A concrete cured by using CO2 and a preparation method thereof

Abstract

The present invention discloses a CO2-cured concrete and its preparation method, belonging to the technical field of building materials. The concrete comprises the following components in parts by weight: 350-500 parts of cementitious materials; 50-200 parts of CO2 load; 600-800 parts of fine aggregate; 700-1000 parts of coarse aggregate; 5-20 parts of polycarboxylate water reducer; and 130-170 parts of water. The present invention utilizes the CO2 load with a double-layer phase change structure to achieve the controlled release of CO2 in stages. The gradually released CO2 reacts with the cementitious materials to undergo a mineralization reaction, forming carbonation products calcium carbonate and silica gel to promote the densification of the matrix, further improving the strength, hardness and durability; the slow-release CO2 curing reduces the energy consumption brought by autoclave curing of concrete and greatly shortens the curing time, reduces the production cost and improves the production efficiency.

Description

Technical Field

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

[0002] With the vigorous development of modern concrete, concrete structures are widely used in various structures such as super high-rise buildings, long-span bridges, and industrial buildings. At the same time, with the continuous increase in the demand for concrete, its impact on the environment is also very significant. Among them, only the cement production link accounts for 8% of the total global anthropogenic CO2 emissions. The productivity of the concrete industry and the CO2 emissions are key issues that need to be solved urgently. Only in this way can the growing construction needs be met while reducing the damage to the environment. Research believes that taking the captured CO2 from the outside world as a component and concentrating on the research and development of concrete and concrete-like composite materials is an opportunity. CO2 can be directly extracted 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 reactions. The CO2 consumed in this reaction can reduce the total carbon emissions during cement production, and the CO2 can be permanently sealed in the concrete in a mineralized form, which will help to cope with the impact of climate change.

[0003] Currently, the technology of using concrete materials to solidify CO2 is mainly divided into two aspects. One is to carry out carbonation curing on small-sized concrete blocks and foam concrete bricks, etc. After the fresh concrete is formed and has not been 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 form calcium carbonate and silica gel, and accelerating the carbonation curing of fresh concrete or mortar with CO2 can also enable it to quickly obtain strength and have good mechanical properties and durability. The other is to carry out carbonation strengthening on industrial wastes such as steel slag, fly ash from power plants, or tailings from mines, etc. After pretreatment, the industrial wastes react with CO2 to form carbonate materials, which precipitate in the pores to make the industrial wastes have higher density and strength, lower water absorption rate and crushing index. After improving the performance of the industrial wastes, they can be used as suitable ingredients for concrete.

[0004] However, in the above methods, CO2 cannot carry out full-stage curing on the concrete, resulting in the problem of incomplete mineralization, leading to low CO2 utilization rate and low concrete carbonation efficiency. Therefore, it is urgent to develop a new type of CO2-cured concrete and a preparation method thereof to solve the above problems. Summary of the Invention

[0005] One object of the present invention is to provide a CO2-cured concrete to solve the problems of low CO2 utilization rate and low concrete carbonation efficiency in the prior art;

[0006] Another object of the present invention is to provide a method for preparing concrete cured by CO2.

[0007] The object of the present invention can be achieved by the following technical solutions:

[0008] In a first aspect, the present invention provides a concrete cured by CO2, which comprises the following components in parts by weight:

[0009] 350 - 500 parts of cementitious material;

[0010] 50 - 200 parts of CO2 carrier;

[0011] 600 - 800 parts of fine aggregate;

[0012] 700 - 1000 parts of coarse aggregate;

[0013] 5 - 20 parts of polycarboxylate superplasticizer;

[0014] 130 - 170 parts of water.

[0015] As a further aspect of the present invention, the preparation method of the CO2 carrier comprises the following steps:

[0016] S1. Grind zeolite and place it in a calcium bicarbonate solution for vacuum impregnation treatment. After vacuum drying, activated zeolite loaded with CaCO3 precursor is obtained;

[0017] S2. Adopt a microfluidic process to inject carbonic acid solution into the fiber cavity of hollow glass fiber; then seal its end with molten paraffin and cool and solidify it to obtain glass fiber coated with carbonic acid solution;

[0018] S3. Mix paraffin particles and activator evenly, place the obtained mixed particles in a fluidized bed, introduce nitrogen to fluidize the particles to form a uniform suspension state; then evenly spray PMMA (polymethyl methacrylate) solution on the surface of the fluidized particles and solidify it to obtain paraffin@PMMA phase change particles;

[0019] S4. Dry - mix the activated zeolite, glass fiber, and paraffin@PMMA phase change particles evenly to obtain the CO2 carrier.

[0020] As a further aspect of the present invention, in S1, the concentration of the calcium bicarbonate solution is 10 - 30 mol / L; in different embodiments, the concentration of the calcium bicarbonate solution can be, but is not limited to, 10 mol / L, 15 mol / L, 20 mol / L, 25 mol / L, 30 mol / L.

[0021] As a further solution of the present invention, in S1, the temperature of the vacuum impregnation treatment is 40-50 , and the time is 2-10h; in different embodiments, the temperature of the vacuum impregnation treatment is 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , and the time is 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h.

[0022] As a further solution of the present invention, in S1, the temperature of the vacuum drying is 30-40 , and the time is 2-4h; in different embodiments, the temperature of the vacuum drying is 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , and the time is 2h, 3h, 4h.

[0023] As a further solution of the present invention, in S2, the mass percentage of the carbonic acid solution is 4%-8%. In different embodiments, the mass percentage of the carbonic acid solution is 4%, 5%, 6%, 7%, 8%.

[0024] As a further solution of the present invention, in S2, the inner diameter of the hollow glass fiber is 100-200μm, the wall thickness is 10-20μm, and the length is 10-20cm.

[0025] As a further solution of the present invention, in S2, the thickness of the sealed end sealing layer is 4-10μm.

[0026] As a further solution of the present invention, in S3, the mass ratio of the paraffin particles to the activator is 3:1.

[0027] As a further solution of the present invention, in S3, the activator is an azo compound or a hydrazine compound; specifically, the activator is any one or a combination of azodicarbonamide or ammonium carbazate.

[0028] 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 1-5 wt%. In different embodiments, the mass concentration of the PMMA solution is 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%.

[0029] As a further solution of the present invention, in S3, the spraying thickness of the PMMA is 3±1 μm.

[0030] As a further solution of the present invention, in S4, the mass percentage of activated zeolite, glass fiber, and paraffin@PMMA phase change particles is 50%:30%:20%.

[0031] As a further solution of the present invention, the cementitious material is a mixture of cement and mineral admixture mixed in any ratio. The cement is one or more of portland cement, sulfoaluminate 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.

[0032] As a further solution of the present invention, the coarse aggregate is one or more of crushed stone, pebble, and recycled aggregate; the fine aggregate is one or more of natural sand and manufactured sand.

[0033] In the second aspect, the present invention provides a preparation method of concrete cured by CO2, including the following steps:

[0034] Step 1: Stir the cementitious material, fine aggregate, and coarse aggregate evenly to obtain Material 1;

[0035] Step 2: Mix the polycarboxylate water reducer and water evenly and then add them to Material 1, and stir evenly to obtain Material 2;

[0036] Step 3: Add the CO2 carrier to Material 2 and stir evenly to obtain the concrete cured by CO2.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] 1. The present invention provides a concrete cured by CO2. The specially added CO2 carrier can not only cure the concrete with CO2 during the mixing stage, but also continuously use CO2 to carry out continuous mineralization curing of the concrete during the solidification stage, realizing the full-stage curing of the concrete with CO2.

[0039] 2. In the present invention, the ground zeolite is impregnated in a calcium bicarbonate solution and then vacuum dried to obtain activated zeolite loaded with a CaCO3 precursor. Using paraffin as a phase change material, on the one hand, paraffin is used to seal the hollow glass fiber injected with a carbonic acid solution. When the ambient temperature reaches the melting point of paraffin (≥60 ), the paraffin serving as the sealing layer of the hollow glass fiber begins to melt and gradually releases the carbonic acid solution to react with the activated and loaded CaCO3 precursor to produce CO2. On the other hand, paraffin particles are uniformly mixed with an activator, and a PMMA shell layer is sprayed using a fluidized bed process to form phase change microcapsules. Due to the PMMA shell layer serving as a wall material, the mechanical strength and thermal stability of the particles are further enhanced. Under the action of temperature, the paraffin phase change core layer melts and expands in volume, and the gas released by the decomposition of the activator increases the internal pressure to further break through the melted sealing layer of the hollow glass fiber, releasing the carbonic acid solution and at the same time penetrating into the cement substrate to undergo a carbonization reaction, improving the CO2 utilization rate and the carbonization efficiency.

[0040] 3. The concrete prepared by the present invention uses a CO2 loading 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 calcium carbonate and silica gel, which promote the densification of the matrix and further improve the strength, hardness and durability. In addition, the slow-release CO2 curing reduces the energy consumption brought by autoclave curing of concrete and greatly shortens the curing time, reducing the production cost and improving the production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be further described below with reference to the accompanying drawings.

[0042] Figure 1 is a schematic process flow diagram for the preparation of the CO2 loading in Preparation Examples 1 - 6 of the present invention;

[0043] Figure 2 is a schematic process flow diagram for the preparation of the concrete cured with CO2 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0044] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0045] Obviously, the following description is only some examples or embodiments of the present application. For those of ordinary skill in the art, without creative efforts, the present application can also be applied to other similar scenarios. In addition, it can also be understood that although the efforts made in such a development process may be complex and lengthy, for those of ordinary skill in the art related to the content disclosed in the present application, some design, manufacturing, or production changes based on the technical content disclosed in the present application are only conventional technical means and should not be understood as the content disclosed in the present application being insufficient.

[0046] However, there will be cases where unnecessary detailed descriptions are omitted. For example, there are cases where the detailed descriptions of well-known matters are omitted and the repeated descriptions of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of 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 recited in the claims.

[0047] If there is no special description, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0048] In the following examples and comparative examples, the selection of concrete raw materials is shown in Table 1:

[0049] Table 1

[0050]

[0051] Preparation Example 1

[0052] Please refer to Figure 1 the schematic diagram of the preparation process shown, a method for preparing a CO2 loading material, comprising the following steps:

[0053] S1. Grind zeolite to a particle size of 500 - 800 μm, place it in a 20 mol / L calcium bicarbonate solution, carry out vacuum impregnation at 45 for 8 h, and then vacuum dry at 35 for 3 h to obtain activated zeolite loaded with CaCO3 precursor;

[0054] S2. Fix hollow glass fibers 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 an injection pump, and inject it into the cavity of the hollow glass fibers; then heat paraffin to 60 After melting it, molten paraffin is used to seal the fiber ends, and the thickness of the end sealing layer is controlled to be 7 ± 1 μm, and it is immediately placed under the condition of ≤ 20 for cooling and solidification to obtain glass fibers coated with carbonic acid solution;

[0055] S3. After mixing paraffin particles and ammonium carbazate evenly at a rotation speed of 1000 rpm according to a mass ratio of 3:1, the obtained mixed particles are placed in a fluidized bed, nitrogen is introduced, the nitrogen flow rate is 0.6 m / s, the bed temperature is 40 , the atomization pressure is 0.2 MPa, and the spraying rate is 3 mL / min to fluidize the mixed particles to form a uniform suspension state; then a PMMA solution with a mass concentration of 3 wt% prepared with acetone as the solvent is evenly sprayed on the surface of the fluidized particles, and the spraying thickness is controlled to be 3 ± 1 μm, and paraffin@PMMA phase change particles are obtained after curing;

[0056] S4. Activated zeolite, glass fibers, and paraffin@PMMA phase change particles are dry-mixed evenly according to a mass percentage of 50%:30%:20% to obtain a CO2 loading.

[0057] Preparation Example 2

[0058] A method for preparing a CO2 loading, which is different 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.

[0059] Preparation Example 3

[0060] A method for preparing a CO2 loading, which is different 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.

[0061] Preparation Example 4

[0062] A method for preparing a CO2 loading, which is different from Preparation Example 1 in that in Step 2, the mass percentage of the carbonic acid solution is 4%, and the remaining steps and parameters remain the same.

[0063] Preparation Example 5

[0064] A method for preparing a CO2 loading, which is different from Preparation Example 1 in that in Step 2, the mass percentage of the carbonic acid solution is 8%, and the remaining steps and parameters remain the same.

[0065] Preparation Example 6

[0066] A method for preparing a CO2 loading, which is different from Preparation Example 1 in that in Step 3, ammonium carbazate is replaced by azodicarbonamide, and the remaining steps and parameters remain the same.

[0067] Example 1

[0068] A CO2-cured concrete, by weight, comprises the following components:

[0069] 400 parts of cementitious materials (cement and mineral admixtures are mixed at a mass ratio of 6:4);

[0070] 150 parts of CO2 carrier (prepared in Preparation Example 1);

[0071] 700 parts of fine aggregate (natural sand);

[0072] 950 parts of coarse aggregate (recycled coarse aggregate and crushed stone are mixed at a mass ratio of 1:1);

[0073] 15 parts of polycarboxylate superplasticizer;

[0074] 150 parts of water;

[0075] For the preparation method of the said concrete, please refer to Figure 2 the schematic diagram of the preparation process shown, which includes the following steps:

[0076] Step 1: Stir the cementitious materials, fine aggregate and coarse aggregate evenly to obtain Material 1;

[0077] Step 2: Mix the polycarboxylate superplasticizer and water evenly and then add them to Material 1, and continue stirring for 120 s to obtain Material 2;

[0078] Step 3: Add the CO2 carrier to Material 2, and continue stirring for 25 s to obtain the CO2-cured concrete;

[0079] Pour the obtained concrete into a mold, vibrate it densely, and cure it for 28 days under standard conditions.

[0080] Example 2

[0081] A CO2-cured concrete, different from Example 1 in that the CO2 carrier is prepared in Preparation Example 2, and the remaining steps and parameters remain the same.

[0082] Example 3

[0083] A CO2-cured concrete, different from Example 1 in that the CO2 carrier is prepared in Preparation Example 3, and the remaining steps and parameters remain the same.

[0084] Example 4

[0085] A CO2-cured concrete, different from Example 1 in that the CO2 carrier is prepared in Preparation Example 4, and the remaining steps and parameters remain the same.

[0086] Example 5

[0087] A concrete cured with CO2, which is different from that of Example 1 in that the CO2 carrier is prepared by Preparation Example 5, and the remaining steps and parameters remain the same.

[0088] Example 6

[0089] A concrete cured with CO2, which is different from that of Example 1 in that the CO2 carrier is prepared by Preparation Example 6, and the remaining steps and parameters remain the same.

[0090] Example 7

[0091] A concrete cured with CO2, by weight, comprises the following components:

[0092] Binder (cement and mineral admixture are mixed in a mass ratio of 6:4) 400 parts;

[0093] CO2 carrier (prepared by Preparation Example 1) 50 parts;

[0094] Fine aggregate (natural sand) 700 parts;

[0095] Coarse aggregate (recycled coarse aggregate and crushed stone are mixed in a mass ratio of 1:1) 950 parts;

[0096] Polycarboxylate water reducer 15 parts;

[0097] Water 130 parts;

[0098] The preparation method of the concrete is the same as that of Example 1.

[0099] Example 8

[0100] A concrete cured with CO2, by weight, comprises the following components:

[0101] Binder (cement and mineral admixture are mixed in a mass ratio of 6:4) 400 parts;

[0102] CO2 carrier (prepared by Preparation Example 1) 200 parts;

[0103] Fine aggregate (natural sand) 700 parts;

[0104] Coarse aggregate (recycled coarse aggregate and crushed stone are mixed in a mass ratio of 1:1) 950 parts;

[0105] Polycarboxylate water reducer 15 parts;

[0106] Water 170 parts;

[0107] The preparation method of the concrete is the same as that of Example 1.

[0108] Comparative Preparation Example 1

[0109] A preparation method of a CO2 loading material, comprising the following steps:

[0110] S1. Grind zeolite to a particle size of 500 - 800 μm, place it in a 15 mol / L calcium bicarbonate solution, and perform vacuum impregnation for 8 h at 45 conditions, and then vacuum dry at 35 for 3 h to obtain activated zeolite loaded with CaCO3 precursor;

[0111] S2. Fix hollow glass fibers 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 an injection pump, and inject it into the cavity of the hollow glass fibers; then heat paraffin to 60 to melt it, and use molten paraffin to seal the ends of the fibers, controlling the thickness of the end sealing layer to be 7 ± 1 μm, and immediately place it under ≤ 20 conditions for cooling and solidification to obtain glass fibers coated with carbonic acid solution;

[0112] S3. Mix paraffin particles and ammonium carbazate evenly at a mass ratio of 3:1 at a rotation speed of 1000 rpm to obtain mixed particles, and dry-mix them evenly with activated zeolite and glass fibers according to a mass percentage of 20%:50%:30% to obtain a CO2 loading material.

[0113] Comparative Example 1

[0114] A concrete cured by CO2, which is different from Example 1 in that the CO2 loading material is prepared by Comparative Preparation Example 1, and the remaining steps and parameters remain the same.

[0115] Comparative Example 2

[0116] An ordinary concrete, by weight, comprises the following components:

[0117] Cementitious materials (cement and mineral admixture are mixed at a mass ratio of 6:4) 400 parts;

[0118] Fine aggregate (natural sand) 800 parts;

[0119] Coarse aggregate (recycled coarse aggregate and crushed stone are mixed at a mass ratio of 1:1) 1000 parts;

[0120] Polycarboxylate superplasticizer 15 parts;

[0121] Water 150 parts;

[0122] The preparation method of the concrete comprises the following steps:

[0123] Step 1: Stir the gelling material, fine aggregate, and coarse aggregate evenly to obtain Material 1;

[0124] Step 2: Mix the polycarboxylate superplasticizer and water evenly and then add them to Material 1, and continue stirring for 120 s to obtain ordinary concrete;

[0125] Pour the obtained ordinary concrete into the mold, vibrate it densely, and cure it for 28 days under standard conditions.

[0126] Performance test:

[0127] (1) Refer to GB / T 50080-2016 Standard Test Methods for Properties of Ordinary Concrete Mixtures to conduct compressive strength tests on the concrete prepared in Examples 1-8 and Comparative Examples 1 and 2. The test results are shown in Table 2.

[0128] Table 2

[0129]

[0130] (2) Refer to GB / T50082-2009 Standard Test Methods for Long-Term and Durability Properties of Ordinary Concrete to conduct frost resistance tests on the concrete prepared in Examples 1-8 and Comparative Examples 1 and 2; refer to JGJ / T12-2019 Technical Standard for Application of Lightweight Aggregate Concrete to conduct softening coefficient tests; the test results are shown in Table 3.

[0131] Table 3

[0132]

[0133] It can be seen from the test results in Table 2 and Table 3 that by comparing 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 staged CO2 slow release, resulting in poor strength; during the freeze-thaw test, since paraffin acts as a phase change material to achieve a buffering effect, after 150 freeze-thaw cycles, for the relative dynamic elastic modulus, Example 1 maintains a better relative elastic modulus; at the same time, the carbonation reaction between CO2 and the cement substrate improves the pore structure of the concrete, indicating that the concrete with a double-layer phase change structure CO2 load has better frost resistance; by comparing Example 1 and Comparative Example 2, under the condition of not adding a double-layer phase change structure CO2 load, the relative elastic modulus of the concrete is 54.7%, which is already lower than 60%, and it is judged to have suffered freeze-thaw damage.

[0134] In summary, it can be seen that the concrete prepared by the present invention utilizes the CO2 load with a double-layer phase change structure to achieve the controlled release of CO2 in stages. The gradually released CO2 undergoes a mineralization reaction with the cementitious material to form carbonation products 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 no freeze-thaw damage occurs. In addition, the softening coefficient is greater than 1.0, indicating no water damage. This shows that the slow-release CO2-cured concrete prepared by the present invention can be used in a relatively humid environment and be protected from damage. The present invention can reduce the energy consumption caused by autoclave curing, greatly shorten the curing time, reduce the production cost, and improve the production efficiency.

[0135] It should be noted that in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0136] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

[0137] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined. The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill 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 still be made, which should all be regarded as belonging to the protection scope 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; 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-mixing the activated zeolite, glass fiber, and paraffin @PMMA phase change particles to obtain a CO2 load; The activator is ammonium carbazate or azodicarbonamide.

2. The CO2-cured concrete according to claim 1, characterized in that: In S1, the concentration of the calcium bicarbonate solution is 10-30 mol / L.

3. The CO2-cured concrete according to claim 1, characterized in that: In S2, the mass percentage of the carbonic acid solution is 4%-8%.

4. The CO2-cured concrete according to claim 1, characterized in that: In S3, the mass ratio of the paraffin particles to the activator is 3:

1.

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

6. The CO2-cured concrete according to claim 1, characterized in that: In S4, the mass percentages of activated zeolite, glass fiber, and paraffin@PMMA phase change particles are 50%:30%:20%.

7. 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.

8. 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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