Method of manufacturing concrete product comprising post-hardening treatment

Abstract

A method of making a concrete product includes mixing a composition comprising a binder, aggregate, and water to produce a concrete mixture, and shaping the concrete mixture to provide a shaped intermediate product. The shaped intermediate product is carbon-cured to obtain a cured intermediate product. The cured intermediate product is subjected to a post-hardening treatment by exposing the cured intermediate product to a temperature above ambient temperature to obtain a concrete product.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Patent Application No. 63 / 364,504, filed on May 11, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates generally to concrete products, and more particularly to systems and methods for making such concrete products. Background Art

[0004] The conventional manufacture of concrete products comprises mixing a dry mix (which may comprise cement and aggregates) with water. The intermediate product obtained may undergo a conditioning step in which some of the water it contains is evaporated. The conditioned intermediate product then undergoes a separate curing step in order to obtain the final concrete product. Continuous improvements are sought for such concrete products and methods for their manufacture, in particular to make the manufacturing process more environmentally friendly and / or to improve the properties of the resulting concrete product. Summary of the invention

[0005] Thus, a method of manufacturing a concrete product is provided, the method comprising: mixing a composition comprising a binder, an aggregate and water to produce a concrete mixture; giving a shape to the concrete mixture to provide a shaped intermediate product; carbon curing the shaped intermediate product to obtain a cured intermediate product; and post-hardening the cured intermediate product by exposing the cured intermediate product to a temperature above ambient temperature to obtain a concrete product.

[0006] The method defined above and described herein may also comprise, in whole or in part and in any combination, one or more of the following features.

[0007] In certain aspects, exposing the cured intermediate product to a temperature above ambient temperature comprises exposing the cured intermediate product to a temperature of at least 30 degrees Celsius.

[0008] In certain aspects, exposing the cured intermediate product to a temperature comprises exposing the cured intermediate product to a temperature of at least 40 degrees Celsius to 150 degrees Celsius.

[0009] In certain aspects, exposing the cured intermediate product to a temperature comprises exposing the cured intermediate product to a temperature of at least 80 degrees Celsius to 100 degrees Celsius.

[0010] In certain aspects, exposing the curing intermediate product to a temperature comprises increasing the temperature of a curing room containing the curing intermediate product at a rate of 20 degrees Celsius per hour to 120 degrees Celsius per hour.

[0011] In certain aspects, the temperature inside the curing chamber is maintained above at least 30 degrees Celsius.

[0012] In certain aspects, exposing the cured intermediate product to a temperature above ambient temperature comprises exposing the cured intermediate product to an environment having a relative humidity of 10% to 90%.

[0013] In certain aspects, exposing the cured intermediate product to a temperature above ambient temperature comprises exposing the cured intermediate product to the temperature for a period of 1 hour to 72 hours.

[0014] In certain aspects, exposing the cured intermediate product to a temperature above ambient temperature comprises exposing the cured intermediate product to the temperature for at least 6 hours.

[0015] In certain aspects, exposing the cured intermediate product to a temperature above ambient temperature occurs immediately following the carbon cure.

[0016] In certain aspects, the curing intermediate product is stored prior to exposing the curing intermediate product to a temperature above ambient temperature.

[0017] In certain aspects, the method includes wetting the cured intermediate product prior to performing the post-hardening treatment.

[0018] In certain aspects, moistening includes one of: immersing the curing intermediate product in water; spraying the curing intermediate product with water; and misting the curing intermediate product with water.

[0019] In certain aspects, wetting is performed simultaneously with post-hardening treatment.

[0020] In certain aspects, wetting is performed for 0.5 hours to 48 hours.

[0021] In certain aspects, the method further comprises conditioning the shaped intermediate product.

[0022] In certain aspects, providing the composition includes providing a composition comprising a binder, the binder including one or more of: fly ash, calcined shale, silica fume, zeolite, ground granulated blast furnace slag, limestone powder, hydraulic cement, and non-hydraulic cement.

[0023] In certain aspects, providing the composition includes providing a composition having a binder comprising slag, wherein the slag includes one or more of the following: steel slag, stainless steel slag, basic oxygen furnace slag, blast furnace slag, a by-product of zinc production, a by-product of iron production, and a by-product of copper production.

[0024] In certain aspects, providing the composition includes adding admixtures and / or additives to the composition.

[0025] Also provided is a method of manufacturing a concrete product, the method comprising: obtaining a carbon-cured intermediate product; and post-hardening the carbon-cured intermediate product by exposing the carbon-cured intermediate product to a temperature above ambient temperature to obtain a concrete product.

[0026] The method defined above and described herein may also comprise, in whole or in part and in any combination, one or more of the following features.

[0027] In certain aspects, exposing the carbon-cured intermediate product to a temperature above ambient temperature comprises exposing the carbon-cured intermediate product to a temperature of at least 30 degrees Celsius.

[0028] In certain aspects, exposing the carbon-cured intermediate product to a temperature comprises exposing the carbon-cured intermediate product to a temperature of at least 40 degrees Celsius to 150 degrees Celsius.

[0029] In certain aspects, exposing the carbon-cured intermediate product to a temperature comprises exposing the carbon-cured intermediate product to a temperature of at least 80 degrees Celsius to 100 degrees Celsius.

[0030] In certain aspects, exposing the carbon-cured intermediate product to a temperature comprises increasing the temperature of a curing chamber containing the carbon-cured intermediate product at a rate of 20 degrees Celsius per hour to 120 degrees Celsius per hour.

[0031] In certain aspects, the temperature inside the curing chamber is maintained above at least 30 degrees Celsius.

[0032] In certain aspects, exposing the carbon-cured intermediate product to a temperature above ambient temperature comprises exposing the carbon-cured intermediate product to an environment having a relative humidity of 10% to 90%.

[0033] In certain aspects, exposing the carbon-cured intermediate product to a temperature above ambient temperature comprises exposing the carbon-cured intermediate product to the temperature for a period of 1 hour to 72 hours.

[0034] In certain aspects, exposing the carbon-cured intermediate product to a temperature above ambient temperature comprises exposing the carbon-cured intermediate product to the temperature for at least 6 hours.

[0035] Also provided is a method of manufacturing a concrete product, the method comprising: giving a shape to a concrete mixture to provide a shaped intermediate product, the concrete mixture comprising a binder, an aggregate and water; carbon curing the shaped intermediate product to obtain a carbon-cured intermediate product; and wetting the cured intermediate product; and post-hardening the carbon-cured intermediate product by exposing the carbon-cured intermediate product to a temperature higher than an ambient temperature to obtain a concrete product.

[0036] The method defined above and described herein may also comprise, in whole or in part and in any combination, one or more of the following features.

[0037] In certain aspects, moistening includes one of: immersing the curing intermediate product in water; spraying the curing intermediate product with water; and misting the curing intermediate product with water.

[0038] In certain aspects, wetting is performed prior to post-hardening treatment.

[0039] In certain aspects, wetting is performed simultaneously with post-hardening treatment.

[0040] In certain aspects, wetting is performed for 0.5 hours to 48 hours.

[0041] In certain aspects, exposing the carbon-cured intermediate product to a temperature above ambient temperature comprises exposing the carbon-cured intermediate product to a temperature of at least 30 degrees Celsius.

[0042] In certain aspects, the method further comprises exposing the carbon-cured intermediate product to a temperature between 40 degrees Celsius and 150 degrees Celsius.

[0043] In certain aspects, the method further comprises exposing the carbon-cured intermediate product to a temperature between 80 degrees Celsius and 100 degrees Celsius.

[0044] In certain aspects, exposing the carbon-cured intermediate product to a temperature further comprises increasing the temperature at a rate of 20 degrees Celsius per hour to 120 degrees Celsius per hour.

[0045] In certain aspects, exposing the carbon-cured intermediate product to the temperature further comprises exposing the carbon-cured intermediate product to the temperature for a period of from 1 hour to 72 hours.

[0046] In certain aspects, the carbon-cured intermediate product is exposed to the temperature for at least 6 hours.

[0047] After reading this disclosure, those skilled in the art will find many additional features and combinations thereof related to the present improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is a schematic diagram of a system for curing, conditioning and hardening concrete products;

[0049] Figure 2 is a flow chart showing the steps of a method of manufacturing a concrete product; and

[0050] Figure 3 is a flow chart showing the steps of another method of manufacturing a concrete product; and

[0051] Figure 4To be used for Figure 1 Schematic diagram of the computing device of the controller of the system. DETAILED DESCRIPTION

[0052] introduce

[0053] Global interest in reducing the environmental footprint of precast concrete continues to grow. Carbonation curing technology is among the most promising solutions. During carbonation curing, precast concrete hardens primarily through the so-called carbonation reaction, which occurs between carbon dioxide and oxides and / or hydroxides of calcium and / or magnesium in the presence of water. With proper raw material selection, mix design, and process control, carbonated precast concrete can be just as strong and durable as conventional precast concrete and is suitable for a wide range of applications.

[0054] Although carbonized precast concrete has many advantages, its strength development after carbonation curing may be a limiting factor for some applications. Therefore, it may be advantageous to improve the strength of carbonized precast concrete after carbonation curing. Insufficient or limited strength development of carbonized precast concrete may be the result of thick coverage of carbonation reaction products (e.g., carbonates of calcium and / or magnesium) on binder particles. Another factor may be pH changes around the unreacted portion of binder particles after carbonation curing. The thick coverage of carbonates and the reduced pH value may hinder the potential hydration of cementitious binders after carbonation hardening. When a considerable amount of ordinary Portland cement or similar cementitious binders are replaced by materials with poor hydraulic activity or no hydraulic activity, insufficient or negligible strength development after carbonation curing is even more obvious. These alternative materials include slag produced by metal processing, ash produced by power generation or waste incineration, etc. Including such alternative materials can help improve the environmental footprint of concrete and make concrete a more environmentally friendly product. Due to the limited strength increase after carbonation curing, carbonized precast concrete often contains a greater binder content than conventional precast concrete at the same strength grade, thereby increasing the material cost of carbonized precast concrete and reducing its sustainability. Therefore, for some applications, it would be desirable to improve the strength development of precast carbonized concrete, especially precast carbonized concrete containing an alternative to conventional cement-based binders such as slag.

[0055] Traditionally, Portland cement has been used as a binder in concrete production where heat and steam are used for curing. However, the present method can replace at least a portion of the Portland cement with a more environmentally friendly substitute, such as slag. Indeed, such a substitution can be advantageously performed because the present method can still provide satisfactory post-hardening strength even when part or all of the cement (e.g., Portland cement) is replaced by other waste materials (e.g., slag).

[0056] In the production of carbonized precast concrete, when greater strength and durability (e.g., freeze-thaw resistance) are desired, increasing the binder content is a common and accepted practice. Since binder is the most expensive component in the main raw materials used in the production of carbonized precast concrete, increasing the binder content for higher performance often results in higher material costs. The present disclosure provides a post-hardening treatment process that can improve the performance of carbonized precast concrete without increasing the binder content of carbonized precast concrete, or reduce the binder content of carbonized precast concrete without sacrificing the strength and durability of carbonized precast concrete. In either way, by implementing the post-hardening treatment process described herein in the manufacture of carbonized precast concrete with desired performance, significant savings in material costs can be achieved. In addition, in some embodiments, as described above, this post-hardening treatment process is particularly suitable for treating carbonized precast concrete made of such a binder: the binder contains a considerable amount of non-traditional binders derived from industrial waste as cement substitutes. This can be beneficial to carbonized precast concrete from an environmental protection perspective on the basis of the already low carbon footprint of carbonized precast concrete.

[0057] Examples of precast concrete products that can be produced using the post-hardening process described herein include, but are not limited to, concrete pipes, traffic barriers, walls (including retaining walls), boxes (including modular boxes), culverts, tiles, pavers, foundations, slabs (including hollow core slabs), patio slabs, steps, edging, concrete blocks, beams, floors, columns, manholes, sewer pipes, railroad ties, and other precast concrete products.

[0058] Before the carbonized precast concrete is treated with the disclosed post-hardening treatment method, it can be produced using known techniques. As given in the examples, the unreinforced carbonized precast concrete can be made with 20% to 50% by weight of a binder. The precast concrete is prepared by a dry casting method (i.e., water is added to provide the concrete mixture with satisfactory workability, but with a slump close to zero). After forming and consolidation, the precast concrete is demolded and then conditioned to lose 20% to 80% of its initial moisture, and then heated in a CO 2 solution having a concentration of 99.9% and a pressure of 6 psi to 15 psi. 2 Carbonation curing is performed in a pressure chamber of gas for 4 to 24 hours. However, the production of carbonized precast concrete suitable for the post-hardening treatment is not limited by the exemplary method. For example, carbonized precast concrete can also be made under the following conditions: a binder content as low as 10% by weight, a wet pouring manufacturing method, a CO pressure ranging from 0.1 psi to 1200 psi, 2 Pressure (CO 2In gaseous or liquid (supercritical) state at concentrations as low as 10%, carbonization curing durations as short as a few minutes or longer than 24 hours, and conventional strengthening methods. In addition, the conditioning process can be performed before demoulding. In addition, when CO 2 The conditioning process can be avoided when the permeability of the precast concrete (e.g., pervious concrete) is high enough, or the duration of the carbonation cure is long enough, or a simultaneous conditioning and carbonation cure process is applied. In addition, a pre-curing step can be added before demoulding, during which the precast concrete acquires a strength high enough to maintain its shape and resist the destructive forces of other manufacturing processes and demoulding before the carbonation cure.

[0059] The density of the carbonized precast concrete subjected to the post-hardening process can be normal, as shown in the examples presented below. However, lightweight and heavy carbonized precast concrete can also be treated with the post-hardening method. Aggregates used for the production of carbonized precast concrete can be of natural, artificial or recycled origin of normal weight, lightweight and heavy weight. Their gradation and dosage in the mix design follow the general practice of conventional precast concrete production. Similarly, chemical additives and mineral additives (such as pigments, air entraining admixtures, water reducing admixtures, waterproofing mixtures, fibers, accelerators, etc.) used to make carbonized precast concrete and their dosages can also follow the general rules of conventional precast concrete production.

[0060] Maintenance system

[0061] Now refer to Figure 1 , an exemplary system for conditioning and curing concrete products is shown at 10. System 10 includes a carbon dioxide source 11, which may be a tank or canister pneumatically connected to chamber 12 via line 13. In the illustrated embodiment, system 10 includes a heater 14 for heating carbon dioxide as it flows from carbon dioxide source 11 to chamber 12. In this configuration, system 10 includes a valve 15 that can be selectively opened or closed to allow or restrict the flow of carbon dioxide to chamber 12.

[0062] The chamber 12 defines an interior space or chamber 12A that is sized to receive a plurality of concrete products 16 to be cured. In the illustrated embodiment, the chamber 12 includes a top, a bottom, and side walls that are interconnected in an airtight manner. In the context of the present disclosure, "airtight" means that there is little leakage of gas through the chamber 12 under the pressure differential to which the chamber 12 is subjected. The pressure differential corresponds to the difference between the pressure inside the chamber 12 and the ambient pressure outside the chamber 12. The chamber 12 may be structurally designed to withstand the pressure differential created by the pressure of the carbon dioxide inside the chamber 12 being greater than the atmospheric pressure outside the chamber 12. A blower 17 may be located in the chamber 12A of the chamber 12 and may be operable to generate an airflow F that may accelerate the conditioning and / or curing process.

[0063] In some embodiments, the chamber 12 can be used to cure the concrete product 16 using low pressure curing. In the context of the present disclosure, the expression "low pressure" means a pressure that exceeds ambient pressure by up to 10% of ambient pressure. More details about low pressure curing are presented in U.S. Patent Application No. 17 / 581,320 filed on January 21, 2022, the entire contents of which are incorporated herein by reference. The chamber 12 can be a deployable structure (e.g., a bag).

[0064] The system 10 may also include one or more sensors 18, which may include one or more of a temperature sensor and a humidity sensor. The temperature sensor and humidity sensor 18 are operably connected to the chamber 12A and are operable to generate one or more signals indicative of the temperature and humidity levels inside the chamber 12. A scale or balance 19 may support the chamber 12 and be used to measure the weight change of the concrete product 16 during the conditioning and curing stages. The balance 19 may send a signal indicative of the weight of the chamber 12 containing the concrete product 16. More specifically, the moisture content of the concrete product 16 is expected to evaporate during the conditioning and curing stages. The balance 19 may measure this weight change and may be used to determine whether the conditioning and curing process is complete.

[0065] In the illustrated embodiment, the system 10 includes a controller 20 that can be operably connected to the temperature and humidity sensor 18, to the scale 19, to the heater 14, to the blower 17, and to the valve 15. Thus, the controller 20 can independently control the injection of carbon dioxide through the valve 15 and the actuation of the blower 17. In the illustrated embodiment, the controller 20 includes a computing device 400, such as described below with reference to Figure 4The computing device 400 shown and described. The controller 20 can act as a data logger to save temperature, weight, pressure, etc. data points during the conditioning and curing process. The controller 20 is operable to receive data from the temperature and humidity sensor 18 and from the scale 19, and is operable to control the operating parameters of the heater 14, valve 15, and blower 17. These operating parameters may include, for example, the temperature of the heater 14; whether the valve 15 should be open, closed, or in an intermediate position to control the flow of carbon dioxide through the valve 15; the speed of the blower 17; etc.

[0066] In some embodiments, the conditioning phase occurs while the concrete product 16 is located inside the chamber 12. During the conditioning phase, it is expected that water will be released from the concrete product 16. Since the chamber 12 is closed relative to the environment outside the chamber 12, it is expected to absorb moisture extracted from the concrete product. In the present case, the desiccant material 21 is located inside the chamber 12 and is used to absorb excess moisture. The desiccant material can be a hygroscopic material used to cause or maintain a dry state in its vicinity. These desiccant materials can absorb water. In a specific example, the desiccant material can include silica gel. The desiccant material can be in a form other than solid and can function by other principles (such as chemical bonding of water molecules). The desiccant material can include activated carbon, calcium sulfate, calcium chloride, zeolite, etc. in any combination. The desiccant material can be an adsorbent material, rather than an absorptive material. An absorptive material will contain water by allowing water to permeate through it. The absorptive material can be porous, and water can be absorbed by penetrating the pores of the absorptive material. The adsorbent material will stick to the water molecules. In other words, water will be retained by the adsorbent material by being adhered to the surface of the adsorbent material. The adsorbent material can attract moisture and hold it on its surface like a magnet. It should be understood that any means capable of extracting moisture from the chamber 12 during simultaneous curing and conditioning can be used. For example, a dehumidifier, air conditioner, and any other suitable means can be used.

[0067] In the illustrated embodiment, the system 10 may include a heating element 22 located in the chamber 12A, the heating element 22 being used to raise the temperature inside the chamber 12A for a post-hardening process, which will be further described below. The heating element 22 may be operably connected to a power source 23 and to a controller 20, which may control the operation of the heating element 22. It should be understood that any suitable means for raising the temperature in the chamber 12A are contemplated. For example, chemical components that produce an exothermic reaction when mixed may be disposed inside the chamber 12A. The chamber 12A may be heated by heating the walls of the chamber 12. This may be done with gas, electricity, induction, hot water, etc.

[0068] method

[0069] Methods of making concrete products are provided. The inventors of the present disclosure unexpectedly discovered that the strength of precast carbonized concrete is significantly improved after a post-hardening heat treatment. A second unexpected discovery is the determination that the strength of carbonized precast concrete can be further improved by performing a wetting / humidification step (e.g., water absorption) prior to the post-hardening heat treatment. After the wetting step and heat treatment are completed, the carbonized precast concrete is found to have improved strength when compared to its counterpart immediately following carbonization curing.

[0070] The current disclosure also includes a post-hardening process to strengthen the carbonized precast concrete. During this process, the precast concrete that has been subjected to carbonization curing is exposed to a heated environment. In other words, the carbonized precast concrete is baked at a temperature higher than the ambient temperature. The post-hardening process can be performed in a carbon dioxide curing chamber, or it can be performed in another suitable chamber. The post-hardening process can be performed on the carbonized precast concrete immediately after the carbonization curing is completed, or it can be performed after the carbonization curing is completed for an unlimited period of time. The temperature range during the post-hardening process can be 40°C to 150°C, wherein higher temperatures are generally conducive to the performance improvement of the carbonized precast concrete. The relative humidity range during the post-hardening process can be 10% to 90%. The duration of the post-hardening process can be from about 1 hour to about 72 hours. The detailed post-hardening process conditions are determined by the concrete mix ratio, the type of raw materials, and the desired performance.

[0071] It is believed that the durability (e.g., freeze-thaw resistance) of the reinforced precast concrete can also be improved with this post-hardening step. Therefore, this added step can enhance the mechanical properties and durability of the carbonized precast concrete, and / or reduce the material costs in its production.

[0072] In the context of the present disclosure, the expression "about" means a variation of plus or minus 10%.

[0073] Now refer to Figure 2 , a method of manufacturing a concrete product is shown at 200. The method includes providing a composition including a binder, an aggregate, and water at 202; mixing the binder, the aggregate, and the water to produce a concrete mixture at 204; giving a shape to the concrete mixture at 206 to provide a shaped intermediate product; carbon curing the shaped intermediate product at 208 to obtain a cured intermediate product; and post-hardening the cured intermediate product by exposing the cured intermediate product to a temperature above ambient temperature at 210 to obtain a concrete product.

[0074] Another method of manufacturing a concrete product is shown at 300. The method 300 includes obtaining a curing intermediate product at 302 and post-hardening the curing intermediate product by exposing the curing intermediate product to a temperature above ambient temperature at 304 to obtain a concrete product.

[0075] Mixing and molding

[0076] In the illustrated embodiment, the step 202 of providing a composition may include providing a composition that does not contain slag. Providing a composition at 202 may include providing a composition comprising a binder, the binder comprising one or more of the following: fly ash, calcined shale, silica fume, zeolite, ground granulated blast furnace slag, limestone powder, hydraulic cement, and non-hydraulic cement. Providing a composition at 202 may include providing a composition with a binder comprising slag, the slag comprising one or more of the following: steel slag, stainless steel slag, basic oxygen converter slag, blast furnace slag, byproducts of zinc production, byproducts of iron production, and byproducts of copper production. Steel slag may include one or more of the following: reduced steel slag, oxidized steel slag, converter steel slag, arc furnace slag, basic oxygen furnace slag, ladle slag, fast cooling steel slag, and slow cooling steel slag. Providing the composition at 202 may include providing a composition further comprising one or more of the following: an accelerator, a retarder, a viscosity modifier, an air entraining agent, a foaming agent, an alkali-silica reaction inhibitor, an anti-scour agent, a corrosion inhibitor, a shrinkage reducer, a concrete crack reducer, a plasticizer, a superplasticizer, a sealant, a paint, a coating, a water reducer, a waterproofing agent, a weathering control agent, a polymer powder, a polymer latex, and a workability retaining agent. Providing the composition at 202 may include providing a composition further comprising one or more of the following: cellulose fibers, glass fibers, microsynthetic fibers, natural fibers, polypropylene fibers, polyvinyl alcohol fibers, and steel fibers.

[0077] Therefore, the carbonized precast concrete suitable for the post-hardening treatment can be made of cement-based binders, limited cement-based binders and / or non-cement-based binders. These binders can have strong hydraulic activity, such as any one or combination of the following materials: ordinary Portland cement (OPC); high alumina cement; white cement; magnesium cement; OPC blended with limestone or supplementary cement-based materials including ground granulated blast furnace slag (GGBFS), fly ash and natural and calcined pozzolanic materials. These binders can also have poor hydraulic activity or no hydraulic activity, such as any one or combination of the following materials: calcium hydroxide, GGBFS, steel slag, stainless steel slag, fly ash, non-hydraulic cement and calcium hydroxide rich in CaO and / or MgO and / or Ca(OH) 2and / or Mg(OH) 2 other materials. These binders can also be a combination of materials with hydraulic activity and poor hydraulic activity or no hydraulic activity. Preferably, the binder suitable for the manufacture of carbonized precast concrete subjected to the post-hardening treatment contains at least 10% by weight of materials with poor hydraulic activity or no hydraulic activity. More preferably, the binder suitable for the manufacture of carbonized precast concrete subjected to the post-hardening treatment contains at least 25% by weight of materials with poor hydraulic activity or no hydraulic activity. More preferably, the binder suitable for the manufacture of carbonized precast concrete subjected to the post-hardening treatment contains at least 50% by weight of materials with poor hydraulic activity or no hydraulic activity. More preferably, the binder suitable for the manufacture of carbonized precast concrete subjected to the post-hardening treatment contains at least 75% by weight of materials with poor hydraulic activity or no hydraulic activity. More preferably, the binder suitable for the manufacture of carbonized precast concrete subjected to the post-hardening treatment contains at least 100% by weight of materials with poor hydraulic activity or no hydraulic activity.

[0078] As shown in the following examples, steel slag can be used as the sole component of a binder for carbonized precast concrete production in this article. "Steel slag" refers to a slag byproduct produced by steelmaking in this article. Steel slag can include slag produced by a basic oxygen furnace (Basic Oxygen Furnace, BOF), also known as slag from the Linz-Donawitz (Linz-Donawitz, LD) process, or LD slag. Steel slag can also include slag produced by an electric arc furnace (Electric Arc Furnace, EAF). Steel slag as used herein can also include ladle slag, which is produced as a byproduct from a ladle refining operation. Steel slag as used herein can also include stainless steel slag produced by stainless steel production, which is mainly produced by argon oxygen decarburization (argonoxygen decarburization, AOD) and / or ladle metallurgy (ladle metallurgy, LM) processes. In addition, steel slag can be a combination of the above slags. For example, "EBH slag" as used herein refers to EAF-BOF mixed slag, which is a type of steel slag formed by a mixture of slags produced by EAF and BOF.

[0079] In one embodiment, the steel slag used herein has a cumulative calcium silicate content of at least about 15 wt.% (Example: CS+C 2 S+C 3 In one embodiment, the steel slag used herein has a cumulative calcium silicate content of at least about 20 wt. % (Example: CS+C 2 S+C 3In one embodiment, the steel slag used herein has a cumulative calcium silicate content of at least about 30 wt. % (Example: CS+C 2 S+C 3 In one embodiment, the steel slag used herein has a cumulative calcium silicate content of at least about 40 wt % (Example: CS+C 2 S+C 3 In one embodiment, the steel slag used herein has at least about 6 wt %, or more preferably at least about 15 wt % SiO 2 content.

[0080] The steel slag may include a mixture of coarse slag pieces and fine slag pieces. The Blaine fineness of the coarse slag pieces may be less than about 50 μm. 2 / kg, and the Blaine fineness of the fine slag can be greater than about 50m 2 / kg. Coarse slag chunks, fine slag chunks, or both can be landfilled as a result from a typical steelmaking process. The received slag from waste materials (e.g., landfills and / or industrial waste) can be optionally refined. Refining the slag can include filtering the received slag to separate the fine slag chunks from the coarse slag chunks. Alternatively, or in addition, refining the received slag can also include crushing the slag into a fine powder. In some exemplary embodiments, the filtered fine chunks are crushed, while the coarser chunks are not crushed. For example, for EAF slag, the slag can be crushed to at least 50m2 / kg, and preferably a Blaine fineness of about 180m2 / kg. For example, for EBH slag (a mixture of EAF and BOF and ladle slag), the slag can be crushed to at least 100m2 / kg, and preferably a Blaine fineness of about 240m2 / kg. In other exemplary embodiments, the slag can be crushed to a finer size. In another example, at least fifty percent of the ground slag may be less than 100 microns, and at least ten percent of the ground slag may be less than 50 microns, ie, D(50) < 100 microns, and D(10) < 50 microns.

[0081] It should be understood that "steel slag" as used herein does not include iron slag and blast furnace slag, such as pozzolanic slag, which is typically produced during iron production and can be used to make cement.

[0082] In the production of concrete products, various types of aggregates (including natural or artificial normal weight and lightweight aggregates) can be incorporated into dry concrete products or wet concrete products as fillers. Examples of potential lightweight aggregates include natural lightweight aggregates (such as pumice), expanded clay aggregates, expanded shale aggregates, and expanded iron slag aggregates. Other available aggregates include: crushed stone, artificial sand, gravel, sand, recycled aggregates, granite, limestone, quartz, chalk powder, marble powder, quartz sand, and artificial aggregates. These aggregates are incorporated into the mixture as fine aggregate and / or coarse aggregate. The aggregate content can be as high as 90% by weight of the concrete composition.

[0083] In some embodiments, providing the composition includes providing a composition comprising one or more chemical admixtures and / or one or more minerals.

[0084] In some embodiments, providing the composition at 202 includes providing a composition that does not contain slag. Providing the composition at 202 may include providing a composition that includes a binder, the binder including one or more of: fly ash, calcined shale, silica fume, zeolite, ground granulated blast furnace slag, limestone powder, hydraulic cement, and non-hydraulic cement.

[0085] In some embodiments, providing the composition at 202 includes providing a composition having a binder including slag, the slag including one or more of: steel slag, stainless steel slag, basic oxygen furnace slag, blast furnace slag, a byproduct of zinc production, a byproduct of iron production, and a byproduct of copper production. The steel slag may include one or more of: reduced steel slag, oxidized steel slag, converter steel slag, electric arc furnace slag, basic oxygen furnace slag, ladle slag, fast cooling steel slag, and slow cooling steel slag.

[0086] Providing the composition at 202 may include providing a composition having one or more of the following: an accelerator, a retarder, a viscosity modifier, an air entraining agent, a foaming agent, an alkali-silica reaction inhibitor, an anti-scour agent, a corrosion inhibitor, a shrinkage reducer, a concrete crack reducer, a plasticizer, a superplasticizer, a sealant, a paint, a coating, a water reducer, a waterproofing agent, a weathering control agent, a polymer powder, a polymer latex, and a workability retaining agent. Providing the composition at 202 may include providing a composition having one or more of the following: cellulose fibers, glass fibers, microsynthetic fibers, natural fibers, polypropylene fibers, polyvinyl alcohol fibers, and steel fibers.

[0087] The binder material intended for use may be reactive towards carbon dioxide. However, the binder may have a certain level of hydraulic properties. In other words, the binder may be reactive towards water.

[0088] In the illustrated embodiment, the step 204 of mixing the binder, aggregate, and water to produce a concrete mixture may include producing a wet mixture having a ratio of mixed water to binder. Mixing the binder, aggregate, and water to produce a concrete mixture at 204 may include producing a dry mixture having a different ratio of mixed water to binder. There are many suitable methods of performing mixing of a concrete mixture (e.g., with a mixing drum).

[0089] Mixing the binder, aggregate, and water to produce the concrete mixture at 204 may include producing a wet mixture having a mixing water to binder ratio. Mixing the binder, aggregate, and water to produce the concrete mixture at 204 may include producing a dry mixture having a different mixing water to binder ratio.

[0090] Herein, giving the concrete mixture a shape at 206 includes pouring the concrete mixture into a mold to provide a molded intermediate product. The method 200 of this embodiment includes the step of demolding the molded intermediate product to provide a demolded intermediate product. In some embodiments, carbon curing of the molded intermediate product at 208 may include simultaneously conditioning and curing the molded intermediate product. In some embodiments, simultaneous conditioning and curing of the molded intermediate product includes simultaneously conditioning and curing the molded intermediate product while the molded intermediate product is still inside the mold.

[0091] At step 206, giving shape to the concrete mixture may include shaping and consolidating the concrete mixture under compaction and vibration to provide a shaped intermediate product. In some embodiments, giving shape may include transferring the freshly prepared concrete mixture by any appropriate means and pouring it into a prepared mold. The mold may be made of steel, iron, aluminum, plastic, FRP or another material. The mold may be pre-lubricated before pouring to facilitate the demoulding process. If a wet mixture is used, it may be consolidated in the mold by an internal vibrator or an external vibrator. In some cases, the consolidation step lasts no more than 120 seconds. Dry cast concrete may be compacted / pressed / pressed / molded into the mold by compaction and / or vibration. Giving shape at 206 may include pouring the concrete mixture in the following shapes: precast, concrete pipe, box culvert, drainage product, paving slab, floor slab, traffic barrier, wall inspection well, retaining wall, paving material, tile or shingle.

[0092] In some embodiments, method 200 may include demolding the shaped intermediate product prior to carbon curing at 208. The method may include conditioning the shaped intermediate product until the water to binder ratio (which corresponds to the first water to binder ratio after imparting shape at 206) reaches a second water to binder ratio that is lower than the first water to binder ratio. After the conditioning step, the conditioned intermediate product may be demolded to provide a demolded conditioned intermediate product. The demolded conditioned intermediate product may then undergo a carbon curing step at 208.

[0093] In some embodiments, method 200 includes inserting a reinforcement material inside the mold before pouring the concrete mixture. Inserting the reinforcement material may include inserting a rod made of a reinforcement material, the reinforcement material including one or more of the following: carbon steel, stainless steel, and fiber reinforced polymer.

[0094] Post-hardening

[0095] In the illustrated embodiment, exposing the cured intermediate product to a temperature above ambient temperature at 210 includes exposing the cured intermediate product to a temperature of at least 30 degrees C. Preferably, the cured intermediate product is exposed to a temperature of at least 40 degrees Celsius to 150 degrees Celsius, preferably 80 degrees Celsius to 100 degrees Celsius.

[0096] In some embodiments, exposing the curing intermediate product to a temperature at 210 may include increasing the temperature of the chamber 12A containing the curing intermediate product at a rate of 20 degrees Celsius per hour to 120 degrees Celsius per hour. The temperature inside the curing chamber may then be maintained above at least 30 degrees Celsius. Exposing the curing intermediate product to a temperature above the ambient temperature at 210 may include exposing the curing intermediate product to an environment with a relative humidity of 10% to 90%. Exposing the curing intermediate product to a temperature above the ambient temperature at 210 may include exposing the curing intermediate product to the temperature for 1 hour to 72 hours, preferably for at least 6 hours.

[0097] In some embodiments, exposing the cured intermediate product to a temperature above ambient temperature at 210 is performed immediately after the carbon curing at 208. Alternatively, prior to exposing the cured intermediate product to a temperature above ambient temperature at 210, the cured intermediate product may be stored under suitable conditions.

[0098] This post-hardening treatment is an additional step to the carbonization step in precast concrete production in order to enhance the CO 2 Cured concrete product. It is generally believed that the durability (e.g., freeze-thaw resistance) of the strengthened precast concrete should also be improved. Therefore, this added step can enhance the mechanical properties and durability of the carbonized precast concrete and / or reduce the material costs in its production.

[0099] The post-hardening treatment as described in the present disclosure is performed on the precast concrete that has been carbonized. During the post-hardening treatment, the carbonized precast concrete is exposed to a temperature higher than the ambient temperature for a specified period of time. In other words, the carbonized precast concrete is baked under hot conditions for a specified period of time after carbonization curing. The temperature for treating the carbonized precast concrete can be 40°C to 150°C. A treatment temperature of 80°C or higher is preferred. In some cases, a treatment temperature of 100°C or higher is preferred. In order to reach the specified treatment temperature, the heating rate at the beginning of the post-hardening treatment can be 20°C / hour to 120°C / hour. After reaching the specified treatment temperature, the temperature can be maintained until the post-hardening treatment is completed. Alternatively, the carbonized precast can be loaded into the treatment chamber after the chamber has been heated to the specified temperature. The duration of the post-hardening treatment can be 1 hour or more. The duration of the post-hardening treatment is more preferably 6 hours or more, but less than 72 hours. During the post-hardening treatment, the relative humidity around the carbonized precast concrete can be 10% to 90%. The detailed temperature and duration of the post-hardening treatment depend on the type of raw materials, in particular the type of binder, the percentage of binder, the thickness of the product, the concrete mix, the relative humidity, the degree of carbonation curing and the desired properties of the treated carbonized precast concrete.

[0100] In some embodiments, the post-hardening treatment is preferably started immediately after the carbonation curing of the precast concrete is completed. However, the post-hardening treatment can also be carried out after the carbonized precast concrete has been stored for an unspecified period of time under normal conditions.

[0101] In some embodiments, the post-hardening treatment is preferably carried out in the chamber where the carbonation curing takes place. However, the post-hardening treatment may be carried out in another chamber after the carbonized precast concrete is removed from the carbonation curing chamber. During the post-hardening treatment, the treatment chamber may be sealed or unsealed, although a sealed chamber is preferred.

[0102] Heating during the post-hardening treatment can be achieved by conventional methods (e.g., gas or oil burners, boilers, infrared heating elements, etc.). In another embodiment, the heat generated during the carbonization curing process can be recovered and reused in the post-heat treatment process. An air circulation system is required to bring the hot air from the heat source to the treatment chamber and also evenly distribute the heat around the carbonized precast concrete. If necessary, the air circulation system can also have the function of taking the moisture accumulated in the air out of the treatment chamber.

[0103] The improved properties of the carbonized precast concrete caused by the present post-hardening treatment are believed to be the result of the production of larger and stronger calcium carbonate particles in the carbonized precast concrete after the post-hardening treatment. In other words, more crystalline calcium carbonate is produced inside the carbonized precast concrete due to the post-hardening treatment, which contributes to the enhanced mechanical and durability properties. In addition, after the temperature is increased, some of the unreacted dissolved calcium ions and carbonic acid in the carbonized precast concrete can have a chance to react, thereby improving the strength and durability of the carbonized precast concrete. In addition, at the elevated temperature, some of the uncarbonated dissolved calcium silicate can be hydrated, which contributes to the strength development of the carbonized precast concrete. In addition, the structure and crystallinity of the calcium carbonate produced during the carbonation curing process can be improved, resulting in an improved microstructure and structure as a result of the proposed post-hardening treatment.

[0104] The post-hardening treatment includes a heat treatment that exposes the precast concrete to a temperature of at least 30°C to obtain a concrete product. In some embodiments, the post-hardening treatment has a duration of at least 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 8 hours, 10 hours, 12 hours, 18 hours or 24 hours, and may have an upper limit of 72 hours. In some embodiments, the post-hardening treatment is carried out at a temperature of at least 35°C, at least 40°C, at least 45°C, at least 50°C, at least 55°C, at least 60°C, at least 65°C, at least 70°C, at least 75°C, at least 80°C, at least 85°C, at least 90°C, at least 95°C, at least 100°C, 30°C to 150°C, 40°C to 150°C, 50°C to 150°C, 60°C to 150°C, 70°C to 150°C, 80°C to 150°C, or 80°C to 110°C.

[0105] The following are some examples whose purpose is to demonstrate that desirable properties can be obtained by post-hardening carbonized precast concrete using the method of the present disclosure. Both the raw materials and the processes are not limited to those given in these examples.

[0106] These examples can demonstrate that the desired properties can be obtained by post-hardening the carbonized precast concrete using the method of the present disclosure. Therefore, as shown below, a post-hardening process 200 is also provided, which includes the following steps: providing carbonized precast concrete 202 and heat treating the carbonized precast concrete at a temperature of 30° C. to 150° C. 204 to obtain reinforced concrete. The carbonized precast concrete can be produced by the steps described herein or other methods known in the art.

[0107] Wet

[0108] Before the post-hardening treatment, or at the same time as the post-hardening treatment, the carbonized precast concrete can be wetted. The wetting step can include, for example; immersing the curing intermediate product in water; spraying the curing intermediate product with water; and / or spraying the curing intermediate product with water. Therefore, in certain embodiments, the curing intermediate product is wetted by: soaking in tap water or water saturated with slaked lime for a period of not longer than 24 hours, or by sprinkling, spraying and / or spraying with tap water. In certain embodiments, the wetting is carried out for a period of 0.5 hours to 48 hours. For the wetted carbonized precast concrete, the preferred moisture content increase is 0.5% by weight or higher. There can be a delay of up to 24 hours between the proposed wetting step and the subsequent post-hardening treatment. For the carbonized precast concrete made of a binder with hydraulic activity, such a wetting step can be advantageous. Optionally, the water used for soaking / spraying can contain minerals / chemicals, such as weathering reducer admixtures or waterproofing agents. Alternatively, the carbonized precast concrete can be surrounded by water vapor during the post-hardening treatment.

[0109] At step 208, carbon curing of the precast concrete is performed to obtain carbonized precast concrete. In some embodiments, the calcium and CO leached from the calcium-rich material 2 After dissolving in water, the carbonation reaction between the calcium-rich material and carbon dioxide occurs. In concrete samples, the reaction usually occurs at a specified pore saturation. After the pores are filled with water and the saturation is at or close to 100%, there is almost no reaction between the slag and carbon dioxide. This observation is also valid when there is no water in the pores or when the pore saturation is zero percent. The optimum pore saturation or, more simply, the moisture content of the mix results in the highest carbonation reaction rate. Deviation from the optimum moisture content may result in a lower carbonation reaction and lower concrete properties.

[0110] In some embodiments, before the post-hardening treatment at step 210, the carbonized precast concrete can be wet or moistened. In some embodiments, the carbonized precast concrete is soaked in tap water or water saturated with slaked lime for a period of no longer than 24 hours, or by spraying with tap water. For wet carbonized precast concrete, the preferred moisture content increase is 0.5 weight % or higher, such as at least 0.55%, at least 0.6%, at least 0.65%, at least 0.7%, or at least 0.75%. There can be a delay of up to 24 hours between the optional wetting / wetting step and the subsequent post-hardening treatment 210. The described wetting or wetting step can be advantageous for the carbonized precast concrete made of a binder with hydraulic activity. Optionally, the water used for soaking / spraying can contain minerals / chemicals, such as weathering reducer admixtures or waterproofing agents. Alternatively, the carbonized precast concrete can be surrounded by water vapor during the post-hardening treatment. Therefore, in some embodiments, the steps of wetting and curing can overlap or can occur simultaneously.

[0111] In some embodiments, during the water absorption test, the carbonized precast concrete is immersed in water for 24 hours and then dried at 100° C. to 115° C. for not less than 24 hours.

[0112] Parallel adjustment and maintenance

[0113] The method 200 may include simultaneously regulating and curing the intermediate product. This may include regulating the intermediate product while curing the intermediate product, wherein the intermediate product is cured and regulated simultaneously to obtain a final water-to-binder ratio that is less than the first water-to-binder ratio. In other words, while curing the intermediate product, the water content of the intermediate product is reduced from the first water-to-binder ratio to the final water-to-binder ratio. In other words, concurrently regulating and curing may include performing a curing process for the intermediate product, the curing process starting at a first time and completing at a second time, and regulating the intermediate product between the first time and the second time.

[0114] In this context, the expression "in parallel" means that two processes occur simultaneously. In other words, while the shaped intermediate product is being cured, some water evaporates from the shaped intermediate product as part of the conditioning process. Typically, the water to binder ratio is constant during the curing process because water that is not required by the concrete composition has been removed during the conditioning process that precedes the curing process. In the present method 200, curing of the shaped intermediate product occurs while excess water evaporates from the shaped intermediate product.

[0115] In the illustrated embodiment, the step of simultaneously conditioning and curing the shaped intermediate product may include inserting the shaped intermediate product in a chamber 12 that is sealed from the environment outside the chamber 12. Then, carbon dioxide at a concentration of at least 5% by volume is injected into the chamber 12. Other concentrations are contemplated. In this embodiment, the step of simultaneously conditioning and curing the shaped intermediate product includes absorbing water evaporated from the shaped intermediate product during parallel conditioning and curing. Absorbing water evaporated from the shaped intermediate product may include absorbing water with a desiccant material contained in the chamber 12. In some embodiments, a dehumidifier may be used to extract moisture from the chamber 12. The parallel conditioning and curing at 208 may be performed without an additional external heat source and / or without pressure (e.g., mechanical pressure).

[0116] In the embodiment shown, the moisture content and / or water content of the concrete mix can be reduced from a high moisture content to an optimal moisture content, and can be even below the optimal moisture content required for the carbonation reaction. During the concurrent conditioning and curing process at 208, the presence of carbon dioxide inside the chamber (chamber / enclosed environment / container) 12 can cause precipitation of calcium carbonate, which can improve strength development in the concrete product. In other words, accelerated carbonation curing occurs while the relative humidity of chamber 12A of chamber 12 remains low. Any precast concrete product (including but not limited to concrete blocks, paving stones, retaining walls, slabs, traffic barriers, pipes, culverts, etc.) can be produced using the proposed process.

[0117] In the present disclosure, pore saturation can be reduced during the concurrent conditioning and carbonation curing at 208. The fresh concrete product is dried or semi-dried with the help of reduced relative humidity. Low RH can be obtained by the presence of absorbent materials and / or elevated temperature combined with airflow (e.g., with blower 17) inside the chamber for better efficiency. In some embodiments, the airflow velocity generated by blower 17 or other suitable means can be at least 0.1 m / sec. The absorbent or desiccant material can be silica gel, clay, calcium oxide, calcium chloride, molecular sieve, activated carbon, any other industrial absorbent, or any combination of these. The presence of absorbent in a closed environment with airflow generated by fan or blower 17 or by other means can gradually reduce the moisture content of the fresh concrete. The circulating air can be cold or hot. Any mechanical device (including dehumidifiers that use heating and ventilation or condensation methods to extract water from the air) can also be used to reduce the RH inside chamber 12A.

[0118] During the concurrent conditioning and curing at 208, the air circulation rate may vary. In some cases, the blower 17 may be non-operating (e.g., no airflow). This means that the carbon dioxide inside the chamber 12 is stationary. This may be done with a controller 20 that varies the speed of the blower 17. The amount of absorbent material 21 required may depend on the type of material used, the total moisture content in the concrete product, the type of concrete product, and the target specifications required or sought. Fresh air may be introduced into the chamber 12A from outside the chamber 12A, or in another embodiment from inside the closed chamber. In other words, a port 12B ( Figure 1 ) to inject air through one of the walls of the chamber 12. Simultaneous regulation at 208 and CO 2 The curing process can continue even after the carbonation reaction stops to reduce the moisture content of the concrete product. The absorbent material 21 can be used for several cycles. The absorbent materials can be replaced with new materials after they lose their ability to capture moisture from the air. The absorbent materials can be placed at any location inside the chamber or can be evenly distributed inside the chamber.

[0119] In another embodiment, the concurrent conditioning and curing steps at 208 may be performed by introducing and circulating hot air. If hot dry air is introduced into the chamber, the use of absorbent materials would be optional.

[0120] In another example, the air inside the chamber can be heated by elements, heaters, and other known means. If the air inside the chamber is heated, then the use of absorbent materials may be optional. In another embodiment, the body of the chamber can be heated by external heating blankets and other means known in the art. If the body of the chamber is heated in CO 2 The use of absorbent materials is optional if the curing process is carried out while being heated. One or a combination of both of the above conditioning methods may be implemented.

[0121] In simultaneous water extraction and CO 2 During the curing process, the fresh concrete removed from the formwork can be exposed to carbon dioxide CO 2 or containing CO 2 The carbon dioxide gas introduced to cure the concrete is 5%, preferably 10%, preferably 20%, preferably 30%, preferably 40%, preferably 50%, preferably 60%, preferably 70%, preferably 80%, preferably 90%, or preferably 99.5%. The gauge pressure of the gas will be gradually increased to the range of 0.1 psi, and optionally to 100 psi.

[0122] Concrete products can be conditioned and CO 2The pressure is maintained for a given time limit, which may be at least 10 minutes, despite the simultaneous regulation at 208 and the CO 2 The curing process can last up to 48 hours.

[0123] Simultaneously conditioning and curing the shaped intermediate product at 208 may include simultaneously conditioning and curing the shaped intermediate product without additional external heat sources and / or pressure.

[0124] In some embodiments, the drying rate can be varied in the presence of carbon dioxide during the concurrent conditioning and curing at step 208. Drying variation can be provided by various means, such as air flow with varying speed, temperature variation, or relative humidity variation (by one or more of desiccant materials and mechanical means).

[0125] The concurrent conditioning and curing steps at 208 may be accomplished without an additional external heat source. In some embodiments, the concurrent conditioning and curing steps at 208 may be accomplished with an additional external heat source.

[0126] At step 202, various types of aggregates (including natural or artificial normal weight and lightweight aggregates) can be provided as fillers in the production of hardened concrete of the present disclosure. Examples of potential lightweight aggregates include, but are not limited to, natural lightweight aggregates (e.g., pumice), expanded clay aggregates, expanded shale aggregates, and expanded iron slag aggregates. Other available aggregates include, but are not limited to, crushed stone, artificial sand, gravel, sand, recycled aggregates, granite, limestone, quartz, chalk powder, marble powder, quartz sand, and artificial aggregates. These aggregates can be incorporated into the mixture as fine aggregate and / or coarse aggregate. The aggregate content in the concrete mixture can be as high as 90% by weight of the concrete mixture.

[0127] Example

[0128] Example 1 - Post-hardening treatment of carbonized precast concrete made with different slag contents

[0129] Precast concrete samples were prepared with the binder contents shown in Table 1. The binder used was steel slag, more specifically a mixture of EAF slag and BOF slag. It was refined to the required fineness before being used as a binder. It had a cumulative calcium silicate content of at least about 2%, a calcium oxide content of at least 20%, and a silicon dioxide content of at least about 6%. Its specific gravity was 3.4. The normal weight aggregate used was crushed stone having a specific gravity of 2.7 and 100% passing a 4.76 mm (No. 4) sieve. Its moisture content and water absorption were 0.25% and 0.75%, respectively. Compressed CO in cylinders with a purity of >99.9% was used. 2 Gas is used for carbonization curing.

[0130] The binder and aggregate are mixed together in a mixer for 5 minutes, wherein a sufficient amount of tap water is added during this time period to obtain the desired workability. The obtained concrete mixture is molded and consolidated to the desired density under compaction and vibration. After demoulding, the precast concrete sample is conditioned with a fan blower to lose about 20% to 80% of its initial moisture content. Afterwards, the conditioned precast concrete sample is loaded into a pressure chamber for accelerated carbonation curing. The pressure adjusted to 9psi to 15psi, carbon dioxide gas is introduced into the sealed pressure chamber. The duration of carbonation curing varies from 4 hours to 24 hours. After carbonation curing, according to ASTM C140 (Standard Test Methods for Sampling and Testing Concrete Masonry Units and Related Units, the standard test method for sampling and testing concrete masonry units and related units), the compressive strength of the comparison sample is immediately evaluated. Other carbonized precast concrete samples were subjected to post-hardening treatment: first, they were completely immersed in tap water at 20°C for 24 hours; thereafter, they were removed from the water tank and then dried in an oven at 110°C for 24 hours; then their compressive strength was evaluated after they were removed from the oven and completely cooled to room temperature. For each numbered sample in Table 1, two repetitions were performed. The average strength, density, and CO of each numbered sample are provided in Table 1. 2 absorb.

[0131] Table 1 .Sample process parameters and test results

[0132]

[0133] Note: Comparative 6 contains 0.6% additives (by weight) which are air entraining admixture and waterproofing admixture.

[0134] After the post-hardening treatment, the strength improvement of the carbonized precast concrete is significant. As shown in Table 1, for the carbonized precast concrete made with 20% binder content, after the post-hardening treatment, its average compressive strength increased from 22.1 MPa to 27.7 MPa, an increase of 25%. For the carbonized precast concrete made with 25% binder content, after the post-hardening treatment, its average compressive strength increased from 15.7 MPa to 27.1 MPa, an increase of 73%. With the help of post-hardening treatment, the carbonized precast concrete with 20% or 25% binder content can be stronger than the sample comparison 3 with 30% slag content.

[0135] For carbonized precast concrete made with 30% binder content, the strength increase after post-hardening ranged from 37% to 112%, with CO2 The average strength of carbonized precast concrete with a binder content of 30% can be greater than 50 MPa with the help of a post-hardening treatment. For carbonized precast concrete without a post-hardening treatment, such a high strength often requires a binder content of 50%, as demonstrated by sample comparison 6 in Table 1. The results obtained show that the binder content of carbonized precast concrete can be saved up to 40% while maintaining its strength when a post-hardening treatment is applied.

[0136] Example 2 - Post-hardening treatment of carbonized precast concrete at different treatment temperatures and durations

[0137] More precast concrete samples were prepared with the binder contents shown in Table 2. The binders used were all EAF steel slags but from different suppliers. The slags were refined to the desired fineness before being used as binders. Each binder had a cumulative calcium silicate content of at least about 20%, a calcium oxide content of at least 20%, and a silica content of at least about 6%. The aggregates and CO used were 2 The gases were the same as those used in Table 1.

[0138] The binder and aggregate were mixed together in a mixer for 5 minutes, wherein a sufficient amount of tap water was added during this period to obtain the desired workability. The obtained concrete mixture was molded and consolidated to the desired density under compaction and vibration. After demoulding, the precast concrete samples were conditioned with a fan blower to lose about 20% to 80% of their initial moisture content. Thereafter, the conditioned precast concrete samples were loaded into a pressure chamber for accelerated carbonation curing. Carbon dioxide gas was introduced into the sealed pressure chamber at a pressure adjusted to 6 psi. The duration of carbonation curing was set to 19 hours. After carbonation curing, the compressive strength of the comparative samples was immediately evaluated according to ASTM C140. Other carbonized precast concrete samples were subjected to post-hardening treatment: for most samples, they were dried in an oven at 40°C to 110°C for 6 hours or 24 hours; for samples 8.5 and 8.6, they were immersed in water for 24 hours, after which they were dried in an oven at 100°C or 110°C for 24 hours. The compressive strength of the samples with post-hardening treatment was evaluated after they were taken out of the oven and completely cooled to room temperature. Three replicates were performed for each numbered sample in Table 2. The average strength, density, and CO of each numbered sample are provided in Table 2. 2 absorb.

[0139] Table 2. Second sample process parameters and test results

[0140]

[0141] Note: Samples 8.5 and 8.6 were immersed in water for 24 hours after carbonization curing and then dried at 100°C and 110°C, respectively.

[0142] A significant increase in the compressive strength of the carbonized precast concrete was observed in the case of post-hardening treatment, as shown in Table 2. For sample comparison 7, its average compressive strength was 26.0 MPa. After 6 hours of post-hardening treatment at a temperature of 40°C to 110°C, its strength increased to 37.4 MPa, an increase of 16% to 44%. When it was subjected to post-hardening treatment at 60°C to 110°C for 24 hours, a similar degree of strength increase was observed. For sample comparison 8, its average compressive strength was 42.2 MPa. After 24 hours of post-hardening treatment at 60°C to 110°C, its strength increased to 64.6 MPa, an increase of 15% to 53%. Post-hardening treatment in the form of water immersion before heating has in this case the same effect on the strength of the carbonized precast concrete as simple heating without water immersion.

[0143] It can also be determined from Table 2 that increasing the heating temperature during the post-hardening treatment generally has a better effect on the strength improvement of the carbonized precast concrete.

[0144] Example 3 - Carbonization of precast concrete at different slag contents and different treatment temperatures and durations Post-hardening treatment

[0145] More precast concrete samples were prepared with the binder contents shown in Table 3. The binder used was ladle slag. The slag was refined to the desired fineness before being used as a binder. The binder had a cumulative calcium silicate content of at least about 20%, a calcium oxide content of at least 20%, and a silicon dioxide content of at least about 6%. The aggregates and CO used were 2 The gases were the same as those used in Table 1.

[0146] The binder and aggregate were mixed together in a mixer for 5 minutes, wherein a sufficient amount of tap water was added during this period to obtain the desired workability. The obtained concrete mixture was molded and consolidated to the desired density under compaction and vibration. After demoulding, the precast concrete samples were conditioned with a fan blower to lose about 20% to 80% of their initial moisture content. Thereafter, the conditioned precast concrete samples were loaded into a pressure chamber for accelerated carbonation curing. Carbon dioxide gas was introduced into the sealed pressure chamber at a pressure adjusted to 6 psi. The duration of carbonation curing was set to 19 hours. Immediately after carbonation curing, the compressive strength of the comparative samples was evaluated according to ASTM C140. The other carbonized precast concrete samples were subjected to post-hardening treatment: for most samples, they were dried in an oven at 80°C to 110°C for 24 hours; for samples 9.4 and 9.5, they were immersed in water for 24 hours, after which they were dried in an oven at 100°C or 110°C for 24 hours. The compressive strength of the samples with post-hardening treatment was evaluated after they were taken out of the oven and completely cooled to room temperature. Four replicates were performed for each numbered sample in Table 3. The average strength, density, and CO of each numbered sample are provided in Table 3. 2 absorb.

[0147] Table 3. The third sample process parameters and test results

[0148]

[0149] Note: Samples 9.4 and 9.5 were immersed in water for 24 hours after carbonization curing and then dried at 100°C and 110°C, respectively.

[0150] As shown in Table 3, a significant increase in the compressive strength of the carbonized precast concrete was observed in the case of post-hardening treatment. For sample comparison 9, its average compressive strength was 43.9 MPa. After 24 hours of post-hardening treatment at a temperature of 80°C to 110°C, its strength increased to 55.9 MPa, an increase of 16% to 27%. When it was immersed in water and then subjected to heat treatment, a more significant increase in strength was observed. In the case of a combination of water immersion and drying after carbonization curing, its strength was greater than 60 MPa, an increase of more than 50%. For sample comparison 10, its average compressive strength was 51.2 MPa. After 24 hours of post-hardening treatment at 80°C to 110°C, its strength increased to 69.8 MPa, an increase of 20% to 36%.

[0151] As expected, the average strength of carbonized precast concrete samples Comparisons 9 and 10 made from the same type of slag increased from 43.9 MPa to 51.2 MPa when the slag content increased from 30% to 50%. However, with the help of post-hardening treatment, almost all carbonized precast concrete with 30% binder content were stronger than Comparison 10. The obtained results confirm that the binder content of carbonized precast concrete can be saved up to 40% while maintaining or improving its strength when post-hardening treatment is applied.

[0152] It can also be determined from Table 3 that increasing the heating temperature during the post-hardening treatment generally has a better effect on the strength improvement of the carbonized precast concrete.

[0153] The disclosed method (including a post-hardening step after carbonation curing) can improve the properties of concrete products. These properties can include, for example, durability, compressive strength, etc.

[0154] Now refer to Figure 4 , the controller 20 may include a computing device 400, which may include a processing unit 402 and a memory 404 having stored therein computer executable instructions 406. The processing unit 402 may include, for example, any type of general purpose microprocessor or microcontroller, a digital signal processing (DSP) processor, a central processing unit (CPU), an integrated circuit, a field programmable gate array (FPGA), a reconfigurable processor, other suitably programmed or programmable logic circuit, or any combination thereof.

[0155] The memory 404 may include any suitable known storage medium or other machine-readable storage medium. The memory 404 may include a non-transitory computer-readable storage medium, such as, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared or semiconductor system, device or apparatus, or any suitable combination of the foregoing. The memory 404 may include a suitable combination of any type of computer memory located inside or outside the device, such as random-access memory (RAM), read-only memory (ROM), compact disk read-only memory (CDROM), electro-optical memory, magneto-optical memory, erasable programmable read-only memory (EPROM) and electrically-erasable programmable read-only memory (EEPROM), ferroelectric RAM (FRAM), etc. The memory 404 may include any storage means (e.g., device) suitable for retrievably storing machine-readable instructions 406 that can be executed by the processing unit 402.

[0156] The methods and systems described herein for operating the system 10 may be implemented in a high-level program or object-oriented programming or scripting language or a combination thereof to communicate with a computer system (e.g., computing device 400) or to assist in the operation of the computer system. Alternatively, the methods and systems for operating the system 10 may be implemented in assembly language or machine language. The language may be a compiled language or an interpreted language. Program code for implementing the methods and systems for operating the system 10 may be stored on a storage medium or device (e.g., a ROM, a disk, an optical disk, a flash drive, or any other suitable storage medium or device). When the storage medium or device is read by a computer to execute the program described herein, the program code may be read by a general or special programmable computer for configuring and operating the computer. The embodiments of the methods and systems for operating the system 10 may also be considered to be implemented by a non-transient computer-readable storage medium having a computer program stored thereon. The computer program may include computer-readable instructions that cause the computer, or more specifically, the processing unit 402 of the computing device 400, to operate in a specific and predefined manner to perform the functions described herein, such as the functions described in the method 200.

[0157] Computer executable instructions can be in many forms, including program modules that are executed by one or more computers or other devices. Typically, program modules include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. Typically, the functionality of program modules can be combined or distributed as needed in various embodiments.

[0158] The embodiments described herein are implemented by physical computer hardware (including computing devices, servers, receivers, transmitters, processors, memories, displays, and networks). The embodiments described herein provide useful physical machines and specially configured computer hardware arrangements. The embodiments described herein relate to electronic machines and methods implemented by electronic machines adapted to process and convert electromagnetic signals representing various types of information. The embodiments described herein generally and integrally relate to machines and their uses; and the embodiments described herein have no meaning or practical applicability except that they are used together with computer hardware, machines, and various hardware components. Replacing physical hardware that is specially configured to implement various actions with non-physical hardware (e.g., using mental steps) may significantly affect the working mode of the embodiments. Such computer hardware limitations are obviously essential elements of the embodiments described herein, and they cannot be omitted or replaced by mental means without having a substantial impact on the operation and structure of the embodiments described herein. Computer hardware is necessary for implementing the various embodiments described herein, not just for executing steps quickly and in an efficient manner.

[0159] The term “connected” or “coupled to” may include both a direct coupling (in which two elements coupled to each other are in contact with each other) and an indirect coupling (in which at least one additional element is located between the two elements).

[0160] The technical solution of the embodiment can be in the form of a software product. The software product can be stored on a non-volatile or non-transient storage medium, which can be a compact disc read-only memory (CD-ROM), a USB flash drive, or a removable hard disk. The software product includes many instructions that enable a computer device (personal computer, server, or network device) to perform the method provided by the embodiment.

[0161] The embodiments described in this document provide non-limiting examples of possible implementations of the present technology. Upon reviewing this disclosure, one of ordinary skill in the art will recognize that changes may be made to the embodiments described herein without departing from the scope of the present technology. In view of this disclosure, one of ordinary skill in the art may implement further modifications that will be within the scope of the present technology.

Claims

1. A method for manufacturing a concrete product, comprising: mixing a composition comprising a binder, an aggregate, and water to produce a concrete mixture; imparting a shape to the concrete mixture to provide a shaped intermediate product; performing carbon curing on the formed intermediate product to obtain a cured intermediate product; as well as The curing intermediate product is subjected to a post-hardening treatment by exposing the curing intermediate product to a temperature higher than an ambient temperature to obtain the concrete product.

2. The method of claim 1, wherein exposing the cured intermediate product to a temperature above ambient temperature comprises exposing the cured intermediate product to a temperature of at least 30 degrees Celsius.

3. The method of claim 2, wherein exposing the cured intermediate product to the temperature comprises exposing the cured intermediate product to a temperature of at least 40 degrees Celsius to 150 degrees Celsius.

4. The method of claim 3, wherein exposing the cured intermediate product to the temperature comprises exposing the cured intermediate product to a temperature of at least 80 degrees Celsius to 100 degrees Celsius.

5. The method according to any one of claims 1 to 4, wherein exposing the curing intermediate product to the temperature comprises increasing the temperature of a curing room containing the curing intermediate product at a rate of 20 degrees Celsius per hour to 120 degrees Celsius per hour.

6. The method of claim 5, comprising maintaining the temperature inside the curing chamber above at least 30 degrees Celsius.

7. The method according to any one of claims 1 to 6, wherein exposing the cured intermediate product to a temperature higher than ambient temperature comprises exposing the cured intermediate product to an environment with a relative humidity of 10% to 90%.

8. The method of any one of claims 1 to 7, wherein exposing the cured intermediate product to a temperature above ambient temperature comprises exposing the cured intermediate product to the temperature for a period of 1 hour to 72 hours.

9. The method of claim 8, wherein exposing the cured intermediate product to a temperature above ambient temperature comprises exposing the cured intermediate product to the temperature for at least 6 hours.

10. The method of any one of claims 1 to 9, wherein exposing the cured intermediate product to a temperature above ambient temperature is performed immediately after the carbon curing.

11. A method according to any one of claims 1 to 10, comprising storing the cured intermediate product before exposing it to a temperature above ambient temperature.

12. The method according to any one of claims 1 to 11, further comprising wetting the curing intermediate product before performing the post-hardening treatment.

13. The method according to claim 12, wherein the moistening comprises one of: immersing the curing intermediate product in water; spraying the curing intermediate product with water; and misting the curing intermediate product with water. The method according to claim 12 , wherein the wetting is performed simultaneously with the post-hardening treatment.

15. The method according to any one of claims 12 to 14, wherein the wetting is performed for 0.5 hours to 48 hours.

16. The method according to any one of claims 1 to 15, further comprising conditioning the shaped intermediate product.

17. The method of any one of claims 1 to 16, further comprising providing the binder to include one or more of: fly ash, calcined shale, silica fume, zeolite, ground granulated blast furnace slag, limestone powder, hydraulic cement, and non-hydraulic cement.

18. The method of any one of claims 1 to 16, further comprising providing the binder to be incorporated into a slag, the slag comprising one or more of: steel slag, stainless steel slag, basic oxygen furnace slag, blast furnace slag, a by-product of zinc production, a by-product of iron production, and a by-product of copper production.

19. The method according to any one of claims 1 to 18, further comprising adding admixtures and / or additives to the composition.

20. A method of manufacturing a concrete product, comprising: Obtain carbon conservation intermediate products; as well as The carbon-cured intermediate product is subjected to a post-hardening treatment by exposing the carbon-cured intermediate product to a temperature higher than ambient temperature to obtain the concrete product.

21. A method of manufacturing a concrete product, comprising: imparting a shape to a concrete mixture to provide a shaped intermediate product, the concrete mixture comprising a binder, an aggregate, and water; performing carbon curing on the shaped intermediate product to obtain a carbon-cured intermediate product; and moistening the cured intermediate product; and The carbon-cured intermediate product is subjected to a post-hardening treatment by exposing the carbon-cured intermediate product to a temperature higher than ambient temperature to obtain the concrete product.

22. The method according to claim 21, wherein the moistening comprises one of: immersing the curing intermediate product in water; spraying the curing intermediate product with water; and misting the curing intermediate product with water.

23. The method according to claim 21 or 22, wherein the wetting is performed before the post-hardening treatment is performed.

24. The method according to claim 21 or 22, wherein the wetting is performed simultaneously with the post-hardening treatment.

25. The method according to any one of claims 21 to 24, wherein the wetting is performed for 0.5 hours to 48 hours.

26. The method of any one of claims 21 to 25, wherein said exposing said carbon-cured intermediate product to a temperature above ambient temperature comprises exposing said carbon-cured intermediate product to a temperature of at least 30 degrees Celsius.

27. The method of claim 26, further comprising exposing the carbon-cured intermediate product to a temperature of 40 degrees Celsius to 150 degrees Celsius.

28. The method of claim 27, further comprising exposing the carbon-cured intermediate product to a temperature of 80 degrees Celsius to 100 degrees Celsius.

29. The method of any one of claims 21 to 28, wherein said exposing said carbon-cured intermediate product to said temperature further comprises increasing the temperature at a rate of 20 degrees Celsius per hour to 120 degrees Celsius per hour.

30. The method of any one of claims 21 to 29, wherein said exposing said carbon-cured intermediate product to said temperature further comprises exposing said carbon-cured intermediate product to said temperature for a period of 1 hour to 72 hours.

31. The method of claim 30, further comprising exposing the carbon-cured intermediate product to the temperature for at least 6 hours.

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