Carbon fixation prefabricated laminated slab based on carbon fixation cement and preparation method

Abstract

The invention provides a carbon fixation prefabricated laminated slab based on carbon fixation and sealing cement and a preparation method. The carbon fixation prefabricated laminated slab is prepared from the carbon fixation and sealing cement. The carbon sealing cement is composed of cement and a carbon sealing precursor; the content of the carbon sealing precursor in the carbon sealing cement is 5wt.%-25wt.%. The carbon solid-sealed precursor is prepared by adopting a mechanochemical method. According to the carbon sequestration prefabricated laminated slab, when the content of the carbon sequestration precursor in the carbon sequestration cement is 25 wt.%, the carbon sequestration amount of the prepared carbon sequestration prefabricated laminated slab per cubic meter reaches 27 kg, and compared with the carbon sequestration prefabricated laminated slab prepared by not containing the carbon sequestration precursor in the raw materials, the carbon sequestration prefabricated laminated slab prepared by the invention has the advantages that the carbon sequestration amount is greatly reduced; and the compressive strength after 7 days of maintenance under standard maintenance conditions can be improved by 16%.

Description

Technical Field

[0001] The present invention belongs to the technical field of inorganic non-metallic materials and relates to prefabricated composite panels, and in particular to a carbon-sealed prefabricated composite panel based on carbon-sealed cement and a preparation method thereof. Background Art

[0002] CO2 is one of many greenhouse gases, and its emission is the main driver of global climate change. Cement is a widely used building material worldwide, and CO2 emissions during cement production account for 8% of total CO2 emissions. Therefore, reducing CO2 emissions in the construction industry is very necessary.

[0003] CO2 capture, utilization, and storage (CCUS) technology holds enormous potential for carbon neutrality. Mineral carbonation, a form of CCUS, converts CO2 into solid inorganic carbonates. It's an effective way to store CO2 and effectively address CO2 emissions from the construction industry. Cement, due to its robust carbonation reactivity, is a highly effective CO2 capture and storage medium. Since ready-mix concrete accounts for over 70% vol. of the total cement and concrete volume, and CO2 emissions generated during the production of ready-mix concrete account for 40% vol. of the construction industry's CO2 emissions, CCUS technology can be employed to advance carbon neutrality in the concrete industry.

[0004] Existing technology uses CO2 to sequester CO2 by injecting it directly into concrete mixers. A small amount of dissolved CO2 can accelerate cement hydration and improve the early strength of concrete. However, if the dissolved CO2 exceeds 0.5% of the cement mass, it can actually reduce the concrete's strength. This method of injecting CO2 directly into concrete mixers results in 40% of the injected CO2 escaping into the atmosphere, ultimately resulting in a net reduction of 4.6% in CO2 emissions. This highlights the limitations of this method in terms of CO2 sequestration.

[0005] Dry carbonation is the process of carbonating calcium-containing materials such as steel slag, cement and recycled concrete fine particles by carbonation. 2+ and Mg 2+ Mineralization of carbonized materials is another approach to CO2 storage. The primary products of this method are amorphous silica gel and carbonates. The reactivity of these products is the primary factor influencing the amount of carbon captured. Silica gel and silica fume are highly reactive, while calcium carbonate, in the form of calcite, is a relatively stable crystalline state. Therefore, to increase carbon capture, other methods are needed to enhance the reactivity of the carbonized products. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a carbon-fixing prefabricated composite board based on carbon-sealing cement and a preparation method, so as to solve the technical problem in the existing technology that it is difficult to take into account both the carbon fixation amount of the carbon-fixing prefabricated composite board and the compressive strength of the carbon-fixing prefabricated composite board obtained after carbon fixation.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A carbon-fixing prefabricated composite board based on carbon-fixing cement, wherein the raw materials for preparing the carbon-fixing prefabricated composite board include carbon-fixing cement.

[0009] The carbon-encapsulated cement consists of cement and a carbon-encapsulated precursor; the content of the carbon-encapsulated precursor in the carbon-encapsulated cement is 5wt.% to 25wt.%.

[0010] The carbon-sealed precursor is prepared by a mechanochemical method.

[0011] The present invention also has the following technical features:

[0012] Specifically, the specific process of the mechanochemical method is: cement and water are added to the ball mill respectively, maintaining the solid-liquid ratio at 1g / (3~5)mL; then, a mixed gas of CO2 and N2 is charged into the ball mill at an intake volume of (1~2)L / min / g cement; the ball mill is started and rotated at a speed of 300~500rpm for 5min, thereby preparing the carbon-sealed precursor by the mechanochemical method.

[0013] Preferably, it is made of the following raw materials in parts by weight: 10% to 20% carbon-encapsulated cement, 1% to 3% water, 15% to 25% fine aggregate, 8% to 13% fly ash, and the remainder is coarse aggregate, and the sum of the parts by weight of the raw materials is 100%.

[0014] Preferably, the composite material is made of the following raw materials in parts by weight: 20% carbon-encapsulated cement, 2% water, 45% coarse aggregate, 20% fine aggregate, and 13% fly ash.

[0015] Preferably, the content of the carbon-encapsulated precursor in the carbon-encapsulated cement is 25 wt.%.

[0016] The present invention also protects a method for preparing the carbon-fixing prefabricated composite board based on carbon-fixing cement as described above, which method specifically comprises the following steps:

[0017] Step 1: Prepare carbon-sealed precursor using a mechanochemical method.

[0018] Step 2: mixing the carbon-encapsulated precursor, cement, coarse aggregate, fine aggregate and fly ash to obtain a mixture.

[0019] Step 3: Pour water into the mixture obtained in step 2 and mix for 5 minutes to obtain a dry hard mixture.

[0020] Step 4: Pour the dry hard mixture obtained in step 3 into a mold, vibrate it to make it dense, place the mold on a vibrator and vibrate it for 2 minutes to remove the gas inside the mold and allow the dry hard mixture to fill the mold; then, cover the mold with a plastic film.

[0021] Step 5: Curing the mold containing the sample after the treatment in step 4 at 20° C. for 24 hours. After demoulding, the sample is further cured in a CO2 atmosphere for 2 hours to obtain a carbon-fixed prefabricated composite board.

[0022] Preferably, in step 1, in the mixed gas of CO2 and N2, the proportion of CO2 is 20 vol.%.

[0023] Specifically, in step five, the specific steps of curing for 2 hours in a CO2 atmosphere are as follows: after the sample is demolded, it is placed on a trolley with tracks so that all surfaces of the sample are exposed to a mixture of CO2 and N2 with a humidity of more than 80% and cured for 2 hours.

[0024] In the mixed gas of CO2 and N2, the proportion of CO2 is 50 vol.%.

[0025] Compared with the prior art, the present invention has the following technical effects:

[0026] (I) The carbon-fixing prefabricated composite board in the present invention, when the content of the carbon-fixing precursor in the carbon-fixing cement is 25 wt.%, the carbon-fixing amount per cubic meter of the prepared carbon-fixing prefabricated composite board reaches 27 kg, and the compressive strength of the prepared carbon-fixing prefabricated composite board can be increased by 16% after curing for 7 days under standard curing conditions compared with the carbon-fixing prefabricated composite board prepared without the carbon-fixing precursor in the raw material.

[0027] (II) The present invention introduces mechanochemical methods into the carbonation process. On the one hand, mechanical force can peel off the carbonation products deposited on the mineral surface, thereby promoting the subsequent carbonation reaction; on the other hand, mechanical force can effectively enhance the reactivity of the carbonation products as supplementary cement-based materials.

[0028] (III) The carbon-fixing prefabricated composite panels in the present invention can not only effectively increase the amount of carbon fixation, but also utilize industrial solid waste fly ash and construction waste, and at the same time can also improve the compressive strength of the carbon-fixing prefabricated composite panels, taking into account economic benefits, social benefits and product performance, and also laying a theoretical foundation for the subsequent development of carbon-fixing product types, expansion of application scope and resource utilization of construction solid waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a scanning electron microscope image of the carbon-encapsulated precursor in the present invention at a scale of 10 μm.

[0030] Figure 2 This is a scanning electron microscope image of the carbon-encapsulated precursor in the present invention at a scale of 50 μm.

[0031] Figure 3 This is the XRD spectrum of the carbon-encapsulated precursor in the present invention.

[0032] The specific contents of the present invention are further described in detail below with reference to the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0033] It should be noted that, unless otherwise specified, the raw materials and instruments used in the present invention are all those known in the prior art, for example, fly ash is known fly ash, and the ball mill is known ball mill.

[0034] The inventive concept of the present invention is that cement, due to its strong carbonation reaction activity, can be used to capture, utilize and store CO2. Converting CO2 into solid inorganic carbonates is an effective way to store CO2. The existing technology directly injects CO2 into concrete mixers, or uses carbonation to convert carbon dioxide into solid inorganic carbonates. 2+ and Mg 2+ The technology of mineralizing materials, on the one hand, can only store 4.6 vol.% to 10 vol.% of CO2; on the other hand, the carbonized amorphous silica gel has high reactivity, and calcium carbonate is calcite, which is a relatively stable crystalline state. Therefore, in order to increase the amount of carbon fixation, the present invention adopts a mechanochemical method to prepare a carbon-sealed precursor, replaces a part of the cement with the carbon-sealed precursor, and adopts CO2 curing in the later stage. On the one hand, mechanical force can peel off the carbonation products deposited on the surface of the mineral, thereby promoting the subsequent carbonation reaction; on the other hand, mechanical force can effectively enhance the reactivity of the carbonation products as a supplementary cement-based material; furthermore, during the later curing process, the cement on the surface of the sample undergoes a carbonation reaction, and the surface layer of the sample is relatively dense, which can improve the strength of the sample while fixing carbon.

[0035] It should be noted that the instruments used in the present invention are:

[0036] Electronic balance (model TP-A500), Fuzhou Huazhi Scientific Instrument Co., Ltd.

[0037] Electric blast drying oven (model 101-1E8S), Xi'an Mojina Instrument Manufacturing Co., Ltd.

[0038] Universal testing machine (model YES-600), Jinan Tianchen Testing Machine Manufacturing Co., Ltd.

[0039] Cement slurry mixer (model NJ-160A), Hebei Dahong Experimental Instrument Co., Ltd.

[0040] It should be noted that the cement in the present invention is 42.5 grade cement.

[0041] In the present invention, dihydrate gypsum is calcium sulfate dihydrate.

[0042] Carbon sequestration refers to the mass of CO2 sealed per cubic meter of prefabricated composite panels.

[0043] In the present invention, the mechanochemical method refers to subjecting particles to strong high-energy impacts, resulting in a large number of microstructural defects inside the particles. These defects will lead to a reduction in grain size and crystallinity, thereby increasing the reactivity of the material.

[0044] In the present invention, both the coarse aggregate and the fine aggregate are particles obtained by crushing construction waste. The particle size of the coarse aggregate is 5 to 10 mm, and the particle size of the fine aggregate is 3 to 5 mm.

[0045] In the present invention, the carbon-fixing prefabricated composite panels based on carbon-fixing cement can be used in the fields of construction, bridges and tunnels.

[0046] In accordance with the above technical solution, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0047] Comparative Example 1:

[0048] This comparative example provides a cement-based carbon-fixing prefabricated composite board. The raw material ratio of the carbon-fixing prefabricated composite board is the same as that of the carbon-fixing prefabricated composite board in Example 1, with the only difference being:

[0049] In this comparative example, cement is used to replace the carbon-encapsulated precursor in Example 1, that is, the content of the carbon-encapsulated precursor in the carbon-encapsulated cement is 0 wt.%.

[0050] In this comparative example, the formula of cement is the same as that of cement in Example 1.

[0051] The preparation method of the cement-based carbon-fixing prefabricated composite board in this comparative example is the same as the preparation method in Example 1.

[0052] Performance testing:

[0053] Microcracks appeared on the surface of the carbon-fixed prefabricated composite plate prepared in this comparative example.

[0054] The carbon-fixed prefabricated composite board prepared in this comparative example was cured under standard curing conditions (temperature is 20±1°C, humidity is greater than 95% and pressure is 1 standard atmosphere) until the performance test time, and the physical and mechanical properties of the carbon-fixed prefabricated composite board were tested. The test results are: the bulk density is 2110kg / m 3 The porosity is 12.50%, the compressive strength is 25.76MPa after 7 days of curing under standard curing conditions, and the compressive strength is 33.48MPa after 28 days of curing under standard curing conditions.

[0055] Example 1:

[0056] This embodiment provides a carbon-encapsulated prefabricated composite panel based on carbon-encapsulated cement, which is made of the following raw materials in parts by weight: 20% carbon-encapsulated cement, 2% water, 45% coarse aggregate, 20% fine aggregate and 13% fly ash.

[0057] The carbon-encapsulated cement consists of cement and a carbon-encapsulated precursor; the content of the carbon-encapsulated precursor in the carbon-encapsulated cement is 5 wt.%.

[0058] The cement is made from the following raw materials, in parts by weight: 51% tricalcium silicate, 12% dicalcium silicate, 5% tricalcium aluminate, 10% tetracalcium aluminoferrite, 4% dihydrate gypsum, 13% fly ash and 5% limestone.

[0059] The method for preparing the carbon-fixing prefabricated composite board based on carbon-fixing cement in this embodiment specifically includes the following steps:

[0060] Step 1: Prepare carbon-sealed precursor using a mechanochemical method.

[0061] The specific process of the mechanochemical method is as follows: cement and water are added to the ball mill respectively, maintaining a solid-liquid ratio of 1g / 4mL; then, a mixed gas of CO2 and N2 is charged into the ball mill at an intake volume of 1.5L / min / g cement; the ball mill is started and rotated at a speed of 400rpm for 5 minutes, thus obtaining a carbon-sealed precursor using the mechanochemical method.

[0062] In step 1, in the mixed gas of CO2 and N2, the proportion of CO2 is 20 vol.%.

[0063] In this embodiment, Figures 1 to 3 As shown, the product contains only calcium carbonate, and no needle-shaped Ca(OH)2 crystals are found. This indicates that the hydration product Ca(OH)2 in the carbon-encapsulated precursor has completely reacted with CO2 to form calcium carbonate. This proves that the carbon-encapsulated precursor in step 1 was successfully prepared.

[0064] Step 2: mixing the carbon-encapsulated precursor, cement, coarse aggregate, fine aggregate and fly ash to obtain a mixture.

[0065] Step 3: Pour water into the mixture obtained in step 2 and mix for 5 minutes to obtain a dry hard mixture.

[0066] Step 4: Pour the dry hard mixture obtained in step 3 into a mold, vibrate it to make it dense, place the mold on a vibrator and vibrate it for 2 minutes to remove the gas inside the mold and allow the dry hard mixture to fill the mold; then, cover the mold with a plastic film.

[0067] Step 5: Curing the mold containing the sample after the treatment in step 4 at 20° C. for 24 hours. After demoulding, the sample is further cured in a CO2 atmosphere for 2 hours to obtain a carbon-fixed prefabricated composite board.

[0068] In step five, the specific steps of curing for 2 hours in a CO2 atmosphere are as follows: after the sample is demoulded, it is placed on a trolley with tracks so that all surfaces of the sample are exposed to a mixture of CO2 and N2 with a humidity of more than 80% and cured for 2 hours.

[0069] In the mixed gas of CO2 and N2, CO2 accounts for 50 vol.%.

[0070] Performance testing:

[0071] Compared with Comparative Example 1, the surface cracks of the carbon-fixing prefabricated composite board prepared in this embodiment are significantly reduced. The carbon fixation amount per cubic meter of the carbon-fixing prefabricated composite board is 9 kg.

[0072] The carbon-fixed prefabricated composite board prepared in this embodiment was cured under standard curing conditions (temperature of 20±1°C, humidity greater than 95% and pressure of 1 standard atmosphere) until the performance test time. The physical and mechanical properties of the carbon-fixed prefabricated composite board were tested. The test results showed that the bulk density was 2150 kg / m 3 The porosity is 12.41%. The compressive strength is 26.29 MPa after 7 days of curing under standard curing conditions, and the compressive strength is 34.24 MPa after 28 days of curing under standard curing conditions.

[0073] Example 2:

[0074] This embodiment provides a carbon-fixing prefabricated composite board based on carbon-sealing cement. The raw material ratio of the carbon-fixing prefabricated composite board is the same as that of the carbon-fixing prefabricated composite board in Example 1, with the only difference being:

[0075] In this embodiment, the carbon-encapsulated cement is composed of cement and a carbon-encapsulated precursor; the content of the carbon-encapsulated precursor in the carbon-encapsulated cement is 10 wt.%.

[0076] In this embodiment, the formula of cement is the same as that of cement in Example 1.

[0077] The preparation method of the carbon-fixing prefabricated composite board based on carbon-sealing cement in this embodiment is the same as the preparation method in Example 1.

[0078] Performance testing:

[0079] Compared with Comparative Example 1, the surface of the carbon-fixing prefabricated composite board prepared in this embodiment is substantially free of cracks. The carbon-fixing amount per cubic meter of the carbon-fixing prefabricated composite board is 12 kg.

[0080] The carbon-fixed prefabricated composite board prepared in this embodiment was cured under standard curing conditions (temperature of 20±1°C, humidity greater than 95% and pressure of 1 standard atmosphere) until the performance test time. The physical and mechanical properties of the carbon-fixed prefabricated composite board were tested. The test results showed that the bulk density was 2218 kg / m 3 The porosity is 12.18%, the compressive strength is 26.52MPa after 7 days of curing under standard curing conditions, and the compressive strength is 35.86MPa after 28 days of curing under standard curing conditions.

[0081] Example 3:

[0082] This embodiment provides a carbon-fixing prefabricated composite board based on carbon-sealing cement. The raw material ratio of the carbon-fixing prefabricated composite board is the same as that of the carbon-fixing prefabricated composite board in Example 1, with the only difference being:

[0083] In this embodiment, the carbon-encapsulated cement is composed of cement and a carbon-encapsulated precursor; the content of the carbon-encapsulated precursor in the carbon-encapsulated cement is 15 wt.%.

[0084] In this embodiment, the formula of cement is the same as that of cement in Example 1.

[0085] The preparation method of the carbon-fixing prefabricated composite board based on carbon-sealing cement in this embodiment is the same as the preparation method in Example 1.

[0086] Performance testing:

[0087] Compared with Comparative Example 1, the surface of the carbon-fixing prefabricated composite board prepared in this embodiment is denser, and the carbon-fixing amount per cubic meter of the carbon-fixing prefabricated composite board is 20 kg.

[0088] The carbon-fixed prefabricated composite board prepared in this embodiment was cured under standard curing conditions (temperature of 20±1°C, humidity greater than 95% and pressure of 1 standard atmosphere) until the performance test time. The physical and mechanical properties of the carbon-fixed prefabricated composite board were tested. The test results showed that the bulk density was 2220 kg / m 3 The porosity is 11.86%, the compressive strength is 27 MPa after 7 days of curing under standard curing conditions, and the compressive strength is 37.71 MPa after 28 days of curing under standard curing conditions.

[0089] Example 4:

[0090] This embodiment provides a carbon-fixing prefabricated composite board based on carbon-sealing cement. The raw material ratio of the carbon-fixing prefabricated composite board is the same as that of the carbon-fixing prefabricated composite board in Example 1, with the only difference being:

[0091] In this embodiment, the carbon-encapsulated cement is composed of cement and a carbon-encapsulated precursor; the content of the carbon-encapsulated precursor in the carbon-encapsulated cement is 20 wt.%.

[0092] In this embodiment, the formula of cement is the same as that of cement in Example 1.

[0093] The preparation method of the carbon-fixing prefabricated composite board based on carbon-sealing cement in this embodiment is the same as the preparation method in Example 1.

[0094] Performance testing:

[0095] Compared with Comparative Example 1, the surface of the carbon-fixing prefabricated composite board prepared in this embodiment is denser, and the carbon-fixing amount per cubic meter of the carbon-fixing prefabricated composite board is 26 kg.

[0096] The carbon-fixed prefabricated composite board prepared in this embodiment was cured under standard curing conditions (temperature of 20±1°C, humidity greater than 95% and pressure of 1 standard atmosphere) until the performance test time. The physical and mechanical properties of the carbon-fixed prefabricated composite board were tested. The test results showed that the bulk density was 2265 kg / m 3 The porosity is 11.91%, the compressive strength is 28.40MPa after 7 days of curing under standard curing conditions, and the compressive strength is 38.12MPa after 28 days of curing under standard curing conditions.

[0097] The compressive strength of the carbon-fixed prefabricated composite board prepared in this embodiment after curing for 7 days under standard curing conditions is increased by 10% compared with that in comparative example 1.

[0098] Table 1 Comparison of the results of the carbon-fixing prefabricated composite panels prepared in Comparative Example 1 and Example 4

[0099]

[0100] A comparative test was conducted on the carbon-fixing prefabricated composite panel produced in this embodiment (denoted as carbon-fixing prefabricated composite panel II) and the carbon-fixing prefabricated composite panel produced in Comparative Example 1 (denoted as carbon-fixing prefabricated composite panel I). The two carbon-fixing prefabricated composite panels were compared in terms of their impermeability, frost resistance, seawater erosion resistance, and carbonization resistance. The results are shown in Table 1. As can be seen from Table 1, the comprehensive performance of the carbon-fixing prefabricated composite panel II produced in Example 4 is significantly superior to that of the carbon-fixing prefabricated composite panel I produced in Comparative Example 1.

[0101] Example 5:

[0102] This embodiment provides a carbon-fixing prefabricated composite board based on carbon-sealing cement. The raw material ratio of the carbon-fixing prefabricated composite board is the same as that of the carbon-fixing prefabricated composite board in Example 1, with the only difference being:

[0103] In this embodiment, the carbon-encapsulated cement is composed of cement and a carbon-encapsulated precursor; the content of the carbon-encapsulated precursor in the carbon-encapsulated cement is 25 wt.%.

[0104] In this embodiment, the formula of cement is the same as that of cement in Example 1.

[0105] The preparation method of the carbon-fixing prefabricated composite board based on carbon-sealing cement in this embodiment is the same as the preparation method in Example 1.

[0106] Performance testing:

[0107] Compared with Comparative Example 1, the surface of the carbon-fixing prefabricated composite board prepared in this embodiment is denser, and the carbon-fixing amount per cubic meter of the carbon-fixing prefabricated composite board is 27 kg.

[0108] The compressive strength of the carbon-fixed prefabricated composite board prepared in this embodiment after curing for 7 days under standard curing conditions is increased by 16% compared with that in Comparative Example 1.

[0109] The carbon-fixed prefabricated composite board prepared in this embodiment was cured under standard curing conditions (temperature of 20±1°C, humidity greater than 95% and pressure of 1 standard atmosphere) until the performance test time. The physical and mechanical properties of the carbon-fixed prefabricated composite board were tested. The test results showed that the bulk density was 2300 kg / m 3 The porosity is 11.23%. The compressive strength is 29.90MPa after 7 days of curing under standard curing conditions, and the compressive strength is 38.17MPa after 28 days of curing under standard curing conditions.

[0110] Comparative Example 2:

[0111] This comparative example provides a carbon-fixing prefabricated composite board based on carbon-sealing cement. The raw material ratio of the carbon-fixing prefabricated composite board is the same as that of the carbon-fixing prefabricated composite board in Example 5, with the only difference being:

[0112] In this comparative example, the carbon-encapsulated cement consists of cement and a carbon-encapsulated precursor; the content of the carbon-encapsulated precursor in the carbon-encapsulated cement is 50 wt.%.

[0113] In this comparative example, the formula of cement is the same as that of cement in Example 5.

[0114] The preparation method of the carbon-fixing prefabricated composite board based on carbon-sealing cement in this comparative example is the same as the preparation method in Example 5.

[0115] Performance testing:

[0116] The compressive strength of the carbon-fixing prefabricated composite board prepared in this comparative example is significantly reduced compared to Example 5. The carbon-fixing amount per cubic meter of the carbon-fixing prefabricated composite board is 30 kg.

[0117] The carbon-fixed prefabricated composite board prepared in this comparative example was cured under standard curing conditions (temperature is 20±1°C, humidity is greater than 95% and pressure is 1 standard atmosphere) until the performance test time, and the physical and mechanical properties of the carbon-fixed prefabricated composite board were tested. The test results are: the bulk density is 2015kg / m 3 The porosity is 22.73%, the compressive strength is 21.64MPa after 7 days of curing under standard curing conditions, and the compressive strength is 25.57MPa after 28 days of curing under standard curing conditions.

[0118] Comparative Example 3:

[0119] This comparative example provides a carbon-fixing prefabricated composite board based on carbon-sealing cement. The raw material ratio of the carbon-fixing prefabricated composite board is the same as that of the carbon-fixing prefabricated composite board in Example 5, with the only difference being:

[0120] In this comparative example, the carbon-encapsulated cement is composed of a carbon-encapsulated precursor; the content of the carbon-encapsulated precursor in the carbon-encapsulated cement is 100 wt.%.

[0121] In this comparative example, the formula of cement is the same as that of cement in Example 5.

[0122] The preparation method of the carbon-fixing prefabricated composite board based on carbon-sealing cement in this comparative example is the same as the preparation method in Example 5.

[0123] Performance testing:

[0124] Compared with Example 5, the dry-hard mixture prepared in this comparative example cannot be formed and the carbon-fixed prefabricated composite board cannot be produced. This is attributed to the fact that there is no cementitious material in the dry-hard mixture, and the coarse and fine aggregates and admixtures in the dry-hard mixture cannot be cemented together.

Claims

1. A carbon-fixing prefabricated composite panel based on carbon-fixing cement, characterized in that: The raw materials for preparing the carbon-fixing prefabricated composite panels include carbon-fixing cement; The carbon-encapsulated cement is composed of cement and a carbon-encapsulated precursor; the content of the carbon-encapsulated precursor in the carbon-encapsulated cement is 5wt.% to 25wt.%; The carbon-sealed precursor is prepared by a mechanochemical method.

2. The carbon-fixing prefabricated composite panel based on carbon-fixing cement according to claim 1, characterized in that: The specific process of the mechanochemical method is as follows: cement and water are added to a ball mill respectively, maintaining a solid-liquid ratio of 1g / (3~5)mL; then, a mixed gas of CO2 and N2 is charged into the ball mill at an intake volume of (1~2)L / min / g cement; the ball mill is started and rotated at a speed of 300~500rpm for 5 minutes, thereby preparing a carbon-sealed precursor using the mechanochemical method.

3. The carbon-fixing prefabricated composite panel based on carbon-fixing cement according to claim 1, characterized in that: The invention is made of the following raw materials in parts by weight: 10% to 20% of carbon-sealed cement, 1% to 3% of water, 15% to 25% of fine aggregate, 8% to 13% of fly ash, and the remainder of coarse aggregate, and the total weight of the raw materials is 100%.

4. The carbon-fixing prefabricated composite panel based on carbon-fixing cement according to claim 3, characterized in that: The invention is prepared from the following raw materials in parts by weight: 20% of carbon-sealed cement, 2% of water, 45% of coarse aggregate, 20% of fine aggregate and 13% of fly ash.

5. The carbon-fixing prefabricated composite panel based on carbon-fixing cement according to claim 3, characterized in that: The content of the carbon-encapsulated precursor in the carbon-encapsulated cement is 25 wt.%.

6. A method for preparing a carbon-fixing prefabricated composite board based on carbon-fixing cement according to any one of claims 1 to 5, characterized in that: The method specifically comprises the following steps: Step 1: preparing a carbon-encapsulated precursor by a mechanochemical method; Step 2: mixing the carbon-encapsulated precursor, cement, coarse aggregate, fine aggregate and fly ash to obtain a mixture; Step 3: Pour water into the mixture obtained in step 2 and mix for 5 minutes to obtain a dry hard mixture; Step 4: Pour the dry hard mixture obtained in step 3 into a mold, vibrate and compact it, and vibrate the mold on a vibrator for 2 minutes to remove the air inside the mold and ensure that the dry hard mixture fills the mold; then, cover the mold with a plastic film; Step 5: Curing the mold containing the sample after the treatment in step 4 at 20° C. for 24 hours. After demoulding, the sample is further cured in a CO2 atmosphere for 2 hours to obtain a carbon-fixed prefabricated composite board.

7. The method for preparing a carbon-fixing prefabricated composite board based on carbon-fixing cement according to claim 6, characterized in that: In step 1, in the mixed gas of CO2 and N2, the proportion of CO2 is 20 vol.%.

8. The method for preparing a carbon-fixing prefabricated composite board based on carbon-fixing cement according to claim 6, characterized in that: In step 5, the specific steps of curing for 2 hours in a CO2 atmosphere are as follows: after demolding the sample, place it on a trolley with a track so that all surfaces of the sample are exposed to a mixture of CO2 and N2 with a humidity of more than 80% for 2 hours; In the mixed gas of CO2 and N2, the proportion of CO2 is 50 vol.%.

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