount of set retarder may be added, followed by carbon dioxide, followed by a final dose of set retarder. This is merely an example, and any suitable number of doses of set retarder and / or carbon dioxide, and any suitable timing of addition, may be used.

[0194] It will be appreciated that set accelerators are available as admixtures. Such set accelerators may be used in addition to carbon dioxide. However, these admixtures tend to be expensive and often contain undesirable species such as chlorides, so it is desirable to use carbon dioxide as a cheaper alternative whenever possible.

[0195] Carbon dioxide supply The concrete or concrete wash water containing the set retarder can be exposed to any suitable dosage of carbon dioxide.For example, the dosage may be less than or equal to 5%, 4%, 3%, 2.5%, 2%, 1.5%, 1.2%, 1%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, 0.1%, 0.05%, 0.01%, or 0.05% bwc and / or at least 0.001, 0.005, 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.2, 1.5, 2.0, 2.5, 3.0, 4.0, or 4.5% bwc, e.g., 0.001-5%, or 0.001-4%, or 0. 0.001-3%, or 0.001-2%, or 0.001-1.5%, 0.001-1.2%, 0.001-1%, 0.001-0.8%, 0.001-0.6%, 0.001-0.5%, 0.001-0.4%, 0.001-0.3%, 0.001-0.2%, or 0.001-0.1% bwc dosage, or 0.01-5%, or 0.01-4%, or 0.01-3%, or 0.01-2%, 0.01-1.5%, 0.01-1.2%, 0.01-1%, 0.01-0.8%, 0.01-0.6%, 0.01-0. 5%, 0.01-0.4%, 0.01-0.3%, 0.01-0.2%, or 0.01-0.1% bwc dosage, or 0.02-1.5%, 0.02-1.2%, 0.02-1%, 0.02-0.8%, 0.02-0.6%, 0.02-0.5%, 0.02-0.4%, 0.02-0.3%, 0.02-0.2%, or 0.02-0.1% bwc dosage, or 0.04-1.5%, 0.04-1.2%, 0.04-1%, 0.04-0.8%, 0.04-0.6%, 0.04-0.5%, 0.04-0.4%, 0.04-0.3% %, 0.04-0.2%, or 0.04-0.1% bwc dosage, or 0.06-1.5%, 0.06-1.2%, 0.06-1%, 0.06-0.8%, 0.06-0.6%, 0.06-0.5%, 0.06-0.4%, 0.06-0.3%, 0.06-0.2%, or 0.06-0.1% bwc dosage, or 0.1-1.5%, 0.1-1.2%, 0.1-1%, 0.1-0.8%, 0.1-0.6%, 0.1-0.5%, 0.1-0.4%, 0.1-0.3%, or 0.1-0.2% bwc dosage.The amount of carbon dioxide dosage may depend on various factors, such as the type of cement in the concrete or concrete wash water, the type and amount of set retarder used, the timing of carbon dioxide addition after the set retarder, the temperature, and the expected time between the addition of carbon dioxide and use of the concrete.

[0196] Forms of carbon dioxide Carbon dioxide may be added to the concrete or concrete wash water containing the set retarder in any suitable form, such as gaseous, liquid, solid, or supercritical form; in certain embodiments, carbon dioxide containing solid carbon dioxide can be used. It may also be in the form of a mixture of solid and gaseous carbon dioxide, which may be formed from liquid carbon dioxide when it exits a conduit under pressure and is exposed to a lower pressure, such as atmospheric pressure. See, e.g., U.S. Pat. No. 9,738,562. Additionally or alternatively, only solid carbon dioxide, such as pellets or shavings, or other suitable form, can be added, which may be determined, at least in part, by the desired rate of carbon dioxide sublimation and subsequent entry into solution. See, e.g., U.S. Pat. No. 9,738,562. In certain embodiments, only gaseous carbon dioxide is used.

[0197] Further admixtures This section summarizes some additional useful admixtures for use in the methods and compositions herein. For an additional list, see Report on Chemical Admixtures for Concrete, Reported by ACI Committee 212, American Concrete Institute, ACI 212.3R-16, ISBN 978-1-942727-80-4, which is incorporated herein by reference in its entirety.

[0198] Admixtures useful in the methods and compositions herein include:

[0199] Accelerators: Increase the rate of hydration, thereby accelerating setting and / or early strength development. Generally, accelerating admixtures for concrete must meet the requirements of ASTM C494 / C494M for Type C (accelerating admixtures) or Type E (water-reducing accelerating admixtures). Examples include inorganic salts such as chlorides, bromides, fluorides, carbonates, thiocyanates, nitrites, nitrates, thiosulfates, silicates, aluminates, and alkali hydroxides. Of particular interest are calcium-containing compounds such as CaO, Ca(NO2), Ca(OH)2, calcium stearate, or CaCl2, and magnesium-containing compounds such as magnesium hydroxide, magnesium oxide, magnesium chloride, or magnesium nitrate. Without being bound by theory, it is believed that in carbonated cements, added calcium or magnesium compounds can provide free calcium or magnesium to react with carbon dioxide, providing a sink for carbon dioxide that leaves calcium in the cement mix, or providing carbonation sites different from those of the cement calcium, or both, thereby maintaining early strength development. Furthermore, anions, such as nitrates from calcium-containing admixtures, can affect the CSH particle structure. Other setting accelerators include, but are not limited to, nitrates of alkali metals, alkaline earth metals, or aluminum; nitrites of alkali metals, alkaline earth metals, or aluminum; thiocyanates of alkali metals, alkaline earth metals, or aluminum; alkanolamines; thiosulfates of alkali metals, alkaline earth metals, or aluminum; hydroxides of alkali metals, alkaline earth metals, or aluminum; carboxylates of alkali metals, alkaline earth metals, or aluminum (preferably calcium formate); polyhydroxyl alkylamines; and halide salts (e.g., chlorides) of alkali metals or alkaline earth metals. Stable CSH species can also be used as accelerators.

[0200] In certain embodiments, the accelerator may include one or more soluble organic compounds, such as one or more alkanolamines, such as triethylamine (TEA) and / or higher trialkanolamines or calcium formate. As used herein, the term "higher trialkanolamine" includes tertiary amine compounds that are tri(hydroxyalkyl)amines having at least one C3-C5 hydroxyalkyl (preferably C3-C4 hydroxyalkyl) group therein. The remaining hydroxyalkyl groups, if any, of the tertiary amine in question may be selected from C1-C2 hydroxyalkyl groups (preferably C2 hydroxyalkyl). Examples of such compounds include hydroxyethyldi(hydroxypropyl)amine, di(hydroxyethyl)hydroxypropylamine, tri(hydroxypropyl)amine, hydroxyethyldi(hydroxy-n-butyl)amine, tri(2-hydroxybutyl)amine, hydroxybutyldi(hydroxypropyl)amine, and the like. The accelerator may also include calcium salts of carboxylic acids, including acetates, propionates, or butyrates. Other organic compounds that may act as accelerators include urea, oxalic acid, lactic acid, various cyclic compounds, and condensation compounds of amines with formaldehyde.

[0201] In some embodiments, quick-setting admixtures can be used to produce quick-setting mortars or concrete suitable for, for example, concrete spraying or 3D printing. These include, for example, ferric salts, sodium fluoride, aluminum chloride, sodium aluminate, and potassium carbonate.

[0202] Various additional facilitating materials include silicates, particulate silica gel, soluble quaternary ammonium silicates, silica fume, particulate magnesium carbonate, or particulate calcium carbonate. Ultrafine materials of various compositions may exhibit facilitating properties. In certain embodiments, the admixture may include nucleation seeds based on calcium silicate hydrate (CSH) phases. See, for example, Thomas, JJ, et al. 2009 J. Phys Chem 113:4327-4334 and Ditter et al. 2013 BFT International, Jan, pp. 44-51 (incorporated herein by reference in their entirety).

[0203] In certain embodiments, a set accelerator comprising one, two, or three of triisopropanolamine (TIPA), N,N-bis(2-hydroxyethyl)-N-(2-hydroxypropyl)amine (BHEHPA), and tri(2-hydroxybutyl)amine (T2BA), e.g., a set accelerator comprising TIPA, is used. Any suitable dosage can be used, e.g., 0.0001-0.5% bwc, e.g., 0.001-0.1%, or 0.005-0.03% bwc. See U.S. Patent No. 5,084,103.

[0204] In certain embodiments, carbonation of a cement mix is ​​combined with the use of an admixture containing an alkanolamine set accelerator (e.g., TIPA), incorporating the alkanolamine set accelerator (e.g., TIPA) in an amount of 0.0001-0.5% bwc, such as 0.001-0.1%, or 0.005-0.03% bwc. In some of these embodiments, the alkanolamine (e.g., TIPA)-containing admixture is added before and / or during carbonation, for example, as part of the initial mix water. In some of these embodiments, the alkanolamine (e.g., TIPA)-containing admixture is added after and / or during carbonation. In some embodiments, the alkanolamine (e.g., TIPA)-containing admixture is added in two or more doses, which can be added at different times from carbonation (e.g., two doses, one before and one after carbonation, etc.). Additionally or alternatively, carbonation can proceed in two or more doses, for example, with one or more doses of an alkanolamine (e.g., TIPA)-containing admixture added before, after, or during one or more carbon dioxide doses. Other ingredients, including one or more of the following, or combinations of: set / strength control agents, set balancers, hydration seeds, dispersants, air control agents, rheology modifiers, and colorants, may also be present in the alkanolamine (e.g., TIPA)-containing admixture. Suitable commercially available products include BASF Master X-Seed 55 (BASF Corporation, Admixture Systems, Cleveland, OH). The total dose of carbon dioxide delivered to the cement mix in these embodiments may be any suitable dose, such as those described herein, for example, 0.001-2% bwc, e.g., 0.001-1.0% bwc, or 0.001-0.5% bwc.

[0205] Deaerating agents: Also known as defoamers or air separating agents, these agents reduce air content. Examples include nonionic surfactants, such as phosphate esters including tributyl phosphate and dibutyl phosphate, phthalate esters including diisodecyl phthalate and dibutyl phthalate, block copolymers including polyoxypropylene-polyoxyethylene block copolymers, and mixtures thereof. Deaerating agents also include octyl alcohol, water-insoluble esters of carbonic acid and boric acid, and silicones. Further examples of deaerating agents include mineral oil, vegetable oil, fatty acid, fatty acid ester, hydroxyl-functional compound, amide, phosphate ester, metal soap, polymers containing propylene oxide moieties, hydrocarbons, alkoxylated hydrocarbons, alkoxylated polyalkylene oxides, acetylenic diol, polydimethylsiloxane, dodecyl alcohol, octyl alcohol, polypropylene glycol, water-soluble esters of carbonic acid and boric acid, and lower sulfonic acid oils.

[0206] Air-entraining admixtures: The term air-entraining agent includes any substance that entrains air in a cementitious composition. Some air-entraining agents can also reduce the surface tension of the composition at low concentrations. Air-entraining admixtures are used to intentionally entrain fine air bubbles in concrete. Air entrainment dramatically improves the durability of concrete exposed to moisture during freeze-thaw cycles. Furthermore, the entrained air greatly improves the concrete's resistance to surface scaling caused by chemical deicers. Air entrainment also increases the workability of fresh concrete while eliminating or reducing material segregation and bleeding. Materials used to achieve these desired effects can be selected from wood resins and their salts, natural resins and their salts, synthetic resins and their salts, sulfonated lignins and their salts, petroleum acids and their salts, proteinaceous materials and their salts, fatty acids and their salts, resin acids and their salts, alkylbenzene sulfonates, sulfonated hydrocarbons, vinsol resins, anionic surfactants, cationic surfactants, nonionic surfactants, natural rosin, synthetic rosin, inorganic air entraining agents, synthetic detergents, and their corresponding salts, and mixtures thereof. Solid materials such as hollow plastic spheres, crushed brick, expanded clay or shale, or suitable diatomaceous earth spheres can also be used. The air entraining agent is added in an amount to provide the desired level of air in the cementitious composition. Examples of air entraining agents that can be utilized in the admixture system include, but are not limited to, MB AE 90, MB VR, and MICRO AIR.RTM. (all available from BASF Admixtures Inc., Cleveland, Ohio).

[0207] Alkali-aggregate reaction inhibitors: reduce the extent of alkali-aggregate reaction. Examples include barium salts, lithium nitrate, lithium carbonate, and lithium hydroxide.

[0208] Anti-segregation admixtures: adhesive concrete for underwater placement. Examples include cellulose and acrylic polymers.

[0209] Bonding admixtures: Increase bond strength. Examples include polyvinyl chloride, polyvinyl acetate, acrylic resins, and butadiene-styrene copolymers.

[0210] Coloring admixtures: Coloring concrete. Examples include modified carbon black, iron oxide, phthalocyanine, amber, chromium oxide, titanium oxide, cobalt blue, and organic colorants.

[0211] Rust inhibitors: Reduce steel corrosion activity in chloride-containing environments. Examples include calcium nitrite, sodium nitrite, sodium benzoate, certain phosphates or fluorosilicates, fluoroaluminates, and esteramines.

[0212] Moisture-proofing admixtures: retard the penetration of moisture into dry concrete. Examples include calcium or ammonium stearate or calcium or ammonium oleate, butyl stearate, and petroleum soaps.

[0213] Foaming agents: produce low-density lightweight cellular concrete. Examples include cationic and anionic surfactants, and hydrolyzed proteins.

[0214] Moldcides, bactericides, and insecticides: inhibit or suppress the growth of bacteria and fungi. Examples include polyhalogenated phenols, dieldrin emulsions, and copper compounds.

[0215] Foaming agents: Foaming agents, or gas-generating substances, are sometimes added in very small quantities to concrete and grout to cause a slight expansion before hardening. The amount of expansion depends on the amount of gas-generating substance used and the temperature of the fresh mix. Aluminum powder, resin soaps, and vegetable or animal glues, saponins, or hydrolyzed proteins can be used as foaming agents.

[0216] Hydration control admixtures: stabilizers and activators used to temporarily arrest and reactivate cement hydration. Examples include carboxylic acids and phosphorus-containing organic acid salts.

[0217] Permeability reducers: Reduces permeability. Examples include latex and calcium stearate.

[0218] Pumping aids: improve pumpability. Examples include organic and synthetic polymers, organic flocculants, organic emulsions of paraffin, coal tar, asphalt, acrylic resins, ventolite and pyrogenic silica, and hydrated lime.

[0219] Retarders: Delays set time. May include water-reducing retarding admixtures (see water-reducing admixtures), which reduce the water requirement of a concrete mix for a given slump and increase the set time, or those that increase the set time of concrete without affecting water requirement. Generally, set retarders can be divided into four categories: 1) lignosulfonic acids and their salts and their modifications and derivatives, 2) hydroxylated carboxylic acids and their salts and their modifications and derivatives, 3) carbohydrate-based compounds such as sugars, sugar acids, and polysaccharides, and 4) inorganic salts such as borates and phosphates, any of which may be used in embodiments herein. Thus, set retarders include carbohydrates, i.e., sugars such as fructose, glucose, and sucrose, as well as sugar acids / bases and their salts, such as sodium gluconate and sodium glucoheptonate; phosphonates, such as nitrilotri(methylphosphonic acid), 2-phosphonobutane-1,2,4-tricarboxylic acid; and chelating agents, such as EDTA, citric acid, and nitrilotriacetic acid. Other sugars and sugar-containing admixtures include molasses and corn syrup. In a specific embodiment, the admixture is sodium gluconate. Other exemplary admixtures that can be used as set retarders include sodium sulfate, citric acid, BASF Pozzolith XR, fumed silica, colloidal silica, hydroxyethyl cellulose, hydroxypropyl cellulose, fly ash (as defined in ASTM C618), mineral oil (such as light naphthenic), hectorite clay, polyoxyalkylene, natural rubber, or mixtures thereof, polycarboxylate superplasticizers, naphthalene HRWR (high performance water reducer). Additional set retarders that can be used include, but are not limited to, oxyboron compounds, lignin, polyphosphonic acids, carboxylic acids, hydroxycarboxylic acids, polycarboxylic acids, hydroxylated carboxylic acids such as fumaric acid, itaconic acid, malonic acid, borax, gluconic acid, and tartaric acid, lignosulfonic acid, ascorbic acid, isoascorbic acid, sulfonic acid-acrylic acid copolymers and their corresponding salts, polyhydroxysilanes, and polyacrylamides.Further retarders include nitrilotri(methylphosphonic acid) and 2-phosphonobutane-1,2,4-tricarboxylic acid. Illustrative examples of retarders are described in U.S. Patent Nos. 5,427,617 and 5,203,919, which are incorporated herein by reference.

[0220] Shrinkage reducing agents: reduce drying shrinkage. Examples include polyoxyalkylene alkyl ethers and propylene glycol.

[0221] Water-reducing admixtures (also called dispersants, especially HRWRs) are used to reduce the amount of mixing water required to produce concrete of a certain slump, reduce the water-to-cement ratio, reduce the cement content, or increase the slump. Typical water-reducing admixtures reduce water content by about 5-10%, while high-performance water-reducing admixtures (HRWRs) reduce water content even further. Adding water-reducing admixtures to concrete without reducing the water content can produce mixes with higher slumps; for example, in certain cases where high doses of carbon dioxide are used to carbonate the cement mix, the slump can be reduced and full slump / workability can be restored by using a water-reducing admixture.

[0222] The water-reducing admixtures used in the compositions and methods herein may conform to one of the seven types of water-reducing admixtures of ASTM C494 / C494M, which define: 1) Type A - water-reducing admixtures, 2) Type B - retarding admixtures (as described above), 3) Type C - accelerating admixtures (also described above), 4) Type D - water-reducing retarding admixtures, 5) Type E - water-reducing accelerating admixtures, 6) Type F - superplasticizers; or 7) Type G - superplasticizers. Materials commonly usable as water-reducing admixtures typically fall into one of seven general categories, and formulations useful herein may include compounds from several of the following categories, including, but not limited to: 1) lignosulfonic acids and their salts and their modifications and derivatives; 2) hydroxylated carboxylic acids and their salts and their modifications and derivatives; 3) carbohydrate-based compounds such as sugars, sugar acids, and polysaccharides; 4) salts of sulfonated melamine polycondensation products; 5) salts of sulfonated naphthalene polycondensation products; 6) carboxylate salts; and 7) other materials that can be used to modify the formulation (including nonionic surfactants; amines and their derivatives; organic phosphonates, including zinc salts, borates, phosphates; and certain polymeric compounds, including cellulose ethers, silicones, and sulfonated hydrocarbon acrylate derivatives).

[0223] Water-reducing admixtures generally provide increased strength due to a reduced water-cement ratio. For concretes with equal cement content, air content, and slump, the 28-day strength of water-reducing concrete containing a water-reducing admixture can be 10% to 25% higher than that of concrete without the admixture. Type A water-reducing admixtures may have little effect on setting, while Type D admixtures provide water reduction with retardation (generally with the addition of a retarder), and Type E admixtures provide water reduction with set acceleration (generally with the addition of an accelerator). Type D water-reducing admixtures typically delay the setting time of concrete by 1 to 3 hours. Some water-reducing admixtures can also entrain some air into the concrete.

[0224] High-range water reducers (HRWRs, also called superplasticizers or superplasticizers), Types F (water reducing) and G (water reducing and retarding), reduce the water content by at least 12%.

[0225] Examples of water reducers include lignosulfonates, casein, hydroxylated carboxylic acids, and carbohydrates. Additional examples, including HRWRs (high flow agents or superplasticizers), include polycarboxylic acid ethers, polycarboxylates, polynaphthalene sulfonates (sulfonated naphthalene formaldehyde condensates (e.g., LOMAR D™ dispersant (Cognis Inc., Cincinnati, Ohio)), polymelamine sulfonates (sulfonated melamine formaldehyde condensates), polyoxyethylene phosphonates (phosphonate-terminated PEG brushes), and vinyl copolymers. Additional examples include beta-naphthalene sulfonates, polyaspartates, or oligomeric dispersants.

[0226] Polycarboxylate dispersants (water reducers also called polycarboxylic acid ethers, polycarboxylic acid esters) can be used, which means dispersants having a carbon skeleton with pendant side chains, at least some of which are attached to the skeleton through carboxyl or ether groups. Examples of polycarboxylate dispersants are described in U.S. Patent Publication No. 2002 / 0019459A1, U.S. Patent No. 6,267,814, U.S. Patent No. 6,290,770, U.S. Patent No. 6,310,143, U.S. Patent No. 6,187,841, U.S. Patent No. 5,158,996, U.S. Patent No. 6,008,275, U.S. Patent No. 6,136,950, U.S. Patent No. 6,284,867, U.S. Patent No. 5,609,681, U.S. Patent No. 5,494,516, U.S. Patent No. 5,674,929, U.S. Patent No. 5,660,626, U.S. Patent No. 5,668,195, U.S. Patent No. 5,661,206, U.S. Patent No. Nos. 5,358,566, 5,162,402, 5,798,425, 5,612,396, 6,063,184, 5,912,284, 5,840,114, 5,753,744, 5,728,207, 5,725,657, 5,703,174, 5,665,158, 5,643,978, 5,633,298, 5,583,183, and 5,393,343. Polycarboxylate dispersants of interest include, but are not limited to, dispersants or water reducers sold under the trademarks GLENIUM RTM 3030NS, GLENIUM RTM 3200 HES, GLENIUM 3000NS RTM (BASF Admixtures Inc., Cleveland, Ohio), ADVA RTM (WR Grace Inc., Cambridge, Mass.), VISCOCRETE RTM (Sika, Zurich, Switzerland), and SUPERFLUX RTM (Axim Concrete Technologies Inc., Middlebranch, Ohio).

[0227] Viscosity and Rheology Modifying Admixtures. Viscosity modifying admixtures (VMAs) are typically water-soluble polymers used in concrete to modify its rheological properties. VMAs affect the rheology of concrete by increasing its plastic viscosity, and the effect on yield stress varies significantly, ranging from no increase to a significant increase, depending on the type of VMA. Plastic viscosity is defined as the property of a material to resist changes in the shape or arrangement of its elements during flow, and yield stress is defined as the critical shear stress value below which a viscoplastic material will not flow and, once exceeded, flows like a viscous liquid. Rheology modifiers can be used to modify, e.g., increase, the viscosity of cementitious compositions. Suitable examples of rheology modifiers include fumed silica, colloidal silica, cellulose ethers (e.g., hydroxyethyl cellulose, hydroxypropyl methylcellulose), fly ash (as specified in ASTM C618), mineral oil (such as light naphthenic), hectorite clay, polyoxyalkylenes, polysaccharides, polyethylene oxide, polyacrylamide or polyvinyl alcohol, natural and synthetic rubbers, alginates (derived from seaweed), or mixtures thereof. Other materials include particulate solids such as starch, clay, lime, and polymer emulsions. Rheology-modifying admixtures (RMAs) are admixtures that affect the flow properties of concrete by reducing the yield stress or force required to initiate flow without necessarily changing the plastic viscosity. The addition of RMAs to concrete may not change its slump, but will improve its workability and flow properties. RMA has been used, for example, in low-slump concrete applications, such as in concrete placement using slip-form pavers to cast concrete pavements, curbs, and barriers, and in some cases in 3D printing. It can also be used with self-compacting concrete (SCC) or high-flow concrete.Rheology-modifying admixtures include those reported by Bury and Bury, 2008, Concrete International, 30:42-45, which is incorporated herein by reference in its entirety.

[0228] Shrinkage reducing and compensating admixtures. Shrinkage compensating admixtures that can be used in cementitious compositions include RO(AO) 1~10 H (wherein R is C 1~5 Alkyl group or C 5~6 A is a cycloalkyl group, and C 2~3 The additives may include, but are not limited to, alkylene groups, alkali metal sulfates, alkaline earth metal sulfates, alkaline earth oxides, preferably sodium sulfate and calcium oxide. TETRAGUARD® is an example of a shrinkage-reducing admixture and is available from BASF Admixtures Inc. of Cleveland, Ohio. Exemplary shrinkage-reducing admixtures (SRAs) include polyoxyalkylene alkyl ethers or similar compositions. Exemplary shrinkage-compensating admixtures (SCAs) include calcium sulfoaluminate and calcium aluminate, calcium hydroxide, magnesium oxide, hard-burned and dead-burned magnesium oxide.

[0229] Long-Term Set Control Admixtures. Long-term set control admixtures (ESCAs) or hydration control admixtures (HCAs) are used to stop or significantly slow the cement hydration process in unhardened concrete. They can be used to stop the ongoing hydration of cementitious products in returned / waste concrete or in wash water processed in trucks or concrete regenerator systems, thereby recycling these products to concrete production and thus eliminating the need for disposal, or to stabilize newly batched concrete, providing moderate to very long set retardation, thereby maintaining concrete plasticity during very long transport or long-distance pumping situations, which require a more predictably extended slump life than conventional retarders. They differ from conventional set control admixtures because they stop the hydration process of both the silicate and aluminate phases in Portland cement, which act only on the silicate phase. Examples include carboxylic acids and phosphorus-containing organic acids and salts.

[0230] Workability retention admixtures. Helps maintain the workability of concrete. Examples include hydration control and retarding admixtures meeting the requirements of ASTM C494 / C494M Type B or D, or neutral setting workability retention admixtures meeting the requirements of ASTM C494 / C494M Type S. See, e.g., Daczko, 2010, Proceedings of the 6th th International Symposium on Self-compacting Concrete and the 4 th See North American Concern on the Design and Use of Self-Consolidating Concrete, Sept.

[0231] Anti-corrosion admixtures. Reduce corrosion of steel materials, such as rebar, in concrete. Examples include chromates, phosphates, hydrophosphates, alkalis, nitrites, and fluorides; amine carboxylates, amine ester organic emulsions, and calcium nitrite.

[0232] Permeability-reducing admixtures (PRAs) have been developed to improve the durability of concrete by controlling water and moisture migration and reducing chloride ion ingress and permeability. These typically include, but are not limited to: 1) hydrophobic water repellents, such as soap and long-chain fatty acid derivative-based materials, vegetable oils, such as hard fats, soybean-based materials, and greases, and petroleum oils, such as mineral oil and paraffin waxes, including calcium stearate, ammonium stearate, and butyl stearate; 2) polymeric products, such as organic hydrocarbons supplied either in emulsion (latex) or liquid form, such as coal tar pitch, bitumen, or other resin-based polymers, or prepolymer materials; and 3) particulate solids, such as inert and chemically active fillers, including talc, bentonite, siliceous powders, clays, lime, silicates, and colloidal silica. Supplementary cementitious materials (SCMs) such as fly ash, raw or calcined natural pozzolans, silica fume, or slag cement, while not strictly speaking chemical admixtures, can contribute to reducing the permeability of concrete and can be auxiliary ingredients; 4) hydrophobic pore blockers; and 5) crystalline products, which can be unique active chemicals delivered in a cement and sand carrier.

[0233] Bonding admixtures include organic polymers (latex) dispersed in water.

[0234] Colorants include natural or synthetic materials in liquid or dry form. Pigments include black iron oxide, carbon black, phthalocyanine blue, cobalt blue, red iron oxide, brown iron oxide, burnt umber, chromium oxide, phthalocyanine green, yellow iron oxide, and titanium dioxide.

[0235] Flocculating admixtures include synthetic polyelectrolytes, such as vinyl acetate-maleic anhydride copolymers.

[0236] Mildewcide, fungicide and insecticide admixtures include polyhalogenated phenols, dieldrin emulsions, and copper compounds.

[0237] Lithium admixtures for reducing harmful expansion from alkali-silica reaction. Harmful expansion due to alkali-silica reaction (ASR) can occur in concrete when susceptible siliceous minerals are present in the aggregate. Exemplary admixtures that prevent these harmful expansion reactions include solid forms (lithium hydroxide monohydrate and lithium carbonate) and liquid forms (30 wt. % aqueous lithium nitrate solution). An additional example includes lithium nitrite.

[0238] Expanding / gas-generating admixtures include metallic aluminum, zinc, or magnesium, hydrogen peroxide, nitrogen and ammonium compounds, and certain forms of activated carbon or fluid coke.

[0239] Admixtures for aerated concrete / flowable fill include those based on proteins or synthetic surfactants.

[0240] Shotcrete Admixtures. Shotcrete is defined as "mortar or concrete sprayed at high speed onto a surface by compressed air." Materials useful as shotcrete admixtures include alkali-based accelerators, such as aqueous silicate or aluminate solutions, or alkali-free accelerators, such as those based on aluminum sulfate and aluminum hydroxysulfate; high-range water-reducing admixtures, such as those known in the art specially formulated for shotcrete mixes; and long-set control admixtures.

[0241] Admixtures for produced concrete products that can be used to add manufacturing efficiencies, improve or modify surface texture, enhance and maintain visual appeal, or provide value-added performance benefits. These include superplasticizers such as soaps, surfactants, lubricants, and cement dispersants; accelerators, both calcium chloride and non-chloride; and water repellent / efflorescence control admixtures such as calcium / aluminum stearate, fatty acids, silicone emulsions, and wax emulsions.

[0242] Admixtures for Flowing Concrete. Flowing concrete is defined as "concrete characterized by a slump of greater than 7.5 inches (190 mm) while maintaining cohesiveness." As described herein, a variety of admixtures can be used, including medium and high performance water reducers, viscosity-adjusting admixtures, set retarders, set accelerators, and workability-preserving admixtures.

[0243] Admixtures for self-compacting concrete (SCC). Exemplary admixtures for inclusion in SCC include high-range water-reducing admixtures, e.g., polycarboxylic acid-based HRWRAs, such as blends of different polycarboxylic acid polymers with different absorption rates on powder substrates; and viscosity-adjusting admixtures.

[0244] Extreme cold weather concrete admixtures. These allow concrete to be placed at temperatures below freezing and contain water reducers, accelerators, retarders, corrosion inhibitors, and shrinkage reducers (to further depress the freezing point).

[0245] An admixture for very high early strength concrete. VHESC is designed to achieve extremely high early strength within the first few hours after pouring. The admixture system may include a superplasticizer, a set accelerator, and optionally an air-entraining admixture. It may also include a workability-retaining admixture.

[0246] Admixtures for Pervious Concrete. Pervious concrete is a low-slump, open-graded material consisting of Portland cement, uniformly sized aggregate, little or no fine aggregate, chemical admixtures, and water, which, when combined, produces hardened concrete with interconnected pores or voids that allow water to pass easily through the concrete. Exemplary admixtures include air-entraining admixtures, long-term set control admixtures, water-reducing admixtures, internal curing admixtures, viscosity-adjusting admixtures, and latex admixtures.

[0247] Admixtures for 3D printing concrete. These include admixtures that allow the printed concrete to stand on its own without formwork and other admixtures suited to the requirements of 3D printing.

[0248] Modification or Influence of Calcium Carbonate: In certain embodiments, admixtures are used that modify the formation of calcium carbonate, e.g., to favor one or more polymorphs compared to a blend without the admixture, e.g., admixtures that control the formation of amorphous calcium carbonate, e.g., aragonite or calcite. Exemplary admixtures of this type include organic polymers, e.g., polyacrylates and polycarboxylic acid ethers, phosphate esters, e.g., hydroxyaminophosphate esters, phosphonates and phosphonic acids, e.g., nitrilotri(methylphosphonic acid), 2-phosphonobutane-1,2,4-tricarboxylic acid, chelating agents, e.g., sodium gluconate, ethylenediaminetetraacetic acid (EDTA), and citric acid, or surfactants, e.g., calcium stearate.

[0249] Additional admixtures of interest include those that affect the formation, reactions, and other aspects of calcium carbonate. For example, magnesium can be a strong inhibitor of calcite growth, and the Mg / Ca ratio can affect the shelf life of amorphous calcium carbonate; e.g., a high ratio can increase shelf life, and can affect the type of crystalline polymorph that forms as an initial and long-term product. 2- / Ca2+ Chemical and physical controls on the transformation of amorphous calcium carbonate into crystalline CaCO3 polymorphs. Geochimica et Cosmochimica Acta 196, 179-196. https: / / doi.org / 10.1016 / j.gca.2016.09.004 (incorporated herein by reference in its entirety).

[0250] In certain embodiments, the admixture can include one or more 2D substrates terminated with functional groups, which can also influence the phase, size, shape, and / or orientation of the crystals. Exemplary strategies for preparing functional substrates include Langmuir monolayers, surface carbonylation, and alkanethiol self-assembled monolayers (SAMs). For example, stearic acid monolayers have been used to direct CaCO3 crystallization. Various functional groups can be micropatterned on the substrate to induce CaCO3 crystallization. Thus, in certain embodiments, 2D substrates with -COOH, NH2, -OH, SO3H, -CH3, -SH, and / or PO4H2 can be used to control the mineralization of CaCO3. The physical and / or chemical properties of the substrate may be manipulated to suit the desired outcome. These include the chemical nature of the terminal functional groups, hydrophilicity, charge (or coordination number) and geometry (or spatial structure), substrate metal, and alkanethiol molecule length. Additionally or alternatively, temperature and / or Ca ++Environmental factors, such as the initial concentration of ACC, may be manipulated. ACC formation and transformation may be favored on strongly hydrophilic surfaces, e.g., -OH or -SH terminated SAMs. Without being bound by theory, it is believed that CaCO3 nucleates via the same mechanism on -OH, NH2, and -CH3 terminated SAMs. A poly(ethylene glycol) (PEG)-based double hydrophilic block copolymer, carboxylated polyaniline (c-PANI), can be used to mediate the crystallization of CaCO3 and control the crystal size, shape, and transformation, for example, promoting the formation of fully crystalline calcite and / or vaterite. The addition of -OH and -COOH compatible functional polymers can in some cases stabilize the ACC precursor phase, which may then be gradually converted to calcite, if desired. Additionally or alternatively, charged functional groups can be added to CaCO3. 2+ ions to promote the crystallization of CaCO. See, e.g., Deng, H., Shen, X.-C., Wang, X.-M., Du, C., 2013. Calcium carbonate crystallization controlled by functional groups: A mini-review. Frontiers of Materials Science 7, 62-68. https: / / doi.org / 10.1007 / s11706-013-0191-y (incorporated herein by reference in its entirety), and in particular Table 1 for the possible effect of various admixtures on morphology.

[0251] In certain embodiments, the admixture may include one or more complexing agents, such as ethylenediaminetetraacetic acid (EDTA) and / or 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP). For example, without being bound by theory, EDTA has been reported to retard the crystal growth of calcite and aragonite. A commercially available grade of HEDP, Aquasoft 330, has been reported to control the morphology of CaCO3 and calcium oxalate. See, e.g., Gopi, SP, Subramanian, VK, Palanisamy, K., 2015. Synergistic Effect of EDTA and HEDP on the Crystal Growth, Polymorphism, and Morphology of CaCO3. Industrial & Engineering Chemistry Research 54, 3618-3625. https: / / doi.org / 10.1021 / ie5034039 (incorporated herein by reference in its entirety).

[0252] In certain embodiments, admixtures may include low-molecular-weight and polymeric additives, such as block copolymers, poly(ethylene glycol) (PEG), polyelectrolytes, polyacrylamides, and cellulose, which can significantly affect the crystallization of CaCO3. See, for example, Xie et al., 2006; Xu et al., 2008; Xu et al., 2011; Sadowski et al., 2010; Su et al., 2010 (all of which are incorporated herein by reference in their entirety). Among various templates, PEG is of particular interest because its molecules contain hydrophilic groups that can act as donors for metal ions to form metal complexes with diverse conformations. CaCO3 mineralized without PEG polymer formed rhombohedral calcite crystals with average sizes of 12.5 and 21.5 μm after 5 minutes and 24 hours of incubation, respectively. In contrast, CaCO3 precipitates obtained in the presence of PEG but recovered after 24 hours of incubation exhibited particles with diameters ranging from 13.4 to 15.9 μm. The slight increase in particle size observed at high polymer concentrations may be due to aggregation effects. Therefore, without being bound by theory, it is believed that the presence of poly(ethylene glycol) inhibits the growth of CaCO3 particles in the system. It is known that low- and high-molecular-weight additives can stabilize non-equilibrium morphologies by altering the relative growth rates of different crystallographic planes through specific molecular interactions with specific surfaces that alter the surface energy, growth mechanism, or both. Furthermore, without being bound by theory, the formation of CaCO3 particles in aqueous solution is thought to be due to the presence of poly(ethylene glycol) in the system. 2+ and CO3 2-It is also believed that ACC initially forms, which rapidly transforms into vaterite and calcite within minutes, but that polymer molecules simultaneously adsorb to the particle surface, which may inhibit crystal growth during the process, resulting in the formation of small particles. See, e.g., Polowczyk, I., Bastrzyk, A., Kozlecki, T., Sadowski, Z., 2013 Calcium carbonate mineralization. Part 1: The effect of poly(ethylene glycol) concentration on the formation of precipitate. Faculty of Geoengineering, Mining and Geology, Wroclaw University of Technology, Wroclaw. https: / / doi.org / 10.5277 / ppmp130222 (incorporated herein by reference in its entirety).

[0253] In certain embodiments, the admixture may include a water-soluble polymer as a soluble additive, which may affect, for example, the crystallization of CaCO3; such additives may be present with an insoluble matrix. Exemplary soluble additives include deoxyribonucleic acid (DNA), such as poly(acrylic acid) (PAA), PAAm:poly(allylamine), PGA:poly(glutamic acid) sodium salt, and DNA:sodium salt derived from salmon sperm. These admixtures may be used with one or more substrates, such as glass, poly(ethylene-co-acrylic acid) (PEAA) (20% acrylic acid by weight), or chitosan, where appropriate. PEAA and chitosan contain carboxylic acid and amino groups, respectively. These polymers can be spin-coated onto glass substrates. In the absence of a soluble additive, rhombohedral calcite crystals can grow on all three substrates. Different substrate / polymer combinations may have different effects. For example, in the case of glass, there is no crystallization with PAA or PAAm, whereas spherical crystals can be obtained with PGA additives (vaterite and calcite) or DNA (calcite). The same effect can be seen with additives on PEAA. When chitosan is used, PAA and PGA can give a thin film state of CaCO3. Without being bound by theory, the carboxylic acid groups of PAA and PGA and the amino groups of chitosan may interact, resulting in the formation of thin film crystals. Spherical particles grow sporadically on the surface in the presence of DNA. For a further discussion of these possible admixtures, see, e.g., Kato, T., Suzuki, T., Amamiya, T., Irie, T., Komiyama, M., Yui, H., 1998. Effects of macromolecules on the crystallization of CaCO3 the Formation of Organic / Inorganic Composites. Supramolecular Science 5, 411-415. https: / / doi.org / 10.1016 / S0968-5677(98)00041-8, which is incorporated by reference herein in its entirety.

[0254] The admixture (or each admixture) can be added to any suitable final percentage (bwc), for example, in the range of 0.01 to 0.5 wt. % of the cement, or 0.01 to 0.3 wt. %, or 0.01 to 0.2 wt. %, or 0.01 to 0.1 wt. %, or 0.01 to 1.0 wt. %, or 0.01 to 0.05 wt. %, or 0.05 wt. % to 5 wt. %, or 0.05 wt. % to 1 wt. %, or 0.05 wt. % to 0.5 wt. %, or 0.1 wt. % to 1 wt. %, or 0.1 wt. % to 0.8 wt. %, or 0.1 wt. % to 0.7 wt. %. The admixture (or each admixture in the admixture combination) is added at 0.0001, 0.0002, 0.0005, 0.001, 0.002, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.15, 0.2, 0.3, 0.4, 0.5%, 0.6%, 0.7%, 0.8%, 0.9, or 1.0% bw c, and in certain cases, to a final percentage of less than 10, 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, 0.01, 0.005, 0.002, 0.001, 0.0005, or 0.002% bwc. Other ranges and amounts are as described herein.

[0255] In certain embodiments, sodium gluconate is used as a set retarder admixture in combination with the carbonation of the wash water. Sodium gluconate can be added one or more times in the processes described herein. Any suitable timing and / or amount of sodium gluconate can be used, which, like any admixture, can depend on the mix design of the concrete in the wash water (e.g., the type and amount of cement) and / or the mix design of the concrete to be produced in subsequent batches from the carbonated mix water (e.g., the type and amount of cement). The exact amount of sodium gluconate can be important and can be determined through testing with the mix design to be processed. In certain embodiments, the amount of sodium gluconate, expressed by weight of cement in the wash water, can be 0.1-5%, or 0.2-4%, or 0.5-3%, or 0.7-2%, or 1.0-2.0%, or 1.2-1.8%, or 1.4-1.6%.

[0256] In certain embodiments, the carbonated wash water can be used by itself to accelerate setting, for example, when used as shotcrete, to produce concrete that adheres to the desired surface. In a shotcrete operation, the concrete mix can be delivered to the nozzle either as a wet mix, i.e., mixed with water first, or as a dry mix that is mixed with water just prior to discharge from the nozzle. In the latter case, some or all of the mixing water can be carbonated wash water, and the use of carbonated wash water can reduce or eliminate the flow of concrete delivered by the nozzle to the desired surface. [Example]

[0257] Example 1 In Examples 1-23, the following general protocol was used unless otherwise stated.

[0258] Concrete Mixing Procedure: 1. Add sand and stones and mix for 15 seconds. 2. Add 80% of the water and knead for 15 seconds. 3. Add the cementitious materials and mix for 15 seconds. 4. Add the remaining water / concrete admixture and mix for 3 minutes. 5. Let stand for 3 minutes. 6. Mix for 2 minutes.

[0259] Wash water preparation procedure 1. Weigh out cementitious materials and water into separate buckets in the ratio required to obtain the desired specific gravity. 2. Add the cement to the water and mix with a drill fitted with a grout paddle attachment for approximately 15 seconds. 3. Mix again every 30 minutes to prevent settling. 4. At the appropriate time, add CO2 (as indicated in the specific examples) and / or sodium gluconate (as indicated in the specific examples) to the treatment reactor for injection.

[0260] Wash water carbon dioxide injection system The wash water treatment injection system included a steel container (drum) to hold the water, a vertical sump pump to agitate the wash water, a CO2 line connected to PVC piping, and a copper cooling coil. The wash water was placed in the container and continuously pumped through a PVC piping system that served as a reaction chamber for the CO2 and wash water slurry. A flow meter attached to the CO2 gas line controlled the CO2. Water was passed through the copper coil to cool the system during the CO2 reaction.

[0261] Unless otherwise stated, all admixture concentrations are w / w % of wash water solids.

[0262] An exemplary embodiment is provided herein in which dried, treated wash water solids are used as a cement substitute at 10% and 25% levels. In this exemplary embodiment, wash water was prepared at a specific gravity of 1.10 and allowed to hydrate for 3 hours. After initial hydration, the wash water was added to a CO injection system and treated to 24% C...

Claims

1. 1. An apparatus for introducing carbon dioxide into concrete reclaimed water, comprising: (i) a first conduit operably connected at a proximal end thereof to a source of reclaimed water for the concrete, the first conduit allowing the reclaimed water to flow therethrough from its proximal end and out of its distal end; (ii) a second conduit located inside the first conduit, the second conduit operably connected to a source of carbon dioxide and configured to allow the carbon dioxide to flow therein and therefrom to the reclaimed water in the first conduit; Including, The apparatus, wherein the first conduit is operably connected at its distal end to a regenerator by a fourth conduit, the diameter of the first conduit being greater than the diameter of the fourth conduit.

2. 10. The apparatus of claim 1, wherein the first conduit has a diameter of 0.5 to 5 inches and the second conduit has a diameter of 0.3 to 3 inches.

3. 10. The apparatus of claim 1, wherein the first conduit is operably connected at its proximal end by a third conduit to a source of water for reclaiming the concrete, the diameter of the first conduit being larger than the diameter of the third conduit.

4. (iii) a sensor that senses the specific gravity of the reclaimed water and transmits information about the specific gravity to a controller; (iv) the controller processing the information from the sensor; The apparatus of claim 1 further comprising a control system including:

5. The apparatus of claim 4 , further comprising: (v) an actuator that receives a signal from the controller based at least in part on the processed information from the sensor.

6. The apparatus of claim 5 , wherein the actuator comprises a valve capable of regulating the flow of the carbon dioxide into the second conduit.

7. 2. The apparatus of claim 1, wherein the second conduit includes perforations configured to allow the carbon dioxide to pass from the second conduit to the reclaimed water in the first conduit when the carbon dioxide exceeds a threshold pressure in the second conduit, but not to allow reclaimed water to enter the second conduit from the first conduit.

8. 6. The apparatus of claim 5, a sensor for detecting the level of reclaimed water in the reclaimed water holding tank; a sensor for detecting the temperature of the regenerated water; a sensor for sensing the flow rate of the carbon dioxide into the second conduit; a sensor for detecting whether and / or how much admixture has been added to the reclaimed water; a device that indicates whether a pump that pumps reclaimed water through the first conduit is operating; or Timer and further comprising at least one of The apparatus, wherein the sensor, the device, or the timer is configured to transmit the information to the controller, which processes the information.

9. 6. The apparatus of claim 5, a sensor for detecting the level of reclaimed water in the reclaimed water holding tank; a sensor for detecting the temperature of the regenerated water; a sensor for sensing the flow rate of the carbon dioxide into the second conduit; a sensor for detecting whether and / or how much admixture has been added to the reclaimed water; a device that indicates whether a pump that pumps reclaimed water through the first conduit is operating; or Timer and further comprising at least two of: The apparatus, wherein the sensor, the device, or the timer is configured to transmit the information to the controller, which processes the information.

10. 6. The apparatus of claim 5, a sensor for detecting the level of reclaimed water in the reclaimed water holding tank; a sensor for detecting the temperature of the regenerated water; a sensor for sensing the flow rate of the carbon dioxide into the second conduit; a sensor for detecting whether and / or how much admixture has been added to the reclaimed water; a device that indicates whether a pump that pumps reclaimed water through the first conduit is operating; or Timer and further comprising at least three of: The apparatus, wherein the sensor, the device, or the timer is configured to transmit the information to the controller, which processes the information.

11. 6. The apparatus of claim 5, a sensor for detecting the level of reclaimed water in the reclaimed water holding tank; a sensor for detecting the temperature of the regenerated water; a sensor for sensing the flow rate of the carbon dioxide into the second conduit; a sensor for detecting whether and / or how much admixture has been added to the reclaimed water; a device that indicates whether a pump that pumps reclaimed water through the first conduit is operating; or Timer and further comprising at least four of The apparatus, wherein the sensor, the device, or the timer is configured to transmit the information to the controller, which processes the information.

12. 6. The apparatus of claim 5, wherein the controller further receives information regarding a composition of the reclaimed water, the information including a percentage of the reclaimed water that is cementitious material.

13. 1. A method for treating concrete reclaimed water with carbon dioxide, comprising: (i) flowing the reclaimed water from a source of the reclaimed water into the first conduit at a proximal end of the first conduit and out of the first conduit at a distal end of the first conduit; (ii) flowing the carbon dioxide from the carbon dioxide source into a second conduit located inside the first conduit; and (iii) allowing the carbon dioxide to flow out of the second conduit and into the reclaimed water in the first conduit; Including, The method, wherein the reclaimed water flows out of the first conduit and into a fourth conduit operably connected at a distal end of the first conduit, the first conduit having a diameter greater than the diameter of the fourth conduit.

14. 14. The method of claim 13, wherein the first conduit has a diameter of 0.5 to 5 inches and the second conduit has a diameter of 0.3 to 3 inches.

15. 14. The method of claim 13, wherein the reclaimed water flows from the source of concrete reclaimed water into the first conduit through a third conduit operably connected to the source of concrete reclaimed water and connected to the first conduit at a proximal end of the first conduit, the diameter of the first conduit being larger than the diameter of the third conduit.

16. 14. The method of claim 13, further comprising determining a specific gravity of the reclaimed water and transmitting information about the specific gravity to a controller that processes the information.

17. The method of claim 16 , further comprising transmitting a signal from the controller to an actuator, the signal being based at least in part on the processed information.

18. 18. The method of claim 17, wherein the actuator comprises a valve that regulates the flow of carbon dioxide to the second conduit based at least in part on the signal received from the controller.

19. 14. The method of claim 13, wherein the carbon dioxide moves from the second conduit to the reclaimed water in the first conduit through perforations, the perforations being configured to allow the carbon dioxide to move from the second conduit to the reclaimed water in the first conduit when the carbon dioxide exceeds a threshold pressure in the second conduit, but not to allow reclaimed water to enter the second conduit from the first conduit.

20. 17. The method of claim 16, transmitting information to the controller from at least one of a sensor sensing the level of reclaimed water in a reclaimed water holding tank, a sensor sensing the temperature of the reclaimed water, a sensor sensing the flow rate of the carbon dioxide into the second conduit, a sensor sensing whether and / or how much admixture has been added to the reclaimed water, a device indicating whether a pump pumping reclaimed water through the first conduit is operating, or a timer; processing said information in said controller; The method further comprises:

21. 17. The method of claim 16, transmitting information to the controller from at least two of a sensor sensing the level of reclaimed water in a reclaimed water holding tank, a sensor sensing the temperature of the reclaimed water, a sensor sensing the flow rate of the carbon dioxide into the second conduit, a sensor sensing whether and / or how much admixture has been added to the reclaimed water, a device indicating whether a pump pumping reclaimed water through the first conduit is operating, or a timer; processing said information in said controller; The method further comprises:

22. 17. The method of claim 16, transmitting information to the controller from at least three of a sensor sensing the level of reclaimed water in a reclaimed water holding tank, a sensor sensing the temperature of the reclaimed water, a sensor sensing the flow rate of the carbon dioxide into the second conduit, a sensor sensing whether and / or how much admixture has been added to the reclaimed water, a device indicating whether a pump pumping reclaimed water through the first conduit is operating, or a timer; processing said information in said controller; The method further comprises:

23. 17. The method of claim 16, transmitting information to the controller from at least four of a sensor sensing the level of reclaimed water in a reclaimed water holding tank, a sensor sensing the temperature of the reclaimed water, a sensor sensing the flow rate of the carbon dioxide into the second conduit, a sensor sensing whether and / or how much admixture has been added to the reclaimed water, a device indicating whether a pump pumping reclaimed water through the first conduit is operating, or a timer; processing said information in said controller; The method further comprises:

24. 17. The method of claim 16, wherein the controller further receives information regarding a composition of the reclaimed water, the information including a percentage of the reclaimed water that is cementitious material.

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