An adjustable foam geopolymer concrete and a method of making the same

Abstract

The application discloses a kind of adjustable foam geopolymer concrete, including the following weight parts of raw materials are made: mine fine tailings 50-70 parts, fly ash 10-30 parts, cement 5-20 parts, carrier foaming agent 18-30 parts, sodium silicate 1.40-5.00 parts, foam stabilizer 0.3-0.6 parts, setting regulator 0.3-0.8 parts, water 45-60 parts;The application also relates to a kind of preparation method of adjustable foam geopolymer concrete.The comprehensive utilization of mine fine tailings and fly ash and other wastes can be realized by the application, and the prepared foam geopolymer concrete has the advantages of light weight, high strength, low water absorption, low thermal conductivity, adjustable foaming rate and comprehensive performance of concrete, and has good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of green building materials technology, and in particular relates to an adjustable foamed geopolymer concrete and its preparation method. Background Technology

[0002] The production of cement-based concrete consumes a large amount of energy and emits a significant amount of carbon dioxide. Geopolymer concrete, on the other hand, is an inorganic cementitious material prepared using aluminosilicate active components under alkaline activation conditions. Common raw materials include waste materials such as fly ash, resulting in lower energy consumption and carbon emissions. Porous, lightweight foamed geopolymer concrete can improve the thermal insulation, sound insulation, and heat insulation performance of walls. However, concrete prepared using conventional foaming methods currently suffers from large internal pore sizes, interconnected pores, uneven distribution, high water absorption, and low compressive strength.

[0003] Existing technologies, such as patent application CN202110662284.0, disclose a fly ash-based foam geopolymer, its preparation method, and its application. This geopolymer includes 900-1000 parts of fly ash-based material; 600-700 parts of composite alkaline solution; 0-10 parts of thickener; 2-6 parts of foam stabilizer A; 5-10 parts of water-reducing agent; and 20-40 parts of foaming agent. The water-reducing agent includes any one or a combination of at least two of polycarboxylate water-reducing agents, naphthalene sulfonate water-reducing agents, aliphatic water-reducing agents, lignin sulfonate water-reducing agents, or aminosulfonate water-reducing agents. This type of water-reducing agent is mainly designed for ordinary cement-based concrete and has poor compatibility with thickeners, foam stabilizers A and B, foaming agents, alkaline solutions, etc., as well as with fly ash and other geopolymer cementitious materials.

[0004] Existing technology, such as patent application CN201811067286.X, discloses a foamed geopolymer, its preparation method, and its application. The foamed geopolymer comprises the following components: 30-50 parts by weight of metakaolin, 40-50 parts by weight of alkali activator, 1-4 parts by weight of fly ash, 2-5 parts by weight of foaming agent, 0.3-0.7 parts by weight of foam stabilizer, 0.3-0.8 parts by weight of modified sisal fiber, 1-4 parts by weight of paraffin emulsion, 5-10 parts by weight of water, and 0.3-0.7 parts by weight of anhydrous ethanol. The foaming agent used is hydrogen peroxide and aluminum powder in a weight ratio of 1:0.8 to 1.2. Aluminum is an active metal that reacts rapidly with water to produce H2, resulting in rapid foaming, but the reaction is difficult to control and the foam is prone to collapse. The foam stabilizer used is a mixture of sodium dodecylbenzenesulfonate and triethanolamine. Sodium dodecylbenzenesulfonate has only one carbon dodecyl chain at its hydrophobic end, so it has poor hydrophobicity and high concrete water absorption. In addition, the carbon chain of sodium dodecylbenzenesulfonate has benzene rings, resulting in poor intermolecular forces, making the foam prone to coalescence, breakage and collapse.

[0005] Existing technology, such as patent application CN202010753230.0, discloses a superhydrophobic geopolymer prepared by microporous foaming and its preparation method. This superhydrophobic geopolymer comprises the following raw materials in parts by weight: 30-45 parts of aluminosilicate mineral raw material, 35-50 parts of alkali activator, 0.5-1.5 parts of polydimethylsiloxane, 0.05-0.15 parts of silane coupling agent, 2-5 parts of silicon carbide powder, 2-4 parts of short fibers, 1-3 parts of alkyl glycoside, and 1-3 parts of hydrogen peroxide. However, directly adding hydrogen peroxide to the geopolymer slurry results in excessively rapid foaming, causing the foam to easily collapse.

[0006] Existing technology, such as patent application CN202211257260.8, discloses a slow-release foaming lightweight polymer material and its preparation method, comprising the following raw materials in parts by weight: 40-50 parts fly ash, 5-10 parts mineral powder, 55-60 parts modified silica gel ceramsite sand, 15-20 parts activator, and 10-15 parts water. The carrier for the foaming agent is 800-grade ceramsite sand, which has an excessively high bulk density of approximately 800 kg / m³. 3 Furthermore, the particle size of the ceramic sand is too large, ranging from 0 to 5 mm. Therefore, the concrete prepared is relatively heavy and has low strength. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art. This invention can realize the comprehensive utilization of waste such as mine tailings and fly ash. The foamed geopolymer concrete prepared has the advantages of light weight, high strength, low water absorption, low thermal conductivity, adjustable foaming rate and comprehensive concrete performance, and has good application prospects.

[0008] To achieve the above-mentioned objectives, the technical solution provided by this invention patent is as follows:

[0009] An adjustable foamed polymer concrete comprises the following raw materials in parts by weight: 50-70 parts of mine tailings, 10-30 parts of fly ash, 5-20 parts of cement, 18-30 parts of carrier foaming agent, 1.40-5.00 parts of sodium silicate, 0.3-0.6 parts of foam stabilizer, 0.3-0.8 parts of setting regulator, and 45-60 parts of water; wherein the carrier foaming agent is obtained by soaking lightweight sand in hydrogen peroxide, and the bulk density of the lightweight sand is 140-160 kg / m³. 3 The particle size range is 0.1-0.5mm, the mass concentration of the hydrogen peroxide is 25-45%, and the hydrogen peroxide accounts for 17%-30% of the mass of the carrier foaming agent.

[0010] Furthermore, the bulk density of the mine tailings is 580-650 kg / m³. 3 The content of inactive SiO2 is 50-60%, Al2O3 is 15-20%, and CaO is 5-8%.

[0011] Furthermore, the fly ash is Class F fly ash, grade I or II, wherein the SiO2 content is 40-50% and the Al2O3 content is 30-40%.

[0012] Furthermore, the cement is silicate cement or ordinary silicate cement.

[0013] Furthermore, the modulus of the sodium silicate is 1.90-2.50.

[0014] Furthermore, the foam stabilizer is calcium stearate, which is AR grade, and the calcium content is 6.6-7.4%.

[0015] Furthermore, the setting regulator is lithium carbonate, which is RG grade and has a content greater than 99%.

[0016] A method for preparing adjustable foamed geopolymer concrete, the method specifically includes the following steps:

[0017] S1, Grind the fine tailings from the mine to obtain pretreated fine tailings A;

[0018] S2, Prepare carrier foaming agent B by placing light sand in hydrogen peroxide and letting it stand for 0.5-1.5 hours to obtain carrier foaming agent B;

[0019] S3, mix the carrier foaming agent B, pretreated mine tailings A, fly ash, cement, sodium silicate, foam stabilizer and setting regulator evenly to obtain dry material C;

[0020] S4. Pour water into dry material C and stir evenly. Allow it to stand and foam to obtain adjustable foamed geopolymer concrete. During the process of mixing and standing foaming, dry material C reacts with water to form a slurry. As the reaction continues, water is gradually consumed and the relative humidity of the slurry decreases. Hydrogen peroxide in the light sand migrates into the slurry along the humidity gradient, adjusting the foaming rate of the slurry.

[0021] Furthermore, in step S1, the fine tailings from the mine are mechanically ground, and the particle size of the mechanically ground fine tailings is less than 20 μm.

[0022] Furthermore, the temperature range of the water poured into the dry material C in step S4 is 30-50℃.

[0023] Based on the above technical solution, the adjustable foamed geopolymer concrete and its preparation method of this invention have achieved the following technical effects through practical application:

[0024] 1. The preparation process of this invention is simple. Compared with traditional fly ash-based polymers, this invention makes extensive use of mine tailings waste, which solves the problem of mine tailings storage and reduces CO2 emissions. At the same time, the low density of mine tailings can significantly reduce the bulk density of foamed concrete. Adding a small amount of cement can compensate for the problem of low early reaction rate and easy collapse of fly ash and other materials.

[0025] 2. This invention uses hydrogen peroxide as a foaming agent, which decomposes under alkaline conditions to generate oxygen, and the Cu in the slurry... 2+ It can act as a catalyst, and appropriately increased temperature can also accelerate the decomposition of hydrogen peroxide and the polymerization of fly ash. Calcium stearate is used as a foam stabilizer to reduce the surface tension of bubbles, refine the pore structure, reduce the porosity, make the pores evenly distributed, and prevent pore collapse. In addition, calcium stearate is insoluble in water and its hydrophobic end extends into the air, so it can be used as a waterproofing agent to reduce the water absorption rate of foamed concrete. Calcium stearate also has a certain air-entraining effect, which assists in the foaming of hydrogen peroxide.

[0026] 3. This invention uses porous lightweight sand as a carrier for hydrogen peroxide, controlling the concentration of hydrogen peroxide, the soaking time of lightweight sand in hydrogen peroxide, and the temperature of the mixing water. As water is consumed in the concrete, the relative humidity decreases, and the hydrogen peroxide in the lightweight sand migrates into the slurry along the humidity gradient, thereby adjusting the foaming rate and avoiding excessively rapid foaming, bubble coalescence, and foam collapse. Lightweight sand has a similar particle size distribution to ordinary sand, and a suitable ratio with geopolymer cementitious materials can improve the density and strength of concrete. Due to its lightweight and porous characteristics, lightweight sand can further reduce the apparent density of foamed concrete and improve its thermal insulation performance.

[0027] 4. This invention uses lithium carbonate as a setting regulator to balance the setting and hardening rate of cement with the foaming rate of hydrogen peroxide, preventing excessively rapid foaming that causes the foam to burst before the cementitious material hardens, or excessively rapid hydration resulting in insufficient foaming. Compared to other setting regulators, lithium carbonate is slightly soluble and can slowly consume the gypsum in cement that has a retarding effect, allowing the C3A in the cement to hydrate and better match the cement setting time with the foaming rate of hydrogen peroxide. Sodium silicate can also react with the hydration product Ca(OH)2, and the resulting sodium hydroxide can not only eliminate the retarding effect of gypsum but also act as an activator, appropriately reducing the modulus of sodium silicate, increasing the alkalinity of the paste, activating the activity of mine tailings and fly ash, and improving the degree of polymerization.

[0028] 5. This invention regulates the setting time of the slurry by controlling the dosage of cement, setting regulator, sodium silicate, and water temperature; it also regulates the foaming rate of concrete by controlling the concentration of hydrogen peroxide, the soaking time of light sand, and the temperature of mixing water. Furthermore, it regulates the foam quality by controlling the dosage of calcium stearate as a foam stabilizer. Through the above-mentioned multi-factor control, the comprehensive properties of concrete, such as strength, density, water absorption, and thermal conductivity, are adjusted, thereby improving the final quality of the prepared foamed geopolymer concrete. Attached Figure Description

[0029] Figure 1 This is a flowchart illustrating the preparation process of adjustable foamed geopolymer concrete in the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and effects of this invention clearer, specific examples are provided below. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this invention.

[0031] The bulk density of the mine tailings in the embodiments of the present invention is 610 kg / m³. 3 The composition of the cement is as follows: 53.93% inactive SiO2, 17.41% Al2O3, and 6.23% CaO; ordinary Portland cement with a strength grade of P.O42.5; Class F fly ash, grade II, with a SiO2 content of 48% and an Al2O3 content of 35%; hydrogen peroxide concentration of 30%; and lightweight sand with a bulk density of 150 kg / m³. 3 The particle size is 0.1-0.5 mm; the sodium silicate modulus is 2.05. Example 1

[0032] An adjustable foamed geopolymer concrete is made from the following raw materials in parts by weight:

[0033] The ingredients are: 60 parts fine tailings from the mine, 25 parts fly ash, 15 parts cement, 22 parts carrier foaming agent, 2.55 parts sodium silicate, 0.5 parts foam stabilizer, 0.6 parts setting regulator, and 50 parts water. The carrier foaming agent is obtained by soaking light sand in hydrogen peroxide.

[0034] The preparation method of the above-mentioned adjustable foamed geopolymer concrete includes the following steps:

[0035] S1, 60 parts of mine tailings were mechanically ground to a particle size of less than 20µm to obtain pretreated mine tailings A;

[0036] S2, a certain amount of light sand is placed in a certain amount of hydrogen peroxide and left to stand for 1 hour to obtain carrier foaming agent B;

[0037] S3, mix 22 parts of carrier foaming agent B, 60 parts of pretreated mine tailings A, 25 parts of fly ash, 15 parts of cement, 2.55 parts of sodium silicate, 0.5 parts of foam stabilizer calcium stearate and 0.6 parts of setting regulator evenly to obtain dry material C.

[0038] S4. Pour 50 parts of water at 35°C into dry material C and stir evenly. Allow it to stand and foam to obtain adjustable foamed polymer concrete. Dry material C reacts with water to form a slurry. As the reaction continues, the water is gradually consumed and the relative humidity of the slurry decreases. Hydrogen peroxide in the light sand migrates into the slurry along the humidity gradient, adjusting the foaming rate of the slurry. Example 2

[0039] An adjustable foamed geopolymer concrete is made from the following raw materials in parts by weight:

[0040] The ingredients are: 60 parts fine tailings from the mine, 25 parts fly ash, 15 parts cement, 22 parts carrier foaming agent, 2.55 parts sodium silicate, 0.5 parts foam stabilizer, 0.3 parts setting regulator, and 50 parts water. The carrier foaming agent is obtained by soaking light sand in hydrogen peroxide.

[0041] The preparation method of the above-mentioned adjustable foamed geopolymer concrete includes the following steps:

[0042] S1, 60 parts of mine tailings were mechanically ground to a particle size of less than 20µm to obtain pretreated mine tailings A;

[0043] S2, a certain amount of light sand is placed in a certain amount of hydrogen peroxide and left to stand for 1 hour to obtain carrier foaming agent B;

[0044] S3, mix 22 parts of carrier foaming agent B, 60 parts of pretreated mine tailings A, 25 parts of fly ash, 15 parts of cement, 2.55 parts of sodium silicate, 0.5 parts of foam stabilizer calcium stearate and 0.3 parts of setting regulator evenly to obtain dry material C.

[0045] S4. Pour 50 parts of water at 35°C into dry material C and stir evenly. Allow it to stand and foam to obtain adjustable foamed polymer concrete. During the mixing and standing foaming process of dry material C and water, dry material C reacts with water to form a slurry. As the reaction continues, water is gradually consumed and the relative humidity of the slurry decreases. Hydrogen peroxide in the light sand migrates into the slurry along the humidity gradient, adjusting the foaming rate of the slurry. Example 3

[0046] An adjustable foamed geopolymer concrete is made from the following raw materials in parts by weight:

[0047] The ingredients are: 60 parts fine tailings from the mine, 25 parts fly ash, 15 parts cement, 22 parts carrier foaming agent, 2.55 parts sodium silicate, 0.3 parts foam stabilizer, 0.6 parts setting regulator, and 50 parts water. The carrier foaming agent is obtained by soaking light sand in hydrogen peroxide.

[0048] The preparation method of the above-mentioned adjustable foamed geopolymer concrete includes the following steps:

[0049] S1, 60 parts of mine tailings were mechanically ground to a particle size of less than 20µm to obtain pretreated mine tailings A;

[0050] S2, a certain amount of light sand is placed in a certain amount of hydrogen peroxide and left to stand for 1 hour to obtain carrier foaming agent B;

[0051] S3, mix 22 parts of carrier foaming agent B, 60 parts of pretreated mine tailings A, 25 parts of fly ash, 15 parts of cement, 2.55 parts of sodium silicate, 0.3 parts of foam stabilizer calcium stearate and 0.6 parts of setting regulator evenly to obtain dry material C.

[0052] S4. Pour 50 parts of water at 35°C into dry material C and stir evenly. Allow it to stand and foam to obtain adjustable foamed polymer concrete. During the mixing and standing foaming process of dry material C and water, dry material C reacts with water to form a slurry. As the reaction continues, water is gradually consumed and the relative humidity of the slurry decreases. Hydrogen peroxide in the light sand migrates into the slurry along the humidity gradient, adjusting the foaming rate of the slurry. Example 4

[0053] An adjustable foamed geopolymer concrete is made from the following raw materials in parts by weight:

[0054] The ingredients are: 60 parts fine tailings from the mine, 25 parts fly ash, 15 parts cement, 22 parts carrier foaming agent, 2.55 parts sodium silicate, 0.5 parts foam stabilizer, 0.6 parts setting regulator, and 50 parts water. The carrier foaming agent is obtained by soaking light sand in hydrogen peroxide.

[0055] The preparation method of the above-mentioned adjustable foamed geopolymer concrete includes the following steps:

[0056] S1, 60 parts of mine tailings were mechanically ground to a particle size of less than 20µm to obtain pretreated mine tailings A;

[0057] S2, a certain amount of light sand is placed in a certain amount of hydrogen peroxide and left to stand for 1 hour to obtain carrier foaming agent B;

[0058] S3, mix 22 parts of carrier foaming agent B, 60 parts of pretreated mine tailings A, 25 parts of fly ash, 15 parts of cement, 2.55 parts of sodium silicate, 0.5 parts of foam stabilizer calcium stearate and 0.6 parts of setting regulator evenly to obtain dry material C.

[0059] S4. Pour 50 parts of water at 45°C into dry material C and stir evenly. Allow it to stand and foam to obtain adjustable foamed polymer concrete. During the process of mixing and standing foaming, dry material C reacts with water to form a slurry. As the reaction continues, the water is gradually consumed and the relative humidity of the slurry decreases. The hydrogen peroxide in the light sand migrates into the slurry along the humidity gradient, adjusting the foaming rate of the slurry. Example 5

[0060] An adjustable foamed geopolymer concrete is made from the following raw materials in parts by weight:

[0061] The ingredients are: 60 parts fine tailings from the mine, 25 parts fly ash, 15 parts cement, 20.4 parts carrier foaming agent, 2.55 parts sodium silicate, 0.5 parts foam stabilizer, 0.6 parts setting regulator, and 50 parts water. The carrier foaming agent is obtained by soaking light sand in hydrogen peroxide.

[0062] The preparation method of the above-mentioned adjustable foamed geopolymer concrete includes the following steps:

[0063] S1, 60 parts of mine tailings were mechanically ground to a particle size of less than 20µm to obtain pretreated mine tailings A;

[0064] S2, a certain amount of light sand is placed in a certain amount of hydrogen peroxide and left to stand for 0.5 hours to obtain carrier foaming agent B;

[0065] S3, mix 20.4 parts of carrier foaming agent B, 60 parts of pretreated mine tailings A, 25 parts of fly ash, 15 parts of cement, 2.55 parts of sodium silicate, 0.5 parts of foam stabilizer calcium stearate and 0.6 parts of setting regulator evenly to obtain dry material C.

[0066] S4. Pour 50 parts of water at 35°C into dry material C and stir evenly. Allow it to stand and foam to obtain adjustable foamed polymer concrete. During the mixing and standing foaming process of dry material C and water, dry material C reacts with water to form a slurry. As the reaction continues, water is gradually consumed and the relative humidity of the slurry decreases. Hydrogen peroxide in the light sand migrates into the slurry along the humidity gradient, adjusting the foaming rate of the slurry.

[0067] The foam stabilizer in Comparative Example 1 of this invention is sodium dodecylbenzenesulfonate with a mass concentration of 90%, and the foam stabilizer in Comparative Example 2 and Comparative Example 3 is calcium stearate; the setting regulator in Comparative Example 3 of this invention is sodium carbonate, which is AR grade and has a sodium carbonate content of ≥99.5%, and the setting regulator in Comparative Example 1 and Comparative Example 2 is lithium carbonate.

[0068] Comparative Example 1

[0069] A foamed geopolymer concrete is made from the following raw materials in parts by weight:

[0070] 60 parts fine tailings from the mine, 25 parts fly ash, 15 parts cement, and 22 parts carrier foaming agent.

[0071] The ingredients are: 2.55 parts sodium silicate, 0.5 parts foam stabilizer, 0.6 parts setting agent, and 50 parts water. The carrier foaming agent is obtained by soaking light sand in hydrogen peroxide.

[0072] The preparation method of the above-mentioned foamed geopolymer concrete includes the following steps:

[0073] S1, 60 parts of mine tailings were mechanically ground to a particle size of less than 20µm to obtain pretreated mine tailings A;

[0074] S2, a certain amount of light sand is placed in a certain amount of hydrogen peroxide and left to stand for 1 hour to obtain carrier foaming agent B;

[0075] S3, mix 22 parts of carrier foaming agent B, 60 parts of pretreated mine tailings A, 25 parts of fly ash, 15 parts of cement, 2.55 parts of sodium silicate, 0.5 parts of foam stabilizer sodium dodecylbenzene sulfonate and 0.6 parts of setting regulator evenly to obtain dry material C.

[0076] S4. Pour 50 parts of water at 35°C into dry material C and stir evenly. Let it stand to foam to obtain foamed polymer concrete.

[0077] Comparative Example 2

[0078] A foamed geopolymer concrete is made from the following raw materials in parts by weight:

[0079] The ingredients are: 60 parts fine tailings from the mine, 40 parts fly ash, 22 parts carrier foaming agent, 3 parts sodium silicate, 0.5 parts foam stabilizer, 0.6 parts setting regulator, and 50 parts water. The carrier foaming agent is obtained by soaking light sand in hydrogen peroxide.

[0080] The preparation method of the above-mentioned foamed geopolymer concrete includes the following steps:

[0081] S1, 60 parts of mine tailings were mechanically ground to a particle size of less than 20µm to obtain pretreated mine tailings A;

[0082] S2, a certain amount of light sand is placed in a certain amount of hydrogen peroxide and left to stand for 1 hour to obtain carrier foaming agent B;

[0083] S3, mix 22 parts of carrier foaming agent B, 60 parts of pretreated mine tailings A, 40 parts of fly ash, 3 parts of sodium silicate, 0.5 parts of foam stabilizer calcium stearate and 0.6 parts of setting agent evenly to obtain dry material C.

[0084] S4. Pour 50 parts of water at 35°C into dry material C and stir evenly. Let it stand to foam to obtain foamed polymer concrete.

[0085] Comparative Example 3

[0086] A foamed geopolymer concrete is made from the following raw materials in parts by weight:

[0087] The ingredients are: 60 parts fine tailings from the mine, 25 parts fly ash, 15 parts cement, 22 parts carrier foaming agent, 2.55 parts sodium silicate, 0.5 parts foam stabilizer, 0.6 parts sodium carbonate setting regulator, and 50 parts water. The carrier foaming agent is obtained by soaking light sand in hydrogen peroxide.

[0088] The preparation method of the above-mentioned foamed geopolymer concrete includes the following steps:

[0089] S1, 60 parts of mine tailings were mechanically ground to a particle size of less than 20µm to obtain pretreated mine tailings A;

[0090] S2, a certain amount of light sand is placed in a certain amount of hydrogen peroxide and left to stand for 1 hour to obtain carrier foaming agent B;

[0091] S3, mix 22 parts of carrier foaming agent B, 60 parts of pretreated mine tailings A, 25 parts of fly ash, 15 parts of cement, 2.55 parts of sodium silicate, 0.5 parts of foam stabilizer calcium stearate and 0.6 parts of setting regulator sodium carbonate evenly to obtain dry material C.

[0092] S4. Pour 50 parts of water at 35°C into dry material C and stir evenly. Let it stand to foam to obtain foamed polymer concrete.

[0093] The dry density, compressive strength, water absorption and thermal conductivity of the foamed geopolymer concrete in Examples 1-5 and Comparative Examples 1-3 were tested, and the test results are shown in Table 1.

[0094] Table 1. Concrete performance test results

[0095]

[0096] According to Table 1, the overall performance of the foamed geopolymer concrete prepared in Examples 1-5 is significantly better than that in Comparative Examples 1-3. The performance difference between Examples 1 and 2 shows that the amount of lithium carbonate retarder affects the performance of foamed concrete. The less retarder added, the slower the concrete sets, the higher the foaming rate, and the lower the concrete density.

[0097] The performance differences between Example 1 and Example 3 show that the amount of calcium stearate, a foam stabilizer, affects the performance of foamed concrete. The higher the amount of foam stabilizer, the greater the volume expansion of the foamed concrete, the lower the density, and the higher the water absorption rate.

[0098] The performance differences between Examples 1 and 4 show that, within a certain range, the higher the temperature, the faster the cement hydration or the polymer polymerization. The exothermic reaction of hydration further accelerates the decomposition of hydrogen peroxide, but the rates of the two differ, which will affect the performance of concrete. Therefore, the overall performance of foamed concrete can be adjusted by controlling the temperature of the water.

[0099] The performance differences between Example 1 and Example 5 show that the shorter the soaking time, the lower the degree of foaming, the greater the density of the foamed concrete, and the higher the compressive strength.

[0100] The performance differences between Example 1 and Comparative Example 1 show that although the water absorption rate of the foamed concrete with sodium dodecylbenzenesulfonate was reduced by 12% compared to the foamed concrete with calcium stearate, its dry density increased by 38%. After adding sodium dodecylbenzenesulfonate, the foamed concrete began to generate large air bubbles, which expanded in volume. Subsequently, the bubbles burst, the concrete collapsed, the volume decreased, and the density increased. This demonstrates that calcium stearate has a better foam-stabilizing effect than sodium dodecylbenzenesulfonate, and the prepared concrete exhibits excellent waterproof performance.

[0101] The performance differences between Example 1 and Comparative Example 2 show that the addition of cement can shorten the setting time of concrete, enabling early setting of concrete and preventing foamed concrete from collapsing, thereby ensuring the overall performance of foamed concrete. In addition, the lithium carbonate setting regulator has no significant effect on the setting time of fly ash.

[0102] The performance differences between Example 1 and Comparative Example 3 show that sodium carbonate has a more significant effect on accelerating the setting of concrete compared with lithium carbonate. In this case, the concrete paste sets too quickly, the foaming resistance of hydrogen peroxide is too high, the volume expansion of concrete is not obvious, and the dry density is too high.

[0103] This invention enables the comprehensive utilization of waste materials such as mine tailings and fly ash. The prepared foamed geopolymer concrete has the advantages of being lightweight, high-strength, low-water-absorption, low-thermal-conductivity, and having adjustable foaming rate and overall concrete performance, thus showing good application prospects.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. An adjustable foamed geopolymer concrete, characterized in that, It is made from the following raw materials in parts by weight: 50-70 parts of fine tailings from mining, 10-30 parts of fly ash, 5-20 parts of cement, 18-30 parts of carrier foaming agent, 1.40-5.00 parts of sodium silicate, 0.3-0.6 parts of foam stabilizer, 0.3-0.8 parts of setting regulator, and 45-60 parts of water; the carrier foaming agent is obtained by soaking light sand in hydrogen peroxide, and the bulk density of the light sand is 140-160 kg / m³. 3 The particle size range is 0.1-0.5 mm, the mass concentration of the hydrogen peroxide is 25-45%, and the hydrogen peroxide accounts for 17%-30% of the mass of the carrier foaming agent. The bulk density of the mine tailings is 580-650 kg / m³. 3 The content of inactive SiO2 is 50-60%, Al2O3 is 15-20%, and CaO is 5-8%. The foam stabilizer is calcium stearate, which is AR grade, and the calcium content is 6.6-7.4%. The setting regulator is lithium carbonate, which is RG grade and has a content greater than 99%.

2. The adjustable foamed geopolymer concrete according to claim 1, characterized in that, The fly ash is Class F fly ash, grade I or II, wherein the SiO2 content is 40-50% and the Al2O3 content is 30-40%.

3. The adjustable foamed geopolymer concrete according to claim 1, characterized in that, The cement is silicate cement or ordinary silicate cement.

4. The adjustable foamed geopolymer concrete according to claim 1, characterized in that, The modulus of the sodium silicate is 1.90-2.

50.

5. A method for preparing adjustable foamed geopolymer concrete according to any one of claims 1-4, characterized in that, The method specifically includes the following steps: S1, Grind the fine tailings from the mine to obtain pretreated fine tailings A; S2, Prepare carrier foaming agent B by placing light sand in hydrogen peroxide and letting it stand for 0.5-1.5 hours to obtain carrier foaming agent B; S3, mix the carrier foaming agent B, pretreated mine tailings A, fly ash, cement, sodium silicate, foam stabilizer and setting regulator evenly to obtain dry material C; S4. Pour water into dry material C and stir evenly. Allow it to stand and foam to obtain adjustable foamed geopolymer concrete. During the process of mixing and standing foaming, dry material C reacts with water to form a slurry. As the reaction continues, water is gradually consumed and the relative humidity of the slurry decreases. Hydrogen peroxide in the light sand migrates into the slurry along the humidity gradient, adjusting the foaming rate of the slurry.

6. The method for preparing adjustable foamed geopolymer concrete according to claim 5, characterized in that, In step S1, the fine tailings from the mine are mechanically ground, and the particle size of the mechanically ground fine tailings is less than 20 μm.

7. The method for preparing adjustable foamed geopolymer concrete according to claim 5, characterized in that, The temperature range of the water poured into the dry material C in step S4 is 30-50℃.

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