Early-strength composite foam concrete foaming agent and preparation method thereof

Abstract

The application discloses an early-strength composite foam concrete foaming agent and a preparation method thereof, and belongs to the technical field of concrete foaming agents.The concrete foaming agent is composed of 20-40 parts of a composite foaming agent, 10-15 parts of an early-strength agent, 5-10 parts of an activator, 0.5-1 part of an organic coagulant, 1-3 parts of a dispersing agent and 70-90 parts of deionized water.The modified plant protein is prepared by taking peanut shells (agricultural waste) and peanut meal (by-product) as raw materials, and is compounded with other raw materials to form the composite foaming agent, the dependence on the surfactant type foaming agent is reduced, the foaming multiple is high, and the stability is good;the 1-day and 28-day strengths of the foam concrete are significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of concrete foaming agent technology, specifically an early-strength composite foamed concrete foaming agent and its preparation method. Background Technology

[0002] Foamed concrete is a lightweight concrete produced through physical and mechanical foaming. A foaming agent is added to cement slurry or cement mortar, and after uniform mixing, it is poured into various sizes and cured to form a lightweight concrete with numerous closed pores. It is characterized by its light weight, good thermal insulation, sound insulation, fire resistance, seismic performance, and environmental friendliness, and is currently widely used. The foaming agent is a key component of foamed concrete, playing a decisive role in its performance. Based on their foaming principle, foaming agents are mainly divided into chemical foaming agents and physical foaming agents. Physical foaming agents are those that produce foam by introducing air into the solution through high-speed stirring or compressed air. Compared to chemical foaming agents, the process of preparing foamed concrete using physical foaming agents involves pre-preparing the foam, then mixing it with concrete slurry, lightweight aggregates, admixtures, and other materials, and finally pouring it into molds for curing to create a foamed concrete sample. Physical foaming agents are characterized by long foam life, generally smaller than 1 mm in diameter, and relatively uniform foam size. Furthermore, the foam is less prone to rupture in concrete slurry, preventing the formation of large air pockets or interconnected pores. Due to their low cost and simple preparation process, physical foaming agents dominate research in this field. Currently, commonly used physical foaming agents are mainly classified into rosin resin-based foaming agents, surfactant-based foaming agents, protein-based foaming agents, and composite foaming agents.

[0003] However, in practical applications, existing physical foaming agents still have many limitations. While rosin resin-based foaming agents have a wide range of raw material sources and low cost, their expansion ratio and foam stability are relatively insufficient, making it difficult to meet the engineering requirements for high foam performance. Surfactant-based foaming agents have strong foaming capabilities, but the uniformity and stability of the foam are greatly affected by environmental factors, with significant performance fluctuations under different temperature and humidity conditions. Protein-based foaming agents have good foam stability, but the raw materials are relatively difficult to obtain, costly, and susceptible to microbial attack, leading to performance degradation. Composite foaming agents, while combining the advantages of various foaming agents to some extent, still need improvement in early strength performance.

[0004] The early strength of foamed concrete is crucial for construction progress and project quality. In many practical projects, such as emergency repairs and construction projects, and winter construction projects, foamed concrete is required to reach a certain strength within a short period of time to facilitate subsequent processes or withstand certain loads. However, the early strength development of foamed concrete prepared with existing physical foaming agents is slow, making it difficult to meet the needs of these special projects. This leads to extended construction cycles, increased costs, and even affects the safety and durability of the engineering structure. Therefore, developing an early-strength composite foamed concrete foaming agent to improve the early strength of foamed concrete while maintaining good foaming performance and stability has become a key problem urgently needing to be solved in the field of foamed concrete technology. Summary of the Invention

[0005] The purpose of this invention is to provide an early-strength composite foamed concrete foaming agent, which has a high foaming ratio and good foam stability, and can significantly improve the early strength of foamed concrete.

[0006] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0007] An early-strength composite foamed concrete foaming agent is made from the following raw materials in parts by weight: 20-40 parts composite foaming agent, 10-15 parts early-strength agent, 5-10 parts activator, 0.5-1 parts organic accelerator, 1-3 parts dispersant, and 70-90 parts deionized water; the early-strength agent is a mixture of modified nano-alumina and modified ultrafine silica fume in a mass ratio of 3:1; the composite foaming agent is composed of sodium dodecyl sulfate, modified plant protein, and guar gum in a mass ratio of 1:(2-3):(0.1-0.3); and the activator is composed of metakaolin and nano-silica in a mass ratio of 5:1.

[0008] Preferably, the modified plant protein is prepared by the following method:

[0009] (1) After drying the peanut shells, crush them and pass them through a 60-mesh sieve to obtain peanut shell powder;

[0010] (2) Mix peanut shell powder with ethanol at a ratio of 1:20 g / mL, sonicate for 20-40 min, stir at 50-70℃ for 2-4 h, remove solvent by rotary evaporation after completion, and dry the product to obtain peanut shell extract.

[0011] (3) The peanut meal is dried and crushed to 80 mesh, soaked in sodium bicarbonate solution according to the solid-liquid ratio, and magnetically stirred at 50°C for 30-40 minutes. The wet meal is then filtered.

[0012] (4) Add wet meal, water, peanut shell extract and ferric chloride to the reaction vessel in proportion, stir magnetically at 40°C and aerate with air for 3-3.5 hours. After the reaction is completed, adjust the pH of the mixture to 7.0 and freeze dry to obtain modified plant protein.

[0013] Preferably, the ethanol concentration in step (2) is 60-65%.

[0014] Preferably, in step (3), the solid-liquid ratio is 1g:10ml, and the mass fraction of the sodium bicarbonate solution is 0.1%.

[0015] Preferably, in step (4), the mass ratio of wet meal to water is 1:5, the amount of peanut shell extract is 0.05-0.1% of the mass of wet meal, and the mass of ferric chloride is 0.2-0.3% of the mass of wet meal.

[0016] Preferably, the modified nano-alumina and modified ultrafine silica fume are both obtained by modification treatment with silane coupling agent KH550.

[0017] Preferably, the ultrafine silica fume has a specific surface area ≥15 m² / g, the nano-alumina particle size is 80-100 nm, and the nano-silica particle size is 10-20 nm.

[0018] Preferably, the organic coagulant is one of triethanolamine, sodium glycine, or disodium ethylenediaminetetraacetate.

[0019] Preferably, the dispersant is a polycarboxylic acid-based dispersant.

[0020] The present invention also provides a method for preparing the above-mentioned early-strength composite foamed concrete foaming agent, which includes the following steps:

[0021] Step 1: Prepare modified plant protein and mix it evenly with sodium dodecyl sulfate and guar gum in a certain proportion to obtain a composite foaming agent;

[0022] Step 2: Take nano-alumina and ultrafine silica fume separately, disperse them in anhydrous ethanol at a solid-liquid ratio of 1:20, add 3wt% silane coupling agent KH550, reflux and stir at 70℃ for 2h, centrifuge and wash, and dry at 80℃ to obtain modified nano-alumina and modified ultrafine silica fume. Mix the two according to the mass ratio to obtain an early strength agent for later use.

[0023] Step 3: Heat the deionized water to 40°C and add the dispersant and organic coagulant in proportion, then magnetically stir to mix evenly.

[0024] Step 4: Add activator to the above mixture, stir at 600 rpm for 10 min, then add early strength agent and disperse at 1200 rpm for 20 min, finally add composite foaming agent and stir at 800 rpm for 15-20 min, transfer to high pressure homogenizer and homogenize 3 times under 35 MPa pressure, let stand for 24 h to obtain early strength composite foam concrete foaming agent.

[0025] The composite foaming agent of this invention is prepared by compounding modified plant protein with surfactants sodium dodecyl sulfate and guar gum in a suitable ratio. The modified plant protein utilizes the tannin hydroxyl groups abundant in peanut shell extract (an agricultural waste), which undergo a valence-donating cross-linking reaction with peanut meal protein under the catalytic oxidation of ferric chloride to obtain the modified protein product, forming a cross-linked network; simultaneously, Fe... 3+ By forming coordination bonds with protein carboxyl groups / polyphenol hydroxyl groups, and constructing a dual network structure through tannin oxidative crosslinking and metal coordination, the foam toughness and stability of protein products can be effectively enhanced. The above-mentioned modified plant protein and sodium dodecyl sulfate work synergistically to achieve good foaming effect. Guar gum acts as a thickener to increase foam viscosity and slow down drainage rate. The foaming agent obtained by combining the three in the optimal ratio improves foaming ratio and stability.

[0026] The early strength agent of this invention is a compound of nano-alumina modified with silane coupling agent and ultrafine silica fume. After silane modification, its dispersibility in foaming aqueous solution and compatibility with organic components are improved, agglomeration is prevented, and the interfacial bonding with cement particles is enhanced. The ultrafine silica fume provides SiO2 with ultra-high specific surface area, which reacts with Ca(OH)2 in the early stage of cement hydration to form CSH gel (secondary hydration). The nano-alumina provides a large number of nucleation sites, which significantly accelerates the initial hydration reaction of minerals such as C3S and C3A, and promotes the rapid formation of early strength skeletons such as CSH and ettringite (AFt). The two work synergistically to build an early strength network before the cement paste is fully hydrated.

[0027] The metakaolin in the activator has high pozzolanic activity. Its layered structure dissociates and releases Al and Si in an alkaline environment, further participating in the early hydration reaction to generate more CASH and other gels, filling pores, refining the pore structure, improving density and early strength, and helping to reduce later shrinkage. Meanwhile, nano-SiO2 provides an instantaneous silicon source to compensate for lag. Through the particle size design of "nano-to-micro" and the chemical reaction of "aluminum and silicon synergistic", the activator achieves dual optimization of porosity and pore size distribution, which greatly reduces the drying shrinkage rate of concrete.

[0028] Organic accelerators not only serve the traditional function of accelerators, but also promote the adsorption of nanoparticles on the surface of cement particles and optimize the overlap of hydration products between particles.

[0029] Compared with existing technologies, the beneficial effects of this invention are as follows: Modified plant protein prepared from peanut shells (agricultural waste) and peanut meal (byproduct) is compounded with other raw materials to form a composite foaming agent, reducing dependence on surfactant-type foaming agents, and exhibiting high foaming ratio and good stability; significantly improving the early (1-day) strength and 28-day strength of foamed concrete; constructing a multi-scale early strength system with early strength agents and activators, and compounding nano-alumina (nanoscale) and ultrafine silica fume (micronscale) to achieve gradient filling from nano to micron, with nanoparticles and active minerals filling and refining pores, improving density, which not only benefits early strength but also significantly improves long-term strength, impermeability and durability; this invention utilizes metakaolin (bauxite tailings), peanut shells, and peanut meal to achieve a circular economy model of "treating waste with waste". Detailed Implementation

[0030] The technical solution of the present invention will be further described below with reference to specific embodiments, but it is not limited thereto.

[0031] Example 1

[0032] An early-strength composite foamed concrete foaming agent is made from the following raw materials in parts by weight: 20 parts composite foaming agent, 10 parts early-strength agent, 5 parts activator, 0.5 parts organic accelerator, 1 part dispersant, and 70 parts deionized water; the early-strength agent is a mixture of modified nano-alumina and modified ultrafine silica fume in a mass ratio of 3:1; the composite foaming agent is composed of sodium dodecyl sulfate, modified plant protein, and guar gum in a mass ratio of 1:2:0.1; and the activator is composed of metakaolin and nano-silica in a mass ratio of 5:1.

[0033] The modified plant protein was prepared using the following method:

[0034] (1) After drying the peanut shells, crush them and pass them through a 60-mesh sieve to obtain peanut shell powder;

[0035] (2) Mix peanut shell powder with 60% ethanol at a ratio of 1:20 g / mL, sonicate for 20 min, stir at 50℃ for 2 h, remove solvent by rotary evaporation after completion, and dry the product to obtain peanut shell extract.

[0036] (3) The peanut meal is dried and crushed to 80 mesh, soaked in 0.1% sodium bicarbonate solution at a solid-liquid ratio of 1g:10ml, and magnetically stirred at 50℃ for 30min. The wet meal is then filtered.

[0037] (4) Add wet meal, water, peanut shell extract and ferric chloride to the reaction vessel in proportion, stir magnetically at 40°C and aerate with air for 3-3.5h. After the reaction is completed, adjust the pH of the mixture to 7.0 and freeze dry to obtain modified plant protein. The mass ratio of wet meal to water is 1:5, the amount of peanut shell extract is 0.05% of the mass of wet meal, and the mass of ferric chloride is 0.2% of the mass of wet meal.

[0038] The modified nano-alumina and modified ultrafine silica fume were both obtained by modification treatment with silane coupling agent KH550.

[0039] The ultrafine silica fume has a specific surface area ≥15 m² / g, the nano-alumina has a particle size of 80 nm, and the nano-silica has a particle size of 10 nm.

[0040] The organic coagulant is triethanolamine. The dispersant is a polycarboxylic acid dispersant.

[0041] A method for preparing the above-mentioned early-strength composite foamed concrete foaming agent includes the following steps:

[0042] Step 1: Prepare modified plant protein and mix it evenly with sodium dodecyl sulfate and guar gum in a certain proportion to obtain a composite foaming agent;

[0043] Step 2: Take nano-alumina and ultrafine silica fume separately, disperse them in anhydrous ethanol at a solid-liquid ratio of 1:20, add 3wt% silane coupling agent KH550, reflux and stir at 70℃ for 2h, centrifuge and wash, and dry at 80℃ to obtain modified nano-alumina and modified ultrafine silica fume. Mix the two according to the mass ratio to obtain an early strength agent for later use.

[0044] Step 3: Heat the deionized water to 40°C and add the dispersant and organic coagulant in proportion, then magnetically stir to mix evenly.

[0045] Step 4: Add activator to the above mixture, stir at 600 rpm for 10 min, then add early strength agent and disperse at 1200 rpm for 20 min, finally add composite foaming agent and stir at 800 rpm for 15-20 min, transfer to high pressure homogenizer and homogenize 3 times under 35 MPa pressure, let stand for 24 h to obtain early strength composite foam concrete foaming agent.

[0046] Example 2

[0047] An early-strength composite foamed concrete foaming agent is made from the following raw materials in parts by weight: 40 parts composite foaming agent, 15 parts early-strength agent, 10 parts activator, 1 part organic accelerator, 3 parts dispersant, and 90 parts deionized water; the early-strength agent is a mixture of modified nano-alumina and modified ultrafine silica fume in a mass ratio of 3:1; the composite foaming agent is composed of sodium dodecyl sulfate, modified plant protein, and guar gum in a mass ratio of 1:3:0.3; and the activator is composed of metakaolin and nano-silica in a mass ratio of 5:1.

[0048] The modified plant protein was prepared using the following method:

[0049] (1) After drying the peanut shells, crush them and pass them through a 60-mesh sieve to obtain peanut shell powder;

[0050] (2) Mix peanut shell powder with 65% ethanol at a ratio of 1:20 g / mL, sonicate for 40 min, stir at 70℃ for 4 h, remove solvent by rotary evaporation after completion, and dry the product to obtain peanut shell extract.

[0051] (3) The peanut meal is dried and crushed to 80 mesh, soaked in 0.1% sodium bicarbonate solution at a solid-liquid ratio of 1g:10ml, and magnetically stirred at 50℃ for 40min. The wet meal is then filtered.

[0052] (4) Add wet meal, water, peanut shell extract and ferric chloride to the reaction vessel in proportion, stir magnetically at 40°C and aerate with air for 3-3.5h. After the reaction is completed, adjust the pH of the mixture to 7.0 and freeze dry to obtain modified plant protein. The mass ratio of wet meal to water is 1:5, the amount of peanut shell extract is 0.1% of the mass of wet meal, and the mass of ferric chloride is 0.3% of the mass of wet meal.

[0053] The modified nano-alumina and modified ultrafine silica fume were both obtained by modification treatment with silane coupling agent KH550.

[0054] The ultrafine silica fume has a specific surface area ≥15 m² / g, the nano-alumina has a particle size of 100 nm, and the nano-silica has a particle size of 20 nm.

[0055] The organic coagulant is sodium glycine; the dispersant is a polycarboxylic acid dispersant.

[0056] A method for preparing the above-mentioned early-strength composite foamed concrete foaming agent includes the following steps:

[0057] Step 1: Prepare modified plant protein and mix it evenly with sodium dodecyl sulfate and guar gum in a certain proportion to obtain a composite foaming agent;

[0058] Step 2: Take nano-alumina and ultrafine silica fume separately, disperse them in anhydrous ethanol at a solid-liquid ratio of 1:20, add 3wt% silane coupling agent KH550, reflux and stir at 70℃ for 2h, centrifuge and wash, and dry at 80℃ to obtain modified nano-alumina and modified ultrafine silica fume. Mix the two according to the mass ratio to obtain an early strength agent for later use.

[0059] Step 3: Heat the deionized water to 40°C and add the dispersant and organic coagulant in proportion, then magnetically stir to mix evenly.

[0060] Step 4: Add activator to the above mixture, stir at 600 rpm for 10 min, then add early strength agent and disperse at 1200 rpm for 20 min, finally add composite foaming agent and stir at 800 rpm for 15-20 min, transfer to high pressure homogenizer and homogenize 3 times under 35 MPa pressure, let stand for 24 h to obtain early strength composite foam concrete foaming agent.

[0061] Example 3

[0062] An early-strength composite foamed concrete foaming agent is made from the following raw materials in parts by weight: 30 parts composite foaming agent, 12 parts early-strength agent, 8 parts activator, 0.8 parts organic accelerator, 2 parts dispersant, and 80 parts deionized water; the early-strength agent is a mixture of modified nano-alumina and modified ultrafine silica fume in a mass ratio of 3:1; the composite foaming agent is composed of sodium dodecyl sulfate, modified plant protein, and guar gum in a mass ratio of 1:2.5:0.2; and the activator is composed of metakaolin and nano-silica in a mass ratio of 5:1.

[0063] The modified plant protein was prepared using the following method:

[0064] (1) After drying the peanut shells, crush them and pass them through a 60-mesh sieve to obtain peanut shell powder;

[0065] (2) Mix peanut shell powder with 65% ethanol at a ratio of 1:20 g / mL, sonicate for 40 min, stir at 60℃ for 3 h, remove solvent by rotary evaporation after completion, and dry the product to obtain peanut shell extract.

[0066] (3) The peanut meal is dried and crushed to 80 mesh, soaked in 0.1% sodium bicarbonate solution at a solid-liquid ratio of 1g:10ml, and magnetically stirred at 50℃ for 40min. The wet meal is then filtered.

[0067] (4) Add wet meal, water, peanut shell extract and ferric chloride to the reaction vessel in proportion, stir magnetically at 40°C and aerate with air for 3-3.5h. After the reaction is completed, adjust the pH of the mixture to 7.0 and freeze dry to obtain modified plant protein. The mass ratio of wet meal to water is 1:5, the amount of peanut shell extract is 0.08% of the mass of wet meal, and the mass of ferric chloride is 0.25% of the mass of wet meal.

[0068] The modified nano-alumina and modified ultrafine silica fume were both obtained by modification treatment with silane coupling agent KH550.

[0069] The ultrafine silica fume has a specific surface area ≥15 m² / g, the nano-alumina has a particle size of 90 nm, and the nano-silica has a particle size of 20 nm.

[0070] The organic coagulant is disodium ethylenediaminetetraacetate. The dispersant is a polycarboxylate-based dispersant.

[0071] A method for preparing the above-mentioned early-strength composite foamed concrete foaming agent includes the following steps:

[0072] Step 1: Prepare modified plant protein and mix it evenly with sodium dodecyl sulfate and guar gum in a certain proportion to obtain a composite foaming agent;

[0073] Step 2: Take nano-alumina and ultrafine silica fume separately, disperse them in anhydrous ethanol at a solid-liquid ratio of 1:20, add 3wt% silane coupling agent KH550, reflux and stir at 70℃ for 2h, centrifuge and wash, and dry at 80℃ to obtain modified nano-alumina and modified ultrafine silica fume. Mix the two according to the mass ratio to obtain an early strength agent for later use.

[0074] Step 3: Heat the deionized water to 40°C and add the dispersant and organic coagulant in proportion, then magnetically stir to mix evenly.

[0075] Step 4: Add activator to the above mixture, stir at 600 rpm for 10 min, then add early strength agent and disperse at 1200 rpm for 20 min, finally add composite foaming agent and stir at 800 rpm for 15-20 min, transfer to high pressure homogenizer and homogenize 3 times under 35 MPa pressure, let stand for 24 h to obtain early strength composite foam concrete foaming agent.

[0076] Comparative Example 1

[0077] An early-strength composite foamed concrete foaming agent, whose raw material composition and preparation method are basically the same as those in Example 1, except that peanut meal is used instead of modified plant protein.

[0078] Comparative Example 2

[0079] An early-strength composite foamed concrete foaming agent, whose raw material composition and preparation method are the same as those in Example 1, except that the composite foaming agent is composed of sodium dodecyl sulfate, modified plant protein and guar gum in a mass ratio of 1:1:0.1.

[0080] Comparative Example 3

[0081] An early-strength composite foamed concrete foaming agent, whose raw material composition and preparation method are the same as in Example 1, except that the composite foaming agent is composed of sodium dodecyl sulfate, modified plant protein and guar gum in a mass ratio of 1:1:0.5.

[0082] Comparative Example 4

[0083] An early-strength composite foamed concrete foaming agent, whose raw material composition and preparation method are the same as those in Example 1, except that the activator is composed of metakaolin and nano-silica in a mass ratio of 4:1.

[0084] Comparative Example 5

[0085] An early-strength composite foamed concrete foaming agent, whose raw material composition and preparation method are the same as those in Example 1, except that the activator is composed of metakaolin and nano-silica in a mass ratio of 6:1.

[0086] Performance testing

[0087] Foamed concrete (cement:water:foaming agent = 1:0.5:0.02) was prepared using the foaming agents obtained in Examples 1-3 and Comparative Examples 1-5 according to the same process. The foaming ratio, bleeding volume and settlement distance of the foaming agent were determined according to the test methods and requirements in standard JG / T266-2011 "Foamed Concrete". The test results are shown in Table 1 below.

[0088] Table 1 Test Results

[0089]

[0090] As can be seen from the results in Table 1 above, the foaming agents prepared in Examples 1-3 of this invention have high foaming ratios, good foam stability, and significantly improve the early strength of foamed concrete, with effects significantly superior to Comparative Examples 1-5. Settlement distance and bleeding volume are important indicators for measuring foam stability. The settlement distances of Examples 1-3 are all relatively small, and the bleeding volumes are also relatively low, showing good foam stability. In contrast, the settlement distances and bleeding volumes of Comparative Examples 1-5 are generally higher, especially Comparative Example 1, whose settlement distance reaches 18.5 mm and bleeding volume is as high as 85 ml, indicating poor foam stability. This is because the dual network (crosslinking + coordination bonds) of the modified plant protein used in this invention significantly enhances foam toughness; the thickening effect of guar gum inhibits foam breakage; and the synergistic effect of each component optimizes the foaming effect. The foaming agent formulation of this invention can effectively maintain foam stability and reduce foam breakage and liquid precipitation. The 1-day and 28-day compressive strengths of Examples 1-3 were also significantly higher than those of Comparative Examples 1-5. This is due to the synergistic effect of the optimally proportioned accelerator and activator, which optimized the structure and density of the cement hydration products. Changing the composition and proportion of raw materials weakened the corresponding effect.

[0091] The early-strength composite foamed concrete foaming agent of this invention significantly improves the foaming ratio and foam stability by optimizing the formulation of the composite foaming agent, early-strength agent, and activator, while also greatly enhancing the early and long-term strength of foamed concrete. These advantages make the foaming agent of this invention widely applicable in the field of foamed concrete, especially suitable for emergency repair and construction projects and winter construction projects with high requirements for construction progress and engineering quality.

[0092] It should be noted that the above embodiments are merely some preferred embodiments of the present invention, and not all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

Claims

1. A foaming agent for early-strength composite foamed concrete, characterized in that, It is made from the following raw materials in parts by weight: 20-40 parts of composite foaming agent, 10-15 parts of early strength agent, 5-10 parts of activator, 0.5-1 parts of organic coagulant, 1-3 parts of dispersant, and 70-90 parts of deionized water; the early strength agent is a mixture of modified nano-alumina and modified ultrafine silica fume in a mass ratio of 3:1; the composite foaming agent is composed of sodium dodecyl sulfate, modified plant protein, and guar gum in a mass ratio of 1:(2-3):(0.1-0.3); the activator is composed of metakaolin and nano-silica in a mass ratio of 5:

1. The modified plant protein was prepared using the following method: (1) After drying the peanut shells, crush them and pass them through a 60-mesh sieve to obtain peanut shell powder; (2) Mix peanut shell powder with ethanol at a ratio of 1:20 g / mL, sonicate for 20-40 min, stir at 50-70℃ for 2-4 h, remove solvent by rotary evaporation after completion, and dry the product to obtain peanut shell extract. (3) The peanut meal is dried and crushed to 80 mesh, soaked in sodium bicarbonate solution according to the solid-liquid ratio, and magnetically stirred at 50°C for 30-40 minutes. The wet meal is then filtered. (4) Add wet meal, water, peanut shell extract and ferric chloride to the reaction vessel in proportion, stir magnetically at 40°C and aerate with air for 3-3.5 hours. After the reaction is completed, adjust the pH of the mixture to 7.0 and freeze dry to obtain modified plant protein.

2. The early-strength composite foamed concrete foaming agent according to claim 1, characterized in that, In step (2), the ethanol concentration is 60-65%.

3. The early-strength composite foamed concrete foaming agent according to claim 1, characterized in that, In step (3), the solid-liquid ratio is 1g:10ml, and the mass fraction of the sodium bicarbonate solution is 0.1%.

4. The early-strength composite foamed concrete foaming agent according to claim 1, characterized in that, In step (4), the mass ratio of wet meal to water is 1:5, the amount of peanut shell extract is 0.05-0.1% of the mass of wet meal, and the mass of ferric chloride is 0.2-0.3% of the mass of wet meal.

5. The early-strength composite foamed concrete foaming agent according to claim 1, characterized in that, The modified nano-alumina and modified ultrafine silica fume were both obtained by modification treatment with silane coupling agent KH550.

6. The early-strength composite foamed concrete foaming agent according to claim 1, characterized in that, The ultrafine silica fume has a specific surface area ≥15 m² / g, the nano-alumina has a particle size of 80-100 nm, and the nano-silica has a particle size of 10-20 nm.

7. The early-strength composite foamed concrete foaming agent according to claim 1, characterized in that, The organic coagulant is one of triethanolamine, sodium glycine, or disodium ethylenediaminetetraacetate.

8. The early-strength composite foamed concrete foaming agent according to claim 1, characterized in that, The dispersant is a polycarboxylic acid-based dispersant.

9. A method for preparing an early-strength composite foamed concrete foaming agent according to any one of claims 1-8, characterized in that, It includes the following steps: Step 1: Prepare modified plant protein and mix it evenly with sodium dodecyl sulfate and guar gum in a certain proportion to obtain a composite foaming agent; Step 2: Take nano-alumina and ultrafine silica fume separately, disperse them in anhydrous ethanol at a solid-liquid ratio of 1:20, add 3wt% silane coupling agent KH550, reflux and stir at 70℃ for 2h, centrifuge and wash, and dry at 80℃ to obtain modified nano-alumina and modified ultrafine silica fume. Mix the two according to the mass ratio to obtain an early strength agent for later use. Step 3: Heat deionized water to 40°C and add dispersant and organic coagulant in proportion, then magnetically stir and mix until homogeneous to obtain a mixture; Step 4: Add activator to the above mixture, stir at 600 rpm for 10 min, then add early strength agent and disperse at 1200 rpm for 20 min, finally add composite foaming agent and stir at 800 rpm for 15-20 min, transfer to high pressure homogenizer and homogenize 3 times under 35 MPa pressure, let stand for 24 h to obtain early strength composite foam concrete foaming agent.

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