A method of carbon sequestration in foamed concrete

Abstract

The application relates to the field of foamed concrete, and particularly discloses a foamed concrete carbon sequestration method. The foamed concrete carbon sequestration method comprises the following steps: S1, mixing an alkaline activator, a cementing material and water according to a mass ratio of 1:(3-5):1 to form a concrete slurry; S2, adding a foaming agent into the concrete slurry, wherein the mass of the foaming agent is 1-5% of the mass of the concrete slurry; S3, pouring the concrete slurry into a foaming mold, placing the foaming mold in a CO2-rich environment, and carrying out a foaming reaction, wherein the foaming time is 10-20 min, and after the foaming is completed, 24-48 h of solidification treatment is carried out to complete the foamed concrete carbon sequestration. The foamed concrete carbon sequestration method has the advantages that the foamed concrete has the ability to absorb CO2 and sequestrate carbon.

Description

Technical Field

[0001] This application relates to the field of foamed concrete, and more specifically, to a method for carbon sequestration in foamed concrete. Background Technology

[0002] Foamed concrete is a special type of building material that offers advantages over traditional concrete, including being lightweight, providing thermal insulation, and retaining heat effectively. It reduces density by introducing air bubbles into the concrete and utilizes these bubbles to provide excellent thermal insulation properties. Foamed concrete is not only widely used in the construction industry but also shows potential in road foundations and infill materials.

[0003] Besides the inherent advantages of foamed concrete, another key environmental advantage is its carbon sequestration capability. Carbon sequestration refers to the process of permanently locking carbon dioxide within building materials, reducing its release into the atmosphere. During its preparation and curing process, foamed concrete absorbs carbon dioxide through chemical reactions and converts it into harmless carbonates. This makes foamed concrete a building material with low carbon emissions.

[0004] Compared to traditional concrete, foamed concrete has greater carbon sequestration potential. Due to its lower density, it can use less cement and aggregate, thus reducing resource consumption and environmental impact. Simultaneously, the thermal insulation properties of foamed concrete can reduce building energy consumption, further decreasing carbon emissions. Carbon sequestration with foamed concrete not only helps mitigate climate change but also provides a solution for sustainable building.

[0005] Currently, the manufacturing technology of foamed concrete usually involves mixing a foaming agent into the concrete slurry. The gas generated by the foaming agent causes the concrete to form a foam structure, thereby achieving the effects of lightweighting and thermal insulation. However, the existing manufacturing method itself does not have the function of absorbing CO2 and fixing carbon. Summary of the Invention

[0006] In order to enable foamed concrete to absorb CO2 and fix carbon, this application provides a method for carbon sequestration of foamed concrete.

[0007] The carbon sequestration method for foamed concrete provided in this application adopts the following technical solution: A method for carbon sequestration using foamed concrete includes the following steps: S1. Mix the alkaline activator, cementitious material and water thoroughly at a mass ratio of 1:(3-5):1 to form a concrete slurry; S2. Add foaming agent to concrete grout, the mass of foaming agent being 1-5% of the mass of concrete grout; S3. Pour the concrete slurry into the foaming mold, place the foaming mold in a CO2 enrichment environment, and carry out the foaming reaction. The foaming time is 10-20 minutes. After foaming, perform a curing treatment for 24-48 hours to complete the carbon sequestration of the foamed concrete.

[0008] By employing the above technical solution, in foamed concrete, the alkaline activator promotes the reaction of CO2 with hydroxide ions in water to form carbonates. These carbonate substances fill the pores of the concrete, forming a dense carbonate cement. The formation of the carbonate cement effectively reduces the porosity of the concrete, thereby improving its density and strength.

[0009] Because CO2 is absorbed and converted into carbonates, the carbon in foamed concrete is permanently fixed during the curing process. Carbonates are stable substances and do not release CO2 over time. Therefore, foamed concrete achieves effective carbon sequestration and has a high carbon fixation effect.

[0010] Traditional cement production often uses large amounts of cement clinker, leading to high carbon emissions. However, the alkaline activator used in foamed concrete carbon sequestration methods can reduce cement usage, thereby lowering carbon emissions. Furthermore, due to its lower density and good thermal insulation properties, foamed concrete can reduce building energy consumption, further reducing carbon emissions.

[0011] Optionally, the alkaline activator in step S1 includes one or more of sodium carbonate, potassium carbonate, and calcium oxide.

[0012] By employing the above-mentioned technical solutions, sodium carbonate and potassium carbonate can effectively catalyze the absorption of CO2. Simultaneously, calcium oxide helps accelerate the reaction rate with CO2, increasing the amount of CO2 absorbed. Therefore, using these alkaline activators can improve the CO2 absorption capacity of foamed concrete.

[0013] The selection of alkaline activators can adjust the alkalinity in concrete, thereby affecting the rate and extent of the reaction between CO2 and the components in the concrete, ensuring a more uniform carbonation reaction, and resulting in the formation of more carbonate cementitious material within the concrete. This helps improve the density, strength, and stability of the concrete, further enhancing its carbon sequestration effect.

[0014] These alkaline activators create an alkaline environment when mixed with foaming agents and water, promoting the activation of the foaming agent and the formation of bubbles. By selecting alkaline activators, the foaming performance can be optimized, giving foamed concrete good thermal insulation properties and lightweight characteristics.

[0015] Optionally, the foaming agent in step S2 is a plant-based cement foaming agent, which includes straw fiber and fatty alcohol polyoxyethylene ether.

[0016] By employing the above technical solution, plant-based cement foaming agents can generate a large number of air bubbles in concrete, resulting in a uniform foamed structure. Straw fiber, as a filler material, provides support and reinforcement, promoting the stability and uniform distribution of air bubbles. Fatty alcohol polyoxyethylene ether, as a surfactant, reduces the surface tension of the liquid, which is beneficial for bubble formation and dispersion. Therefore, using plant-based cement foaming agents can achieve excellent foaming results in foamed concrete.

[0017] Straw fiber is a natural insulating material with a low thermal conductivity. Adding straw fiber to foamed concrete can increase the thermal insulation performance of the concrete, reduce heat conduction, and improve the energy efficiency of buildings. Plant-based cement foaming agents use plant fibers and natural fatty alcohol polyoxyethylene ethers as ingredients, contain no harmful substances, and are environmentally friendly.

[0018] Optionally, the mass ratio of straw fiber to fatty alcohol polyoxyethylene ether in the plant-based cement foaming agent is 1:(0.5-2).

[0019] By adopting the above technical solutions, the number, size, and distribution of air bubbles in concrete can be adjusted, thereby affecting the pore structure and density of foamed concrete.

[0020] Optionally, the humidity of the curing process in step S3 is 60-80% and the temperature is 10-30℃.

[0021] By adopting the above technical solutions and controlling humidity and temperature, the drying speed of concrete can be effectively reduced, thereby reducing the risk of shrinkage and cracking.

[0022] Optionally, the cementitious material in step S1 includes 30-50 parts cement, 40-80 parts admixture, 120-150 parts fine sand, and 120-180 parts recycled coarse aggregate by weight.

[0023] By adopting the above technical solution and adjusting the proportions of each component, the mechanical properties of foamed concrete can be improved.

[0024] Optionally, the admixture includes one or more of slag, fly ash, and metallurgical slag.

[0025] By adopting the above technical solutions, adding an appropriate amount of admixtures can improve the workability of concrete, such as its fluidity, slump, and pumpability.

[0026] Optionally, the recycled coarse aggregate is pulverized and calcined concrete waste, and the particle size of the recycled coarse aggregate is 5-15mm.

[0027] By adopting the above-mentioned technical solutions, the use of recycled coarse aggregate can effectively reduce the environmental pollution caused by concrete waste. Waste concrete typically requires treatment and landfill, consuming significant land resources and potentially polluting water and soil. Recycled coarse aggregate is obtained by crushing and calcining concrete waste. This method allows waste concrete to be reused, achieving resource recycling and reuse. Simultaneously, it reduces the demand for natural aggregates and lowers the pressure on natural resource extraction.

[0028] In summary, this application has the following beneficial effects: 1. In this application, an alkaline activator in foamed concrete promotes the reaction of CO2 with hydroxide ions in water to form carbonates. These carbonates fill the pores of the concrete, forming a dense carbonate gel. The formation of the carbonate gel effectively reduces the porosity of the concrete, thereby improving its density and strength. Because CO2 is absorbed and converted into carbonates, the carbon in the foamed concrete is permanently fixed during the curing process. Carbonates are stable substances and do not release CO2 over time. Therefore, foamed concrete achieves effective carbon sequestration and has a high carbon fixation effect.

[0029] 2. In this application, a plant-based cement foaming agent is preferably used, which can generate a large number of air bubbles in the concrete, resulting in a uniform foamed structure. Straw fiber, as a filler material, provides support and reinforcement, promoting the stability and uniform distribution of air bubbles. Fatty alcohol polyoxyethylene ether, as a surfactant, reduces the surface tension of the liquid, which is beneficial for the formation and dispersion of air bubbles. Therefore, using a plant-based cement foaming agent can achieve a good foaming effect in foamed concrete.

[0030] 3. This application preferably utilizes the fact that slag, fly ash, and metallurgical slag contain a large amount of active silicates and vitreous substances. These substances can react with cement colloids to form cementitious materials, filling micropores and cracks in concrete, thereby improving the density and durability of the concrete. Using admixtures can partially replace the amount of cement used, reducing the demand for cement and thus reducing carbon dioxide emissions from the mining and calcination of limestone ore. This is beneficial to environmental protection and sustainable development. Detailed Implementation

[0031] The present application will be further described in detail below with reference to the embodiments. Example

[0032] Example 1 A method for carbon sequestration using foamed concrete: S1. Mix the alkaline activator, cementitious materials and water thoroughly in a mass ratio of 1:4:1. The cementitious materials include 3000g of cement, 4000g of admixture, 12000g of fine sand and 12000g of recycled coarse aggregate to form a concrete slurry. S2. Add plant-based cement foaming agent to the concrete slurry. The mass ratio of straw fiber to fatty alcohol polyoxyethylene ether in the plant-based cement foaming agent is 1:1.5, and the mass of the foaming agent is 4% of the mass of the concrete slurry. S3. Pour the concrete slurry into the foaming mold and place the foaming mold in a CO2 enrichment environment for foaming reaction. The foaming time is 15 minutes. After foaming, perform a 36-hour curing treatment with a humidity of 70% and a temperature of 20°C to complete the carbon sequestration of the foamed concrete.

[0033] Among them, slag is selected as the admixture; the recycled coarse aggregate is the crushed and roasted concrete waste, and the particle size of the recycled coarse aggregate is 10mm; sodium carbonate is selected as the alkaline activator.

[0034] Example 2 A method for carbon sequestration using foamed concrete: S1. Mix the alkaline activator, cementitious materials and water thoroughly in a mass ratio of 1:4:1. The cementitious materials include 5000g of cement, 8000g of admixtures, 15000g of fine sand and 18000g of recycled coarse aggregate to form a concrete slurry. S2. Add plant-based cement foaming agent to the concrete slurry. The mass ratio of straw fiber to fatty alcohol polyoxyethylene ether in the plant-based cement foaming agent is 1:1.5, and the mass of the foaming agent is 4% of the mass of the concrete slurry. S3. Pour the concrete slurry into the foaming mold and place the foaming mold in a CO2 enrichment environment for foaming reaction. The foaming time is 15 minutes. After foaming, perform a 36-hour curing treatment with a humidity of 70% and a temperature of 20°C to complete the carbon sequestration of the foamed concrete.

[0035] Among them, slag is selected as the admixture; the recycled coarse aggregate is the crushed and roasted concrete waste, and the particle size of the recycled coarse aggregate is 10mm; sodium carbonate is selected as the alkaline activator.

[0036] Example 3 A method for carbon sequestration using foamed concrete: S1. Mix the alkaline activator, cementitious materials and water thoroughly in a mass ratio of 1:4:1. The cementitious materials include 4000g of cement, 6000g of admixture, 13000g of fine sand and 15000g of recycled coarse aggregate to form a concrete slurry. S2. Add plant-based cement foaming agent to the concrete slurry. The mass ratio of straw fiber to fatty alcohol polyoxyethylene ether in the plant-based cement foaming agent is 1:1.2, and the mass of the foaming agent is 4% of the mass of the concrete slurry. S3. Pour the concrete slurry into the foaming mold and place the foaming mold in a CO2 enrichment environment for foaming reaction. The foaming time is 15 minutes. After foaming, perform a 36-hour curing treatment with a humidity of 70% and a temperature of 20°C to complete the carbon sequestration of the foamed concrete.

[0037] Among them, slag is selected as the admixture; the recycled coarse aggregate is the crushed and roasted concrete waste, and the particle size of the recycled coarse aggregate is 10mm; sodium carbonate is selected as the alkaline activator.

[0038] Example 4 A method for carbon sequestration in foamed concrete differs from Example 3 in that: in step S1, the alkaline activator, cementitious material, and water are thoroughly mixed in a mass ratio of 1:3:1.

[0039] Example 5 A method for carbon sequestration in foamed concrete differs from Example 3 in that: in step S1, the alkaline activator, cementitious material, and water are thoroughly mixed in a mass ratio of 1:5:1.

[0040] Example 6 A method for carbon sequestration in foamed concrete differs from Example 3 in that the mass ratio of straw fiber to fatty alcohol polyoxyethylene ether in the plant-based cement foaming agent in step S2 is 1:0.5.

[0041] Example 7 A method for carbon sequestration in foamed concrete differs from Example 3 in that the mass ratio of straw fiber to fatty alcohol polyoxyethylene ether in the plant-based cement foaming agent in step S2 is 1:2.

[0042] Example 8 A method for carbon sequestration in foamed concrete differs from Example 3 in that the humidity and temperature of the curing treatment in step S3 are 60% and 10°C.

[0043] Example 9 A method for carbon sequestration in foamed concrete differs from Example 3 in that the humidity and temperature of the curing treatment in step S3 are 80% and 20°C.

[0044] Example 10 A method for carbon sequestration in foamed concrete differs from Example 3 in that potassium carbonate is used as the alkaline activator in step S1.

[0045] Example 11 A method for carbon sequestration in foamed concrete differs from Example 3 in that calcium oxide is used as the alkaline activator in step S1.

[0046] Example 12 A method for carbon sequestration in foamed concrete differs from Example 3 in that fly ash is used as the admixture in step S1.

[0047] Example 13 A method for carbon sequestration in foamed concrete differs from Example 3 in that metallurgical slag is used as the admixture in step S1.

[0048] Comparative Example Comparative Example 1 A method for carbon sequestration using foamed concrete: S1. Mix the cementitious materials and water thoroughly at a mass ratio of 4:1. The cementitious materials include 4000g of cement, 6000g of admixtures, 13000g of fine sand and 15000g of recycled coarse aggregate to form a concrete slurry. S2. Add plant-based cement foaming agent to the concrete slurry. The mass ratio of straw fiber to fatty alcohol polyoxyethylene ether in the plant-based cement foaming agent is 1:1.2, and the mass of the foaming agent is 4% of the mass of the concrete slurry. S3. Pour the concrete slurry into the foaming mold and place the foaming mold in a CO2 enrichment environment for foaming reaction. The foaming time is 15 minutes. After foaming, perform a 36-hour curing treatment with a humidity of 70% and a temperature of 20°C to complete the carbon sequestration of the foamed concrete.

[0049] Among them, slag is selected as the admixture; the recycled coarse aggregate is the crushed and roasted concrete waste, and the particle size of the recycled coarse aggregate is 10mm.

[0050] Comparative Example 2 A method for carbon sequestration using foamed concrete: S1. Mix the alkaline activator, cementitious materials and water thoroughly in a mass ratio of 1:4:1. The cementitious materials include 4000g of cement, 6000g of admixture, 13000g of fine sand and 15000g of recycled coarse aggregate to form a concrete slurry. S2. Add sodium dodecylbenzene sulfonate foaming agent to the concrete grout, with the foaming agent mass being 4% of the concrete grout mass; S3. Pour the concrete slurry into the foaming mold and place the foaming mold in a CO2 enrichment environment for foaming reaction. The foaming time is 15 minutes. After foaming, perform a 36-hour curing treatment with a humidity of 70% and a temperature of 20°C to complete the carbon sequestration of the foamed concrete.

[0051] Among them, slag is selected as the admixture; the recycled coarse aggregate is the crushed and roasted concrete waste, and the particle size of the recycled coarse aggregate is 10mm; sodium carbonate is selected as the alkaline activator.

[0052] Comparative Example 3 A method for carbon sequestration using foamed concrete: S1. Mix calcium hydroxide, cementitious materials and water thoroughly in a mass ratio of 1:4:1. The cementitious materials include 4000g of cement, 6000g of admixtures, 13000g of fine sand and 15000g of recycled coarse aggregate to form a concrete slurry. S2. Add sodium dodecylbenzene sulfonate foaming agent to the concrete grout, with the foaming agent mass being 4% of the concrete grout mass; S3. Pour the concrete slurry into the foaming mold and place the foaming mold in a CO2 enrichment environment for foaming reaction. The foaming time is 15 minutes. After foaming, perform a 36-hour curing treatment with a humidity of 70% and a temperature of 20°C to complete the carbon sequestration of the foamed concrete.

[0053] Among them, slag is selected as the admixture; the recycled coarse aggregate is the crushed and roasted concrete waste, and the particle size of the recycled coarse aggregate is 10mm.

[0054] Performance testing Detection methods Carbonate content detection: The acid washing method is used to analyze and detect the carbonate content in foamed concrete. It can measure the total carbon content in the concrete sample and calculate the carbon fixation amount with carbonates.

[0055] Density and porosity testing: Gas adsorption method was used to evaluate the density and porosity of foamed concrete.

[0056] Strength testing: The mechanical properties of carbon-sequestered concrete are evaluated through compression tests.

[0057] Table 1 Statistical Table of Test Data Combining Example 3 and Comparative Example 1 with Table 1, it can be seen from the test data that, since no alkaline activator was added in Comparative Example 1, the carbon fixation content of the foamed concrete obtained in Comparative Example 1 is significantly lower than that in Example 3. Furthermore, the performance of the foamed concrete in Comparative Example 1 is also inferior to that in Example 3. This indicates that in foamed concrete, the alkaline activator promotes the reaction of CO2 with hydroxide ions in water to form carbonates. These carbonate substances fill the pores of the concrete, forming a dense carbonate cement. The formation of the carbonate cement effectively reduces the porosity of the concrete, thereby improving its density and strength.

[0058] Combining Example 3 and Comparative Example 2 with Table 1, it can be seen that the difference between Example 3 and Comparative Example 2 is that Comparative Example 2 uses sodium dodecylbenzenesulfonate foaming agent, while Example 3 uses plant-based cement foaming agent. The carbon fixation and mechanical properties of Comparative Example 2 are also lower than those of Example 3. This indicates that plant-based cement foaming agents can generate a large number of air bubbles in concrete, resulting in a uniform foamed structure. Straw fiber, as a filler material, can provide support and reinforcement, promoting the stability and uniform distribution of air bubbles. Fatty alcohol polyoxyethylene ether, as a surfactant, can reduce the surface tension of the liquid, which is beneficial for the formation and dispersion of air bubbles.

[0059] Combining Example 3 and Comparative Example 3 with Table 1, it can be seen that the difference between Example 3 and Comparative Example 3 is that Example 3 uses an alkaline activator and a plant-based cement foaming agent, while Comparative Example 3 uses calcium hydroxide and sodium dodecylbenzene sulfonate foaming agent. The test data shows that the alkaline activator and the plant-based cement foaming agent not only improve the carbon fixation capacity of the foamed concrete, but also improve the mechanical properties and density of the foamed concrete.

[0060] As can be seen from Examples 1-3 and Table 1, by adjusting the proportion of gel material, the mechanical properties of foamed concrete can be adjusted, the density can be increased and the porosity can be reduced.

[0061] As can be seen from Examples 3-9 and Table 1, adjusting the ratio of cementitious material to water can affect the fluidity and consistency of the concrete slurry, thereby affecting the density of the foamed concrete. Increasing the amount of cementitious material can make the concrete denser, thus improving its compressive strength and load-bearing capacity. By changing the mass ratio of straw fiber to fatty alcohol polyoxyethylene ether, the number, size, and distribution of air bubbles in the concrete can be adjusted, thereby affecting the pore structure and density of the foamed concrete. By controlling humidity and temperature, the drying rate of the concrete can be effectively reduced, decreasing the risk of shrinkage and cracking. Example 3 is the preferred embodiment of this application.

[0062] As can be seen from Examples 3, 10-13, and Table 1, using different types of alkaline activators can improve the CO2 absorption capacity of foamed concrete, thereby affecting the rate and extent of the reaction between CO2 and the components in the concrete, promoting uniform carbonation, and resulting in the formation of more carbonate cementitious aggregates within the concrete. This helps improve the density, strength, and stability of the concrete, further enhancing the carbon sequestration effect, with sodium carbonate being the most preferred. Adding different admixtures can improve the workability of concrete, enhance the durability and stability of foamed concrete, and improve compressive strength, with slag being the most preferred.

[0063] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for carbon sequestration using foamed concrete, characterized in that, Includes the following steps: S1. Mix the alkaline activator, cementitious material, and water thoroughly at a mass ratio of 1:(3-5):1 to form a concrete slurry; S2. Add a foaming agent to the concrete slurry, with the foaming agent mass being 1-5% of the concrete slurry mass; S3. Pour the concrete slurry into a foaming mold, place the foaming mold in a CO2-rich environment, and allow it to foam for 10-20 minutes. After foaming, allow it to cure for 24-48 hours to complete the carbon sequestration of the foamed concrete; In step S2, the foaming agent is a plant-based cement foaming agent, which includes straw fiber and fatty alcohol polyoxyethylene ether. The mass ratio of straw fiber to fatty alcohol polyoxyethylene ether in the plant-based cement foaming agent is 1:(0.5-2).

2. The method for carbon sequestration in foamed concrete according to claim 1, characterized in that: The alkaline activator in step S1 includes one or more of sodium carbonate, potassium carbonate, and calcium oxide.

3. The carbon sequestration method for foamed concrete according to claim 1, characterized in that: In step S3, the curing process involves a humidity of 60-80% and a temperature of 10-30℃.

4. The method for carbon sequestration in foamed concrete according to claim 1, characterized in that: The cementitious materials in step S1 include 30-50 parts cement, 40-80 parts admixture, 120-150 parts fine sand, and 120-180 parts recycled coarse aggregate by weight.

5. The method for carbon sequestration in foamed concrete according to claim 4, characterized in that: The admixture includes one or more of slag, fly ash, and metallurgical slag.

6. The method for carbon sequestration in foamed concrete according to claim 4, characterized in that: The recycled coarse aggregate is concrete waste after crushing and calcination, and the particle size of the recycled coarse aggregate is 5-15mm.

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