Method for manufacturing a concrete product including a post-curing treatment

Abstract

A method for manufacturing a concrete product includes a step of mixing a composition containing a binder, an aggregate, and water to produce a concrete mixture, and a step of providing a shaped intermediate by giving a mold to the concrete mixture. The shaped intermediate is carbon-cured to obtain a cured intermediate. The post-curing treatment of the cured intermediate is performed by exposing the cured intermediate to a temperature higher than the ambient temperature, and as a result, the concrete product is obtained.

Description

Cross - reference to related applications

[0001] This application claims priority to U.S. Patent Application No. 63 / 364,504, filed on May 11, 2022, the entire content of which is incorporated herein by reference.

Technical Field

[0002] The present disclosure generally relates to concrete products, and more particularly, to systems and methods used to manufacture such concrete products.

Background Art

[0003] Conventional manufacture of concrete products involves mixing a dry mixture that may include cement and aggregates with water. The resulting intermediate can undergo a conditioning process to evaporate some of the water contained therein. The conditioned intermediate product is then subjected to a separate curing process to obtain the final concrete product. In particular, there is a need for continuous improvement of such concrete products and their manufacturing methods in order to make the manufacturing process more environmentally friendly and / or to improve the properties of the resulting concrete products.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure generally relates to concrete products, and more particularly, to systems and methods used to manufacture such concrete products.

Means for Solving the Problems

[0005] Accordingly, a method for manufacturing a concrete product is provided. The method includes mixing a composition containing a binder, an aggregate, and water to produce a concrete mixture, providing a shaped intermediate by applying a mold to the concrete mixture, carbon curing the shaped intermediate to obtain a cured intermediate, and performing post-curing treatment on the cured intermediate by exposing the cured intermediate to a temperature higher than the ambient temperature, thereby obtaining the concrete product.

[0006] The method defined above and described in the present application may further include all or part of one or more of the following features and any combination thereof.

[0007] In a particular embodiment, the step of exposing the cured intermediate to a temperature higher than the ambient temperature includes exposing the cured intermediate to a temperature of at least 30°C.

[0008] In a particular embodiment, the step of exposing the cured intermediate to a temperature higher than the ambient temperature includes exposing the cured intermediate to a temperature of at least 40°C to 150°C.

[0009] In a particular embodiment, the step of exposing the cured intermediate to a temperature higher than the ambient temperature includes exposing the cured intermediate to a temperature of at least 80°C to 100°C.

[0010] In a particular embodiment, the step of exposing the cured intermediate to the temperature includes raising the temperature of the curing chamber containing the cured intermediate at a rate of 20°C to 120°C per hour.

[0011] In a particular embodiment, the temperature inside the curing chamber is maintained at a temperature higher than at least 30°C.

[0012] In a particular embodiment, the step of exposing the cured intermediate to a temperature higher than the ambient temperature includes exposing the cured intermediate to an environment having a relative humidity of 10% to 90%.

[0013] In certain embodiments, the step of exposing the cured intermediate to a temperature higher than the ambient temperature includes the step of exposing the cured intermediate to the temperature for 1 hour to 72 hours.

[0014] In certain embodiments, the step of exposing the cured intermediate to a temperature higher than the ambient temperature includes the step of exposing the cured intermediate to the temperature for at least 6 hours.

[0015] In certain embodiments, the step of exposing the cured intermediate to a temperature higher than the ambient temperature is carried out immediately after the step of carbon curing.

[0016] In certain embodiments, the cured intermediate is filled before the step of exposing the cured intermediate to a temperature higher than the ambient temperature.

[0017] In certain embodiments, the method has a step of humidifying the cured intermediate before performing the post-curing treatment.

[0018] In certain embodiments, the humidifying step includes one of the steps of immersing the cured intermediate in water, spraying water on the cured intermediate, and atomizing water on the cured intermediate.

[0019] In certain embodiments, the humidifying step is carried out simultaneously with the step of performing the post-curing treatment.

[0020] In certain embodiments, the humidifying step is carried out for 0.5 hour to 48 hours.

[0021] In certain embodiments, the method further has a step of adjusting the shaped intermediate.

[0022] In certain embodiments, the step of providing the composition has the step of providing the composition including the binder including one or more of fly ash, calcined shale, silica fume, zeolite, granulated blast furnace slag, limestone powder, hydraulic cement, and non-hydraulic cement.

[0023] In certain embodiments, the step of providing the composition includes the step of providing the binder including slag to the composition. The slag includes one or more of steel slag, stainless slag, basic oxygen conversion sludge, blast furnace sludge, by-products of zinc products, by-products of iron products, and by-products of copper products.

[0024] In certain embodiments, the step of providing the composition includes the step of adding a mixture and / or an additive to the composition.

[0025] Also provided is a method of manufacturing a concrete product. The method includes obtaining a carbon-cured intermediate and performing a post-curing treatment on the carbon-cured intermediate by exposing the carbon-cured intermediate to a temperature higher than the ambient temperature, thereby obtaining the concrete product.

[0026] The method defined above and described in the present application may further include all or part of one or more of the following features and any combination thereof.

[0027] In certain embodiments, the step of exposing the carbon-cured intermediate to a temperature higher than the ambient temperature includes the step of exposing the carbon-cured intermediate to a temperature of at least 30°C.

[0028] In certain embodiments, the step of exposing the carbon-cured intermediate to a temperature higher than the ambient temperature includes the step of exposing the carbon-cured intermediate to a temperature of at least 40°C to 150°C.

[0029] In certain embodiments, the step of exposing the carbon-cured intermediate to the temperature includes the step of increasing the temperature of the curing chamber containing the carbon-cured intermediate at a rate of 20°C to 120°C per hour.

[0030] In certain embodiments, the step of exposing the carbon-cured intermediate to the temperature includes the step of increasing the temperature of the curing chamber containing the carbon-cured intermediate at a rate of 20°C to 120°C per hour.

[0031] In certain embodiments, the temperature inside the curing chamber is maintained at a temperature higher than at least 30°C.

[0032] In certain embodiments, the step of exposing the carbon-cured intermediate to a temperature higher than the ambient temperature includes exposing the carbon-cured intermediate to an environment having a relative humidity of 10% to 90%.

[0033] In certain embodiments, the step of exposing the carbon-cured intermediate to a temperature higher than the ambient temperature includes exposing the carbon-cured intermediate to the temperature for 1 hour to 72 hours.

[0034] In certain embodiments, the step of exposing the carbon-cured intermediate to a temperature higher than the ambient temperature includes exposing the carbon-cured intermediate to the temperature for at least 6 hours.

[0035] A method of manufacturing a concrete product is further provided. The method includes providing a shaped intermediate by shaping a concrete mixture including a binder, an aggregate, and water, obtaining a carbon-cured intermediate by carbon-curing the shaped intermediate, humidifying the cured intermediate, and performing a post-curing treatment on the carbon-cured intermediate by exposing the carbon-cured intermediate to a temperature higher than the ambient temperature, thereby obtaining the concrete product.

[0036] The method defined above and described in the present application may further include all or part of one or more of the following features and any combination thereof.

[0037] In certain embodiments, the humidifying step includes one of the steps of immersing the cured intermediate in water, spraying water on the cured intermediate, and spraying atomized water on the cured intermediate.

[0038] In certain embodiments, the humidifying step is performed before the step of performing the post-curing treatment.

[0039] In certain embodiments, the humidifying step is carried out simultaneously with the step of performing the post-curing treatment.

[0040] In certain embodiments, the humidifying step is carried out for 0.5 hours to 48 hours.

[0041] In certain embodiments, the step of exposing the carbon-cured intermediate to a temperature higher than the ambient temperature includes the step of exposing the carbon-cured intermediate to a temperature of at least 30°C.

[0042] In certain embodiments, the method further comprises the step of exposing the carbon-cured intermediate to a temperature of 40°C to 150°C.

[0043] In certain embodiments, the method further comprises the step of exposing the carbon-cured intermediate to a temperature of 80°C to 100°C.

[0044] In certain embodiments, the step of exposing the carbon-cured intermediate to the temperature further includes the step of raising the temperature of the curing chamber containing the carbon-cured intermediate at a rate of 20°C to 120°C per hour.

[0045] In certain embodiments, the step of exposing the carbon-cured intermediate to the temperature further includes the step of exposing the carbon-cured intermediate to the temperature for 1 hour to 72 hours.

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

[0047] Upon reading this disclosure, many further features and combinations thereof related to this improvement will be understood by those skilled in the art.

Brief Description of the Drawings

[0048]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0049] [Introduction] There is a growing global interest in reducing the environmental footprint of precast concrete. Carbonation curing technology is one of the most promising solutions. During carbonation curing, precast concrete hardens mainly by a so-called carbonation reaction that occurs between carbon dioxide and oxides and / or hydroxides of calcium and / or magnesium in the presence of water. Under appropriate raw material selection, mix design, and process control, carbonated precast concrete is as strong and durable as conventional precast concrete and suitable for various applications.

[0050] Carbonated precast concrete has many advantages, but the strength development after carbonation curing can be a limiting factor for some applications. Therefore, it is considered advantageous to improve the strength of carbonated precast concrete after carbonation curing. As a result of the lack or only slight development of the strength of carbonated precast concrete, the coverage rate of carbonate reaction products such as calcium and / or magnesium carbonates on the binder particles becomes thick. Another factor is considered to be the change in pH surrounding the unreacted portion of the binder particles after carbonation curing. The thickening of the carbonate coverage rate and the decrease in the pH value may prevent the potential hydration of the cementitious binder after carbonation curing. The lack of or negligible strength development after carbonation curing is even more pronounced when a significant amount of ordinary Portland cement or a similar cementitious binder is replaced by a material with low or no hydraulic activity. These alternative materials include slag generated from metal processing, ash generated from power generation or waste incineration, etc. Including such alternative materials can help improve the environmental footprint of concrete and make concrete a more green product. Since the strength increase after carbonation curing is limited, carbonated precast concrete often contains a higher binder content than conventional precast concrete of the same strength grade, which increases the material cost of carbonated precast concrete and reduces its sustainability. Therefore, for some applications, it is desirable to improve the strength development of precast carbonated concrete, especially precast carbonated concrete containing an alternative to a conventional cementitious binder, such as slag.

[0051] Traditionally, Portland cement has been used as a binder in the production of concrete that is cured using heat and steam. However, this method can replace at least a portion of the Portland cement with a more environmentally friendly alternative such as slag. In fact, the method of the present invention can advantageously be implemented because it can still provide satisfactory post-curing strength even when a portion or all of the cement (e.g., Portland cement) is replaced with other waste materials (e.g., slag).

[0052] When greater strength and durability such as freeze-thaw resistance are desired, an increase in binder content is a common and accepted practice in the production of carbonated precast concrete. Since the binder is the most expensive ingredient among the main raw materials used in the production of carbonated precast concrete, increasing the binder content for higher performance usually results in higher material costs in most cases. The present disclosure provides a post-curing process that can improve the performance of carbonated precast concrete without sacrificing its strength and durability, without increasing the binder content of the carbonated precast concrete, or without decreasing the binder content of the carbonated precast concrete. In any case, by implementing the post-curing process described herein in the production of carbonated precast concrete with desired performance, a significant savings in material costs can be achieved. Further, in some embodiments, as described above, the post-curing process is particularly suitable for treating carbonated precast concrete made with a binder containing a significant amount of non-traditional binder supplied from industrial waste materials as a cement alternative. This can be advantageous for carbonated precast concrete from an environmental protection perspective in addition to its already low carbon footprint.

[0053] Examples of precast concrete products that can be manufactured using the post-curing process described herein include, but are not limited to, concrete pipes, traffic barriers, walls including retaining walls, modular boxes, culverts, tiles, pavements, foundations, slabs including hollow core slabs, patio slabs, steps, edges, concrete blocks, beams, floors, columns, manholes, sewer pipes, railway sleepers, and other precast concrete products.

[0054] Carbonated precast concrete can be manufactured by known techniques prior to being treated by the disclosed post-curing method. As shown in the examples, un-reinforced carbonated precast concrete can be manufactured using 20 - 50 wt% binder. The precast concrete is prepared by the dry-cast method, i.e., adding water to provide sufficient workability to the concrete mixture but with a slump close to zero. After molding and compaction, the precast concrete is demolded and then adjusted to lose 20 - 80% of its initial moisture, after which carbonation curing is carried out in a pressure chamber with CO 2 gas at a concentration of 99.9% and a pressure of 6 - 15 psi for 4 - 24 hours. However, the manufacture of carbonated precast concrete suitable for the above-described post-curing is not limited by the exemplary method. For example, carbonated precast concrete can also be manufactured with a low binder content of about 10 mass%, by the wet-cast manufacturing method, with a low concentration of gas or liquid (supercritical) CO 2 at a CO 2 pressure of 0.1 - 1200 psi, a short carbonation curing time of about a few minutes or a carbonation curing time of 24 hours or more, and by conventional reinforcement methods. Further, the adjustment process can be carried out before demolding. In addition, this adjustment process can be carried out with CO 2It can be avoided when the permeability of the compacted or consolidated precast concrete (such as permeable concrete) is sufficiently high, or when the duration of carbonation curing is sufficiently long, or when a process of performing adjustment and carbonation curing simultaneously is applied. Further, a pre-curing process may be added before demolding, where the precast concrete obtains a strength high enough to maintain its shape and withstand the damaging forces during other manufacturing processes before demolding and carbonation curing.

[0055] The density of the carbonated precast concrete subjected to the described post-curing process can be normal, as shown in the examples presented below. However, lightweight and heavyweight carbonated precast concrete can also be processed by the described post-curing method. The aggregates used for manufacturing carbonated precast concrete can be of normal weight, lightweight, and heavy weight of natural, artificial, or recycled origin. Their gradation and dosage in the mix design follow the general practice of conventional precast concrete manufacturing. Similarly, chemical and mineral additives such as pigments, air-entraining mixtures, water-reducing mixtures, water-repellent mixtures, fibers, accelerators, etc., and their dosages used for manufacturing carbonated precast concrete can also follow the general rules of conventional precast concrete manufacturing.

[0056] [Curing System] Referring now to FIG. 1, an exemplary system for conditioning and curing a concrete product is shown at 10. System 10 includes a carbon dioxide source 11, which may be a reservoir or tank pneumatically connected to a seal 12 via line 13. In the illustrated embodiment, system 10 includes a heater 14 for heating the carbon dioxide as it flows from the carbon dioxide source 11 to the seal 12. In this configuration, system 10 includes a valve 15 that can be selectively opened and closed to allow or restrict the flow of carbon dioxide towards the seal 12.

[0057] The sealing body 12 defines an internal space or chamber 12A dimensioned to receive a plurality of cured concrete products 16. In the illustrated embodiment, the sealing body 12 includes a top wall and side walls that are airtightly interconnected. In the context of the present disclosure, "airtight" means that there is little or no leakage of gas through the sealing body 12 at the pressure differential received by the sealing body 12. The pressure differential corresponds to the difference between the pressure inside the sealing body 12 and the ambient atmospheric pressure outside the sealing body 12. The sealing body 12 may be structurally designed to withstand a pressure differential generated by a greater pressure of carbon dioxide inside the sealing body 12 than the atmospheric pressure outside the sealing body 12. The blower 17 can be disposed within the chamber 12A of the sealing body 12 and is operable to generate an air flow F that can accelerate the conditioning and / or curing process.

[0058] In some embodiments, the sealing body 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 atmospheric pressure by up to 10% of atmospheric pressure. More details regarding low-pressure curing are presented in U.S. Patent Application Publication No. 17 / 581,320, filed on January 21, 2022, the entire content of which is incorporated herein by reference. The sealing body 12 may be a deployable structure (e.g., a bag).

[0059] The system 10 can further include one or more sensors 18 that can 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 within the sealing body 12. A scale or weighing device 19 can support the sealing body 12 and is used to measure weight fluctuations of the concrete product 16 during the conditioning and curing process. More specifically, the water content of the concrete product 16 is expected to evaporate during the conditioning and curing process. The weighing device 19 can measure this weight fluctuation and can be utilized to determine whether the conditioning and curing process is complete.

[0060] In the illustrated embodiment, system 10 includes a temperature and humidity sensor 18, a scale 19, a heater 14, a blower 17, and a control unit 20 that can be operably connected to them. Thus, control unit 20 can independently control the injection of carbon dioxide through valve 15 and the operation of blower 17. In the illustrated embodiment, control unit 20 includes, for example, an information processing device 400 as shown in and described later with reference to FIG. 4. Control unit 20 can act as a data logger for storing data points such as temperature, weight, pressure, etc. during the adjustment and curing processes. Control unit 20 is operable to receive data from temperature and humidity sensor 18 and from scale 19 and control the operating parameters of heater 14, valve 15, and blower 17. These operating parameters can include, for example, the temperature of heater 14, whether valve 15 should be opened, closed, or in an intermediate position to control the flow of carbon dioxide through valve 15, the rotational speed of blower 17, and the like.

[0061] In some embodiments, an adjustment process occurs while the concrete product 16 is disposed inside the encapsulation 12. During the adjustment process, it is expected that water will be released from the concrete product 16. Since the encapsulation 12 is closed to the environment outside the encapsulation 12, it may be desirable for the encapsulation 12 to absorb the humidity extracted from the concrete product. In this case, the desiccant material 21 is disposed inside the encapsulation 12 and is used to absorb excess humidity. The desiccant material may be a hygroscopic substance used to induce or maintain a dry state in its vicinity. These desiccant materials can absorb water. In one particular example, the desiccant material can include silica gel. The desiccant material may be in a form other than solid and may act by other principles such as chemical bonding of water molecules. The desiccant material can include, in any combination, activated carbon, calcium sulfate, calcium chloride, zeolite, and the like. The desiccant material may be an adsorbent material as opposed to an absorbent material. An absorbent material contains water by allowing water to penetrate through it. The absorbent material may be porous and water may be absorbed by the through porosity of the absorbent material. An adsorbent material adheres to water molecules. In other words, water is constrained by the adsorbent material by adhering to the surface of the adsorbent material. The adsorbent material can attract moisture and hold it on its surface like a magnet. It will be understood that any means capable of extracting moisture from the encapsulation 12 while simultaneously performing curing and adjustment can be used. For example, a humidifier, air conditioning, and any other suitable means can be used.

[0062] In the illustrated embodiment, system 10 can include a heating element 22 disposed within chamber 12A to raise the temperature within chamber 12A to perform a post-cure process, which will be further described below. Heating element 22 can be operably connected to a power source 23 and a controller 20 that can control the operation of heating element 22. Of course, any suitable means for raising the temperature within chamber 12A can be considered. For example, chemical components that cause an exothermic reaction upon mixing may be disposed inside chamber 12A. Chamber 12A can be heated by heating the walls of enclosure 12. This can be done using gas, electricity, induction, warm water, and the like.

[0063] [Method] A method of manufacturing a concrete product is provided. The inventors of the present disclosure have surprisingly found that the strength of precast carbonated concrete is significantly improved after post-cure heat treatment. A second unexpected discovery is that the strength of carbonated precast concrete can be further improved by performing a wetting / humidifying step, such as a water absorption step, prior to the post-cure heat treatment. After completing the wetting step and the heat treatment, it has been found that the carbonated precast concrete has improved strength compared to the corresponding product immediately after carbonation curing.

[0064] The present disclosure also includes a post-curing process for strengthening precast concrete that has already been carbonated. During this process, precast concrete that has already undergone carbonation curing is exposed to a heated environment. In other words, the carbonated precast concrete is fired at a temperature higher than the ambient temperature. The post-curing can be carried out in a carbon dioxide curing chamber or in another suitable sealed enclosure. The post-curing can be carried out on the carbonated precast concrete immediately after the carbonation curing is completed, or it can be carried out after an indefinite period of carbonation curing. The temperature range during the post-curing may be 40 to 150 °C, and higher temperatures are generally advantageous for improving the performance of the carbonated precast concrete. The relative humidity range during the post-curing process may be 10 to 90%. The post-curing time may be from about 1 hour to about 72 hours. The detailed post-curing conditions are determined by the concrete mix, the type of raw materials, and the desired performance.

[0065] It is also believed that the durability, such as the freeze-thaw resistance of the strengthened precast concrete, can also be improved in this post-curing step. Therefore, this additional step can improve the mechanical properties and durability of the carbonated precast concrete and / or reduce the material costs in its manufacture.

[0066] In the context of the present disclosure, the expression "about" means a variation of ±10%.

[0067] Referring now to FIG. 2, a method of manufacturing a concrete product is shown at 200. This method includes, at 202, providing a composition including a binder, an aggregate, and water; at 204, mixing the binder, the aggregate, and the water to produce a concrete mixture; at 206, applying a mold to the concrete mixture to provide a formed intermediate; at 208, carbon curing the formed intermediate to obtain a cured intermediate; and at 210, performing a post-curing treatment on the cured intermediate by exposing the cured intermediate to a temperature higher than the ambient temperature to obtain a concrete product.

[0068] Another method of manufacturing a concrete product is shown at 300. Method 300 includes, at 302, obtaining a cured intermediate; and at 304, performing a post-curing treatment on the cured intermediate by exposing the cured intermediate to a temperature higher than the ambient temperature to obtain a concrete product.

[0069] [Mixing & Forming] In the illustrated embodiment, step 202 of providing the composition may include providing a composition that does not contain slag. The provision of the composition at 202 may include providing a composition that includes a 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. The provision of the composition at 202 may include providing a binder containing slag to the composition, the slag including one or more of steel slag, stainless steel slag, basic oxygen conversion sludge, blast furnace sludge, by-products of zinc production, by-products of pig iron production, and by-products of copper production. The steel slag can include one or more of reduced steel slag, oxidized steel slag, converter steel slag, electric arc furnace slag, basic oxygen furnace slag, ladle slag, rapidly cooled steel slag, and slowly cooled steel slag. The provision of the composition at 202 may further include providing a composition that further includes one or more of an accelerator, a retarder, a viscosity modifier, an air entrainer, a foaming agent, an alkali-silica reaction inhibitor, a washout inhibitor, a corrosion inhibitor, a shrinkage inhibitor, a concrete crack reducer, a plasticizer, a superplasticizer, a sealant, a paint, a coating, a water reducer, a water repellent, a rash control agent, a polymer powder, a polymer latex, and a workability retention agent. The provision of the composition at 202 may further include providing a composition that further includes one or more of cellulose fiber, glass fiber, micro synthetic fiber, natural fiber, polypropylene fiber, polyvinyl alcohol fiber, and steel fiber.

[0070] Therefore, the precast carbonated concrete suitable for the described post-curing treatment can be made from cementitious, limited cementitious and / or non-cementitious binders. These binders can be made from the following materials: ordinary Portland cement (OPC), high alumina cement, white cement, magnesium cement, OPC blended with limestone, or ground granulated blast furnace slag (GGBFS), fly ash, and supplementary cementitious materials including natural and calcined pozzolanic materials, and can have strong hydraulic activity, either alone or in combination. These binders can also have poor or no hydraulic activity, such as any one or combination of calcium hydroxide, GGBFS, steel slag, stainless steel slag, fly ash, non-hydraulic cement, and other materials rich in CaO, and / or MgO, and / or Ca(OH)2, and / or Mg(OH)2 content. These binders can be a combination of materials with low hydraulic activity, low or no hydraulic activity. Preferably, the binder suitable for manufacturing the precast carbonated concrete subjected to the above-described post-curing treatment contains at least 10% by weight of materials with poor or no hydraulic activity. More preferably, the binder suitable for manufacturing the precast carbonated concrete subjected to the above-described post-curing treatment contains at least 25% by weight of materials with poor or no hydraulic activity. More preferably, the binder suitable for manufacturing the precast carbonated concrete subjected to the above-described post-curing treatment contains at least 50% by weight of materials with poor or no hydraulic activity. More preferably, the binder suitable for manufacturing the precast carbonated concrete subjected to the above-described post-curing treatment contains at least 75% by weight of materials with poor or no hydraulic activity. More preferably, the binder suitable for manufacturing the precast carbonated concrete subjected to the above-described post-curing treatment contains at least 100% by weight of materials with poor or no hydraulic activity.

[0071] As shown in the following examples, steel slag can be used herein as the sole component of a binder for the production of carbonate precast concrete. "Steel slag" as used herein refers to slag by-products generated from steelmaking. Steel slag can include slag generated from a basic oxygen furnace (BOF), also known as LD slag, or LD slag, which is also known as slag from the LD process. Steel slag may also include slag generated from an electric arc furnace (EAF). The steel slag used herein may further include ladle slag generated as a by-product from ladle refining operations. The steel slag used herein may further include stainless steel slag generated from stainless steel production, which is mainly generated from argon oxygen decarburization (AOD) and / or ladle metallurgy (LM) processes. Further, the steel slag may be a combination of the above slags. For example, when used herein, "EBH slag" refers to an EAF-BOF hybrid, which is a type of steel slag formed from a mixture of EAF and BOF generated slag.

[0072] In one embodiment, the steel slag used herein has a cumulative calcium silicate content (e.g., CS + C2S + C3S phase concentration) of at least about 15% by weight. In one embodiment, the steel slag used herein has a cumulative calcium silicate content (e.g., CS + C2S + C3S phase concentration) of at least about 20% by weight. In one embodiment, the steel slag used herein has a cumulative calcium silicate content (e.g., CS + C2S + C3S phase concentration) of at least about 30% by weight. In one embodiment, the steel slag used herein has a cumulative calcium silicate content (e.g., CS + C2S + C3S phase concentration) of at least about 40% by weight. In one embodiment, the steel slag used herein has an SiO2 content of at least about 6% by weight, or more preferably at least about 15% by weight.

[0073] Steel slag can include a mixture of coarse slag pieces and fine slag pieces. Coarse slag pieces are about 50 m 2may have a brain fineness of less than / kg, and the fine slag pieces are about 50 m 2 / kg may have a brain fineness exceeding. Coarse slag pieces, fine slag pieces, or both may be landfilled as a result of typical steelmaking processes. The received steel slag, which is derived from waste (such as landfill and / or industrial waste), may optionally be purified. Purifying the steel slag may include filtering the received steel slag to separate fine slag pieces from coarse slag pieces. Alternatively, or additionally, purifying the received steel slag may also include pulverizing the steel slag into fine powder. In some exemplary embodiments, the filtered fine pieces are pulverized, while the coarse pieces are not. For example, in the case of electric furnace steel slag, the slag may be pulverized to a brain fineness of at least 50 m 2 / kg, preferably about 180 m 2 / kg. For example, in the case of EBH steel slag (a mixture of EAF, BOF, and ladle slag), the slag may be pulverized to a brain fineness of at least 100 m 2 / kg, preferably about 240 m 2 / kg. In other exemplary embodiments, the steel slag may be pulverized to a finer size. In another example, at least 50 percent of the grounded slag may be smaller than 100 microns, and at least 10 percent of the grounded slag may be smaller than 50 microns, i.e., D(50) < 100 microns and D(10) < 50 microns may be acceptable.

[0074] It will be understood that "steel slag" as used herein excludes iron slag and blast furnace slag that are typically generated during the production of iron and can be used in the production of cement such as pozzolanic slag.

[0075] Various types of aggregates, including natural or artificial normal and lightweight aggregates, can be incorporated into dry or wet concrete products as fillers in the manufacture of concrete products. Examples of potential lightweight aggregates include natural lightweight aggregates (e.g., pumice), expanded clay aggregates, expanded shale aggregates, and expanded iron slag aggregates. Other usable aggregates include crushed stone, manufactured sand, gravel, sand, recycled aggregates, granite, limestone, quartz, chalk powder, marble powder, silica sand, and artificial aggregates. These aggregates are incorporated into the mixture as fine and / or coarse aggregates. The aggregate content can be as high as about 90% of the weight of the concrete composition.

[0076] In some embodiments, providing a composition includes providing a composition that includes one or more chemical mixtures and / or one or more minerals.

[0077] In some embodiments, providing the composition at 202 includes providing a composition that does not include slag. Providing the composition at 202 can include providing a composition that includes a binder that includes one or more of fly ash, calcined shale, silica fume, zeolite, ground granulated blast furnace slag, limestone powder, hydraulic cement, and non-hydraulic cement.

[0078] In some embodiments, providing the composition at 202 includes providing a binder that includes slag to the composition, and the slag includes one or more of steel slag, stainless steel slag, basic oxygen conversion sludge, blast furnace sludge, by-products of zinc production, by-products of pig iron production, and by-products of copper production. The steel slag can include one or more of reduced steel slag, oxidized steel slag, converter steel slag, electric arc furnace slag, basic oxygen furnace slag, ladle slag, rapidly cooled steel slag, and slowly cooled steel slag.

[0079] The provision of the composition at 202 may include providing to the composition one or more of an accelerator, a retarder, a viscosity modifier, an air entrainer, a foaming agent, an alkali-silica reaction inhibitor, a washout preventer, a corrosion inhibitor, a shrinkage inhibitor, a concrete crack reducer, a plasticizer, a superplasticizer, a sealant, a paint, a coating, a water reducer, a water repellent, a rash controller, a polymer powder, a polymer latex, and a processability retainer. The provision of the composition at 202 may include providing to the composition one or more of cellulose fibers, glass fibers, micro synthetic fibers, natural fibers, polypropylene fibers, polyvinyl alcohol fibers, and steel fibers.

[0080] The binder material intended to be used may be reactive with respect to carbon dioxide. However, the binder can have a certain level of hydraulicity. In other words, the binder can be reactive with respect to water.

[0081] In the illustrated embodiment, step 204 of mixing a binder, an aggregate, and water to produce a concrete mixture can include producing a wet mixture having a mixing water-to-binder ratio. In 204, the mixing of the binder, aggregate, and water to produce the concrete mixture can include producing a dry mixture having a different mixing water-to-binder ratio. There are many suitable methods for performing the mixing of the concrete mixture, for example, using a mixing drum.

[0082] In 204, the mixing of the binder, aggregate, and water to produce the concrete mixture can include producing a wet mixture having a mixing water-to-binder ratio. In 204, the mixing of the binder, aggregate, and water to produce the concrete mixture can include producing a dry mixture having a different mixing water-to-binder ratio.

[0083] Here, the application of the mold to the concrete mixture at 206 includes casting the concrete mixture into the mold to provide a formed intermediate. The method 200 of the present embodiment includes the step of demolding the molded intermediate to provide a demolded intermediate. In some embodiments, the carbon curing of the formed intermediate at 208 can include simultaneously conditioning and curing the formed intermediate. In some embodiments, conditioning and curing the formed intermediate includes simultaneously conditioning and curing the formed intermediate, while the formed intermediate remains inside the mold.

[0084] In step 206, applying the mold to the concrete mixture can include forming and densifying the concrete mixture under compression and vibration to provide a formed intermediate. In some embodiments, applying the mold can include transferring a newly prepared concrete mixture by any suitable means and casting it in a prepared mold. The mold may be made of steel, iron, aluminum, plastic, FRP, or another material. The mold may be pre-lubricated before casting to facilitate the demolding process. When using a wet mixture, it can be densified in the mold by an internal or external vibrator. In some cases, the densification process lasts 120 seconds or less. Dry-cast concrete can be compressed / pressed / pressurized / formed into the mold by compression and / or vibration. The application of the mold at 206 can include casting the concrete mixture into the shape of a precast, concrete pipe, box culvert, drainage product, paving slab, floor slab, traffic barrier, wall manhole, retaining wall, paver, tile, or roof slab.

[0085] In some embodiments, method 200 may include, at 208, demolding the formed intermediate before carbon curing. The method may include adjusting the formed intermediate until the water-to-binder ratio corresponding to the water-to-binder ratio after the application of the form at 206 reaches a second water-to-binder ratio that is lower than the first water-to-binder ratio. After the adjustment step, the adjusted intermediate is demolded, and the demolded adjusted intermediate can be provided. Next, this demolded adjusted intermediate can undergo a carbon curing process at 208.

[0086] In some embodiments, method 200 includes inserting a reinforcing material inside a mold before casting a concrete mixture. The step of inserting the reinforcing material can include inserting a bar made of the reinforcing material, and the reinforcing material includes one or more of carbon steel, stainless steel, and fiber-reinforced polymer.

[0087] [After curing] In the illustrated embodiment, exposing the cured intermediate to a temperature higher than the ambient temperature at 210 includes exposing the cured intermediate to a temperature of at least 30°C. Preferably, the cured intermediate is exposed to a temperature of at least 40 - 150°C, preferably 80 - 100°C.

[0088] In some embodiments, exposing the cured intermediate to the temperature at 210 may include raising the temperature of chamber 12A containing the cured intermediate at a rate in the range of 20 - 120°C per hour. Thereafter, the temperature inside the curing chamber may be maintained at at least 30°C or higher. Exposing the cured intermediate to a temperature higher than the ambient temperature at 210 can include exposing the cured intermediate to an environment having a relative humidity of 10% - 90%. Exposing the cured intermediate to a temperature higher than the ambient temperature at 210 can include exposing the cured intermediate to the temperature for 1 hour - 72 hours, preferably at least 6 hours.

[0089] In some embodiments, the exposure of the cured intermediate to a temperature above the ambient temperature at 210 is carried out immediately after the carbon curing at 208. Alternatively, the cured intermediate can be stored under appropriate conditions before exposing the cured intermediate to a temperature higher than the ambient temperature at 210.

[0090] This post-curing treatment is an additional step in the carbonation process in precast concrete manufacturing to strengthen the cured concrete product. Generally, it is considered that the durability such as the freeze-thaw resistance of the strengthened precast concrete should also be improved. Therefore, this additional step can improve the mechanical properties and durability of the carbonated precast concrete and / or reduce the material cost in its manufacturing. 2 This post-curing treatment described in the present disclosure is already carried out on carbonated precast concrete. During the post-curing treatment, the carbonated precast concrete is exposed to a temperature higher than the ambient temperature for a specific period. In other words, the carbonated precast concrete is fired under heating for a specific period after carbonation curing. The temperature used to treat the carbonated precast concrete can be from 40°C to 150°C. A treatment temperature of 80°C or higher is preferred. In some cases, a treatment of 100°C or higher is preferred. To reach the specified treatment temperature, the rate of temperature increase can be 20 - 120°C / h at the start of the post-curing treatment. It can be maintained until the completion of the post-curing treatment after reaching the specified treatment temperature. Alternatively, the carbonated precast can be loaded into the treatment enclosure after the enclosure has been heated to the specified temperature. The period of the post-curing treatment can be 1 hour or more. The period of the post-curing treatment is more preferably 6 hours or more and less than 72 hours. During the post-curing treatment, the relative humidity around the carbonated precast concrete can be 10% - 90%. The detailed temperature and time of the post-curing treatment depend on the type of raw materials, especially the type of binder, the proportion of the binder, the thickness of the product, the proportion of the concrete mixture, the relative humidity, the degree of carbonation curing, and the desired performance of the treated carbonated precast concrete.

[0091]

[0092] ​ In some embodiments, it is preferable to start the post-curing treatment after the carbonation curing of the precast concrete is completed without delay. However, the post-curing treatment can also be performed after storing the carbonated precast concrete under normal conditions for an unspecified period.

[0093] In some embodiments, the post-curing treatment is preferably carried out in the chamber where the carbonation curing is performed. However, the post-curing treatment can be carried out in another enclosure after the carbonated precast concrete is taken out of the carbonation curing chamber. During the post-curing treatment, the treatment enclosure may or may not be sealed, but a sealed enclosure is preferred.

[0094] The heating during the post-curing treatment can be achieved by conventional methods such as gas or oil burners, boilers, and infrared heaters. In another embodiment, the heat generated during the carbonation curing process can be recycled and reused for the post-heat treatment process. An air circulation system is required to guide hot air from the heat source to the treatment enclosure and evenly distribute the heat surrounding the carbonated precast concrete. This air circulation system may also have the function of removing moisture accumulated in the air from the treatment enclosure if necessary.

[0095] The improvement in the performance of carbonated precast concrete by the current post-curing treatment is considered to be the result of the formation of larger and stronger calcium carbonate particles in the carbonated precast concrete after the post-curing treatment. In other words, more crystalline calcium carbonate is generated in the carbonated precast concrete for the post-curing treatment, which contributes to the improvement of mechanical properties and durability. In addition, some of the unreacted dissolved calcium ions and carbonic acid in the carbonated precast concrete can increase the strength and durability of the carbonated precast concrete by obtaining the opportunity to react when the temperature rises. Furthermore, a part of the uncarbonated dissolved calcium silicate can hydrate at high temperatures, which contributes to the strength development of the carbonated precast concrete. In addition, the structure and crystallinity of the calcium carbonate generated during the carbonation curing process can be improved, resulting in an improved microstructure and structure as a result of the proposed post-curing treatment.

[0096] The post-curing treatment includes exposing the precast concrete to a heat treatment at at least 30 °C to obtain a concrete product. In some embodiments, the post-curing treatment has a duration of at least 1, 2, 3, 4, 5, 6, 8, 10, 12, 18 or 24 hours and may have an upper limit of 72 hours. In some embodiments, the post-curing 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, at least 30 - 150 °C, 40 - 150 °C, 50 - 150 °C, 60 - 150 °C, 70 - 150 °C, 80 - 150 °C, or 80 - 110 °C.

[0097] The following are some examples aimed at demonstrating that desirable properties can be obtained by the post-curing treatment of carbonated precast concrete using the method of the present disclosure. Neither the raw materials nor the treatment are limited to those shown in these examples.

[0098] These examples can demonstrate that desirable properties can be obtained by post - curing of carbonated precast concrete using the methods of the present disclosure. Thus, as demonstrated below, a post - curing process 200 is further provided that includes a step of providing a carbonated precast concrete 202 and a step 204 of heat - treating the carbonated precast concrete at a temperature of 30 to 150 °C to obtain reinforced concrete. The carbonated precast concrete can be manufactured by the processes described herein or by other methods known in the art.

[0099] [Humidification] Before or currently alternating with the post - curing treatment, the carbonated precast concrete can be humidified. This humidification step can include, for example, the step of immersing the cured intermediate in water, the step of spraying water on the cured intermediate, and / or the step of atomizing water on the cured intermediate. Thus, in certain embodiments, the cured intermediate is humidified by immersion in tap water or water saturated with hydrated lime for 24 hours or less, or by sprinkling, spraying, and / or atomizing tap water. In certain embodiments, this humidification is carried out over a time of 0.5 to 48 hours. The preferred increase in the water content of the humidified carbonated precast concrete is 0.5 wt% or more. There can be a delay of up to 24 hours between the proposed humidification step and the subsequent post - curing treatment. Such a humidification step can be advantageous for carbonated precast concrete made with binders having hydraulic activity. Optionally, the water used for immersion / spray can contain mineral / chemical substances such as a rash - reducing agent mixture or a water - repellent agent. Alternatively, the carbonated precast concrete can be surrounded by steam during the post - curing treatment.

[0100] In step 208, carbon curing of the precast concrete is carried out to obtain carbonated precast concrete. In some embodiments, the carbonation reaction between the calcium - rich material and carbon dioxide is the material and CO 2This occurs when the calcium leached from [substance] dissolves in water. In concrete samples, the reaction generally occurs at a specific pore saturation. When the pores are filled with water and the saturation rate is 100% or near it, there is little or 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 0 percent. The optimal pore saturation, or more simply, the moisture content of the mixture, results in the highest carbonation reaction rate. Deviations from the optimal moisture content can lead to lower carbonation reactions and lower concrete performance.

[0101] In some embodiments, before the post-curing treatment in step 210, the carbonated precast concrete can be wetted or humidified. In some embodiments, the carbonated precast concrete is immersed in tap water or water saturated with hydrated lime for a period of 24 hours or less, or is immersed by spraying tap water. The preferred increase in the moisture content of the wet carbonated precast concrete is 0.5 wt% or more, for example 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 maximum delay of 24 hours between any wetting / humidifying step and the subsequent post-curing treatment 210. The described wetting or humidifying steps can be advantageous for carbonated precast concrete made with binders having hydraulic activity. Optionally, the water used for immersion / spraying can contain minerals / chemicals such as a rash reducing agent mixture or a water repellent. Alternatively, the carbonated precast concrete can be surrounded by steam during the post-curing treatment. Thus, in some embodiments, the steps of humidification and curing can be repeated or performed simultaneously.

[0102] In some embodiments, during the water absorption test, the carbonated precast concrete is immersed in water for 24 hours and then dried in an oven at 100 - 115 °C for 24 hours or more.

[0103] [Simultaneous Adjustment and Curing] Method 200 can include simultaneously conditioning and curing a formed intermediate. This may include conditioning the formed intermediate while curing the formed intermediate, where the formed intermediate is simultaneously cured and conditioned to obtain a final water-to-binder ratio that is less than a first water-to-binder ratio. In other words, while the formed intermediate is being cured, the water content of the formed intermediate decreases from the first water-to-binder ratio to the final water-to-binder ratio. Put another way, simultaneous conditioning and curing can include performing the curing process of the formed intermediate starting at a first point in time and ending at a second point in time, and conditioning the formed intermediate between the first point in time and the second point in time.

[0104] As used herein, the expression "simultaneously" means that two processes occur at the same time. In other words, while the formed intermediate is being cured, some water evaporates from the intermediate as part of the conditioning process. Typically, the water-to-binder ratio is constant during the curing process. The reason is that the water not required for the concrete composition is removed during the conditioning process that is performed before the hardening process. In this method 200, surplus water evaporates from the formed intermediate at the same time as the curing of the formed intermediate occurs.

[0105] In the illustrated embodiment, the step of simultaneously conditioning and curing the formed intermediate can include inserting the formed intermediate into a sealed enclosure 12 that is sealed from the external environment. Then, carbon dioxide at a concentration of at least 5 volume % is injected into the enclosure 12. Other concentrations are also contemplated. In this embodiment, the step of simultaneously conditioning and curing the formed intermediate includes absorbing the water that has evaporated from the formed intermediate during conditioning and curing. Absorbing the water that has evaporated from the formed intermediate can include absorbing the water with a desiccant material contained within the enclosure 12. In some embodiments, a dehumidifier can be used to extract humidity from the enclosure 12. The simultaneous performance of conditioning and curing at 208 can be performed without using an additional external heat source and / or without using pressure (e.g., mechanical pressure).

[0106] In the illustrated embodiment, the moisture content and / or water content of the concrete mixture can be reduced from a high water content to an optimum water content and may even fall below the optimum water content required for the carbonation reaction. The presence of carbon dioxide within the seal (chamber / closed environment / container) 12 during the adjustment at 208 and the curing process can result in calcium carbonate precipitation that can improve strength development in the concrete product. In other words, accelerated carbonation curing occurs while the relative humidity of chamber 12A of seal 12 is kept low. Any precast concrete product, including but not limited to concrete blocks, paving stones, retaining walls, slabs, traffic barriers, pipes, culverts, etc., can be manufactured by the proposed process.

[0107] In the present disclosure, pore saturation can be reduced during the simultaneous implementation of the adjustment at 208 and carbonation curing. Fresh concrete products are dried or semi-dried with the aid of a reduction in relative humidity. Low RH can be obtained by the presence of an absorbent material and / or high temperature in combination with an indoor air flow (e.g., blower 17) for better efficiency. In some embodiments, the air flow velocity generated by blower 17 or other suitable means can be at least 0.1 m / s. The absorbent or desiccant material may be silica gel, clay, calcium oxide, calcium chloride, molecular sieve, activated carbon, any other industrial absorbent, or any combination thereof. The presence of an absorbent in a sealed environment with an air flow generated by a fan or blower 17 or other means can gradually reduce the moisture content of fresh concrete. The circulating air can be at a low or high temperature. The RH within chamber 12A can also be reduced using any mechanical device including a dehumidifier that uses heating and ventilation or condensation methods to extract water from the air.

[0108] The air circulation speed can change while simultaneously performing the adjustment and curing at 208. In some cases, the blower 17 may be non-operational (e.g., no air flow). This means that the carbon dioxide in the housing 12 is stationary. This can be done by the control unit 20 changing the rotational speed of the blower 17. The amount of absorbent material 21 required can depend on the type of material used, the total moisture content in the concrete product, the type of concrete product, and the required or target specifications. Fresh air can be introduced into the chamber 12A from the outside of the chamber or, in another embodiment, from the inside of a closed chamber. In other words, a port 12B (Figure 1) can be provided to insert air through one of the walls of the seal 12. Adjustment at 208 and CO 2 By simultaneously performing curing, even after the carbonation reaction has stopped, the water content of the concrete product can be further reduced. The absorbent material 21 may be used over several cycles. The absorbent material can be replaced with a new material after it has lost its ability to capture moisture from the air. The absorbent material can be placed at any position within the chamber or can be evenly distributed within the chamber.

[0109] In another embodiment, the simultaneous process of adjustment and curing at 208 may be performed by introducing and circulating hot air. If hot and dry air is introduced into the chamber, the use of absorbent material is optional.

[0110] In another example, the air within the chamber may be heated by members, heaters, and other known means. If the air within the chamber is heated, the use of absorbent material may be optional. In another embodiment, the chamber body may be heated by an external heating blanket and other known means in the prior art. CO 2 If the body of the chamber is heated during the progress of the curing process, the use of absorbent material is optional. One or a combination of two of the above adjustment methods can be implemented.

[0111] The freshly cast concrete can be brought into contact with a gas containing carbon dioxide, CO 2 or CO 2 while its moisture content is simultaneously reduced during moisture extraction and CO 2 curing treatment. The carbon dioxide gas introduced to harden the concrete is of a purity of 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 increases gradually up to a range of 0.1 psi and optionally up to 100 psi.

[0112] The concrete product can be maintained under conditioning and CO 2 pressure for a given limited time (which can be at least 10 minutes), while the conditioning and CO 2 curing process at 208 can continue for up to 48 hours.

[0113] Conditioning and curing of the formed intermediate at 208 can include simultaneously conditioning and curing the formed intermediate without an additional external heat source and / or external pressure source.

[0114] In some embodiments, the drying rate can be varied in the presence of carbon dioxide while simultaneously performing conditioning and curing in step 208. The drying variations can be provided by different means such as an air stream having a varying rate, temperature variations, or relative humidity variations (by one or more of desiccant materials and mechanical means).

[0115] The step of simultaneously performing conditioning and curing at 208 can be achieved without an additional external heat source. In some embodiments, the step of simultaneously performing conditioning and curing at 208 can be achieved using an additional external heat source.

[0116] In Project 202, various types of aggregates, including natural or artificial normal and lightweight aggregates, can be provided as fillers in the production of the 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 usable aggregates include, but are not limited to, crushed stone, manufactured 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 and / or coarse aggregates. The aggregate content in the concrete mixture can be as high as about 90% of the weight of the concrete mixture.

[0117] [Examples] [Example 1 - Post - curing Treatment of Carbonated Precast Concrete with Different Slag Contents] Precast concrete samples were prepared with the binder contents shown in Table 1. The binder used was steel slag, and more specifically, a mixture of EAF and BOF slag was used. Before being used as a binder, it was purified to the required fineness. 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%. The specific gravity was 3.4. The standard weight aggregate used was crushed stone with a specific gravity of 2.7 and 100% passing through a 4.76 mm (No. 4) sieve. The moisture content was 0.25% and the water absorption rate was 0.75%. Compressed CO 2 gas in a cylinder with a purity exceeding 99.9% was used for carbonation curing.

[0118] The binder and aggregate were mixed in a mixer for 5 minutes, during which a sufficient amount of tap water was added to obtain the required workability. The resulting concrete mixture was molded and compacted to the desired density under compression and vibration. After demolding, the precast concrete samples were adjusted with a blower fan to lose about 20 - 80% of their initial moisture content. Thereafter, the adjusted precast concrete samples were loaded into a pressure chamber to accelerate carbonation curing. The pressure was adjusted to 9 - 15 psi and carbon dioxide gas was introduced into the sealed pressure chamber. The duration of carbonation curing varied from 4 hours to 24 hours. After carbonation curing, the comparative samples were immediately evaluated for their compressive strength according to ASTM C140 (Standard Test Method for Sampling and Testing Concrete Blocks and Related Units). Other carbonated precast concrete samples were subjected to post - curing treatment. First, the samples were completely immersed in tap water at 20°C for 24 hours, then they were taken out of the water tank. Next, the samples were dried in an oven at 110°C for 24 hours. Then, after the samples were taken out of the oven and completely cooled to room temperature, the compressive strength of those samples was evaluated. Two replicates were performed for each numbered sample in Table 1. The average strength, density, and CO 2 uptake of each numbered sample are shown in Table 1.

Table 1

[0119] The increase in strength of the carbonated precast concrete was significant after post - curing treatment. As shown in Table 1, for the carbonated precast concrete manufactured with a 20% binder content, its average compressive strength increased from 22.1 MPa to 27.7 MPa after post - curing treatment, an increase of 25%. For the carbonated precast concrete with a 25% binder content, its average compressive strength increased from 15.7 MPa to 27.1 MPa after post - curing treatment, an increase of 73%. With the help of post - curing treatment, the carbonated precast concrete with a 20% or 25% binder content can be stronger than Sample 3 with a 30% slag content.

[0120] For the carbonated precast concrete made with a binder content of 30%, the strength increase after post-curing treatment was between 37% and 112%, and the CO 2 changed under the curing conditions. With the help of post-curing treatment, the average strength of carbonated precast concrete with a binder content of 30% can exceed 50 MPa. Such high strength often requires a binder content of 50% for carbonated precast concrete without post-curing treatment, as demonstrated by Sample Comparison 6 in Table 1. The results obtained showed that the binder content of carbonated precast concrete can be saved up to 40% while maintaining its strength when post-curing treatment is applied.

[0121] [Example 2 Post-curing Treatment of Carbonated Precast Concrete at Different Treatment Temperatures and Times] More precast concrete samples were prepared with the binder contents shown in Table 2. The binder used was EAF steel slag, but from different suppliers. The slag was refined to the required fineness before being used as a binder. Each 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 2 used were the same as those used in Table 1.

[0122] The binder and aggregate were mixed in a mixer for 5 minutes, during which a sufficient amount of tap water was added to obtain the required workability. The resulting concrete mixture was molded and compacted to the desired density under compression and vibration. After demolding, the precast concrete samples were adjusted with a blower fan to lose about 20 - 80% of their initial moisture content. Then, the adjusted precast concrete samples were loaded into a pressure chamber for accelerated carbonation curing. The pressure was adjusted to 6 psi and carbon dioxide gas was introduced into the sealed pressure chamber. The carbonation curing time was 19 hours. After carbonation curing, the comparative samples were immediately evaluated for their compressive strength according to ASTM C140. Other carbonated precast concrete samples were subjected to post - curing treatment. For most samples, they were dried in an oven at 40 - 110°C for 6 or 24 hours. For samples 8.5 and 8.6, they were immersed in water for 24 hours and then dried in an oven at 100°C or 110°C for 24 hours. After the samples were taken out of the oven and completely cooled to room temperature, the compressive strength of the samples subjected to post - curing treatment was evaluated. For each numbered sample in Table 2, three replicates were performed. The average strength, density, and CO 2 uptake are shown in Table 2.

Table 2

[0123] As shown in Table 2, a significant increase in the compressive strength of carbonated precast concrete was observed with post - curing treatment. For sample comparison 7, its average compressive strength was 26.0 MPa. After 6 - hour post - curing treatment at 40 - 110°C, its strength increased to 37.4 MPa, an increase of 16 - 44%. A similar increase in strength was also observed when 24 - hour post - curing treatment was carried out at 60 - 110°C. For sample comparison 8, its average compressive strength was 42.2 MPa. After 24 - hour post - curing treatment at 60 - 110°C, its strength increased to 64.6 MPa, an increase of 15 - 53%. Post - curing treatment by water immersion before heating had the same effect on the strength of carbonated precast concrete in this case as simple heating without water immersion.

[0124] From Table 2, it can also be determined that an increase in the heating temperature during post-curing generally has a better effect on the increase in the strength of the carbonated precast concrete.

[0125] [Example 3 Post-curing of Carbonated Precast Concrete at Different Slag Contents, Different Treatment Temperatures, and Times] With the binder contents shown in Table 3, more precast concrete samples were prepared. The binder used was pot furnace slag. The slag was refined to the required 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 2 used were the same as those used in Table 1.

[0126] The binder and aggregates were mixed in a mixer for 5 minutes, during which a sufficient amount of tap water was added to obtain the required workability. The resulting concrete mixture was molded and compacted to the desired density under compression and vibration. After demolding, the precast concrete samples were adjusted with a fan blower to lose about 20 - 80% of their initial moisture content. Thereafter, the adjusted precast concrete samples were loaded into a pressure chamber for accelerated carbonation curing. The pressure was adjusted to 6 psi, and carbon dioxide gas was introduced into the sealed pressure chamber. The carbonation curing time was 19 hours. After carbonation curing, the comparative samples were immediately evaluated for their compressive strength according to ASTM C140. The other carbonated precast concrete samples were subjected to post-curing: for most samples, they were dried in an oven at 80 - 110 °C for 24 hours; for Samples 9.4 and 9.5, they were immersed in water for 24 hours and then dried in an oven at 100 °C or 110 °C for 24 hours. The compressive strength of the samples subjected to post-curing was evaluated after they were removed from 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 2The uptake is shown in Table 3.

Table 3

[0127] As shown in Table 3, a significant increase in the compressive strength of the carbonated precast concrete was observed in the post-curing treatment. For sample Comparative Example 9, its average compressive strength was 43.9 MPa. After the post-curing treatment at 80 - 110 °C for 24 hours, its strength increased to 55.9 MPa, an increase of 16 - 27%. When heat-treated after immersion in water, a more significant increase in strength was observed. With the combination of water immersion and drying after carbonation curing, its strength was greater than 60 MPa, an increase of more than 50%. For sample Comparative Example 10, its average compressive strength was 51.2 MPa. After the post-curing treatment at 80 - 110 °C for 24 hours, its strength increased to 69.8 MPa, an increase of 20 - 36%.

[0128] As expected, the average strengths of the carbonated precast concrete samples of Comparative Examples 9 and 10 were made of the same type of slag and increased from 43.9 MPa to 51.2 MPa when the slag content increased from 30% to 50%. However, with the help of the post-curing treatment, almost all carbonated precast concretes with a binder content of 30% were stronger than Comparative Example 10. The results obtained demonstrated that the binder content of carbonated precast concrete can be saved up to 40% while maintaining or increasing its strength when the post-curing treatment is applied.

[0129] It can also be determined from Table 3 that an increase in the heating temperature during the post-curing treatment generally has a better effect on the strength increase of carbonated precast concrete.

[0130] The disclosed method, including the post-curing process carried out after carbonation curing, can improve the properties of concrete products. These properties include, for example, durability, compressive strength, etc.

[0131] Referring now to FIG. 4, the control unit 20 can include an information processing apparatus 400 that can include a processing unit 402 and a memory 404 storing computer-executable instructions 406. The processing unit 402 can comprise, for example, any type of general-purpose microprocessor or microcontroller, digital signal processing (DSP) processor, central processing unit (CPU), integrated circuit, field programmable gate array (FPGA), reconfigurable processor, other suitably programmed or programmable logic circuit, or any combination thereof.

[0132] The memory 404 can comprise any suitable known or other machine-readable storage medium. The storage unit 404 can comprise, for example, without limitation, a non-transitory computer-readable storage medium including an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. The memory 404 can include, for example, any suitable combination of computer memories of any type located either internally or externally to 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 storage unit 404 can comprise any storage means (e.g., device) suitable for storing the machine-readable instructions 406 executable by the processing unit 402 in a retrievable manner.

[0133] The methods and systems for operating the system 10 described herein can be implemented in a high-level procedural or object-oriented programming language or scripting language, or a combination thereof, to communicate with or assist in the operation of a computer system, such as information processing device 400. 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 or interpreted language. The program code for implementing the methods and systems for operating the system 10 can be stored on a storage medium or device, such as a ROM, magnetic disk, optical disk, flash drive, or any other suitable storage medium or device. The program code can be readable by a general-purpose or special-purpose programmable computer for the purpose of configuring and operating the computer when the storage medium or device is read by the computer to execute the procedures described herein. Embodiments of the methods and systems for operating the system 10 can also be implemented by a non-transitory computer-readable storage medium having a computer program stored thereon. The computer program can comprise computer-readable instructions that cause a computer, or more specifically, the processing unit 402 of the information processing device 400, to operate in a specific predetermined manner to perform the functions described herein, such as the functions described in method 200.

[0134] Computer-executable instructions can be in many forms, including program modules executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform a particular task or implement a particular abstract data type. Typically, the functionality of program modules may be combined or distributed as desired in various embodiments.

[0135] The embodiments described in this specification 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, particularly configured computer hardware configurations. The embodiments described in this specification are directed to electromechanical machines and methods implemented by electromechanical means adapted to process and transform electromagnetic signals representing various types of information. The embodiments described in this specification relate broadly and integrally to machines and their use, and the embodiments described in this specification have no meaning or practical utility outside the scope of their use with computer hardware, machines, and various hardware components. For example, using mental processes to replace physical hardware specifically configured to implement various operations for non-physical hardware can substantially affect the way the embodiments function. Such limitations of computer hardware are clearly essential elements of the embodiments described herein, and mental means cannot be omitted or replaced without significantly affecting the operation and structure of the embodiments described herein. Computer hardware is essential for implementing the various embodiments described in this specification and is not merely used to execute steps quickly and efficiently.

[0136] The terms "connected" or "coupled" can include both direct coupling (where two elements that are coupled together are in contact with each other) and indirect coupling (where at least one additional member is located between the two members).

[0137] The technical solution of the embodiment may be in the form of a software product. The software product can be stored in a non-volatile or non-transitory 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 several instructions that enable a computer device (personal computer, server, or network device) to execute the method provided by the embodiment.

[0138] The embodiments described herein provide non-limiting examples of possible implementations of the present technology. Upon reviewing the present disclosure, those skilled in the art will recognize that they can make changes to the embodiments described herein without departing from the scope of the present technology. Further, those skilled in the art can, in view of the present disclosure, implement further modifications, which are within the scope of the present technology.

Claims

1. A method for manufacturing a concrete product, comprising: mixing a composition containing a binder, an aggregate, and water to produce a concrete mixture; providing a shaped intermediate by applying a mold to the concrete mixture; carbon-curing the shaped intermediate to obtain a cured intermediate; performing post-curing treatment on the cured intermediate by exposing the cured intermediate to a temperature higher than the ambient temperature, thereby obtaining the concrete product. A method having the above steps.

2. The method according to claim 1, wherein the step of exposing the cured intermediate to a temperature higher than the ambient temperature includes exposing the cured intermediate to a temperature of at least 30°C.

3. The method according to claim 2, wherein the step of exposing the cured intermediate to a temperature higher than the ambient temperature includes exposing the cured intermediate to a temperature of at least 40°C to 150°C.

4. The method according to claim 3, wherein the step of exposing the cured intermediate to a temperature higher than the ambient temperature includes exposing the cured intermediate to a temperature of at least 80°C to 100°C.

5. The method according to any one of claims 1 to 4, wherein the step of exposing the cured intermediate to the temperature includes raising the temperature of a curing chamber containing the cured intermediate at a rate of 20°C to 120°C per hour.

6. The method according to claim 5, further comprising maintaining the temperature inside the curing chamber at a temperature higher than at least 30°C.

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

8. The method according to any one of claims 1 to 7, wherein the step of exposing the cured intermediate to a temperature higher than the ambient temperature includes exposing the cured intermediate to the temperature for 1 hour to 72 hours.

9. The method according to claim 8, wherein the step of exposing the cured intermediate to a temperature higher than the ambient temperature includes exposing the cured intermediate to the temperature for at least 6 hours.

10. The method according to any one of claims 1 to 9, wherein the step of exposing the cured intermediate to a temperature higher than the ambient temperature is carried out immediately after the step of carbon curing.

11. The method according to any one of claims 1 to 10, having a step of filling the cured intermediate before the step of exposing the cured intermediate to a temperature higher than the ambient temperature.

12. The method according to any one of claims 1 to 11, having a step of humidifying the cured intermediate before carrying out the post-curing treatment.

13. The method according to claim 12, wherein the humidifying step includes one of the steps of immersing the cured intermediate in water, spraying water onto the cured intermediate, and spraying atomized water onto the cured intermediate.

14. The method according to claim 12, wherein the humidifying step is carried out simultaneously with the step of carrying out the post-curing treatment.

15. The method according to any one of claims 12 to 14, wherein the humidifying step is carried out for 0.5 hours to 48 hours.

16. The method according to any one of claims 1 to 15, further having a step of adjusting the shaped intermediate.

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

18. The method according to any one of claims 1 to 16, further having a step of providing the binder containing slag containing one or more of steel slag, stainless steel slag, basic oxygen converter sludge, blast furnace sludge, by-products of zinc products, by-products of iron products, and by-products of copper products.

19. The method according to any one of claims 1 to 18, further having a step of adding a mixture and / or an additive to the composition.

20. A method for manufacturing a concrete product, comprising the steps of obtaining a carbon-cured intermediate and performing a post-curing treatment on the carbon-cured intermediate by exposing the carbon-cured intermediate to a temperature higher than the ambient temperature, thereby obtaining the concrete product. The method comprising these steps.

21. A method for manufacturing a concrete product, comprising: providing a shaped intermediate by shaping a concrete mixture containing a binder, an aggregate, and water; obtaining a carbon-cured intermediate by carbon-curing the shaped intermediate; humidifying the cured intermediate; performing post-curing treatment on the carbon-cured intermediate by exposing the carbon-cured intermediate to a temperature higher than the ambient temperature, thereby obtaining the concrete product. A method having the above steps. **Claim 22** The method according to claim 21, wherein the humidifying step includes one of the steps of immersing the cured intermediate in water, spraying water onto the cured intermediate, and atomizing water onto the cured intermediate. **Claim 23** The method according to claim 21 or 22, wherein the humidifying step is performed before the step of performing the post-curing treatment. **Claim 24** The method according to claim 21 or 22, wherein the humidifying step is performed simultaneously with the step of performing the post-curing treatment. **Claim 25** The method according to any one of claims 21 to 24, wherein the humidifying step is performed for 0.5 hours to 48 hours. **Claim 26** The method according to any one of claims 21 to 25, wherein the step of exposing the carbon-cured intermediate to a temperature higher than the ambient temperature includes exposing the carbon-cured intermediate to a temperature of at least 30°C. **Claim 27** The method according to claim 26, further comprising exposing the carbon-cured intermediate to a temperature of at least 40°C to 150°C. **Claim 28** The method according to claim 27, further comprising exposing the carbon-cured intermediate to a temperature of 80°C to 100°C. **Claim 29** The method according to any one of claims 21 to 28, wherein the step of exposing the carbon-cured intermediate to the temperature further includes raising the temperature of the curing chamber containing the carbon-cured intermediate at a rate of 20°C to 120°C per hour. **Claim 30** The method according to any one of claims 21 to 29, wherein the step of exposing the carbon-cured intermediate to the temperature further includes exposing the carbon-cured intermediate to the temperature for 1 hour to 72 hours. **Claim 31** The method according to claim 30, further comprising the step of exposing the carbon-cured intermediate to the temperature for at least 6 hours.

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