Lightweight foamed concrete, its preparation method and application in thermal and sound insulation wall

Abstract

The application relates to the field of building materials, in particular to light-weight foam concrete, a preparation method thereof and application of the light-weight foam concrete in thermal insulation and sound insulation wall bodies. The raw materials of the light-weight foam concrete include ordinary Portland cement, acrylic resin, a foaming agent, a foam stabilizer, a water reducing agent, a filler, an early strength agent and anti-cracking fibers. When the light-weight foam concrete prepared by the application is applied in the thermal insulation and sound insulation wall bodies, not only excellent thermal insulation and sound insulation performances can be ensured, but also good density and mechanical strength can be considered, and the performances of waterproofing and corrosion resistance are further enhanced, the foam concrete is endowed with excellent comprehensive performances, the high demand of the existing building material industry field for the comprehensive performances is met, the practical application field and environment of the material are widened, and the light-weight foam concrete has great application prospects.

Description

Technical Field

[0001] This application relates to the field of building materials, and more specifically to a lightweight foamed concrete, its preparation method, and its application in thermal and sound insulation walls. Background Technology

[0002] With the development of the construction industry and the increasing demands on building performance, the requirements for wall materials are becoming increasingly stringent. Traditional building materials such as solid clay bricks and ordinary concrete are gradually failing to meet the needs of modern buildings due to their heavy weight, high thermal conductivity, and complex construction. Especially in areas such as thermal insulation and sound insulation, traditional materials often perform poorly.

[0003] Lightweight foamed concrete, as a novel building material, significantly reduces the density of concrete by introducing a foaming agent into the concrete slurry, forming numerous microbubbles. This, in turn, improves its thermal insulation and sound insulation properties. It has garnered widespread attention due to its lightweight, moderate strength, excellent thermal and sound insulation performance, and superior workability. Compared to traditional thermal and sound insulation wall materials, lightweight foamed concrete, by controlling the type of foaming agent, can effectively control the pore structure, thereby significantly reducing the thermal conductivity and enhancing low-frequency sound wave absorption, effectively meeting the performance requirements of existing foamed concrete materials.

[0004] However, while existing lightweight foamed concrete technology demonstrates good thermal insulation and soundproofing effects, it also presents some significant practical application challenges. For example, achieving a balance between low density and high strength is difficult, limiting its application in integrated load-bearing and thermal insulation walls; the pore structure is poorly controlled, resulting in uneven pore size distribution and low closed-cell rate, leading to high moisture expansion and long-term degradation of thermal insulation performance; and its overall performance is poor, failing to effectively balance good waterproofing, corrosion resistance, and weather resistance, thus failing to meet the needs of more application scenarios. Summary of the Invention

[0005] As the building materials industry develops towards functionalization and integration, effectively improving the aforementioned practical application problems becomes particularly crucial. Therefore, through dedicated research in this area, the applicant has proposed a lightweight foamed concrete and its preparation method. When the lightweight foamed concrete prepared by this application is applied to thermal insulation and soundproofing walls, it not only ensures excellent thermal insulation and soundproofing performance but also maintains good density and mechanical strength. Furthermore, it enhances its waterproof and corrosion-resistant properties, endowing the foamed concrete with excellent comprehensive performance. This meets the high demands of the existing building materials industry for its comprehensive performance, broadens the practical application areas and environments of this type of material, and has enormous application prospects.

[0006] A lightweight foamed concrete, by weight, comprises the following raw materials: 90-120 parts ordinary silicate cement, 10-18 parts acrylic resin, 2-5 parts foaming agent, 0.5-1.5 parts foam stabilizer, 0.3-0.8 parts water-reducing agent, 12-20 parts filler, 0.5-1.2 parts early-strength agent, 0.3-0.6 parts crack-resistant fiber, 0.2-0.4 parts retarder, 0.1-0.3 parts defoamer, and 35-45 parts water.

[0007] As a preferred embodiment, the ordinary silicate cement has a strength grade of 42.5 or 42.5R.

[0008] As a preferred embodiment, the ordinary silicate cement is a highly homogeneous Conch Cement.

[0009] As a preferred embodiment, the mass ratio of the ordinary silicate cement, acrylic resin and filler is (10~11):(1~1.5):(1.4~1.8).

[0010] As a preferred embodiment, the mass ratio of the ordinary silicate cement, acrylic resin and filler is (10~10.5):(1.1~1.2):(1.5~1.7).

[0011] As a preferred embodiment, the acrylic resin is a functionally modified acrylic resin.

[0012] As a preferred embodiment, the preparation method of the functional modified acrylic resin specifically includes the following steps: S1: butyl acrylate, perfluoroalkyl ethyl acrylate, vinyltriisopropoxysilane and 2-acrylamido-2-methylpropanesulfonic acid are mixed and then butyl acetate is added to obtain a monomer pre-emulsion; S2: dodecyl mercaptan and sodium dihydrogen phosphate are added to the pre-emulsion, the temperature is raised and a portion of azobisisobutyronitrile is added; S3: the remaining azobisisobutyronitrile is added and the temperature is continued to rise, then tetraethylenepentamine is added dropwise and kept at the temperature; S4: after the reaction is completed, the mixture is cooled, nano-hydroxyapatite is added, the solvent is removed, and the mixture is pulverized to obtain the final product.

[0013] As a preferred embodiment, the preparation method of the functional modified acrylic resin specifically includes the following steps: S1: butyl acrylate, perfluoroalkyl ethyl acrylate, vinyltriisopropoxysilane and 2-acrylamido-2-methylpropanesulfonic acid are mixed in proportion, butyl acetate is added, and the mixture is emulsified at 30~40℃ and 1500~2000rpm for 20~25min to form a uniform monomer pre-emulsion; S2: the pre-emulsion is transferred to a reaction vessel, dodecyl mercaptan and sodium dihydrogen phosphate are added, nitrogen gas is purged, the temperature is raised to 65~70℃, and 50wt% of azobisisobutyronitrile is added and reacted for 2~3h; S3: the remaining azobisisobutyronitrile is added and the temperature is raised to 80~85℃, tetraethylenepentamine is added dropwise and the reaction is maintained for 3~4h; S4: after the reaction is completed, the temperature is cooled to 45~50℃, nano-hydroxyapatite is added and ultrasonic treatment is performed at 500~600W for 1~1.5h, then the solvent is removed by vacuum distillation and pulverized to obtain the final product.

[0014] As a preferred embodiment, the mass ratio of butyl acrylate, perfluoroalkyl ethyl acrylate, vinyltriisopropoxysilane and 2-acrylamido-2-methylpropanesulfonic acid is (5~7):(2~2.5):(1~1.4):(0.2~0.4).

[0015] As a preferred embodiment, the mass ratio of butyl acrylate, perfluoroalkyl ethyl acrylate, vinyltriisopropoxysilane and 2-acrylamido-2-methylpropanesulfonic acid is (5.5~6):(2~2.2):(1.2~1.3):(0.2~0.3).

[0016] As a preferred embodiment, the mass ratio of butyl acrylate to nano-hydroxyapatite is (5~7):(0.2~0.3).

[0017] As a preferred embodiment, the average particle size of the nano-hydroxyapatite is 40~100nm.

[0018] By incorporating functionally modified acrylic resin, the overall performance of lightweight foamed concrete, including mechanical properties, thermal insulation, sound insulation, waterproofing, and corrosion resistance, is significantly improved. In particular, through chemical bonding and physical entanglement, it fills the interfacial gaps between the cement matrix and fillers, forming an elastic network structure that enhances the overall material's crack resistance and ductility. The sulfonic acid groups in the modified resin form ionic crosslinks with Ca²⁺ generated during cement hydration, while the siloxanes undergo hydrolysis and condensation to chemically bond with the cement matrix, forming an organic-inorganic hybrid network. Furthermore, the resin's elastic modulus falls between that of cement paste and foam pores. Through gradient modulus design, it disperses localized stress, inhibits crack propagation, and enhances mechanical properties.

[0019] On the other hand, the nano-hydroxyapatite it contains is anchored in the resin skeleton through hydrogen bonds. Its high specific surface area provides heterogeneous nucleation sites, promoting the microcrystallization of CSH gel, a cement hydration product, and increasing the matrix density. The perfluoroalkyl chains it contains form a low-energy surface with the siloxane network, inhibiting water molecule wetting, and the electronic shielding effect of the chain segments hinders the penetration of acidic corrosive molecules. In addition, the addition of modified acrylic resin can inhibit interconnected pores through the cross-linking of nano-hydroxyapatite and siloxanes, blocking heat convection, thereby effectively ensuring the thermal insulation and sound insulation effect of the concrete material.

[0020] As a preferred embodiment, the foaming agent is at least one selected from hydrogen peroxide solution, aluminum powder, azodicarbonamide, and sodium bicarbonate.

[0021] As a preferred embodiment, the foaming agent is hydrogen peroxide solution or azodicarbonamide.

[0022] As a preferred embodiment, the foaming agent is a hydrogen peroxide solution with a mass concentration of 20-35%.

[0023] As a preferred embodiment, the foam stabilizer is at least one of sodium dodecyl sulfate, lauryl alcohol polyoxyethylene ether, stearamide, hydroxypropyl methylcellulose, and polyvinyl alcohol.

[0024] As a preferred embodiment, the foam stabilizer is sodium dodecyl sulfate or polyvinyl alcohol.

[0025] As a preferred embodiment, the water-reducing agent is a polycarboxylate water-reducing agent or a naphthalene-based water-reducing agent.

[0026] As a preferred embodiment, the water-reducing agent is a high-efficiency polycarboxylate water-reducing agent.

[0027] As a preferred embodiment, the filler is modified perlite powder.

[0028] As a preferred embodiment, the preparation method of the modified perlite powder specifically includes the following steps: S1: soaking expanded perlite in hydrofluoric acid solution, washing and drying to obtain activated perlite powder; S2: dispersing nano-zirconia and nano-alumina in isopropanol, adding a coupling agent to obtain a composite sol, and impregnating the activated perlite powder in the composite sol; S3: after impregnation, the product is pre-dried and calcined, and then cooled to obtain the final product.

[0029] As a preferred embodiment, the preparation method of the modified perlite powder specifically includes the following steps: S1: Immerse expanded perlite in a 10-15 wt% hydrofluoric acid solution for 10-15 min, wash with water until neutral, and dry at 120-125℃ for 2-3 h to obtain activated perlite powder; S2: Disperse nano-zirconia and nano-alumina in isopropanol, add aluminate coupling agent and titanate coupling agent, and ultrasonically disperse for 2-3 h to form a stable composite sol. Then, immerse the activated perlite powder in the composite sol and vacuum impregnate it 2-3 times at -0.09~-0.08 MPa, each time for 10-15 min, to ensure that the sol fully penetrates into the pores; S3: After impregnation, take out the product and pre-dry it at 80-85℃ for 1-2 h, then calcine it at 500-550℃ under nitrogen protection for 2-2.5 h, and then naturally cool it to obtain the final product.

[0030] As a preferred embodiment, the expanded perlite has an average particle size of 0.5~1.5 mm.

[0031] As a preferred embodiment, the mass ratio of the expanded perlite, nano-zirconia, and nano-alumina is (7~8):(0.3~0.6):(0.2~0.5).

[0032] As a preferred embodiment, the mass ratio of the expanded perlite, nano-zirconia, and nano-alumina is (7.2~7.6):(0.4~0.5):(0.3~0.4).

[0033] As a preferred embodiment, the average particle size of the nano-zirconia is 20~40 nm.

[0034] As a preferred embodiment, the average particle size of the nano-alumina is 30~50nm.

[0035] As a preferred embodiment, the early strength agent is a combination of lithium nitrate and calcium formate.

[0036] As a preferred embodiment, the mass ratio of lithium nitrate to calcium formate is (7~8):(1~2).

[0037] As a preferred embodiment, the mass ratio of lithium nitrate to calcium formate is (7~7.5):(1.5~2).

[0038] As a preferred embodiment, the crack-resistant fiber is at least one of polypropylene fiber, glass fiber, carbon fiber, and basalt fiber.

[0039] As a preferred embodiment, the crack-resistant fiber is carbon fiber or basalt fiber.

[0040] As a preferred embodiment, the retarder is at least one of sodium gluconate, trisodium phosphate, and calcium lignosulfonate.

[0041] As a preferred embodiment, the retarder is sodium gluconate.

[0042] As a preferred embodiment, the defoamer is a polyether-modified silicone or a mineral oil.

[0043] The preparation method of the above-mentioned lightweight foamed concrete specifically includes the following steps: S1: Ordinary silicate cement, filler, and crack-resistant fibers are added to a planetary mixer and mixed at 100-150 rpm for 3-5 minutes, then the speed is switched to 400-450 rpm and mixed for 8-15 minutes to ensure uniform dispersion; S2: Water-reducing agent, defoamer, accelerator, retarder, and part of water are added in sequence and mixed at 300-400 rpm for 5-7 minutes, then the remaining water is mixed with acrylic resin and added at 200 rpm. Stir at 250 rpm for 3-5 minutes to form a uniform slurry; S3: Slowly add the foaming agent to the slurry and simultaneously add the foam stabilizer, stir at 100-120 rpm for 1-2 minutes, then let it stand for 4-8 minutes to foam, controlling the foaming ratio to 3-3.5 times. Then pour the foamed slurry into a steel mold and let it stand for 4-5 hours at 25-30℃ and relative humidity ≥90%. Increase the temperature to 60℃ at 5-10℃ / h and maintain the temperature for 30-40 hours. Then let it cool naturally to room temperature to obtain the final product.

[0044] This application further defines the application of the aforementioned lightweight foamed concrete in thermal and sound insulation walls.

[0045] The beneficial effects of this application are:

[0046] 1. The lightweight foamed concrete provided in this application, when applied to thermal and sound insulation walls, not only ensures excellent thermal and sound insulation performance, but also maintains good density and mechanical strength, and further enhances its waterproof and corrosion-resistant properties, giving foamed concrete excellent comprehensive performance. This meets the high demand for comprehensive performance in the existing building materials industry, broadens the practical application fields and environments of this type of material, and has great application prospects.

[0047] 2. The lightweight foamed concrete provided in this application significantly improves the comprehensive properties of lightweight foamed concrete, such as mechanical properties, thermal insulation, sound insulation, waterproofing, and corrosion resistance, by adding functional modified acrylic resin. In particular, through chemical bonding and physical winding, it fills the interface gaps between the cement matrix and the filler to form an elastic network structure, thereby improving the crack resistance and ductility of the overall material.

[0048] 3. The lightweight foamed concrete provided in this application contains modified perlite powder that can absorb energy and induce microcrack deflection under stress, providing rigid support, achieving toughening and dispersion strengthening. The presence of the coating layer forces the cracks to extend the fracture path along the interface of nanoparticles, dissipating energy. On the other hand, the contained alumina particles can react with the cement hydration product calcium hydroxide to generate calcium aluminate hydrate, thereby enhancing the interfacial bonding effect and improving the overall performance of the foamed concrete. Detailed Implementation

[0049] Example 1: Lightweight foamed concrete, by weight, is composed of the following raw materials: 105 parts ordinary silicate cement, 12 parts acrylic resin, 3.8 parts foaming agent, 1.2 parts foam stabilizer, 0.4 parts water-reducing agent, 16 parts filler, 0.8 parts early strength agent, 0.5 parts crack-resistant fiber, 0.2 parts retarder, 0.2 parts defoamer, and 41.5 parts water.

[0050] The ordinary Portland cement is Conch Cement, with a strength grade of 42.5.

[0051] The acrylic resin is a functional modified acrylic resin. The preparation method, by weight, specifically includes the following steps: S1: Mix 5.8 parts butyl acrylate, 2.1 parts perfluoroalkyl ethyl acrylate, 1.3 parts vinyltriisopropoxysilane, and 0.3 parts 2-acrylamido-2-methylpropanesulfonic acid in a specified ratio, add 30 parts butyl acetate, and emulsify at 40°C and 1800 rpm for 22 minutes to form a uniform monomer pre-emulsion; S2: Transfer the pre-emulsion to the reaction vessel... In a container, add 0.06 parts of dodecyl mercaptan and 0.1 parts of sodium dihydrogen phosphate, purge with nitrogen, heat to 70°C, add 0.04 parts of azobisisobutyronitrile and react for 2 hours; S2: add the remaining 0.04 parts of azobisisobutyronitrile and heat to 85°C, add 0.05 parts of tetraethylenepentamine dropwise and keep the temperature for 4 hours; S3: after the reaction is complete, cool to 50°C, add 0.2 parts of nano-hydroxyapatite and sonicate at 500W for 1 hour, then remove the solvent by vacuum distillation and pulverize to obtain the final product.

[0052] The average particle size of nano-hydroxyapatite is 60 nm.

[0053] The foaming agent is an aqueous solution of hydrogen peroxide with a mass concentration of 30%.

[0054] The foam stabilizer is polyvinyl alcohol PVA-1788; the water-reducing agent is a high-efficiency polycarboxylate water-reducing agent, which is a national standard industrial grade product purchased from Jinan Mingjiang Chemical Co., Ltd. in China.

[0055] The filler is modified perlite powder. The preparation method includes the following steps: S1: 7.8 parts of expanded perlite are soaked in 30 parts of 10wt% hydrofluoric acid solution for 12 min, washed with water until neutral, and dried at 120℃ for 2 h to obtain activated perlite powder; S2: 0.5 parts of nano-zirconia and 0.4 parts of nano-alumina are dispersed in 10 parts of isopropanol, 0.2 parts of aluminate coupling agent DL-411 and 0.15 parts of titanate coupling agent KR-TTS are added, and ultrasonically dispersed for 2 h to form a stable composite sol. Then, the activated perlite powder is immersed in the composite sol and impregnated three times under vacuum of -0.08 MPa for 10 min each time to ensure that the sol fully penetrates into the pores; S3: After impregnation, the product is taken out and pre-dried at 85℃ for 2 h, followed by calcination at 550℃ under nitrogen protection for 2 h, and then naturally cooled to obtain the final product.

[0056] The average particle size of expanded perlite is 1.1 mm.

[0057] The average particle size of nano-zirconia is 25 nm, and the average particle size of nano-alumina is 40 nm.

[0058] The early strength agent is a combination of lithium nitrate and calcium formate in a mass ratio of 7.2:1.8.

[0059] The crack-resistant fiber is basalt fiber, purchased from China Taian Haosong Fiber Co., Ltd., 9mm grade basalt fiber; the retarder is sodium gluconate; the defoamer is mineral oil BYK-088.

[0060] The preparation method of lightweight foamed concrete includes the following steps: S1: Ordinary silicate cement, filler, and crack-resistant fiber are added to a planetary mixer and mixed at 120 rpm for 4 minutes, then the speed is switched to 450 rpm for 10 minutes to ensure uniform dispersion; S2: Water-reducing agent, defoamer, early-strength agent, retarder, and 70 wt% water are added in sequence and mixed at 400 rpm for 6 minutes. Then, the remaining water is mixed with acrylic resin and added, and the mixture is stirred at 240 rpm for 4 minutes to form a uniform slurry; S3: Foaming agent is slowly added to the slurry along with foam stabilizer, and the mixture is stirred at 100 rpm for 1 minute. After that, the mixture is allowed to stand for 5 minutes to foam, controlling the foaming ratio to 3.5 times. The foamed slurry is then poured into a steel mold and allowed to stand for 5 hours at 30℃ and relative humidity ≥90%. The temperature is then increased to 60℃ at 10℃ / h and maintained at a constant temperature for 40 hours. After that, the mixture is allowed to cool naturally to room temperature to obtain the final product.

[0061] Example 2: This example differs from Example 1 only in the following aspects: Lightweight foamed concrete, by weight, is composed of the following raw materials: 110 parts ordinary silicate cement, 10 parts acrylic resin, 4 parts foaming agent, 1.1 parts foam stabilizer, 0.4 parts water-reducing agent, 14 parts filler, 0.8 parts early strength agent, 0.6 parts crack-resistant fiber, 0.2 parts retarder, 0.2 parts defoamer, and 44 parts water.

[0062] Example 3: This example differs from Example 1 only in the following aspects: Lightweight foamed concrete, by weight, is composed of the following raw materials: 100 parts ordinary silicate cement, 15 parts acrylic resin, 3.8 parts foaming agent, 1.2 parts foam stabilizer, 0.4 parts water-reducing agent, 18 parts filler, 0.8 parts early strength agent, 0.5 parts crack-resistant fiber, 0.4 parts retarder, 0.3 parts defoamer, and 41.5 parts water.

[0063] Comparative Example 1

[0064] The only difference between this comparative example and Example 1 is as follows: The lightweight foamed concrete, by weight, is composed of the following components: 105 parts ordinary silicate cement, 3.5 parts acrylic resin, 4.1 parts foaming agent, 1.1 parts foam stabilizer, 0.4 parts water-reducing agent, 25 parts filler, 0.8 parts early strength agent, 0.5 parts crack-resistant fiber, 0.3 parts retarder, 0.3 parts defoamer, and 43 parts water.

[0065] Comparative Example 2

[0066] The only difference between this comparative example and Example 1 is as follows: The lightweight foamed concrete, by weight, is composed of the following components: 120 parts ordinary silicate cement, 14.5 parts acrylic resin, 3.8 parts foaming agent, 1.2 parts foam stabilizer, 0.5 parts water-reducing agent, 4.5 parts filler, 0.8 parts early strength agent, 0.5 parts crack-resistant fiber, 0.4 parts retarder, 0.3 parts defoamer, and 40 parts water.

[0067] Comparative Example 3

[0068] The only difference between this comparative example and Example 1 is the following: the acrylic resin is a functionally modified acrylic resin. The preparation method, by weight, specifically includes the following steps: S1: Mix 9.5 parts butyl acrylate, 1 part perfluoroalkyl ethyl acrylate, 0.6 parts vinyltriisopropoxysilane, and 0.1 parts 2-acrylamido-2-methylpropanesulfonic acid in a specified ratio, add 30 parts butyl acetate, and emulsify at 40°C and 1800 rpm for 22 minutes to form a uniform monomer pre-emulsion; S2: ... The pre-emulsion was transferred to a reaction vessel, and 0.06 parts of dodecyl mercaptan and 0.1 parts of sodium dihydrogen phosphate were added. Under nitrogen protection, the temperature was raised to 70°C, and 0.04 parts of azobisisobutyronitrile were added and reacted for 2 hours. S2: The remaining 0.04 parts of azobisisobutyronitrile were added and the temperature was raised to 85°C. 0.05 parts of tetraethylenepentamine were added dropwise and the reaction was maintained at this temperature for 4 hours. S3: After the reaction was completed, the temperature was cooled to 50°C, 0.2 parts of nano-hydroxyapatite were added, and the mixture was ultrasonically treated at 500W for 1 hour. The solvent was then removed by vacuum distillation, and the mixture was pulverized to obtain the final product.

[0069] Comparative Example 4

[0070] The only difference between this comparative example and Example 1 is the following: the acrylic resin is a functionally modified acrylic resin. The preparation method, by weight, specifically includes the following steps: S1: Mix 5.8 parts butyl acrylate, 2.1 parts perfluoroalkyl ethyl acrylate, and 1.3 parts vinyltriisopropoxysilane in a specified ratio, add 30 parts butyl acetate, and emulsify at 40°C and 1800 rpm for 22 minutes at high speed to form a homogeneous monomer pre-emulsion; S2: Transfer the pre-emulsion to a reaction vessel. Add 0.06 parts of dodecyl mercaptan and 0.1 parts of sodium dihydrogen phosphate, purge with nitrogen, heat to 70°C, add 0.04 parts of azobisisobutyronitrile and react for 2 hours; S2: Add the remaining 0.04 parts of azobisisobutyronitrile and heat to 85°C, add 0.05 parts of tetraethylenepentamine and keep the temperature for 4 hours; S3: After the reaction is complete, cool to 50°C, add 0.05 parts of nano-hydroxyapatite and sonicate at 500W for 1 hour, then remove the solvent by vacuum distillation and pulverize to obtain the final product.

[0071] The average particle size of nano-hydroxyapatite is 200 nm.

[0072] Comparative Example 5

[0073] The only difference between this comparative example and Example 1 is the following: the filler is modified perlite powder. The preparation method specifically includes the following steps: S1: 5.5 parts of expanded perlite are soaked in 30 parts of 10wt% hydrofluoric acid solution for 12 min, washed with water until neutral, and dried at 120℃ for 2 h to obtain activated perlite powder; S2: 1 part of nano-zirconia and 0.2 parts of nano-alumina are dispersed in 10 parts of isopropanol, 0.2 parts of aluminate coupling agent DL-411 and 0.15 parts of titanate coupling agent KR-TTS are added, and ultrasonically dispersed for 2 h to form a stable composite sol. Then, the activated perlite powder is immersed in the composite sol and impregnated three times under vacuum of -0.08 MPa for 10 min each time to ensure that the sol fully penetrates into the pores; S3: After impregnation, the product is taken out and pre-dried at 85℃ for 2 h, followed by calcination at 550℃ under nitrogen protection for 2 h, and then naturally cooled to obtain the final product.

[0074] Comparative Example 6

[0075] The only difference between this comparative example and Example 1 is the following: the filler is modified perlite powder. The preparation method specifically includes the following steps: S1: 15.5 parts of expanded perlite are soaked in 30 parts of 10wt% hydrofluoric acid solution for 12 min, washed with water until neutral, and dried at 120℃ for 2 h to obtain activated perlite powder; S2: 0.2 parts of nano-zirconia and 0.8 parts of nano-alumina are dispersed in 10 parts of isopropanol, 0.2 parts of aluminate coupling agent DL-411 and 0.15 parts of titanate coupling agent KR-TTS are added, and ultrasonically dispersed for 2 h to form a stable composite sol. Then, the activated perlite powder is immersed in the composite sol and impregnated three times under vacuum of -0.08 MPa for 10 min each time to ensure that the sol fully penetrates into the pores; S3: After impregnation, the product is taken out and pre-dried at 85℃ for 2 h, followed by calcination at 550℃ under nitrogen protection for 2 h, and then naturally cooled to obtain the final product.

[0076] Performance evaluation of examples and comparative examples

[0077] 1. Compressive strength: Referring to standard GB / T 23451-2009, 100mm×100mm×100mm cube specimens (dry density 560~600 kg / m³) were prepared from concrete prepared in the examples and comparative examples. Standard curing (temperature 20±2℃, humidity ≥95%) was carried out for 28 days. The maximum load at which the specimen failed was recorded using a universal testing machine. The test results were taken as the average value of 10 tests and recorded in Table 1.

[0078] 2. Flexural strength: 40 mm × 40 mm × 160 mm prism specimens (dry density 560~600 kg / m³) were prepared from the concrete obtained in the examples and comparative examples. The three-point bending method was used for loading, with a span of 100 mm and a speed of 50 N / s. The test results were taken as the average value of 10 tests and recorded in Table 1.

[0079] 3. Thermal insulation: The thermal conductivity was tested using a flat plate thermal conductivity meter. The specimen size was 300 mm × 300 mm × 30 mm (dry density 560~600 kg / m³). The temperature difference between the hot and cold plates was set to 20℃ (hot plate 30℃, cold plate 10℃). The thermal conductivity was obtained by measuring the heat flux density under steady state. The test results were the average of 10 tests and recorded in Table 1.

[0080] 4. Water absorption rate: Refer to standard JC / T 1062-2007. Dry 100mm×100mm×100mm cubic specimens (dry density 560~600 kg / m³) to constant weight (105℃ oven) and weigh (m1). Soak in water for 24 hours, take out, wipe off the surface moisture and weigh (m2). Calculate the water absorption rate = (m2-m1) / m1×100%. The test results are the average of 10 tests and recorded in Table 1.

[0081] 5. Alkali corrosion resistance: 100mm×100mm×100mm cubic specimens (dry density 560~600 kg / m³) were immersed in NaOH solution (concentration 1 mol / L) at pH=13 for 30 days, dried and weighed, and the mass loss rate was calculated. The test results were the average of 10 tests and recorded in Table 1.

[0082] Table 1 Performance Evaluation Results

[0083]

[0084] Based on the final performance test results of the examples and comparative examples, comparative examples 1-6 achieved worse performance results compared to the examples. The examples, on the other hand, obtained better modified acrylic resin and functional filler through a better technical solution. The combined effect of the two can absorb energy under stress and induce microcrack deflection, providing rigid support, achieving toughening and dispersion strengthening. Moreover, the presence of the filler coating layer forces the crack to extend the fracture path along the interface of nanoparticles, dissipating energy. On the other hand, the contained alumina particles can react with the cement hydration product calcium hydroxide to generate calcium aluminate hydrate, thereby enhancing the interfacial bonding effect and improving the overall performance of foamed concrete.

Claims

1. A lightweight foamed concrete, characterized in that: By weight, the raw materials include: 90-120 parts of ordinary silicate cement, 10-18 parts of acrylic resin, 2-5 parts of foaming agent, 12-20 parts of filler, 35-45 parts of water, 0.5-1.5 parts of foam stabilizer, 0.3-0.8 parts of water-reducing agent, 0.5-1.2 parts of early strength agent, 0.3-0.6 parts of crack-resistant fiber, 0.2-0.4 parts of retarder, and 0.1-0.3 parts of defoamer; The early strength agent is a combination of lithium nitrate and calcium formate in a mass ratio of (7~8):(1~2). The acrylic resin is a functionally modified acrylic resin, and its preparation method includes: S1: mixing butyl acrylate, perfluoroalkyl ethyl acrylate, vinyltriisopropoxysilane and 2-acrylamido-2-methylpropanesulfonic acid, and then adding butyl acetate to obtain a monomer pre-emulsion; S2: adding dodecyl mercaptan and sodium dihydrogen phosphate to the pre-emulsion, heating and adding a portion of azobisisobutyronitrile; S3: adding the remaining azobisisobutyronitrile and continuing to heat, then adding tetraethylenepentamine dropwise and maintaining the temperature; S4: cooling after the reaction is complete, adding nano-hydroxyapatite, removing the solvent, and pulverizing to obtain the final product; The mass ratio of butyl acrylate, perfluoroalkyl ethyl acrylate, vinyltriisopropoxysilane and 2-acrylamido-2-methylpropanesulfonic acid is (5~7):(2~2.5):(1~1.4):(0.2~0.4). The filler is modified perlite powder, and the preparation method includes: S1: soaking expanded perlite in hydrofluoric acid solution, washing and drying to obtain activated perlite powder; S2: dispersing nano-zirconia and nano-alumina in isopropanol, adding a coupling agent to obtain a composite sol, and impregnating the activated perlite powder in the composite sol; S3: after impregnation, the product is pre-dried and calcined, and then cooled to obtain the final product; The expanded perlite has a mass ratio of nano-zirconia and nano-alumina of (7~8):(0.3~0.6):(0.2~0.5). The expanded perlite has an average particle size of 0.5~1.5mm; The average particle size of the nano-zirconia is 20-40 nm; the average particle size of the nano-alumina is 30-50 nm.

2. The lightweight foamed concrete according to claim 1, characterized in that: The average particle size of the nano-hydroxyapatite is 40~100nm.

3. The lightweight foamed concrete according to claim 2, characterized in that: The mass ratio of the ordinary silicate cement, acrylic resin and filler is (10~11):(1~1.5):(1.4~1.8).

4. The lightweight foamed concrete according to claim 3, characterized in that: The foaming agent is at least one of hydrogen peroxide solution, aluminum powder, azodicarbonamide, and sodium bicarbonate.

5. A method for preparing lightweight foamed concrete according to claim 4, characterized in that: Specifically, the following steps are included: S1: Add ordinary silicate cement, filler, and crack-resistant fibers to a planetary mixer and mix at 100-150 rpm for 3-5 minutes. Then switch to 400-450 rpm and mix for 8-15 minutes to ensure uniform dispersion. S2: Add water-reducing agent, defoamer, accelerator, retarder, and some water in sequence. Mix at 300-400 rpm for 5-7 minutes. Then add the remaining water mixed with acrylic resin at a speed of 200... Stir at 250 rpm for 3-5 minutes to form a uniform slurry; S3: Slowly add the foaming agent to the slurry and simultaneously add the foam stabilizer, stir at 100-120 rpm for 1-2 minutes, then let it stand for 4-8 minutes to foam, controlling the foaming ratio to 3-3.5 times. Then pour the foamed slurry into a steel mold and let it stand for 4-5 hours at 25-30℃ and relative humidity ≥90%. Increase the temperature to 60℃ at 5-10℃ / h and maintain the temperature for 30-40 hours. Then let it cool naturally to room temperature to obtain the final product.

6. The application of lightweight foamed concrete according to any one of claims 1 to 4 in thermal insulation and soundproofing walls.

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