Concrete cured by CO2 and preparation method thereof

Abstract

The invention discloses concrete cured by CO2 and a preparation method of the concrete, and belongs to the technical field of building materials. The concrete comprises the following components in parts by weight: 350-500 parts of a cementing material; 50 to 200 parts of a CO2 load substance; 600 to 800 parts of fine aggregate; 700 to 1000 parts of coarse aggregate; 5-20 parts of a polycarboxylate superplasticizer; and 130 to 170 parts of water. According to the invention, the CO2 load with a double-layer phase change structure is utilized to realize the controlled release of CO2 in stages, the gradually slowly released CO2 and the cementing material are subjected to mineralization reaction to form carbonized products, namely calcium carbonate and silica gel, so that the densification of a matrix is promoted, and the strength, hardness and durability are further improved; the slow-release CO2 curing reduces the energy consumption caused by autoclaved curing of the concrete, greatly shortens the curing time, reduces the production cost and improves the production efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and in particular relates to concrete cured by CO2 and a preparation method thereof. Background Art

[0002] With the vigorous development of modern concrete, concrete structures are widely used in structures such as various super-high-rise buildings, long-span bridges and industrial buildings. At the same time, as the demand for concrete continues to increase, its impact on the environment is also very significant. Among them, cement production alone accounts for 8% of the total global anthropogenic CO2 emissions. The productivity of the concrete industry and CO2 emissions are key issues that need to be addressed urgently. Only in this way can the growing construction needs be met while reducing damage to the environment. The study believes that it is an opportunity to focus on the research and development of concrete and concrete-like composite materials using captured CO2 as an ingredient. CO2 can be extracted directly from the air, but it can also be obtained from power plants or cement plants. CO2 can react with calcium hydroxide, calcium silicate hydrate and cement particles in cement-based materials to undergo mineral carbonation. The CO2 consumed in this reaction can reduce the total carbon emissions during cement production and permanently seal CO2 in concrete in a mineralized form, which will help to cope with the impact of climate change.

[0003] At present, the technology of using concrete materials to solidify CO2 is mainly divided into two aspects. The first is to perform carbonization curing on small concrete blocks and foam concrete bricks. When the fresh concrete is formed but not yet fully hydrated, the concrete is placed in an environment with appropriate temperature and humidity and CO2 is introduced for curing. During the curing process, the carbonizable substances in the cement clinker react with CO2 to generate calcium carbonate and silica gel. In addition, CO2 accelerates the carbonization curing of fresh concrete or mortar, which can also make it quickly gain strength and have good mechanical properties and durability. The second is to perform carbonization strengthening on industrial waste, such as steel slag, fly ash from power plants or tailings from mines. After pretreatment, the industrial waste reacts with CO2 to form carbonate materials, which are precipitated in the pores to make the industrial waste have higher density and strength, lower water absorption and crushing index. After improving the performance of industrial waste, it can be used as a suitable ingredient for concrete.

[0004] However, in the above method, CO2 cannot cure concrete in all stages, resulting in incomplete mineralization, which leads to low CO2 utilization and concrete carbonization efficiency. Therefore, it is urgent to develop a new type of concrete cured by CO2 and a preparation method thereof to solve the above problems. Summary of the invention

[0005] One of the purposes of the present invention is to provide a concrete cured by CO2 to solve the problems of low CO2 utilization and low concrete carbonization efficiency in the prior art; A second object of the present invention is to provide a method for preparing concrete using CO2 curing.

[0006] The purpose of the present invention can be achieved through the following technical solutions: In a first aspect, the present invention provides a concrete cured by CO2, comprising the following components in parts by weight: 350-500 parts of cementitious materials; CO2 loading 50-200 parts; 600-800 parts of fine aggregate; 700-1000 parts of coarse aggregate; 5-20 parts of polycarboxylate water reducer; 130-170 parts of water.

[0007] As a further embodiment of the present invention, the method for preparing the CO2 load comprises the following steps: S1. The zeolite was ground and placed in a calcium bicarbonate solution for vacuum impregnation treatment, and then vacuum dried to obtain an activated zeolite loaded with a CaCO3 precursor; S2. Using a microfluidic process, a carbonate solution is injected into the fiber cavity of the hollow glass fiber; the ends are capped with molten paraffin and then cooled and solidified to obtain a glass fiber coated with a carbonate solution; S3. After the paraffin particles and the activator are uniformly mixed, the obtained mixed particles are placed in a fluidized bed, and nitrogen is introduced to fluidize the particles to form a uniform suspension state; then the PMMA (polymethyl methacrylate) solution is uniformly sprayed onto the surface of the fluidized particles, and after solidification, the paraffin@PMMA phase change particles are obtained; S4. Dry-mix the activated zeolite, glass fiber, and paraffin@PMMA phase change particles to obtain a CO2 load.

[0008] As a further embodiment of the present invention, in S1, the concentration of the calcium bicarbonate solution is 10-30 mol / L; for example, in different embodiments, the concentration of the calcium bicarbonate solution may be, but is not limited to, 10 mol / L, 15 mol / L, 20 mol / L, 25 mol / L, or 30 mol / L.

[0009] As a further embodiment of the present invention, in S1, the vacuum impregnation treatment temperature is 40-50 , time is 2-10h; as in different embodiments, the vacuum impregnation treatment temperature is 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 The time is 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h.

[0010] As a further embodiment of the present invention, in S1, the vacuum drying temperature is 30-40 , time is 2-4h; as in different embodiments, the vacuum drying temperature is 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , the time is 2h, 3h, 4h.

[0011] As a further solution of the present invention, in S2, the mass percentage of the carbonate solution is 4%-8%. For example, in different embodiments, the mass percentage of the carbonate solution is 4%, 5%, 6%, 7%, or 8%.

[0012] As a further solution of the present invention, in S2, the inner diameter of the hollow glass fiber is 100-200 μm, the wall thickness is 10-20 μm, and the length is 10-20 cm.

[0013] As a further solution of the present invention, in S2, the thickness of the end-capping sealing layer is 4-10 μm.

[0014] As a further solution of the present invention, in S3, the mass ratio of the paraffin particles to the activator is 3:1.

[0015] As a further embodiment of the present invention, in S3, the exciter is an azo compound or a hydrazine compound; specifically, the exciter is any one or a combination of azodicarbonamide or ammonium carbazate.

[0016] As a further solution of the present invention, in S3, the solvent in the PMMA solution is acetone, and the mass concentration of the PMMA solution is 1-5wt%. For example, in different embodiments, the mass concentration of the PMMA solution is 1wt%, 2wt%, 3wt%, 4wt%, and 5wt%.

[0017] As a further solution of the present invention, in S3, the spraying thickness of the PMMA is 3±1 μm.

[0018] As a further solution of the present invention, in S4, the mass percentages of activated zeolite, glass fiber, and paraffin@PMMA phase change particles are 50%:30%:20%.

[0019] As a further embodiment of the present invention, the cementitious material is a mixture of cement and mineral admixtures in any proportion, the cement is one or more of silicate cement, sulphoaluminate cement, and aluminate cement; the mineral admixture is industrial solid waste, specifically one or more of fly ash, slag powder, silica fume, steel slag powder, gypsum powder, and limestone powder.

[0020] As a further solution of the present invention, the coarse aggregate is one or more of crushed stone, pebbles, and recycled aggregate; and the fine aggregate is one or more of natural sand and machine-made sand.

[0021] In a second aspect, the present invention provides a method for preparing concrete using CO2 curing, comprising the following steps: Step 1: Mix the cementitious material, fine aggregate and coarse aggregate to obtain material 1; Step 2: Mix the polycarboxylate water reducer and water evenly, add the mixture to material 1, and stir evenly to obtain material 2; Step 3: Add the CO2 load to material 2, stir evenly, and obtain concrete cured by CO2.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a concrete cured by CO2. The CO2 carrier added specifically can not only be used to perform CO2 curing on the concrete in the mixing stage, but also can be used continuously to perform continuous mineralization curing on the concrete in the curing stage, thereby achieving full-stage CO2 curing of the concrete.

[0023] 2. In the present invention, the ground zeolite is immersed in a calcium bicarbonate solution and then vacuum dried to obtain an activated zeolite loaded with a CaCO3 precursor; paraffin is used as a phase change material. On the one hand, the hollow glass fiber injected with the carbonate solution is capped with paraffin. When the ambient temperature reaches the melting point of the paraffin (≥60 ), the paraffin wax as the end capping layer of the hollow glass fiber begins to melt, gradually releasing the carbonic acid solution to react with the activated loaded CaCO3 precursor to produce CO2; on the other hand, the paraffin wax particles and the activator are evenly mixed, and the PMMA shell layer is sprayed by the fluidized bed process to form a phase change microcapsule; due to the PMMA shell layer as the wall material, the mechanical strength and thermal stability of the particles are further enhanced. Under the action of temperature, the paraffin wax phase change core layer melts to expand the volume, and the gas released by the decomposition of the activator increases the internal pressure to further break through the melted hollow glass fiber end capping layer, while releasing the carbonic acid solution, it penetrates into the cement matrix to undergo a carbonization reaction, thereby improving the CO2 utilization rate and the carbonization efficiency.

[0024] 3. The concrete prepared by the present invention utilizes a CO2 carrier with a double-layer phase change structure to achieve a controlled release of CO2 in stages. The gradually released CO2 undergoes a mineralization reaction with the cementitious material to form carbonized products of calcium carbonate and silica gel, which promotes the densification of the matrix and further improves the strength, hardness and durability. In addition, the slow-release CO2 curing reduces the energy consumption caused by concrete autoclave curing and greatly shortens the curing time, thereby reducing production costs and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below in conjunction with the accompanying drawings.

[0026] Figure 1 It is a schematic diagram of the preparation process of CO2 loading materials in Preparation Examples 1 to 6 of the present invention; Figure 2 It is a schematic diagram of the preparation process flow of concrete cured by CO2 according to the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Obviously, the following descriptions are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in the field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0029] However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially the same structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the following description is provided for those skilled in the art to fully understand the present application and is not intended to limit the subject matter described in the claims.

[0030] If not otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution, and all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0031] In the following examples and comparative examples, the selection of concrete raw materials is shown in Table 1: Table 1

[0032] Preparation Example 1

[0033] See also Figure 1 The preparation process flow diagram shown in the figure is a method for preparing a CO2-loaded material, comprising the following steps: S1. Grind the zeolite to a particle size of 500-800 μm, place it in a 20 mol / L calcium bicarbonate solution, and After vacuum impregnation for 8 hours under 35 After vacuum drying at a temperature of 3 h, the activated zeolite loaded with the CaCO3 precursor was obtained; S2. Fix a hollow glass fiber with an inner diameter of 100-200 μm, a wall thickness of 10-20 μm, and a length of 10-20 cm on a microfluidic operation bed, inject a 6% by mass carbonic acid solution into the hollow glass fiber cavity by injecting the solution into the syringe pump; then heat the paraffin to 60 After melting, the fiber ends were sealed with molten paraffin, and the thickness of the end sealing layer was controlled to be 7±1μm. Cooling and solidifying under the conditions of , to obtain glass fiber coated with carbonic acid solution; S3. After the paraffin particles and ammonium carbazate were mixed at a mass ratio of 3:1 at a speed of 1000 rpm, the mixed particles were placed in a fluidized bed and nitrogen was introduced at a nitrogen flow rate of 0.6 m / s and a bed temperature of 40 , the atomization pressure is 0.2MPa, the spray rate is 3mL / min, the mixed particles are fluidized to form a uniform suspension state; then, a PMMA solution with a mass concentration of 3wt% prepared with acetone as the solvent is evenly sprayed on the surface of the fluidized particles, the spraying thickness is controlled to be 3±1μm, and paraffin@PMMA phase change particles are obtained after solidification; S4. Dry-mix the activated zeolite, glass fiber, and paraffin@PMMA phase change particles in a mass percentage of 50%:30%:20% to obtain a CO2 load.

[0034] Preparation Example 2

[0035] A method for preparing a CO2 load, which differs from Preparation Example 1 in that in step 1, the concentration of the calcium bicarbonate solution is 10 mol / L, and the remaining steps and parameters remain the same.

[0036] Preparation Example 3

[0037] A method for preparing a CO2 load, which differs from Preparation Example 1 in that in step 1, the concentration of the calcium bicarbonate solution is 30 mol / L, and the remaining steps and parameters remain the same.

[0038] Preparation Example 4

[0039] A method for preparing a CO2 load, which differs from Preparation Example 1 in that in step 2, the mass percentage of the carbonic acid solution is 4%, and the other steps and parameters remain the same.

[0040] Preparation Example 5

[0041] A method for preparing a CO2 load, which differs from Preparation Example 1 in that in step 2, the mass percentage of the carbonic acid solution is 8%, and the other steps and parameters remain the same.

[0042] Preparation Example 6

[0043] A method for preparing a CO2 load, which differs from Preparation Example 1 in that in step 3, ammonium hydrazinecarboxylate is replaced by azodicarbonamide, and the remaining steps and parameters remain the same.

[0044] Example 1

[0045] A CO2-cured concrete comprising the following components in parts by weight: 400 parts of cementitious material (cement and mineral admixture mixed in a mass ratio of 6:4); 150 parts of CO2 loading material (prepared in Preparation Example 1); Fine aggregate (natural sand) 700 parts; 950 parts of coarse aggregate (recycled coarse aggregate and crushed stone mixed in a mass ratio of 1:1); 15 parts of polycarboxylate water reducer; 150 parts water; The preparation method of the concrete is shown in Figure 2 The schematic diagram of the preparation process shown comprises the following steps: Step 1: Mix the cementitious material, fine aggregate and coarse aggregate to obtain material 1; Step 2: Mix the polycarboxylate water reducer and water evenly, add them into material 1, and continue stirring for 120 seconds to obtain material 2; Step 3: Add the CO2 loading substance to material 2 and continue stirring for 25 seconds to obtain concrete cured by CO2; The obtained concrete was poured into a mold, vibrated to compact it, and cured for 28 days under standard conditions.

[0046] Example 2

[0047] A concrete cured by CO2, which is different from Example 1 in that the CO2 loading material is prepared by Preparation Example 2, and the other steps and parameters remain the same.

[0048] Example 3

[0049] A concrete cured by CO2, which is different from Example 1 in that the CO2 loading material is prepared by Preparation Example 3, and the other steps and parameters remain the same.

[0050] Example 4

[0051] A concrete cured by CO2, which differs from Example 1 in that the CO2 loading material is prepared by Preparation Example 4, and the other steps and parameters remain the same.

[0052] Example 5

[0053] A concrete cured by CO2, which is different from Example 1 in that the CO2 loading material is prepared by Preparation Example 5, and the other steps and parameters remain the same.

[0054] Example 6

[0055] A concrete cured by CO2, which differs from Example 1 in that the CO2 loading material is prepared by Preparation Example 6, and the other steps and parameters remain the same.

[0056] Example 7

[0057] A CO2-cured concrete comprising the following components in parts by weight: 400 parts of cementitious material (cement and mineral admixture mixed in a mass ratio of 6:4); 50 parts of CO2 loading material (prepared in Preparation Example 1); Fine aggregate (natural sand) 700 parts; 950 parts of coarse aggregate (recycled coarse aggregate and crushed stone mixed in a mass ratio of 1:1); 15 parts of polycarboxylate water reducer; 130 parts water; The preparation method of the concrete is the same as that of Example 1.

[0058] Example 8

[0059] A CO2-cured concrete comprising the following components in parts by weight: 400 parts of cementitious material (cement and mineral admixture mixed in a mass ratio of 6:4); 200 parts of CO2 loading material (prepared in Preparation Example 1); Fine aggregate (natural sand) 700 parts; 950 parts of coarse aggregate (recycled coarse aggregate and crushed stone mixed in a mass ratio of 1:1); 15 parts of polycarboxylate water reducer; 170 parts water; The preparation method of the concrete is the same as that of Example 1.

[0060] Comparative Preparation Example 1

[0061] A method for preparing a CO2-loaded material comprises the following steps: S1. Grind the zeolite to a particle size of 500-800 μm, place it in a 15 mol / L calcium bicarbonate solution, and After vacuum impregnation for 8 hours under 35 After vacuum drying at a temperature of 3 h, the activated zeolite loaded with the CaCO3 precursor was obtained; S2. Fix a hollow glass fiber with an inner diameter of 100-200 μm, a wall thickness of 10-20 μm, and a length of 10-20 cm on a microfluidic operation bed, inject a 6% by mass carbonic acid solution into the hollow glass fiber cavity by injecting the solution into the syringe pump; then heat the paraffin to 60 After melting, the fiber ends were sealed with molten paraffin, and the thickness of the end sealing layer was controlled to be 7±1μm. Cooling and solidifying under the conditions of , to obtain glass fiber coated with carbonic acid solution; S3. The paraffin particles and ammonium carbazate are mixed at a mass ratio of 3:1 at a rotation speed of 1000 rpm to obtain mixed particles, and the mixed particles are dry-mixed with activated zeolite and glass fiber at a mass percentage of 20%:50%:30% to obtain a CO2 load.

[0062] Comparative Example 1

[0063] A concrete cured by CO2, which differs from Example 1 in that the CO2 loading material is prepared by Comparative Preparation Example 1, and the other steps and parameters remain the same.

[0064] Comparative Example 2

[0065] A common concrete, calculated by weight, comprises the following components: 400 parts of cementitious material (cement and mineral admixture mixed in a mass ratio of 6:4); 800 parts of fine aggregate (natural sand); 1000 parts of coarse aggregate (recycled coarse aggregate and crushed stone mixed in a mass ratio of 1:1); 15 parts of polycarboxylate water reducer; 150 parts water; The method for preparing the concrete comprises the following steps: Step 1: Mix the cementitious material, fine aggregate and coarse aggregate to obtain material 1; Step 2: Mix the polycarboxylate water reducer and water evenly and add them to material 1, and continue stirring for 120 seconds to obtain ordinary concrete; The obtained ordinary concrete was poured into a mold, vibrated to make it dense, and cured for 28 days under standard conditions.

[0066] Performance Test: (1) Referring to GB / T 50080-2016 "Standard for Test Methods for Performance of Ordinary Concrete Mixtures", the compressive strength test of the concrete prepared in Examples 1 to 8 and Comparative Examples 1 and 2 was carried out. The test results are shown in Table 2.

[0067] Table 2

[0068] (2) The frost resistance of the concrete prepared in Examples 1 to 8 and Comparative Examples 1 and 2 was tested with reference to GB / T50082-2009 "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete"; the softening coefficient was tested with reference to JGJ / T12-2019 "Technical Standard for Application of Lightweight Aggregate Concrete"; the test results are shown in Table 3.

[0069] Table 3

[0070] From the test results in Table 2 and Table 3, it can be seen that, compared with Example 1 and Comparative Example 1, since the paraffin particles in the CO2 load in Comparative Example 1 are not coated with PMMA, the CO2 load with only a single-layer phase change structure cannot achieve phased CO2 sustained release, resulting in poor strength; in the freeze-thaw test process, since paraffin as a phase change material achieves a buffering effect, after 150 freeze-thaw cycles, the relative dynamic elastic modulus of Example 1 maintains a better relative elastic modulus; at the same time, the carbonization reaction of CO2 and the cement matrix improves the pore structure of the concrete, indicating that the concrete with the addition of a double-layer phase change structure CO2 load has better antifreeze performance; comparing Example 1 and Comparative Example 2, without adding a double-layer phase change structure CO2 load, the relative elastic modulus of the concrete is 54.7%, which is lower than 60%, and is determined to have suffered freeze-thaw damage.

[0071] In summary, it can be seen that the concrete prepared by the present invention utilizes the CO2 carrier with a double-layer phase change structure to achieve the controlled release of CO2 in stages, and the gradually released CO2 undergoes a mineralization reaction with the cementitious material to form carbonized products such as calcium carbonate and silica gel, which promote the densification of the matrix and further improve the strength, hardness and durability. After 150 freeze-thaw cycles, the relative dynamic elastic modulus remains stable and does not suffer from freeze-thaw damage. In addition, the softening coefficient is greater than 1.0 and is not damaged by water, indicating that the slow-release CO2 cured concrete prepared by the present invention can be used in a relatively humid environment and is not damaged. The present invention can reduce the energy consumption caused by autoclave curing and greatly shorten the curing time, reduce production costs, and improve production efficiency.

[0072] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0073] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

[0074] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be deemed to belong to the scope of protection of the present invention.

Claims

1. A concrete cured by CO2, characterized in that: According to weight parts, it includes the following components: 350-500 parts of cementitious materials; CO2 loading 50-200 parts; 600-800 parts of fine aggregate; 700-1000 parts of coarse aggregate; 5-20 parts of polycarboxylate water reducer; 130-170 parts of water.

2. The CO2-cured concrete according to claim 1, characterized in that: The method for preparing the CO2 load comprises the following steps: S1. The zeolite was ground and placed in a calcium bicarbonate solution for vacuum impregnation, and the activated zeolite was obtained after vacuum drying; S2. Using a microfluidic process, a carbonate solution is injected into the fiber cavity of the hollow glass fiber; the ends are capped with molten paraffin and then cooled and solidified to obtain a glass fiber coated with a carbonate solution; S3. After the paraffin particles and the activator are uniformly mixed, the mixed particles are placed in a fluidized bed, and nitrogen is introduced to fluidize the particles to form a uniform suspension state; then the PMMA solution is evenly sprayed onto the surface of the fluidized particles, and after solidification, the paraffin @ PMMA phase change particles are obtained; S4. Dry-mix the activated zeolite, glass fiber, and paraffin@PMMA phase change particles to obtain a CO2 load.

3. The CO2-cured concrete according to claim 2, characterized in that: In S1, the concentration of the calcium bicarbonate solution is 10-30 mol / L.

4. The CO2-cured concrete according to claim 2, characterized in that: In S2, the mass percentage of the carbonic acid solution is 4%-8%.

5. The CO2-cured concrete according to claim 2, characterized in that: In S3, the mass ratio of the paraffin particles to the activator is 3:

1.

6. The CO2-cured concrete according to claim 2, characterized in that: In S3, the activator is an azo compound or a hydrazine compound.

7. The CO2-cured concrete according to claim 2, characterized in that: In S3, the solvent in the PMMA solution is acetone, and the mass concentration of the PMMA solution is 1-5wt%.

8. The CO2-cured concrete according to claim 2, characterized in that: In S4, the mass percentages of activated zeolite, glass fiber, and paraffin@PMMA phase change particles are 50%:30%:20%.

9. The CO2-cured concrete according to claim 1, characterized in that: The cementitious material is a mixture of cement and mineral admixtures; the coarse aggregate is one or more of crushed stone, pebble, and recycled aggregate; and the fine aggregate is one or more of natural sand and machine-made sand.

10. A method for preparing concrete using CO2 curing as claimed in claim 1, characterized in that: The following steps are involved: Step 1: Mix the cementitious material, fine aggregate and coarse aggregate to obtain material 1; Step 2: Mix the polycarboxylate water reducer and water evenly, add the mixture to material 1, and stir evenly to obtain material 2; Step 3: Add the CO2 load to material 2, stir evenly, and obtain concrete cured by CO2.

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