Low-carbon foam concrete and preparation method thereof

Abstract

The present invention provides low-carbon foamed concrete, obtained by coating carbon-fixing foamed concrete with a carbon-fixing coating. The carbon-fixing foamed concrete comprises the following raw materials by weight: 500-2000 parts of cement, 10-100 parts of a composite foaming agent, 300-1500 parts of aggregate, 10-40 parts of a carbon-fixing material, 1-20 parts of an admixture, and 300-600 parts of water. Through multi-component carbon fixation, the low-carbon foamed concrete achieves a carbon fixation efficiency of 13.1% to 23.7% over 28 days.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and in particular to low-carbon foamed concrete and a preparation method thereof. Background Art

[0002] Accelerating the green and low-carbon transformation of the economy and society is a consensus in today's society. Concrete, the most widely used building material, emits approximately 12% of China's total carbon emissions during its production process. Its main component, cement, accounts for over 60% of industrial carbon emissions, making it a highly energy-intensive and carbon-intensive industry. Within the building materials sector, developing new energy-efficient building materials and implementing CO2 capture, utilization, and storage are key pathways to achieving a green and low-carbon economy. Compared to other building materials, conventional concrete has a higher carbon footprint and relatively dense internal pores, limiting its carbon sequestration potential and making it difficult to effectively address environmental challenges like climate change.

[0003] Foamed concrete combines fire resistance, lightweight porosity, and thermal insulation. Its preparation consumes minimal resources, reduces building energy consumption, and emits no toxic or hazardous substances. It has become the most widely used specialty concrete. Because foamed concrete has more pores than conventional concrete, allowing CO2 to flow between these pores, technological improvements could potentially increase its carbon sequestration capacity. Summary of the Invention

[0004] In order to solve the problems existing in the background technology, the present invention provides a low-carbon foam concrete and a preparation method thereof, which is prepared by a multi-component carbon fixation system and has high carbon fixation efficiency.

[0005] The technical solution of the present invention to solve the above technical problems is as follows:

[0006] In a first aspect, the present invention provides a low-carbon foam concrete, which is obtained by coating carbon-fixing foam concrete with a carbon-fixing coating. The carbon-fixing foam concrete comprises the following raw materials in parts by mass: 500-2000 parts of cement, 10-100 parts of a composite foaming agent, 300-1500 parts of aggregate, 10-40 parts of a carbon-fixing material, 1-20 parts of an admixture, and 300-600 parts of water.

[0007] Furthermore, the composite foaming agent is composed of the following components in mass fraction: 1-40% nanomaterial, 1-10% polyacrylamide, 10-20% polyether polyol, 1-10% lauryl dimethyl ammonium acetate, and the remainder is CO2 foaming agent.

[0008] Furthermore, the nanoparticles are at least one of nano-silicon dioxide, nano-titanium dioxide, and carbon nanotubes, and have a particle size range of 10 to 100 nm.

[0009] Furthermore, the carbon-fixing material is at least one of propylene carbonate, triethanolamine, and tetraethylenepentamine.

[0010] Furthermore, the carbon-fixing coating is obtained by immersing carbon-fixing foam concrete in a carbon-fixing coating solution and drying it. The carbon-fixing coating solution is composed of the following components by mass fraction: 1-20% polyurethane, 1-20% polyepoxysuccinic acid, 1-20% trisodium dicarboxymethyl alanine, 10-20% sodium bicarbonate, 10-20% calcium silicate powder, and the balance is water.

[0011] Furthermore, the aggregate includes 30% to 70% of machine-made sand and 30% to 70% of waste from sedimentation tanks of ready-mixed concrete mixing plants that have been wet-ground and CO2 mineralized.

[0012] Furthermore, the cement is at least one of Portland cement, sulphoaluminate cement and magnesia cement.

[0013] In a second aspect, the present invention provides a method for preparing the low-carbon foamed concrete, comprising the following steps:

[0014] 1) Weighing cement, composite foaming agent, aggregate, carbon-fixing material, admixture and water according to mass to prepare carbon-fixing foam concrete;

[0015] 2) preparing a carbon-fixing coating solution, immersing the carbon-fixing foamed concrete in the carbon-fixing coating solution, and drying the resulting low-carbon foamed concrete.

[0016] Furthermore, the specific preparation steps of step 1) are: first, cement, aggregate, water, admixture and carbon-fixing material are mixed and stirred to obtain a slurry, after the composite foaming agent is evenly mixed with the slurry, it is foamed with 0.1MPa~0.3MPa high-pressure CO2, and fully stirred to fully mix the slurry and foam; the mixture is poured into a mold, and then placed in the mold for 10-30 minutes, waiting for foaming and forming; the obtained foamed concrete is placed in air natural curing for 5~10 hours and 0.2MPa CO2 atmosphere curing for 3 hours to obtain the carbon-fixing foamed concrete.

[0017] Furthermore, the soaking time in step 2) is 5 to 10 minutes.

[0018] The beneficial effects of the present invention are:

[0019] 1) The present invention utilizes a multi-element carbon fixation system to prepare low-carbon foamed concrete. The foamed concrete is porous, and the carbon-fixing material fixes carbon within the concrete, thereby increasing the internal strength. The carbon-fixing coating on the outside slowly carbonizes to form a dense layer, which resists external corrosion factors from entering the concrete and causing degradation. Through multi-pathway carbon fixation, the carbon fixation efficiency of the low-carbon foamed concrete over 28 days is between 13.1% and 23.7%.

[0020] 2) The present invention wet-grinds and carbonizes the waste residue in the sedimentation tank of the mixing station and then mixes it with machine-made sand for use as aggregate. The surface of the wet-grinded and carbonized waste residue is porous and its strength is greatly improved compared to that before treatment. This can fully utilize the waste resources of the mixing station, not only achieving a significant effect in utilizing solid waste in large quantities, but also achieving the effect of saving resources and reducing environmental pollution.

[0021] 3) The composite foaming agent used in the present invention is modified by using nanoparticles, polyacrylamide, polyether polyol and lauryl dimethyl ammonium acetate to improve the CO2 foaming performance and the mechanical strength of the CO2 foam film. Compared with traditional foam concrete, the resulting foamed concrete has fewer pinholes, a delicate feel and uniform foam cells. DETAILED DESCRIPTION

[0022] The principles and features of the present invention are described below in conjunction with specific embodiments. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0023] The present invention adopts a physical foaming process, cement, aggregate, carbon-fixing material, admixture and water are mixed and stirred evenly to form a cement-based slurry, which is then mixed with foam generated by a composite foaming agent to prepare foamed concrete.

[0024] The technical solution of the present invention to solve the above technical problems is as follows:

[0025] In a first aspect, the present invention provides a low-carbon foam concrete, which is obtained by coating carbon-fixing foam concrete with a carbon-fixing coating. The carbon-fixing foam concrete comprises the following raw materials in parts by mass: 500-2000 parts of cement, 10-100 parts of a composite foaming agent, 300-1500 parts of aggregate, 10-40 parts of a carbon-fixing material, 1-20 parts of an admixture, and 300-600 parts of water.

[0026] Preferably, the composite foaming agent is composed of the following components in mass fraction: 1-40% nanomaterial, 1-10% polyacrylamide, 10-20% polyether polyol, 1%-10% lauryl dimethyl ammonium acetate, and the remainder is CO2 foaming agent.

[0027] Preferably, the molecular weight of the polyether polyol is 1000 to 4000, which can make the foaming more uniform.

[0028] Preferably, the nanoparticles are at least one of nano-silicon dioxide, nano-titanium dioxide, and carbon nanotubes, and have a particle size range of 10 to 100 nm.

[0029] Preferably, the carbon-fixing material is at least one of propylene carbonate, triethanolamine, and tetraethylenepentamine.

[0030] Preferably, the carbon-fixing coating is obtained by immersing carbon-fixing foam concrete in a carbon-fixing coating solution and then air-drying it. The carbon-fixing coating solution is composed of the following components by weight: 1-20% polyurethane, 1-20% polyepoxysuccinic acid, 1-20% trisodium dicarboxymethyl alanine, 10-20% sodium bicarbonate, 10-20% calcium silicate powder, and the balance is water. The polyepoxysuccinic acid and trisodium dicarboxymethyl alanine have low surface tension, making the coating easier to penetrate and form a film, and achieving higher film-forming efficiency.

[0031] Preferably, the aggregate comprises 30% to 70% machine-made sand and 30% to 70% waste from the sedimentation tank of a ready-mixed concrete mixing station that has been wet-ground and CO2 mineralized.

[0032] The waste from the sedimentation tanks of ready-mixed concrete plants is recycled concrete, primarily composed of cement hydration products and calcium-containing products such as calcium hydroxide, CSH, and ettringite. The waste is first wet-milled to adjust the particle size. At this point, the particles are smaller, which are then broken down by the grinding discs, increasing their activity. CO2 mineralization then carbonizes the particles, enhancing their strength.

[0033] Preferably, the cement is at least one of Portland cement, sulphoaluminate cement and magnesia cement.

[0034] Preferably, the admixture is a water reducing agent.

[0035] In a second aspect, the present invention provides a method for preparing the low-carbon foamed concrete, comprising the following steps:

[0036] 1) Weighing cement, composite foaming agent, aggregate, carbon-fixing material, admixture and water according to mass to prepare carbon-fixing foam concrete;

[0037] 2) preparing a carbon-fixing coating solution, immersing the carbon-fixing foamed concrete in the carbon-fixing coating solution, and drying the resulting low-carbon foamed concrete.

[0038] Furthermore, the specific preparation steps of step 1) are: first, cement, aggregate, water, admixture and carbon-fixing material are mixed and stirred to obtain a slurry, after the composite foaming agent is evenly mixed with the slurry, it is foamed with 0.1MPa~0.3MPa high-pressure CO2, and fully stirred to fully mix the slurry and foam; the mixture is poured into a mold, and then placed in the mold for 10-30 minutes, waiting for foaming and forming; the obtained foamed concrete is placed in air natural curing for 5~10 hours and 0.2MPa CO2 atmosphere curing for 3 hours to obtain the carbon-fixing foamed concrete.

[0039] Furthermore, the soaking time in step 2) is 5 to 10 minutes.

[0040] The carbon-fixing material used in this invention reacts fully with CO₂ in its natural state. The nanoparticles in the composite foaming agent not only provide bubble nucleation sites and contact points, improving bubble stability, but also contribute to the rigidity of the foamed concrete structure, increasing early concrete strength and reducing cement usage. The carbon-fixing coating material used can stably adhere to the foamed concrete and react with CO₂ in the air to form a dense protective layer, effectively protecting against external corrosive environments.

[0041] The present invention adopts a physical foaming process to mix cement, machine-made sand, waste residue from the sedimentation tank of the mixing station, carbon-fixing material and water and stir them evenly to form a cement-based slurry, which is then mixed with foam generated by a foaming agent to prepare foamed concrete. During the entire life cycle of the foamed concrete, the generation of carbon dioxide is reduced or fixed in multiple ways, and the adsorption and solidification of carbon dioxide are achieved. The foamed concrete after carbon fixation has better strength and durability.

[0042] In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples.

[0043] In the following examples, the cement used is P·O 42.5 Portland cement.

[0044] The aggregate used is machine-made sand, which is a well-graded medium sand in Zone II that is compounded with waste from the sedimentation tank of a ready-mixed concrete batching plant after wet grinding and CO2 mineralization.

[0045] The admixture used is polycarboxylate water reducer, produced by Hubei Xijian New Material Technology Co., Ltd., with a solid content of 15.80% and a water reduction rate of 26.3%;

[0046] A carbon-fixing coating solution comprising: 10% polyurethane, 10% polyepoxysuccinic acid, 10% trisodium dicarboxymethylalanine, 10% sodium bicarbonate, 10% calcium silicate powder and 50% water;

[0047] The carbon-fixing materials used are: propylene carbonate, triethanolamine, and tetraethylenepentylamine, each accounting for 33.3%;

[0048] The composite foaming agent used is: nano silicon dioxide accounts for 15%, nano titanium dioxide accounts for 15%, polyacrylamide accounts for 5%, polyether polyol accounts for 5%, lauryl dimethyl ammonium acetate accounts for 5%, and the balance is CO2 foaming agent.

[0049] Example 1

[0050] 1) Weigh the raw materials, including 1000 parts of cement, 40 parts of composite foaming agent, 200 parts of machine-made sand, 200 parts of treated sedimentation tank waste, 30 parts of carbon-fixing material, 10 parts of admixture, and 500 parts of water;

[0051] 2) First, mix and stir water, cement, admixtures, carbon-fixing materials, and aggregates; add the slurry to the CO2 foaming and stir until uniform; after the two are mixed, foam them with 0.1MPa to 0.3MPa high-pressure CO2 and stir thoroughly to fully mix the slurry and foam; pour the mixture into a mold and leave it in the mold for 30 minutes to wait for foaming and forming;

[0052] 3) The foamed concrete is placed in air for natural curing for 10 hours and in a 0.2 MPa CO2 atmosphere for curing for 3 hours. Finally, the mold is removed and the foamed concrete is immersed in the coating solution. After soaking for 5 minutes, the product is obtained by drying.

[0053] Example 2

[0054] 1) Weigh the raw materials, including 1000 parts of cement, 40 parts of composite foaming agent, 100 parts of machine-made sand, 300 parts of treated sedimentation tank waste, 30 parts of carbon-fixing material, 10 parts of admixture, and 500 parts of water;

[0055] 2) First, mix and stir water, cement, admixtures, carbon-fixing materials, and aggregates; add the slurry to the CO2 foaming and stir until uniform; after the two are mixed, foam them with 0.1MPa to 0.3MPa high-pressure CO2 and stir thoroughly to fully mix the slurry and foam; pour the mixture into a mold and leave it in the mold for 30 minutes to wait for foaming and forming;

[0056] 3) The foamed concrete is placed in air for natural curing for 10 hours and in a 0.2 MPa CO2 atmosphere for curing for 3 hours. Finally, the mold is removed and the foamed concrete is immersed in the coating solution. After soaking for 5 minutes, the product is obtained by drying.

[0057] Example 3

[0058] 1) Weigh the raw materials, including: 1000 parts of cement, 40 parts of composite foaming agent, 300 parts of machine-made sand, 100 parts of treated sedimentation tank waste, 30 parts of carbon-fixing material, 10 parts of admixture, and 500 parts of water;

[0059] 2) First, mix and stir water, cement, admixtures, carbon-fixing materials, and aggregates; add the slurry to the CO2 foaming and stir until uniform; after the two are mixed, foam them with 0.1MPa to 0.3MPa high-pressure CO2 and stir thoroughly to fully mix the slurry and foam; pour the mixture into a mold and leave it in the mold for 30 minutes to wait for foaming and forming;

[0060] 3) The foamed concrete is placed in air for natural curing for 10 hours and in a 0.2 MPa CO2 atmosphere for curing for 3 hours. Finally, the mold is removed and the foamed concrete is immersed in the coating solution. After soaking for 5 minutes, the product is obtained by drying.

[0061] Example 4

[0062] The raw materials in this embodiment and their weight proportions include: 800 parts of cement, 40 parts of composite foaming agent, 400 parts of machine-made sand, 400 parts of treated sedimentation tank waste, 10 parts of carbon-fixing material, 20 parts of admixture, and 500 parts of water. The remaining steps are the same as those in Example 3.

[0063] Example 5

[0064] The raw materials in this embodiment and their weight proportions include: 2000 parts of cement, 80 parts of composite foaming agent, 100 parts of machine-made sand, 200 parts of treated sedimentation tank waste, 30 parts of carbon-fixing material, 20 parts of admixture, and 600 parts of water. The remaining steps are the same as those in Example 3.

[0065] Example 6

[0066] The raw materials in this embodiment and their weight proportions include: 1000 parts of cement, 10 parts of composite foaming agent, 200 parts of machine-made sand, 200 parts of treated sedimentation tank waste, 40 parts of carbon-fixing material, 10 parts of admixture, and 600 parts of water. The remaining steps are the same as those in Example 3.

[0067] Comparative Example 1

[0068] A method for preparing low-carbon foamed concrete, comprising the following steps:

[0069] 1) Weigh the raw materials, including 1000 parts of cement, 40 parts of composite foaming agent, 200 parts of machine-made sand, 200 parts of treated sedimentation tank waste, 10 parts of admixture, and 500 parts of water;

[0070] 2) First, mix and stir water, cement, admixtures, and aggregates; add the slurry to the CO2 foaming and stir until uniform; after the two are mixed, foam them with 0.1MPa~0.3MPa high-pressure CO2 and stir them thoroughly to fully mix the mud and foam; pour the mixture into a mold and leave it in the mold for 30 minutes to wait for foaming and forming;

[0071] 3) The foamed concrete is placed in air for natural curing for 10 hours and in a 0.2 MPa CO2 atmosphere for curing for 3 hours. Finally, the mold is removed and the foamed concrete is immersed in the coating solution. After soaking for 5 minutes, the product is obtained by drying.

[0072] Comparative Example 2

[0073] A method for preparing low-carbon foamed concrete, comprising the following steps:

[0074] 1) Weigh the raw materials, including 1000 parts of cement, 40 parts of composite foaming agent, 100 parts of machine-made sand, 300 parts of treated sedimentation tank waste, 10 parts of admixture, and 500 parts of water;

[0075] 2) First, mix and stir water, cement, admixtures, and aggregates; add the slurry to the CO2 foaming and stir until uniform; after the two are mixed, foam them with 0.1MPa~0.3MPa high-pressure CO2 and stir them thoroughly to fully mix the mud and foam; pour the mixture into a mold and leave it in the mold for 30 minutes to wait for foaming and forming;

[0076] 3) The foamed concrete is placed in air for natural curing for 10 hours and in a 0.2 MPa CO2 atmosphere for curing for 3 hours. Finally, the mold is removed and the foamed concrete is immersed in the coating solution. After soaking for 5 minutes, the product is obtained by drying.

[0077] Comparative Example 3

[0078] A method for preparing low-carbon foamed concrete, comprising the following steps:

[0079] 1) Weigh the raw materials, including 1000 parts of cement, 40 parts of composite foaming agent, 300 parts of machine-made sand, 100 parts of treated sedimentation tank waste, 10 parts of admixture, and 500 parts of water;

[0080] 2) First, mix and stir water, cement, admixtures, and aggregates; add the slurry to the CO2 foaming and stir until uniform; after the two are mixed, foam them with 0.1MPa~0.3MPa high-pressure CO2 and stir them thoroughly to fully mix the mud and foam; pour the mixture into a mold and leave it in the mold for 30 minutes to wait for foaming and forming;

[0081] 3) The foamed concrete is placed in air for natural curing for 10 hours and in a 0.2 MPa CO2 atmosphere for curing for 3 hours. Finally, the mold is removed and the foamed concrete is immersed in the coating solution. After soaking for 5 minutes, the product is obtained by drying.

[0082] Comparative Example 4

[0083] A method for preparing low-carbon foamed concrete, comprising the following steps:

[0084] 1) Weigh the raw materials, including 1000 parts of cement, 30 parts of carbon-fixing material, 40 parts of composite foaming agent, 200 parts of machine-made sand, 200 parts of treated sedimentation tank waste, 10 parts of admixture, and 500 parts of water;

[0085] 2) First, mix and stir water, cement, admixtures, carbon-fixing materials, and aggregates; add the slurry to the CO2 foaming and stir until uniform; after the two are mixed, foam with 0.1MPa~0.3MPa high-pressure CO2 and stir thoroughly to fully mix the slurry and foam; pour the mixture into a mold, then leave it in the mold for 30 minutes, wait for foaming and forming, and cure it to 28 days;

[0086] Comparative Example 5

[0087] A method for preparing low-carbon foamed concrete, comprising the following steps:

[0088] 1) Weigh the raw materials, including: 1000 parts of cement, 30 parts of carbon-fixing material, 40 parts of composite foaming agent, 100 parts of machine-made sand, 300 parts of treated sedimentation tank waste, 10 parts of admixture, and 500 parts of water;

[0089] 2) First, mix and stir water, cement, admixtures, carbon-fixing materials, and aggregates; add the slurry to the CO2 foaming and stir until uniform; after the two are mixed, foam with 0.1MPa~0.3MPa high-pressure CO2 and stir thoroughly to fully mix the slurry and foam; pour the mixture into a mold, then leave it in the mold for 30 minutes, wait for foaming and forming, and cure it to 28 days;

[0090] Comparative Example 6

[0091] A method for preparing low-carbon foamed concrete, comprising the following steps:

[0092] 1) Weigh the raw materials, including 1000 parts of cement, 30 parts of carbon-fixing material, 40 parts of composite foaming agent, 300 parts of machine-made sand, 100 parts of treated sedimentation tank waste, 10 parts of admixture, and 500 parts of water;

[0093] 2) First, mix and stir water, cement, admixtures, carbon-fixing materials, and aggregates; add the slurry to the CO2 foaming and stir until uniform; after the two are mixed, foam with 0.1MPa~0.3MPa high-pressure CO2 and stir thoroughly to fully mix the slurry and foam; pour the mixture into a mold, then leave it in the mold for 30 minutes, wait for foaming and forming, and cure it to 28 days;

[0094] Comparative Example 7

[0095] A method for preparing low-carbon foamed concrete, comprising the following steps:

[0096] 1) Weigh the raw materials, including 1000 parts of cement, 40 parts of composite foaming agent, 200 parts of machine-made sand, 200 parts of treated sedimentation tank waste, 10 parts of admixture, and 500 parts of water;

[0097] 2) First, mix and stir water, cement, admixtures, and aggregates; add the slurry to the CO2 foaming and stir until uniform; after the two are mixed, foam with 0.1MPa~0.3MPa high-pressure CO2 and stir thoroughly to fully mix the slurry and foam; pour the mixture into the mold, then leave it in the mold for 30 minutes, wait for foaming and forming, and cure to 28 days;

[0098] Comparative Example 8

[0099] A method for preparing low-carbon foamed concrete, comprising the following steps:

[0100] 1) Weigh the raw materials, including 1000 parts of cement, 40 parts of composite foaming agent, 100 parts of machine-made sand, 300 parts of treated sedimentation tank waste, 10 parts of admixture, and 500 parts of water;

[0101] 2) First, mix and stir water, cement, admixtures, and aggregates; add the slurry to the CO2 foaming and stir until uniform; after the two are mixed, foam with 0.1MPa~0.3MPa high-pressure CO2 and stir thoroughly to fully mix the slurry and foam; pour the mixture into the mold, then leave it in the mold for 30 minutes, wait for foaming and forming, and cure to 28 days;

[0102] Comparative Example 9

[0103] A method for preparing low-carbon foamed concrete, comprising the following steps:

[0104] 1) Weigh the raw materials, including 1000 parts of cement, 40 parts of composite foaming agent, 300 parts of machine-made sand, 100 parts of treated sedimentation tank waste, 10 parts of admixture, and 500 parts of water;

[0105] 2) First, mix and stir water, cement, admixtures, and aggregates; add the slurry to the CO2 foaming and stir until uniform; after the two are mixed, foam with 0.1MPa~0.3MPa high-pressure CO2 and stir thoroughly to fully mix the slurry and foam; pour the mixture into the mold, then leave it in the mold for 30 minutes, wait for foaming and forming, and cure to 28 days;

[0106] Comparative Example 10

[0107] 1) Weigh the raw materials, including 1000 parts of cement, 40 parts of composite foaming agent, 400 parts of machine-made sand, 10 parts of admixture, and 500 parts of water;

[0108] 2) First, mix and stir water, cement, admixtures, and aggregates; add the slurry to the CO2 foaming and stir until uniform; after the two are mixed, foam with 0.1MPa~0.3MPa high-pressure CO2 and stir thoroughly to fully mix the slurry and foam; pour the mixture into the mold, then leave it in the mold for 30 minutes, wait for foaming and forming, and cure to 28 days;

[0109] Comparative Example 11

[0110] 1) Weigh the raw materials, including 1000 parts of cement, 40 parts of composite foaming agent, 400 parts of treated sedimentation tank waste, 10 parts of admixture, and 500 parts of water;

[0111] 2) First, mix and stir water, cement, admixtures, and aggregates; add the slurry to the CO2 foaming and stir until uniform; after the two are mixed, foam with 0.1MPa~0.3MPa high-pressure CO2 and stir thoroughly to fully mix the slurry and foam; pour the mixture into the mold, then leave it in the mold for 30 minutes, wait for foaming and forming, and cure to 28 days;

[0112] In the above examples, Examples 1-6 used multiple carbon fixation, Examples 1-3 used only coating for carbon fixation, Examples 4-6 only added carbon-fixing materials to fix carbon within the foamed concrete, and Comparative Examples 7-11 did not employ any carbon-fixing measures, only varying the aggregate ratio. All specimens were prepared and cured for 28 days. The compressive strength of each specimen was measured, and the carbon fixation rate was analyzed by thermogravimetric analysis. The calculated results are shown in Table 1.

[0113] Table 1 Test results of each sample

[0114]

[0115]

[0116] As shown in Table 1, adding wet-ground, CO2-mineralized mixing station waste slag and machine-made sand to foam concrete can significantly improve its strength. The strength of low-carbon foam concrete prepared by a multi-carbon fixation system that takes both internal and external factors into consideration can be increased by 5 to 8 times compared to ordinary foam concrete under the same density conditions, and the carbon fixation rate is also greatly improved. In summary, the low-carbon foam concrete in the present invention can adsorb carbon dioxide in industrial waste gas to achieve a good carbon fixation effect; and as carbonization continues, the strength of the foam concrete will gradually increase.

[0117] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A low-carbon foamed concrete, characterized in that: The carbon-fixing foam concrete is coated with a carbon-fixing coating, wherein the carbon-fixing foam concrete comprises the following raw materials in parts by weight: 500-2000 parts of cement, 10-100 parts of a composite foaming agent, 300-1500 parts of aggregate, 10-40 parts of a carbon-fixing material, 1-20 parts of an admixture, and 300-600 parts of water; The composite foaming agent is composed of the following components by mass fraction: 1-40% nanomaterial, 1-10% polyacrylamide, 10-20% polyether polyol, 1-10% lauryl dimethyl ammonium acetate, and the balance is CO2 foaming agent; The carbon-fixing material is at least one of propylene carbonate, triethanolamine, and tetraethylenepentylamine; The carbon-fixing coating is obtained by immersing carbon-fixing foam concrete in a carbon-fixing coating solution and then air-drying the solution. The carbon-fixing coating solution is composed of the following components by mass fraction: 1-20% polyurethane, 1-20% polyepoxysuccinic acid, 1-20% trisodium dicarboxymethyl alanine, 10-20% sodium bicarbonate, 10-20% calcium silicate powder, and the balance is water.

2. The low-carbon foamed concrete according to claim 1, characterized in that The nanomaterial is at least one of nano silicon dioxide, nano titanium dioxide and carbon nanotubes, and has a particle size range of 10 to 100 nm.

3. The low-carbon foamed concrete according to claim 1, characterized in that The aggregate includes 30% to 70% machine-made sand and 30% to 70% waste from the sedimentation tank of a ready-mixed concrete mixing station that has been wet-ground and CO2 mineralized.

4. The low-carbon foamed concrete according to claim 1, characterized in that The cement is at least one of silicate cement, sulphoaluminate cement and magnesia cement.

5. The method for preparing low-carbon foamed concrete according to any one of claims 1 to 4, characterized in that: The following steps are involved: 1) Weigh cement, composite foaming agent, aggregate, carbon-fixing material, admixture, and water according to mass to prepare carbon-fixing foamed concrete; 2) preparing a carbon-fixing coating solution, immersing the carbon-fixing foamed concrete in the carbon-fixing coating solution, and drying the concrete after immersion to obtain the low-carbon foamed concrete.

6. The method for preparing low-carbon foamed concrete according to claim 5, characterized in that: The specific preparation steps of step 1) are as follows: first, cement, aggregate, water, admixture and carbon-fixing material are mixed and stirred to obtain a slurry; after the composite foaming agent is evenly mixed with the slurry, it is foamed with 0.1 MPa~0.3 MPa high-pressure CO2 and fully stirred to fully mix the slurry and foam; the mixture is poured into a mold, and then placed in the mold for 10-30 minutes to wait for foaming and forming; the obtained foamed concrete is placed in air for natural curing for 5~10 hours and in a 0.2 MPa CO2 atmosphere for 3 hours to obtain the carbon-fixing foamed concrete.

7. The method for preparing low-carbon foamed concrete according to claim 5, characterized in that: The soaking time in step 2) is 5 to 10 minutes.

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