Lightweight thermal insulation concrete as well as preparation method and application thereof

Abstract

The invention discloses lightweight thermal insulation concrete as well as a preparation method and application thereof, and belongs to the technical field of lightweight concrete materials. The concrete is prepared from 190 to 210 parts of cement, 1000 to 1100 parts of thermal-insulation lightweight aggregate, 100 to 120 parts of fly ash, 20 to 40 parts of silica fume, 3 to 5 parts of a water reducing agent, 3 to 5 parts of a composite microbubble foaming agent, 2 to 4 parts of a foam stabilizer and 90 to 105 parts of water. The light filler expanded perlite, the hollow glass beads and the kaolin are used, so that the thermal insulation and fireproof performance of the concrete is improved; according to the present invention, the protein foaming agent is prepared, and the foam stabilizer is used, such that the formed foam structure is uniform and stable, the obtained concrete material has characteristics of low dry density, low heat conductivity coefficient, high sound absorption coefficient, good thermal insulation, good sound insulation and good flame retardation effect, is suitable for use in various complex environments, and avoids the use of various fibers and organic fillers; therefore, the method is suitable for practical application and popularization.

Description

Technical Field

[0001] The invention belongs to the technical field of lightweight concrete materials, and specifically relates to lightweight thermal insulation concrete and a preparation method and application thereof. Background Art

[0002] In our daily life, we call materials with low thermal conductivity as thermal insulation materials. The thermal insulation materials used in construction projects are called thermal insulation building materials. There are many types of thermal insulation materials in the construction industry. According to the types of raw materials, they can be divided into inorganic thermal insulation materials, organic thermal insulation materials and composite thermal insulation materials. According to the form of materials, some are loose, some can have an overall shape, some are plate-like, and some are coiled. The thermal insulation building materials commonly used in life now include foam concrete, polyurethane thermal insulation materials, extruded boards, expanded perlite, etc.

[0003] Foamed concrete, also known as foamed concrete or lightweight concrete, is a new type of lightweight thermal insulation material containing a large number of closed pores formed by using the foaming system of a foaming machine to fully foam the foaming agent mechanically, and evenly mix the foam with cement slurry, and then pass through the pumping system of the foaming machine for cast-in-place construction or mold forming, and then naturally curing. However, due to the large number of pores in foamed concrete, the strength of foamed concrete decreases due to the decrease in density, making it difficult to apply to structures with high requirements for pressure bearing capacity, which limits the application of foamed concrete.

[0004] In order to improve the strength of foam concrete, fibers are usually added for reinforcement.

[0005] For example, Chinese patent application CN202111555088.X discloses a pumpable lightweight thermal insulation concrete and a preparation method thereof, wherein the concrete comprises the following raw materials in parts by weight: 40-60 parts of cement, 15-25 parts of fly ash, 8-10 parts of mineral powder, 1-5 parts of gelling agent, 20-35 parts of modified polystyrene foam particles, and 20-40 parts of coarse aggregate, wherein the modified polystyrene foam particles are made of polystyrene foam particles, and the surface of the polystyrene foam particles are coated with mixed powder and reinforcing fibers in sequence, wherein the mixed powder is heavy calcium carbonate and flame retardant, and the weight ratio of heavy calcium carbonate to flame retardant is 1:(0.8-1.2).

[0006] For example, Chinese patent application CN201910586214.4 discloses a lightweight thermal insulation concrete and a preparation method thereof, wherein the lightweight thermal insulation concrete is made of the following raw material components in mass percentage: 33-71% cementitious material, 7-37% expanded pearls, 0-30% sand, 6-38% vitrified microspheres, 0-1.5% hemp fiber, 2-13% ultrafine mineral powder and 19-27.4% water. The invention also discloses a preparation method for the above-mentioned lightweight thermal insulation concrete, which uses perlite as coarse aggregate, vitrified microspheres and sand as fine aggregate, and optimizes the concrete's compression, tension, bending and impact resistance by adding natural hemp fiber.

[0007] However, the addition of fibers is usually repelled by the surface tension of the foam, so that the fibers usually stick to the foam surface and are difficult to pass through the foam. Moreover, when a small amount of fibers pass through the foam, the foam will rupture. Therefore, fiber reinforcement can usually only reinforce the concrete body, and it is difficult to reinforce the concrete pores, resulting in a general reinforcement effect and a small increase in strength. In addition, the current lightweight foam insulation concrete has a single performance and cannot take into account all aspects. It is difficult to be effectively used in complex environments. Therefore, the development of lightweight thermal insulation concrete with fire prevention, impermeability, sound insulation and other functions to meet the multi-functional needs of modern buildings is a technical problem that needs to be solved urgently. Summary of the invention

[0008] The present invention aims at solving the problems existing in the prior art. By preparing a composite protein foaming agent and combining it with a foam stabilizer for efficient stabilization, the obtained concrete has a uniform pore structure, stable mechanical properties, and effectively improved comprehensive properties.

[0009] In order to achieve the above technical objectives, the technical solution adopted by the present invention is: A lightweight thermal insulation concrete comprises the following raw materials in parts by weight: 190-210 parts of cement, 1000-1100 parts of thermal insulation lightweight aggregate, 100-120 parts of fly ash, 20-40 parts of silica fume, 3-5 parts of water reducer, 3-5 parts of composite micro-foaming agent, 2-4 parts of foam stabilizer and 90-105 parts of water.

[0010] Furthermore, the cement is selected from one or a combination of two or more of silicate cement, sulphoaluminate cement and ferroaluminate cement.

[0011] Furthermore, the thermal insulation lightweight aggregate includes expanded perlite, hollow glass microspheres and kaolin, and the mass ratio of the three is 1:1:0.3.

[0012] Furthermore, the expanded perlite adopts expanded perlite particles with a particle size of 2-4 mm; the hollow glass microspheres adopt hollow glass microsphere particles with a particle size of 60-80 μm.

[0013] Furthermore, the water reducer is a polycarboxylate water reducer.

[0014] Furthermore, the preparation method of the composite microfoam foaming agent is: (1) After mixing ox horn powder and soybean powder in a mass ratio of 1:5, water and sodium hydroxide are added in a solid-liquid ratio of 100 g:150 mL, and the mixture is hydrolyzed at 50-60° C. for 6-8 hours, and filtered to obtain a composite foaming agent mother liquor; (2) Acetylation treatment: add 1-3% by weight of acetic anhydride to the composite foaming agent mother liquor of step (1), maintain the pH at 7.5-8.5 at a temperature not exceeding 35°C, and react with magnetic stirring for 1-2 hours. After the pH of the solution stabilizes at 8.0, continue the reaction for another hour to complete the acylation reaction. Then, adjust the pH to 7.0 with 1 mol / L HCl solution to terminate the acylation reaction, and obtain a composite microbubble foaming agent.

[0015] Furthermore, the amount of sodium hydroxide added in step (1) is 1-3% of the mass of the horn powder and soybean powder.

[0016] Furthermore, the foam stabilizer is obtained by mixing gelatin, nano zinc oxide and hydroxyethyl cellulose in a mass ratio of 1:1:1.

[0017] A method for preparing lightweight thermal insulation concrete comprises the following steps: (1) preparing a composite microfoam blowing agent; (2) Weighing all components except the composite microfoaming agent according to the concrete formula, stirring evenly, and preparing cement paste; (3) diluting the foaming agent by 25 times and pouring it into a foaming machine to prepare foam, adding the foam into the uniformly stirred cement slurry, and stirring until there is no floating foam to obtain a concrete mixture; (4) The concrete mixture is injected into a mold, cured, and demolded to obtain lightweight thermal insulation concrete.

[0018] The lightweight thermal insulation concrete of the present invention is mainly used in thermal insulation of building exterior walls, and has the effects of thermal insulation, heat insulation and fire prevention.

[0019] In the prior art, in order to increase the mechanical properties of lightweight foam concrete, fibers are usually added. However, the addition of fibers often results in uneven dispersion and stress concentration, which directly affects the mechanical properties of concrete. In order to improve flame retardancy, the prior art often adds some flame retardants or flame retardant particles to achieve flame retardant effects. For example, hexabromocyclododecane (HBCD) is a commonly used flame retardant, but it produces toxic gases and organic pollutants when burned, which have a negative impact on the environment and human health. At the same time, the addition of flame retardants may cause the mechanical properties of the material to deteriorate. For example, some flame retardants reduce the hardness of the foam and increase the foaming time, which may affect the overall performance of the material. In addition, excessive addition of flame retardants may cause the physical structure of the material to be destroyed, thereby weakening its thermal insulation properties.

[0020] Therefore, for foamed concrete, the pore structure is the core factor of its thermal insulation performance. Therefore, how to optimize the pore structure of foamed concrete is more direct and effective than using various fillers.

[0021] The present invention abandons traditional chemical foaming agents such as hydrogen peroxide, and uses animal protein and plant protein to prepare a composite foaming agent, while protein foaming agents often have the problem of poor foaming effect. Therefore, the present invention mainly uses plant protein, adds a small amount of animal protein, and effectively improves the stability of the foam through alkali treatment, prolongs the half-life of the foam, and reduces the speed of foam rupture; and further introduces acetyl groups to reduce the number of positive charges of the protein, making the molecules smaller, and accelerating their migration to the air-water interface, thereby improving the foaming ability, and the bubbles formed are uniform and delicate. After adding concrete, a large number of uniform closed pore structures can be formed in the concrete, which can effectively disperse stress and reduce the generation of cracks. At the same time, the closed pore structure can effectively improve its thermal insulation performance.

[0022] In combination with a protein foaming agent, the present invention further adds a foam stabilizer component consisting of gelatin, nano zinc oxide and hydroxyethyl cellulose. Among them, gelatin, as a typical protein foam stabilizer, has strong intramolecular forces and hydrogen bonding between its molecules, which can significantly improve the toughness of the foam. The addition of an inorganic foam stabilizer-nano zinc oxide, on the one hand, has a certain flame retardant effect, and on the other hand, the nano zinc oxide particles can form a physical barrier to prevent the fusion and rupture of bubbles. This barrier effect helps to maintain the uniformity and stability of the foam. The added hydroxyethyl cellulose achieves a foam stabilizing effect by adjusting the viscosity. After hydroxyethyl cellulose is dissolved in water, its molecular chains will fully extend and form a three-dimensional network structure, thereby significantly increasing the viscosity of the solution. This high viscosity contributes to the stability and durability of the foam, because the increase in viscosity can reduce the speed of foam rupture and make the foam more stable. The three foam stabilizers with different functions show significant synergy, making the formed foam uniform and stable.

[0023] Beneficial effects: (1) The present invention uses lightweight fillers such as expanded perlite, hollow glass microspheres and kaolin. Expanded perlite is a porous material formed by high-temperature treatment of natural volcanic glass rock, and has the characteristics of lightness, heat insulation, sound insulation and flame retardancy; hollow glass microspheres are lightweight materials with a hollow structure inside, and have good flame retardancy and heat insulation properties, and are suitable for building materials that require fire protection; and the added kaolin component can improve the compressive strength and durability of concrete. At the same time, when kaolin is used in combination with other materials (such as silica fume), the fire resistance of concrete can be further improved; (2) The present invention prepares a protein foaming agent and uses a foam stabilizer at the same time. The foam structure formed is uniform and stable. The obtained concrete material has a low dry density and thermal conductivity, a high sound absorption coefficient, good heat insulation, sound insulation and flame retardant effects, and is suitable for use in various complex environments. At the same time, it avoids the use of various fibers and organic fillers, reduces environmental pollution, and reduces costs, making it suitable for practical application and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The pore morphology and pore size distribution of the concrete specimen obtained in Example 5 of the present invention; Figure 2 The pore morphology and pore size distribution of the concrete specimen obtained in Comparative Example 1; Figure 3 The pore morphology and pore size distribution of the concrete specimen obtained in Comparative Example 2; Figure 4 The pore morphology and pore size distribution of the concrete specimen obtained in Comparative Example 3; Figure 5 The pore morphology and pore size distribution of the concrete specimen obtained in Comparative Example 4; Figure 6 The pore morphology and pore size distribution of the concrete specimen obtained in Comparative Example 5. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described below in conjunction with specific embodiments, but is not limited thereto.

[0026] Example 1 A lightweight thermal insulation concrete comprises the following raw materials in parts by weight: 190 parts of cement, 1,100 parts of thermal insulation lightweight aggregate, 110 parts of fly ash, 40 parts of silica fume, 5 parts of water reducer, 3 parts of composite micro-foam foaming agent, 2 parts of foam stabilizer and 105 parts of water.

[0027] The cement is silicate cement.

[0028] The thermal insulation lightweight aggregate comprises expanded perlite, hollow glass microspheres and kaolin, and the mass ratio of the three is 1:1:0.3.

[0029] The expanded perlite is made of expanded perlite particles with a particle size of 2-4 mm; the hollow glass microspheres are made of hollow glass microsphere particles with a particle size of 60-80 μm.

[0030] The water reducer is a polycarboxylate water reducer.

[0031] The preparation method of the composite microfoam foaming agent is: (1) After mixing ox horn powder and soybean powder in a mass ratio of 1:5, water and sodium hydroxide are added in a solid-liquid ratio of 100 g:150 mL, and the mixture is hydrolyzed at 50-60° C. for 6 hours, and filtered to obtain a composite foaming agent mother liquor; (2) Acetylation treatment: add 1% by weight of acetic anhydride to the composite foaming agent mother solution of step (1), maintain the pH at 7.5-8.5 under magnetic stirring at a temperature not exceeding 35°C for 1 hour, and continue the reaction for 1 hour after the pH of the solution stabilizes at 8.0 to complete the acylation reaction; then adjust the pH to 7.0 with 1 mol / L HCl solution to terminate the acylation reaction, and obtain a composite microbubble foaming agent.

[0032] The amount of sodium hydroxide added in step (1) is 1% of the mass of ox horn powder and soybean powder.

[0033] The foam stabilizer is obtained by mixing gelatin, nano zinc oxide and hydroxyethyl cellulose in a mass ratio of 1:1:1.

[0034] A method for preparing lightweight thermal insulation concrete comprises the following steps: (1) preparing a composite microfoam blowing agent; (2) Weighing all components except the composite microfoaming agent according to the concrete formula, stirring evenly, and preparing cement paste; (3) diluting the foaming agent by 25 times and pouring it into a foaming machine to prepare foam, adding the foam into the uniformly stirred cement slurry, and stirring until there is no floating foam to obtain a concrete mixture; (4) The concrete mixture is injected into a mold, cured, and demolded to obtain lightweight thermal insulation concrete.

[0035] Example 2 A lightweight thermal insulation concrete comprises the following raw materials in parts by weight: 200 parts of cement, 1000 parts of thermal insulation lightweight aggregate, 110 parts of fly ash, 30 parts of silica fume, 4 parts of water reducer, 3 parts of composite micro-foam foaming agent, 2.5 parts of foam stabilizer and 95 parts of water.

[0036] The cement is sulphoaluminate cement.

[0037] The thermal insulation lightweight aggregate comprises expanded perlite, hollow glass microspheres and kaolin, and the mass ratio of the three is 1:1:0.3.

[0038] The expanded perlite is made of expanded perlite particles with a particle size of 2-4 mm; the hollow glass microspheres are made of hollow glass microsphere particles with a particle size of 60-80 μm.

[0039] The water reducer is a polycarboxylate water reducer.

[0040] The preparation method of the composite microfoam foaming agent is: (1) After mixing ox horn powder and soybean powder in a mass ratio of 1:5, water and sodium hydroxide are added in a solid-liquid ratio of 100 g:150 mL, and the mixture is hydrolyzed at 50-60° C. for 6 hours, and filtered to obtain a composite foaming agent mother liquor; (2) Acetylation treatment: add 2% by weight of acetic anhydride to the composite foaming agent mother solution of step (1), maintain the pH at 7.5-8.5 under magnetic stirring at a temperature not exceeding 35°C for 1 hour, and continue the reaction for 1 hour after the pH of the solution stabilizes at 8.0 to complete the acylation reaction; then adjust the pH to 7.0 with 1 mol / L HCl solution to terminate the acylation reaction, and obtain a composite microbubble foaming agent.

[0041] The amount of sodium hydroxide added in step (1) is 2% of the mass of ox horn powder and soybean powder.

[0042] The foam stabilizer is obtained by mixing gelatin, nano zinc oxide and hydroxyethyl cellulose in a mass ratio of 1:1:1.

[0043] A method for preparing lightweight thermal insulation concrete comprises the following steps: (1) preparing a composite microfoam blowing agent; (2) Weighing all components except the composite microfoaming agent according to the concrete formula, stirring evenly, and preparing cement paste; (3) diluting the foaming agent by 25 times and pouring it into a foaming machine to prepare foam, adding the foam into the uniformly stirred cement slurry, and stirring until there is no floating foam to obtain a concrete mixture; (4) The concrete mixture is injected into a mold, cured, and demolded to obtain lightweight thermal insulation concrete.

[0044] Example 3 A lightweight thermal insulation concrete comprises the following raw materials in parts by weight: 205 parts of cement, 1050 parts of thermal insulation lightweight aggregate, 100 parts of fly ash, 35 parts of silica fume, 3 parts of water reducing agent, 3 parts of composite micro-foam foaming agent, 3 parts of foam stabilizer and 98 parts of water.

[0045] The cement is ferroaluminate cement.

[0046] The thermal insulation lightweight aggregate comprises expanded perlite, hollow glass microspheres and kaolin, and the mass ratio of the three is 1:1:0.3.

[0047] The expanded perlite is made of expanded perlite particles with a particle size of 2-4 mm; the hollow glass microspheres are made of hollow glass microsphere particles with a particle size of 60-80 μm.

[0048] The water reducer is a polycarboxylate water reducer.

[0049] The preparation method of the composite microfoam foaming agent is: (1) After mixing ox horn powder and soybean powder in a mass ratio of 1:5, water and sodium hydroxide are added in a solid-liquid ratio of 100 g:150 mL, and the mixture is hydrolyzed at 50-60° C. for 7 hours, and filtered to obtain a composite foaming agent mother liquor; (2) Acetylation treatment: add 3% by weight of acetic anhydride to the composite foaming agent mother solution of step (1), maintain the pH at 7.5-8.5 under magnetic stirring at a temperature not exceeding 35°C for 1 hour, and continue the reaction for 1 hour after the pH of the solution stabilizes at 8.0 to complete the acylation reaction; then adjust the pH to 7.0 with 1 mol / L HCl solution to terminate the acylation reaction, and obtain a composite microbubble foaming agent.

[0050] The amount of sodium hydroxide added in step (1) is 2% of the mass of ox horn powder and soybean powder.

[0051] The foam stabilizer is obtained by mixing gelatin, nano zinc oxide and hydroxyethyl cellulose in a mass ratio of 1:1:1.

[0052] A method for preparing lightweight thermal insulation concrete comprises the following steps: (1) preparing a composite microfoam blowing agent; (2) Weighing all components except the composite microfoaming agent according to the concrete formula, stirring evenly, and preparing cement paste; (3) diluting the foaming agent by 25 times and pouring it into a foaming machine to prepare foam, adding the foam into the uniformly stirred cement slurry, and stirring until there is no floating foam to obtain a concrete mixture; (4) The concrete mixture is injected into a mold, cured, and demolded to obtain lightweight thermal insulation concrete.

[0053] Example 4 A lightweight thermal insulation concrete comprises the following raw materials in parts by weight: 195 parts of cement, 1080 parts of thermal insulation lightweight aggregate, 105 parts of fly ash, 25 parts of silica fume, 5 parts of water reducing agent, 4 parts of composite micro-foaming agent, 3 parts of foam stabilizer and 100 parts of water.

[0054] The cement is selected from Portland cement.

[0055] The thermal insulation lightweight aggregate comprises expanded perlite, hollow glass microspheres and kaolin, and the mass ratio of the three is 1:1:0.3.

[0056] The expanded perlite is made of expanded perlite particles with a particle size of 2-4 mm; the hollow glass microspheres are made of hollow glass microsphere particles with a particle size of 60-80 μm.

[0057] The water reducer is a polycarboxylate water reducer.

[0058] The preparation method of the composite microfoam foaming agent is: (1) After mixing ox horn powder and soybean powder in a mass ratio of 1:5, water and sodium hydroxide are added in a solid-liquid ratio of 100 g:150 mL, and the mixture is hydrolyzed at 50-60° C. for 8 hours, and filtered to obtain a composite foaming agent mother liquor; (2) Acetylation treatment: add 2% by weight of acetic anhydride to the composite foaming agent mother solution of step (1), maintain the pH at 7.5-8.5 under magnetic stirring at a temperature not exceeding 35°C for 2 h, and continue the reaction for 1 h after the pH of the solution stabilizes at 8.0 to complete the acylation reaction; then adjust the pH to 7.0 with 1 mol / L HCl solution to terminate the acylation reaction, and obtain a composite microbubble foaming agent.

[0059] The amount of sodium hydroxide added in step (1) is 2% of the mass of ox horn powder and soybean powder.

[0060] The foam stabilizer is obtained by mixing gelatin, nano zinc oxide and hydroxyethyl cellulose in a mass ratio of 1:1:1.

[0061] A method for preparing lightweight thermal insulation concrete comprises the following steps: (1) preparing a composite microfoam blowing agent; (2) Weighing all components except the composite microfoaming agent according to the concrete formula, stirring evenly, and preparing cement paste; (3) diluting the foaming agent by 25 times and pouring it into a foaming machine to prepare foam, adding the foam into the uniformly stirred cement slurry, and stirring until there is no floating foam to obtain a concrete mixture; (4) The concrete mixture is injected into a mold, cured, and demolded to obtain lightweight thermal insulation concrete.

[0062] Example 5 A lightweight thermal insulation concrete comprises the following raw materials in parts by weight: 210 parts of cement, 1050 parts of thermal insulation lightweight aggregate, 120 parts of fly ash, 20 parts of silica fume, 3 parts of water reducing agent, 5 parts of composite micro-foaming agent, 4 parts of foam stabilizer and 90 parts of water.

[0063] The cement is a mixture of silicate cement, sulphoaluminate cement and other cements.

[0064] The thermal insulation lightweight aggregate comprises expanded perlite, hollow glass microspheres and kaolin, and the mass ratio of the three is 1:1:0.3.

[0065] The expanded perlite is made of expanded perlite particles with a particle size of 2-4 mm; the hollow glass microspheres are made of hollow glass microsphere particles with a particle size of 60-80 μm.

[0066] The water reducer is a polycarboxylate water reducer.

[0067] The preparation method of the composite microfoam foaming agent is: (1) After mixing ox horn powder and soybean powder in a mass ratio of 1:5, water and sodium hydroxide are added in a solid-liquid ratio of 100 g:150 mL, and the mixture is hydrolyzed at 50-60° C. for 8 hours, and filtered to obtain a composite foaming agent mother liquor; (2) Acetylation treatment: add 3% by weight of acetic anhydride to the composite foaming agent mother solution of step (1), maintain the pH at 7.5-8.5 under magnetic stirring at a temperature not exceeding 35°C for 2 h, and continue the reaction for 1 h after the pH of the solution stabilizes at 8.0 to complete the acylation reaction; then adjust the pH to 7.0 with 1 mol / L HCl solution to terminate the acylation reaction, and obtain a composite microbubble foaming agent.

[0068] The amount of sodium hydroxide added in step (1) is 3% of the mass of the horn powder and soybean powder.

[0069] The foam stabilizer is obtained by mixing gelatin, nano zinc oxide and hydroxyethyl cellulose in a mass ratio of 1:1:1.

[0070] A method for preparing lightweight thermal insulation concrete comprises the following steps: (1) preparing a composite microfoam blowing agent; (2) Weighing all components except the composite microfoaming agent according to the concrete formula, stirring evenly, and preparing cement paste; (3) diluting the foaming agent by 25 times and pouring it into a foaming machine to prepare foam, adding the foam into the uniformly stirred cement slurry, and stirring until there is no floating foam to obtain a concrete mixture; (4) The concrete mixture is injected into a mold, cured, and demolded to obtain lightweight thermal insulation concrete.

[0071] Comparative Example 1 A lightweight thermal insulation concrete comprises the following raw materials in parts by weight: 210 parts of cement, 1050 parts of thermal insulation lightweight aggregate, 120 parts of fly ash, 20 parts of silica fume, 3 parts of water reducing agent, 5 parts of composite micro-foaming agent, 4 parts of foam stabilizer and 90 parts of water.

[0072] The cement is a mixture of silicate cement, sulphoaluminate cement and other cements.

[0073] The preparation method of the composite microfoam foaming agent is: (1) After mixing ox horn powder and soybean powder in a mass ratio of 1:5, water and sodium hydroxide are added in a solid-liquid ratio of 100 g:150 mL, and the mixture is hydrolyzed at 50-60° C. for 8 hours, and filtered to obtain a composite foaming agent mother liquor; (2) Add 3% by weight of acetic anhydride to the composite foaming agent mother liquor of step (1) to obtain a composite microbubble foaming agent.

[0074] In this comparative example, except that the acetylation treatment of the mother liquor is not performed in the preparation of the composite microbubble foaming agent, the other raw materials and process steps are the same as those of Example 5.

[0075] Comparative Example 2 A lightweight thermal insulation concrete comprises the following raw materials in parts by weight: 210 parts of cement, 1050 parts of thermal insulation lightweight aggregate, 120 parts of fly ash, 20 parts of silica fume, 3 parts of water reducing agent, 5 parts of composite micro-foaming agent, 4 parts of foam stabilizer and 90 parts of water.

[0076] The foam stabilizer is gelatin.

[0077] In this comparative example, except that only gelatin is used as the foam stabilizer, the other raw materials and process steps are the same as those of Example 5.

[0078] Comparative Example 3 A lightweight thermal insulation concrete comprises the following raw materials in parts by weight: 210 parts of cement, 1050 parts of thermal insulation lightweight aggregate, 120 parts of fly ash, 20 parts of silica fume, 3 parts of water reducing agent, 5 parts of composite micro-foaming agent, 4 parts of foam stabilizer and 90 parts of water.

[0079] The foam stabilizer is nano zinc oxide.

[0080] In this comparative example, except that only nano zinc oxide is used in the foam stabilizer, the other raw materials and process steps are the same as those in Example 5.

[0081] Comparative Example 4 A lightweight thermal insulation concrete comprises the following raw materials in parts by weight: 210 parts of cement, 1050 parts of thermal insulation lightweight aggregate, 120 parts of fly ash, 20 parts of silica fume, 3 parts of water reducing agent, 5 parts of composite micro-foaming agent, 4 parts of foam stabilizer and 90 parts of water.

[0082] The foam stabilizer is hydroxyethyl cellulose.

[0083] In this comparative example, except that only hydroxyethyl cellulose was used as the foam stabilizer, the other raw materials and process steps were the same as those of Example 5.

[0084] Comparative Example 5 A lightweight thermal insulation concrete comprises the following raw materials in parts by weight: 210 parts of cement, 1050 parts of thermal insulation lightweight aggregate, 120 parts of fly ash, 20 parts of silica fume, 3 parts of water reducer, 5 parts of hydrogen peroxide, 4 parts of foam stabilizer and 90 parts of water.

[0085] In this comparative example, except that the composite microbubble foaming agent is replaced by the chemical foaming agent hydrogen peroxide, the other raw materials and process steps are the same as those of Example 5.

[0086] Performance Testing Foaming performance test and dynamics test: The composite microbubble foaming agent obtained in the embodiment of the present invention, the traditional chemical foaming agent (hydrogen peroxide), and the commercially available protein foaming agent (FP-180 of Shandong Guanming Biotechnology Co., Ltd.) were used as the experimental group for testing.

[0087] After diluting the foaming agent to be tested by 25 times, take 100 mL of the diluted solution and disperse it at a speed of 2500 r / min for 1 min, then quickly pour it into a 500 mL measuring cylinder, and record the foaming volume V (mL), the time for 50 mL of liquid to precipitate, and the precipitation half-life (s).

[0088] The comprehensive foam index characterizes the foaming efficiency and foam stability of the foaming agent. The larger the value, the better the foam performance. The calculation formula is: Bubble Composite Index ; where t 1 / 2 is the dialysis half-life, h max is the foaming volume, mL.

[0089] The test results are shown in Table 1: Table 1 Foaming performance test of different foaming agents The foaming volume of the composite microfoam foaming agent optimized by the present invention is not less than 490 mL, which is equivalent to that of hydrogen peroxide, and the liquid separation half-life is not less than 750 s, which is far greater than that of hydrogen peroxide and commercial protein foaming agents. The foam comprehensive index is also high, and the foam stability is good.

[0090] Concrete performance test: Concrete mixtures were prepared according to the methods of Examples 1-5 and Comparative Examples 1-5, and the mixtures were poured into the pre-prepared strength test specimen molds (100mm×100mm×100mm) and thermal conductivity test specimen molds (300mm×300mm×30mm), and the surfaces were scraped flat. After curing at room temperature for 2 days, the molds were removed. After demolding, the specimens were placed in a standard curing box for curing for 25 days, and then transferred to a drying box and dried continuously at (60±5)°C for 1 day. After being completely dried, the mechanical properties, thermal conductivity, porosity, and microscopic pore structure were tested. All experimental groups were repeated 5 times, and the test results were averaged.

[0091] Performance testing and characterization: Dry density test: Test according to JC / T 2357-2016; Thermal conductivity test: Tested in accordance with GB / T 10294-2008; Water absorption test: Test according to JG / T 266-2011.

[0092] Compressive strength: The test is carried out in accordance with JG / T 266-2011 "Foamed Concrete" and the testing equipment is NYL-2000 pressure testing machine.

[0093] Combustion mass loss rate: Weigh the mass M1 of the cured and dried test block with an electronic scale. Place the test block in a high-temperature furnace, burn it to 300 degrees Celsius, and continue to burn for half an hour. After cooling to room temperature, weigh the test block and measure the mass at this time to be M2. The combustion mass loss rate is calculated according to the following formula: ε=(M1-M2)M1×100%; ε is the combustion mass loss rate, in %, accurate to 0.1; M1 is the initial mass of the test block after curing, in g; M2 is the mass of the test block after combustion, in g; Open flame vertical combustion test: Fix the top of the test block with an instrument and burn the lower part with an open flame. Observe whether the test block burns, whether black smoke is produced, and whether the surface is carbonized.

[0094] Pore ​​structure analysis: When testing the microscopic pore structure, the 100mm×100mm×100mm specimen was first cut in half, with the cut surface being the test surface. The cut surface pore structure was then photographed using a DJCK-2 crack width gauge manufactured by Precision Instruments. The photographed cross-sectional size was 11mm×9mm, and the magnification was 60 times. Finally, the Namo Measurer software was used to perform statistical analysis of the pore structure parameters.

[0095] Sound absorption coefficient: The foam concrete test block was cut into a circular test piece with a size of 30 mm × 30 mm, and its sound absorption coefficient was measured using a SW-477 standing wave tube according to the national standard GBJ88-85 "Standing Wave Tube Method Sound Absorption Coefficient and Acoustic Resistance Porosity Measurement Specification", and the measurement frequency was 2000 Hz.

[0096] The specific test results are shown in Table 2: Table 2 Concrete performance test results According to the data in the table, the foamed concrete obtained in the embodiment of the present invention has a thermal conductivity of less than 0.04W / (m·K), a combustion mass loss of no more than 3%, and has good thermal insulation and flame retardant properties. At the same time, the high sound absorption coefficient makes the material have a good sound insulation effect. This is because, under the efficient foaming action of the foaming agent, a large number of uniformly closed pore structures are formed, and these tiny bubbles also promote the uniform dispersion and filling of lightweight aggregates such as expanded perlite, hollow glass microspheres and kaolin, thereby improving the overall comprehensive performance of the concrete. The pore structure morphology and pore size distribution are key factors affecting the physical and mechanical properties of foamed concrete. From the concrete pore morphology and pore size distribution diagram ( Figure 1-6 ) We can also see that compared with comparative examples 1-5, the test block of Example 5 of the present invention has a higher proportion of small-diameter pores, which is much higher than other groups. This is the main reason why it has the smallest dry density, the highest strength and the smallest thermal conductivity. However, in comparative examples 1-5, which have changed the composition of foaming agent and foam stabilizer, due to the decline in foaming performance and the weakening of the synergistic effect between foam stabilizers such as gelatin, nano zinc oxide and hydroxyethyl cellulose, the bubble performance is poor, the pore structure formed is large and uneven, and tends to be "discrete", resulting in a decline in its comprehensive performance.

[0097] It should be noted that the above embodiments are only partial embodiments of the preferred methods of implementing the present invention, rather than all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

Claims

1. A lightweight thermal insulation concrete, characterized in that: The invention comprises the following raw materials in parts by weight: 190-210 parts of cement, 1000-1100 parts of thermal insulation lightweight aggregate, 100-120 parts of fly ash, 20-40 parts of silica fume, 3-5 parts of water reducing agent, 3-5 parts of composite micro-foaming agent, 2-4 parts of foam stabilizer and 90-105 parts of water.

2. The lightweight thermal insulation concrete according to claim 1, characterized in that: The cement is selected from one or a combination of two or more of silicate cement, sulphoaluminate cement and ferroaluminate cement.

3. The lightweight thermal insulation concrete according to claim 1, characterized in that: The thermal insulation lightweight aggregate comprises expanded perlite, hollow glass microspheres and kaolin, and the mass ratio of the three is 1:1:0.

3.

4. The lightweight thermal insulation concrete according to claim 3, characterized in that: The expanded perlite is made of expanded perlite particles with a particle size of 2-4 mm; the hollow glass microspheres are made of hollow glass microsphere particles with a particle size of 60-80 μm.

5. The lightweight thermal insulation concrete according to claim 1, characterized in that: The water reducer is a polycarboxylate water reducer.

6. The lightweight thermal insulation concrete according to claim 1, characterized in that: The preparation method of the composite microfoam foaming agent is: (1) After mixing ox horn powder and soybean powder in a mass ratio of 1:5, water and sodium hydroxide are added in a solid-liquid ratio of 100 g:150 mL, and the mixture is hydrolyzed at 50-60° C. for 6-8 hours, and filtered to obtain a composite foaming agent mother liquor; (2) Acetylation treatment: add 1-3% by weight of acetic anhydride to the composite foaming agent mother solution of step (1), maintain the pH at 7.5-8.5 at a temperature not exceeding 35°C, and react for 1-2 hours with magnetic stirring. After the pH of the solution stabilizes at 8.0, continue the reaction for another hour to complete the acylation reaction. Then, adjust the pH to 7.0 with 1 mol / L HCl solution to terminate the acylation reaction, and obtain a composite microbubble foaming agent.

7. The lightweight thermal insulation concrete according to claim 1, characterized in that: The foam stabilizer is obtained by mixing gelatin, nano zinc oxide and hydroxyethyl cellulose in a mass ratio of 1:1:

1.

8. A method for preparing the lightweight thermal insulation concrete according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) preparing a composite microfoam blowing agent; (2) Weighing all components except the composite microfoaming agent according to the concrete formula, stirring evenly, and preparing cement paste; (3) diluting the foaming agent by 25 times and pouring it into a foaming machine to prepare foam, adding the foam into the uniformly stirred cement paste, and stirring until there is no floating foam to obtain a concrete mixture; (4) The concrete mixture is injected into a mold, cured, and demolded to obtain lightweight thermal insulation concrete.

9. Use of the lightweight thermal insulation concrete according to any one of claims 1 to 7 in thermal insulation of building exterior walls.

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