Carbon sequestration concrete block and preparation method thereof

Abstract

The invention provides a carbon-sequestration concrete block and a preparation method thereof, the carbon-sequestration concrete block is prepared from the following raw materials by weight: 10%-15% of carbon-sequestration cement, 1%-3% of water, 25%-30% of fine aggregate, 3%-8% of fly ash, and the balance of coarse aggregate, and the sum of the weight parts of the raw materials is 100%; 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 10wt.%-50wt.%. According to the carbon-sequestration concrete block, when the content of the carbon-sequestration precursor in the carbon-sequestration cement is 30 wt.%, the net carbon sequestration amount per cubic meter of the prepared carbon-sequestration concrete block reaches 50 kg, and compared with the carbon-sequestration concrete block prepared by not containing the carbon-sequestration precursor in the raw materials, the prepared carbon-sequestration concrete block has the advantages that the carbon-sequestration effect is better; and the compressive strength after 7 days of maintenance under standard maintenance conditions can be improved by 30%.

Description

Technical Field

[0001] The present invention belongs to the technical field of inorganic non-metallic materials and relates to a carbon-fixing concrete building block, in particular to a carbon-fixing concrete building block 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 concrete block and a preparation method to solve the technical problem in the existing technology that it is difficult to balance the carbon fixation amount of the carbon-fixing concrete block and the compressive strength of the carbon-fixing concrete block 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 concrete block is made of the following raw materials, calculated by weight: 10% to 15% carbon-fixing cement, 1% to 3% water, 25% to 30% fine aggregate, 3% to 8% fly ash, and the balance being coarse aggregate, the total weight of the raw materials being 100%.

[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 10 wt.% to 50 wt.%.

[0010] The present invention also has the following technical features:

[0011] Specifically, the invention is made of the following raw materials in parts by weight: 12.98% carbon-encapsulated cement, 2.19% water, 51.91% coarse aggregate, 25.96% fine aggregate and 6.96% fly ash.

[0012] Preferably, the content of the carbon-encapsulated precursor in the carbon-encapsulated cement is 30 wt.%.

[0013] Specifically, the carbon-sealed precursor is prepared by a mechanochemical method.

[0014] 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.

[0015] The present invention also protects a method for preparing the carbon-fixing concrete block as described above, which specifically comprises the following steps:

[0016] Step 1: Prepare carbon-sealed precursor using a mechanochemical method.

[0017] Step 2: mixing the carbon-encapsulated precursor, cement, coarse aggregate, fine aggregate and fly ash to obtain a mixture.

[0018] Step 3: Pour water into the mixture obtained in step 2 and stir for 5 minutes to obtain a mixture.

[0019] Step 4: Pour the mixture obtained in step 3 into the mold according to the prescribed method, scrape off the excess mixture on the top of the mold, place the mold on a vibrator and vibrate for 1 minute to remove the gas inside the mold so that the mixture fills the mold; then, cover the mold with a plastic film.

[0020] Step 5: Curing the mold containing the sample after the treatment in step 4 at 20° C. for 24 hours. After demolding, the sample is further cured in a CO2 atmosphere for 2 hours to obtain a carbon-fixing concrete block.

[0021] Preferably, in step 1, in the mixed gas of CO2 and N2, the proportion of CO2 is 20 vol.%.

[0022] Preferably, in step 4, the prescribed method specifically includes the following steps:

[0023] First, the mixture is loaded into the mold in two layers, with each layer being of equal thickness.

[0024] Second, the tamping is carried out evenly in a spiral direction from the edge of the mold to the center of the mold.

[0025] Third, when tamping the bottom layer mixture, the tamping rod reaches the bottom of the mold; when tamping the upper layer mixture, the tamping rod penetrates the upper layer and then inserts 20 to 30 mm into the lower layer.

[0026] Fourth, keep the tamping rod vertical when inserting and not tilting, and then use a spatula to insert and pull out several times along the inner wall of the test mold.

[0027] Fifth, the number of ramming times per layer is 10000mm 2 There must be no less than 12 times within the cross-sectional area.

[0028] Sixth, after tamping, gently tap the mold around with a rubber hammer until the hole left by the tamping rod disappears.

[0029] 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.

[0030] In the mixed gas of CO2 and N2, the proportion of CO2 is 50 vol.%.

[0031] Compared with the prior art, the present invention has the following technical effects:

[0032] (I) The carbon-fixing concrete blocks of the present invention, when the content of the carbon-fixing precursor in the carbon-fixing cement is 30 wt.%, can produce a net carbon-fixing capacity of 50 kg per cubic meter of the carbon-fixing concrete blocks. Furthermore, the compressive strength of the carbon-fixing concrete blocks produced can be increased by 30% after seven days of curing under standard curing conditions compared to carbon-fixing concrete blocks produced without the carbon-fixing precursor in the raw materials.

[0033] (II) The carbon-fixing concrete blocks of 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 concrete blocks, 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, the expansion of application scope and the resource utilization of construction solid waste.

[0034] (III) 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a scanning electron microscope image of the carbon-encapsulated precursor in the present invention at a scale of 10 μm.

[0036] Figure 2 This is a scanning electron microscope image of the carbon-encapsulated precursor in the present invention at a scale of 50 μm.

[0037] Figure 3 This is the XRD spectrum of the carbon-encapsulated precursor in the present invention.

[0038] The specific contents of the present invention are further described in detail below with reference to the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0039] 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.

[0040] 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.

[0041] It should be noted that the instruments used in the present invention are:

[0042] Electronic balance (model TP-A500), Fuzhou Huazhi Scientific Instrument Co., Ltd.

[0043] Electric blast drying oven (model 101-1E8S), Xi'an Mojina Instrument Manufacturing Co., Ltd.

[0044] Universal testing machine (model YES-600), Jinan Tianchen Testing Machine Manufacturing Co., Ltd.

[0045] Cement slurry mixer (model NJ-160A), Hebei Dahong Experimental Instrument Co., Ltd.

[0046] It should be noted that the cement in the present invention is 42.5 grade cement.

[0047] In the present invention, dihydrate gypsum is calcium sulfate dihydrate.

[0048] Carbon sequestration capacity refers to the mass of CO2 sequestered per cubic meter of carbon sequestration concrete blocks.

[0049] 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.

[0050] 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.

[0051] In the present invention, the carbon-fixing concrete blocks can be used as building filling walls and roadbed surface layers.

[0052] 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.

[0053] Comparative Example 1:

[0054] This comparative example provides a cement-based carbon-fixing concrete block. The raw material ratio of the carbon-fixing concrete block is the same as that of the carbon-fixing concrete block in Example 1, with the only difference being:

[0055] 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.%.

[0056] In this comparative example, the formula of cement is the same as that of cement in Example 1.

[0057] The preparation method of the cement-based carbon-fixing concrete block of this comparative example is the same as that in Example 1.

[0058] Performance testing:

[0059] Microcracks appeared on the surface of the carbon-fixing concrete blocks prepared in this comparative example.

[0060] The carbon-fixing concrete blocks prepared in this comparative example were 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-fixing concrete blocks were tested. The test results showed that the bulk density was 2260 kg / m 3 The porosity is 13.76%, the compressive strength is 29.71MPa after 7 days of curing under standard curing conditions, and the compressive strength is 38.38MPa after 28 days of curing under standard curing conditions.

[0061] Example 1:

[0062] This embodiment provides a carbon-sealing concrete block, which is made of the following raw materials, by weight: 12.98% carbon-sealing cement, 2.19% water, 51.91% coarse aggregate, 25.96% fine aggregate, and 6.96% fly ash.

[0063] 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 10 wt.%.

[0064] 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.

[0065] The preparation method of the carbon sequestration concrete block of this embodiment specifically includes the following steps:

[0066] Step 1: Prepare carbon-sealed precursor using a mechanochemical method.

[0067] 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.

[0068] In step 1, in the mixed gas of CO2 and N2, the proportion of CO2 is 20 vol.%.

[0069] 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.

[0070] Step 2: mixing the carbon-encapsulated precursor, cement, coarse aggregate, fine aggregate and fly ash to obtain a mixture.

[0071] Step 3: Pour water into the mixture obtained in step 2 and stir for 5 minutes to obtain a mixture.

[0072] Step 4: Pour the mixture obtained in step 3 into the mold according to the prescribed method, scrape off the excess mixture on the top of the mold, place the mold on a vibrator and vibrate for 1 minute to remove the gas inside the mold so that the mixture fills the mold; then, cover the mold with a plastic film.

[0073] In step 4, the prescribed method specifically includes the following steps:

[0074] First, the mixture is loaded into the mold in two layers, with each layer being of equal thickness.

[0075] Second, the tamping is carried out evenly in a spiral direction from the edge of the mold to the center of the mold.

[0076] Third, when tamping the bottom layer mixture, the tamping rod reaches the bottom of the mold; when tamping the upper layer mixture, the tamping rod penetrates the upper layer and is inserted into the lower layer 25mm.

[0077] Fourth, keep the tamping rod vertical when inserting and not tilting, and then use a spatula to insert and pull out several times along the inner wall of the test mold.

[0078] Fifth, the number of ramming times per layer is 10000mm 2There must be no less than 12 times within the cross-sectional area.

[0079] Sixth, after tamping, gently tap the mold around with a rubber hammer until the hole left by the tamping rod disappears.

[0080] Step 5: Curing the mold containing the sample after the treatment in step 4 at 20° C. for 24 hours. After demolding, the sample is further cured in a CO2 atmosphere for 2 hours to obtain a carbon-fixing concrete block.

[0081] 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.

[0082] In the mixed gas of CO2 and N2, CO2 accounts for 50 vol.%.

[0083] Performance testing:

[0084] Compared with Comparative Example 1, the surface cracks of the carbon-fixing concrete blocks prepared in this embodiment are significantly reduced. The carbon-fixing capacity per cubic meter of carbon-fixing concrete blocks is 13 kg.

[0085] The carbon-fixing concrete blocks prepared in this embodiment were 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-fixing concrete blocks were tested. The test results showed that the bulk density was 2310 kg / m 3 The porosity is 13.64%, the compressive strength is 35.29MPa after 7 days of curing under standard curing conditions, and the compressive strength is 40.24MPa after 28 days of curing under standard curing conditions.

[0086] Example 2:

[0087] This embodiment provides a carbon-fixing concrete block. The raw material ratio of the carbon-fixing concrete block is the same as that of the carbon-fixing concrete block in Example 1, with the only difference being:

[0088] 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.%.

[0089] In this embodiment, the formula of cement is the same as that of cement in Example 1.

[0090] The preparation method of the carbon-fixing concrete blocks in this embodiment is the same as that in Example 1.

[0091] Performance testing:

[0092] Compared with Comparative Example 1, the carbon-fixing concrete blocks prepared in this embodiment have substantially no cracks on their surfaces. The carbon-fixing capacity per cubic meter of carbon-fixing concrete blocks is 33 kg.

[0093] The carbon-fixing concrete blocks prepared in this embodiment were 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-fixing concrete blocks were tested. The test results showed that the bulk density was 2318 kg / m 3 The porosity is 12.58%, the compressive strength is 36.52MPa after 7 days of curing under standard curing conditions, and the compressive strength is 40.86MPa after 28 days of curing under standard curing conditions.

[0094] Example 3:

[0095] This embodiment provides a carbon-fixing concrete block. The raw material ratio of the carbon-fixing concrete block is the same as that of the carbon-fixing concrete block in Example 1, with the only difference being:

[0096] 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 30 wt.%.

[0097] In this embodiment, the formula of cement is the same as that of cement in Example 1.

[0098] The preparation method of the carbon-fixing concrete blocks in this embodiment is the same as that in Example 1.

[0099] Performance testing:

[0100] Compared with Comparative Example 1, the surface of the carbon-fixing concrete blocks prepared in this embodiment is denser, and the carbon-fixing capacity per cubic meter of carbon-fixing concrete blocks is 50 kg.

[0101] The carbon-fixing concrete blocks prepared in this embodiment were 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-fixing concrete blocks were tested. The test results showed that the bulk density was 2320 kg / m 3 The porosity is 11.66%, the compressive strength is 39 MPa after 7 days of curing under standard curing conditions, and the compressive strength is 42.71 MPa after 28 days of curing under standard curing conditions.

[0102] The compressive strength of the carbon-fixing concrete blocks prepared in this embodiment after curing for 7 days under standard curing conditions is increased by 30% compared with that in Comparative Example 1.

[0103] The carbon-fixing concrete blocks prepared in this example (denoted as carbon-fixing concrete blocks II) were compared with the carbon-fixing concrete blocks prepared in Comparative Example 1 (denoted as carbon-fixing concrete blocks I) to compare the impermeability, frost resistance, seawater erosion resistance, and carbonation resistance of the two carbon-fixing concrete blocks. The results are shown in Table 1. As can be seen from Table 1, the comprehensive performance of the carbon-fixing concrete blocks II prepared in Example 3 is significantly better than that of the carbon-fixing concrete blocks I prepared in Comparative Example 1.

[0104] Table 1 Comparison of the results of carbon-fixing concrete blocks prepared in Comparative Example 1 and Example 3

[0105]

[0106] Example 4:

[0107] This embodiment provides a carbon-fixing concrete block. The raw material ratio of the carbon-fixing concrete block is the same as that of the carbon-fixing concrete block in Example 1, with the only difference being:

[0108] 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 40 wt.%.

[0109] In this embodiment, the formula of cement is the same as that of cement in Example 1.

[0110] The preparation method of the carbon-fixing concrete blocks in this embodiment is the same as that in Example 1.

[0111] Performance testing:

[0112] Compared with Comparative Example 1, the surface of the carbon-fixing concrete blocks prepared in this embodiment is denser, and the carbon-fixing capacity per cubic meter of carbon-fixing concrete blocks is 46 kg.

[0113] The carbon-fixing concrete blocks prepared in this embodiment were 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-fixing concrete blocks were tested. The test results showed that the bulk density was 2321 kg / m 3 The porosity is 11.91%, the compressive strength is 37.76MPa after 7 days of curing under standard curing conditions, and the compressive strength is 42.10MPa after 28 days of curing under standard curing conditions.

[0114] Example 5:

[0115] This embodiment provides a carbon-fixing concrete block. The raw material ratio of the carbon-fixing concrete block is the same as that of the carbon-fixing concrete block in Example 1, with the only difference being:

[0116] 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 50 wt.%.

[0117] In this embodiment, the formula of cement is the same as that of cement in Example 1.

[0118] The preparation method of the carbon-fixing concrete blocks in this embodiment is the same as that in Example 1.

[0119] Performance testing:

[0120] Compared with Comparative Example 1, the surface of the carbon-fixing concrete blocks prepared in this embodiment is denser, and the carbon-fixing capacity per cubic meter of carbon-fixing concrete blocks is 47 kg.

[0121] The carbon-fixing concrete blocks prepared in this embodiment were 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-fixing concrete blocks were tested. The test results showed that the bulk density was 2315 kg / m 3 The porosity is 12.23%. The compressive strength is 35.90MPa after 7 days of curing under standard curing conditions, and the compressive strength is 41.17MPa after 28 days of curing under standard curing conditions.

[0122] Comparative Example 2:

[0123] This comparative example provides a carbon-fixing concrete block. The raw material ratio of the carbon-fixing concrete block is the same as that of the carbon-fixing concrete block in Example 3, with the only difference being:

[0124] 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 60 wt.%.

[0125] In this comparative example, the formula of cement is the same as that of cement in Example 3.

[0126] The preparation method of the carbon-fixing concrete blocks in this comparative example is the same as that in Example 3.

[0127] Performance testing:

[0128] The compressive strength of the carbon-fixing concrete blocks prepared in this comparative example was significantly lower than that of Example 3. The carbon-fixing capacity of each cubic meter of carbon-fixing concrete blocks was 45 kg.

[0129] The carbon-fixing concrete blocks prepared in this comparative example were 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-fixing concrete blocks were tested. The test results showed that the bulk density was 2015 kg / m 3 The porosity is 20.73%, the compressive strength is 19.64MPa after 7 days of curing under standard curing conditions, and the compressive strength is 22.57MPa after 28 days of curing under standard curing conditions.

[0130] Comparative Example 3:

[0131] This comparative example provides a carbon-fixing concrete block. The raw material ratio of the carbon-fixing concrete block is the same as that of the carbon-fixing concrete block in Example 3, with the only difference being:

[0132] 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.%.

[0133] In this comparative example, the formula of cement is the same as that of cement in Example 3.

[0134] The preparation method of the carbon-fixing concrete blocks in this comparative example is the same as that in Example 3.

[0135] Performance testing:

[0136] Compared with Example 3, the mixture prepared in this comparative example cannot be formed and carbon-fixing concrete blocks cannot be produced. This is attributed to the lack of cementitious materials in the mixture, which cannot bind the coarse and fine aggregates and admixtures in the mixture together.

Claims

1. A carbon-fixing concrete block, characterized in that: The invention is prepared from the following raw materials in parts by weight: 10% to 15% of carbon-encapsulated cement, 1% to 3% of water, 25% to 30% of fine aggregate, 3% to 8% of fly ash, and the balance of coarse aggregate, the total weight of the raw materials being 100%; 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 10 wt.% to 50 wt.%.

2. The carbon-fixing concrete block according to claim 1, characterized in that: The invention is prepared from the following raw materials in parts by weight: 12.98% of carbon-encapsulated cement, 2.19% of water, 51.91% of coarse aggregate, 25.96% of fine aggregate and 6.96% of fly ash.

3. The carbon-fixing concrete block according to claim 1, wherein: The content of the carbon-encapsulated precursor in the carbon-encapsulated cement is 30 wt.%.

4. The carbon-fixing concrete block according to claim 1, wherein: The carbon-encapsulated precursor is prepared by a mechanochemical method; 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.

5. A method for preparing a carbon-fixing concrete block according to any one of claims 1 to 4, 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 stir for 5 minutes to obtain a mixture; Step 4: Pour the mixture obtained in step 3 into the mold according to the prescribed method, scrape off the excess mixture on the top of the mold, and vibrate the mold on a vibrator for 1 minute to expel the gas inside the mold so that the mixture fills the mold; then, cover the mold with plastic film; Step 5: Curing the mold containing the sample after the treatment in step 4 at 20° C. for 24 hours. After demolding, the sample is further cured in a CO2 atmosphere for 2 hours to obtain a carbon-fixing concrete block.

6. The method for preparing the carbon sequestration concrete block according to claim 5, wherein: In step 1, in the mixed gas of CO2 and N2, the proportion of CO2 is 20 vol.%.

7. The method for preparing the carbon sequestration concrete block according to claim 5, wherein: In step 4, the prescribed method specifically includes the following steps: First, the mixture is loaded into the mold in two layers, with each layer being of equal thickness; Second, the tamping is carried out evenly from the edge of the mold to the center of the mold in a spiral direction; Third, when inserting the tamping rod into the bottom layer, the tamping rod should reach the bottom of the mold; when inserting the tamping rod into the upper layer, the tamping rod should penetrate the upper layer and then be inserted into the lower layer 20 to 30 mm. Fourth, keep the tamping rod vertical when inserting and tamping, and do not tilt it. Then use a spatula to insert and pull it out along the inner wall of the test mold several times. Fifth, the number of ramming times per layer is 10000mm. 2 There shall be no less than 12 times within the cross-sectional area; Sixth, after tamping, gently tap the mold around with a rubber hammer until the hole left by the tamping rod disappears.

8. The method for preparing the carbon-fixing concrete block according to claim 5, wherein: 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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