Thermal insulation foam concrete and preparation method thereof

Abstract

The invention discloses thermal insulation foam concrete, and belongs to the technical field of concrete. The thermal insulation foam concrete is prepared from the following raw materials in parts by weight: 100-150 parts of cement, 30-50 parts of fly ash, 50-80 parts of diatomite, 1-3 parts of modified polypropylene fiber, 3-6 parts of a composite foaming agent, 1-2 parts of a polycarboxylic acid water reducer and 70-110 parts of water, the modified polypropylene fibers are functional graphene oxide modified polypropylene fibers. The modified polypropylene fiber used in the invention enhances the strength of the matrix, and the composite foaming agent optimizes the pore structure and has a synergistic effect with other raw material components, so that the prepared foam concrete has excellent thermal insulation performance and mechanical properties at the same time.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of concrete, in particular to a thermal insulation foam concrete and a preparation method thereof. BACKGROUND

[0002] Under the background of the increasingly severe global energy crisis and environmental problems, building energy saving has become an important way to reduce energy consumption and carbon emissions. Countries around the world have successively formulated and continuously improved building energy saving design standards and specifications, and put forward higher and higher requirements for the thermal insulation performance of building envelope (wall, roof, floor). Traditional single material wall (such as ordinary concrete, brick wall) is difficult to meet the increasingly stringent thermal insulation performance indicators (such as heat transfer coefficient K value or U value).

[0003] Foam concrete is a kind of porous material, which is formed by pouring and curing after mixing foam and cement slurry. Compared with ordinary concrete, foam concrete can reduce the basic cost due to its low density, and has excellent sound insulation and thermal insulation performance, and at the same time, foam concrete also has a low elastic modulus, which can make the building absorb seismic energy, thereby reducing the seismic effect. As a new type of lightweight porous building material, foam concrete has shown great application potential in the field of building energy saving due to its good thermal insulation performance, light weight, high strength, convenient construction and other advantages. However, with the continuous development of building materials, the performance requirements of foam concrete in the field of building are also getting higher and higher, that is, it is necessary to improve the mechanical properties of foam concrete and reduce the density of foam concrete to improve the thermal insulation performance, but in general, the strength and thermal conductivity of foam concrete are difficult to meet the above requirements. Therefore, how to obtain a foam concrete with good mechanical properties and thermal insulation performance is a technical problem to be solved in the field. SUMMARY

[0004] The purpose of the present application is to provide a thermal insulation foam concrete which has good thermal insulation performance and excellent mechanical properties.

[0005] To achieve the above technical purpose, the technical solution adopted by the present application is: A thermal insulation foam concrete is prepared from the following raw materials by weight: cement 100-150 parts, fly ash 30-50 parts, diatomite 50-80 parts, modified polypropylene fiber 1-3 parts, composite foaming agent 3-6 parts, polycarboxylic acid water reducer 1-2 parts, and water 70-110 parts; the modified polypropylene fiber is a functionalized graphene oxide modified polypropylene fiber.

[0006] Preferably, the functionalized graphene oxide modified polypropylene fiber is prepared by the following method: (1) Bisphenol A diglycidyl ether and formaldehyde are mixed according to a molar ratio, an appropriate amount of n-butanol solvent is added to dissolve completely, the mixed solution is magnetically stirred and heated to 70°C, then an appropriate amount of ammonia water catalyst is added, stirring and heating to 80-85°C is continued, and after 2h of incubation, the temperature is lowered and the solvent is removed by distillation under reduced pressure to obtain an intermediate product; (2) The intermediate product obtained in step (1) is mixed uniformly with 1% boric acid solution according to a mass ratio, heated to 70°C for 10min under normal pressure, then distilled under reduced pressure for 10min, heated to 80°C again for 10min under normal pressure, then distilled under reduced pressure for 10min, heated to 90°C again for 10min under normal pressure, and distilled under reduced pressure until the liquid is in a string state to obtain a boron phenolic aldehyde epoxy resin; (3) The graphene oxide is dispersed in deionized water, ultrasonic dispersion is performed for 30-45min, then transferred into a high-pressure homogenizer at 200MPa for 3 cycles to obtain a dispersion liquid, and vacuum freeze-drying is performed to obtain pretreated graphene oxide; (4) The pretreated graphene oxide is mixed with N,N-dimethylformamide according to a proportion and stirred uniformly, ultrasonic dispersion is performed for 2h to obtain a dispersion liquid, the boron phenolic aldehyde epoxy resin is added thereto and stirred uniformly, then an appropriate amount of 10% sodium hydroxide solution is added dropwise, heated to 70°C for 5-6h of incubation, the mixed solution is sequentially washed with DMF and deionized water, centrifuged, and dried to obtain functionalized graphene oxide; (5) The polypropylene fiber is placed in an oxygen plasma cabin at 150W for 5min to obtain an activated polypropylene fiber; (6) The activated polypropylene fiber is immersed in a 0.5wt% functionalized graphene oxide dispersion liquid, ultrasonic treatment is performed for 20-30min, then the fiber is taken out and hot-pressed by a hot-pressing roller, the linear pressure of the hot-pressing roller is controlled to be 0.5-1.0 MPa, the roller speed is controlled to be 0.5-1.0 m / min, and the temperature is controlled to be 120°C, and then the fiber is placed in a 60°C vacuum drying box for drying for 4h to obtain a functionalized graphene oxide modified polypropylene fiber.

[0007] Preferably, the molar ratio of bisphenol A diglycidyl ether to formaldehyde in step (1) is 1:1.1; and the amount of ammonia water is 2-3% of the mass of bisphenol A diglycidyl ether.

[0008] Preferably, the mass ratio of the intermediate product to 1% boric acid solution in step (2) is 1:20.

[0009] Preferably, the mass ratio of graphene oxide to deionized water in step (3) is 1:400.

[0010] Preferably, the amount ratio of pretreated graphene oxide, N,N-dimethylformamide, boron phenolic aldehyde epoxy resin and sodium hydroxide solution in step (4) is 100mg:100ml:5g:0.1-0.2g.

[0011] Preferably, the composite foaming agent is made from the following raw materials by weight: soybean protein 50-60 parts, hydroxypropyl methylcellulose 6-8 parts, dodecyl dimethyl betaine 6-8 parts, modified nano-silicon dioxide 3-5 parts, calcium gluconate 1-3 parts, metakaolin micro powder 10-15 parts, and polyether modified siloxane 1-3 parts.

[0012] Preferably, the modified nano-silicon dioxide is prepared by the following method: (a) anhydrous ethanol and deionized water are mixed to obtain a mixed solvent in a volume ratio of 9:1, and nano-silicon dioxide is added thereto in a ratio of 1g:50ml, and after ultrasonic dispersion for 30min, a nano-silicon dioxide suspension is obtained; (b) silane coupling agent KH560 is added dropwise to the above nano-silicon dioxide suspension, and after the dropwise addition is completed, the pH value of the reaction system is adjusted to 4-6 with dilute hydrochloric acid, heated to 70-80℃, and magnetically stirred for 2-3h, and after the reaction is completed, centrifugal separation is performed and the precipitate is washed with anhydrous ethanol for 3-5 times, and dried to obtain modified nano-silicon dioxide.

[0013] Preferably, the amount of silane coupling agent KH560 is 5% of the amount of nano-silicon dioxide.

[0014] The present application also provides a preparation method of the above-mentioned thermal insulation foam concrete, comprising the following steps: A, preparing modified polypropylene fibers; B, preparing a composite foaming agent; C, adding cement, fly ash, diatomite and polycarboxylate superplasticizer into a forced stirrer, and dry mixing for 5-8 minutes at a speed of 300-500 rpm until uniform, slowly adding 70% of the total water amount into the dry mixture, and continuing to stir for 2-3 minutes to form a base slurry; D, premixing the remaining 30% of water with the composite foaming agent, and processing for 1 minute at 8000 rpm by a high-speed emulsifier to form a foaming liquid; E, uniformly injecting the foaming liquid into the base slurry, while increasing the stirring speed to 800-1000 rpm, and continuously stirring for 3-5 minutes until the slurry volume is expanded to 2-2.5 times of the original volume to form a uniform foam slurry, and finally adding the modified polypropylene fibers thereto, and adjusting the stirring speed to 200-300 rpm, and continuing to stir for 1-2 minutes until the fibers are uniformly dispersed to obtain a foam slurry; F, pouring and demolding the mixed slurry, and curing to obtain the thermal insulation foam concrete.

[0015] The raw materials used in the present application are commercially available unless otherwise specified. The percentages involved in the present application are mass percentages unless otherwise specified.

[0016] The beneficial effects of the present application are: 1. The present application adopts specially modified polypropylene fibers, the functionalized graphene oxide formed on the surface of which has a stable three-dimensional network structure, significantly improving the interfacial adhesion between the fibers and the cement matrix. After using the modified polypropylene fibers, the 28-day compressive strength and flexural strength of the prepared foam concrete are significantly improved compared with ordinary foam concrete, effectively solving the problems of large brittleness and easy cracking of traditional foam concrete.

[0017] 2. In the composite foaming agent used in the present application, the soybean protein, hydroxypropyl methyl cellulose and dodecyl dimethyl betaine form a composite stable foam system, the modified nano silicon dioxide forms a nano reinforced film at the bubble interface to inhibit the merging and rupture of the foam; the metakaolin powder fills the pores and promotes the hydration reaction to improve the bubble wall strength; the calcium gluconate adjusts the setting time to optimize the uniformity of the bubble structure; the polyether modified siloxane further improves the fluidity and reduces the pouring defects. The multi-component synergistic effect gives the foam concrete a lower density and a more uniform closed cell structure, achieving a significant reduction in thermal conductivity while maintaining sufficient mechanical strength.

[0018] 3. The modified polypropylene fibers used in the present application reinforce the matrix strength, the composite foaming agent optimizes the pore structure, and the synergistic effect with other raw material components results in foam concrete with excellent thermal insulation performance and mechanical properties. DETAILED DESCRIPTION

[0019] The technical solutions of the present application are further described below in conjunction with specific examples, but are not limited thereto. The cement used in the present application is ordinary Portland cement of Haoli brand, specification P.O. 42.5; the nano silicon dioxide is purchased from Nanjing Tianxing New Material Co., Ltd., particle size 20 nm, product code TSP-F90; the polypropylene fibers are purchased from Dezhou Jirian New Material Technology Co., Ltd.

[0020] Example 1 A kind of thermal insulation foam concrete, it is made of the following weight parts of raw materials: cement 100 kg, fly ash 30 kg, diatomite 50 kg, modified polypropylene fiber 1 kg, composite foaming agent 3 kg, polycarboxylic acid water reducing agent 1 kg, water 70 kg;The modified polypropylene fiber is a functionalized graphene oxide modified polypropylene fiber.

[0021] The functionalized graphene oxide modified polypropylene fiber is prepared by the following method: (1) Bisphenol A diglycidyl ether and formaldehyde are mixed in a molar ratio of 1:1.1, an appropriate amount of n-butanol solvent is added to dissolve completely, the mixed solution is magnetically stirred and heated to 70℃, then catalyst ammonia water is added, stirring and heating to 80-85℃ is continued, after 2h of incubation, the solvent is removed by distillation under reduced pressure, and the intermediate product is obtained; the amount of ammonia water is 2% of the mass of bisphenol A diglycidyl ether; (2) The intermediate product obtained in step (1) is mixed with 1% boric acid solution at a mass ratio of 1:20, heated to 70°C for 10 min under normal pressure, distilled under reduced pressure for 10 min, heated to 80°C for 10 min under normal pressure, distilled under reduced pressure for 10 min again, heated to 90°C for 10 min under normal pressure, and distilled under reduced pressure until the liquid is in a string state, to obtain a boron phenolic epoxy resin; (3) 1 g of graphene oxide is dispersed in 400 ml of deionized water, ultrasonic dispersion is performed for 30-45 min, and then transferred to a high-pressure homogenizer at 200 MPa for 3 cycles to obtain a dispersion liquid, and vacuum freeze-drying is performed to obtain pretreated graphene oxide; (4) 100 mg of pretreated graphene oxide is mixed with 100 ml of N,N-dimethylformamide and stirred uniformly, ultrasonic dispersion is performed for 2 h to obtain a dispersion liquid, 5 g of boron phenolic epoxy resin is added and stirred uniformly, 0.1 g of 10% sodium hydroxide solution is added dropwise, heated to 70°C for 5-6 h, the mixed solution is sequentially washed with DMF and deionized water, centrifuged, and dried to obtain functionalized graphene oxide; (5) The polypropylene fiber is placed in an oxygen plasma chamber at 150 W for 5 min to obtain an activated polypropylene fiber; (6) The activated polypropylene fiber is immersed in a 0.5 wt% functionalized graphene oxide dispersion liquid, ultrasonic treatment is performed for 20-30 min, the fiber is taken out and hot-pressed by a hot-pressing roller, the linear pressure of the hot-pressing roller is controlled to be 0.5-1.0 MPa, the roller speed is controlled to be 0.5-1.0 m / min, and the temperature is controlled to be 120°C, and then the fiber is placed in a vacuum drying box at 60°C for drying for 4 h to obtain a functionalized graphene oxide modified polypropylene fiber.

[0022] The composite foaming agent is prepared from the following raw materials by weight: 50 kg of soybean protein, 6 kg of hydroxypropyl methyl cellulose, 6 kg of dodecyl dimethyl betaine, 3 kg of modified nano silicon dioxide, 1 kg of calcium gluconate, 10 kg of metakaolin powder, and 1 kg of polyether modified siloxane.

[0023] The modified nano silicon dioxide is prepared by the following method: (a) Anhydrous ethanol and deionized water are mixed at a volume ratio of 9:1 to obtain a mixed solvent, and 1 g of nano silicon dioxide is added to the mixed solvent at a ratio of 1 g:50 ml, ultrasonic dispersion is performed for 30 min to obtain a nano silicon dioxide suspension; (b) adding silane coupling agent KH560 dropwise to the above nano-silica suspension, adjusting the pH value of the reaction system to 4-6 with dilute hydrochloric acid after the dropwise addition is completed, heating to 70-80℃, and magnetically stirring the reaction for 2-3h, after the reaction is completed, centrifugal separation and washing the precipitate with anhydrous ethanol for 3-5 times, and drying to obtain modified nano-silica. The amount of silane coupling agent KH560 is 5% of the amount of nano-silica.

[0024] A method for preparing the thermal insulation foam concrete, comprising the following steps: A, preparing modified polypropylene fibers; B, preparing a composite foaming agent; C, adding cement, fly ash, diatomite, and polycarboxylic acid water reducing agent into a forced stirrer, dry mixing at a speed of 300-500 rpm for 5-8 minutes until uniform, slowly adding 70% of the total water amount into the dry mixture, and continuing to stir for 2-3 minutes to form a base slurry; D, premixing the remaining 30% water with the composite foaming agent, processing for 1 minute at 8000 rpm with a high-speed emulsifier to form a foaming liquid; E, injecting the foaming liquid into the base slurry at a constant speed, increasing the stirring speed to 800-1000 rpm, and continuously stirring for 3-5 minutes until the slurry volume expands to 2-2.5 times of the original volume to form a uniform foam slurry, finally adding the modified polypropylene fibers, reducing the stirring speed to 200-300 rpm, and continuing to stir for 1-2 minutes until the fibers are uniformly dispersed to obtain a foam slurry; F, pouring and demolding the mixed slurry, and curing to obtain the thermal insulation foam concrete.

[0025] Example 2 A thermal insulation foam concrete is prepared from the following raw materials by weight: cement 150 kg, fly ash 50 kg, diatomite 80 kg, modified polypropylene fibers 3 kg, composite foaming agent 6 kg, polycarboxylic acid water reducing agent 2 kg, and water 110 kg; the modified polypropylene fibers are functionalized graphene oxide modified polypropylene fibers.

[0026] The functionalized graphene oxide modified polypropylene fibers are prepared by the following method: (1) mixing bisphenol A diglycidyl ether and formaldehyde according to a molar ratio of 1:1.1, adding an appropriate amount of n-butanol solvent to completely dissolve, magnetically stirring the mixed solution and heating to 70℃, then adding catalyst ammonia water, continuing to stir and heating to 80-85℃, maintaining the reaction for 2h, then cooling and distilling under reduced pressure to remove the solvent to obtain an intermediate product; the amount of ammonia water is 3% of the mass of bisphenol A diglycidyl ether; (2) The intermediate product obtained in step (1) is mixed with 1% boric acid solution at a mass ratio of 1:20, heated to 70°C, and kept at normal pressure for 10 min, then distilled under reduced pressure for 10 min, heated to 80°C, and kept at normal pressure for 10 min, then distilled under reduced pressure for 10 min again, heated to 90°C, and kept at normal pressure for 10 min, and distilled under reduced pressure until the liquid is in a string state, to obtain a boron phenolic epoxy resin; (3) 1 g of graphene oxide is dispersed in 400 ml of deionized water, ultrasonic dispersion is performed for 30-45 min, then transferred into a high-pressure homogenizer at 200 MPa, and 3 cycles are performed to obtain a dispersion liquid, and vacuum freeze-drying is performed to obtain pretreated graphene oxide; (4) 100 mg of pretreated graphene oxide is mixed with 100 ml of N,N-dimethylformamide and stirred uniformly, ultrasonic dispersion is performed for 2 h to obtain a dispersion liquid, 5 g of boron phenolic epoxy resin is added and stirred uniformly, 0.1-0.2 g of 10% sodium hydroxide solution is added dropwise, heated to 70°C and kept for 5-6 h of reaction, the mixed solution is sequentially washed with DMF and deionized water, centrifuged, and dried to obtain functionalized graphene oxide; (5) The polypropylene fiber is placed in an oxygen plasma cabin at 150 W for 5 min to obtain an activated polypropylene fiber; (6) The activated polypropylene fiber is immersed in a 0.5 wt% functionalized graphene oxide dispersion liquid, ultrasonic treatment is performed for 20-30 min, the fiber is taken out and hot-pressed by a hot-pressing roller, the linear pressure of the hot-pressing roller is controlled to be 0.5-1.0 MPa, the roller speed is controlled to be 0.5-1.0 m / min, and the temperature is controlled to be 120°C, and then the fiber is placed in a vacuum drying box at 60°C for drying for 4 h to obtain a functionalized graphene oxide modified polypropylene fiber.

[0027] The composite foaming agent is prepared from the following raw materials by weight: 60 kg of soybean protein, 8 kg of hydroxypropyl methyl cellulose, 8 kg of dodecyl dimethyl betaine, 5 kg of modified nano silicon dioxide, 3 kg of calcium gluconate, 15 kg of metakaolin powder, and 3 kg of polyether modified siloxane.

[0028] The modified nano silicon dioxide is prepared by the following method: (a) Anhydrous ethanol and deionized water are mixed at a volume ratio of 9:1 to obtain a mixed solvent, and 1 g of nano silicon dioxide is added to the mixed solvent at a ratio of 1 g:50 ml, ultrasonic dispersion is performed for 30 min to obtain a nano silicon dioxide suspension; (b) adding silane coupling agent KH560 dropwise to the above nano-silica suspension, adjusting the pH value of the reaction system to 4-6 with dilute hydrochloric acid after the dropwise addition is completed, heating to 70-80℃, and magnetically stirring the reaction for 2-3h, after the reaction is completed, centrifugal separation and washing the precipitate with anhydrous ethanol for 3-5 times, and drying to obtain modified nano-silica. The amount of silane coupling agent KH560 is 5% of the amount of nano-silica.

[0029] A method for preparing the thermal insulation foam concrete, comprising the following steps: A, preparing modified polypropylene fibers; B, preparing a composite foaming agent; C, adding cement, fly ash, diatomite, and polycarboxylic acid water reducing agent into a forced stirrer, dry mixing at a speed of 300-500 rpm for 5-8 minutes until uniform, slowly adding 70% of the total water amount into the dry mixture, and continuing to stir for 2-3 minutes to form a base slurry; D, premixing the remaining 30% water with the composite foaming agent, processing through a high-speed emulsifier at 8000 rpm for 1 minute to form a foaming liquid; E, injecting the foaming liquid into the base slurry at a uniform speed, at the same time, increasing the stirring speed to 800-1000 rpm, and continuously stirring for 3-5 minutes until the slurry volume expands to 2-2.5 times of the original volume to form a uniform foam slurry, finally adding modified polypropylene fibers into the foam slurry, reducing the stirring speed to 200-300 rpm, and continuing to stir for 1-2 minutes until the fibers are uniformly dispersed to obtain a foam slurry; F, pouring the mixed slurry, demolding, and curing to obtain the thermal insulation foam concrete.

[0030] Example 3 A thermal insulation foam concrete is prepared from the following raw materials by weight: cement 130 kg, fly ash 40 kg, diatomite 60 kg, modified polypropylene fibers 2 kg, composite foaming agent 5 kg, polycarboxylic acid water reducing agent 1.5 kg, and water 90 kg; the modified polypropylene fibers are functionalized graphene oxide modified polypropylene fibers.

[0031] The functionalized graphene oxide modified polypropylene fibers are prepared by the following method: (1) mixing bisphenol A diglycidyl ether and formaldehyde according to a molar ratio of 1:1.1, adding an appropriate amount of n-butanol solvent to completely dissolve, magnetically stirring the mixed solution and heating to 70℃, then adding catalyst ammonia water, continuing to stir and heating to 80-85℃, maintaining the reaction for 2h, then cooling and distilling under reduced pressure to remove the solvent to obtain an intermediate product; the amount of ammonia water is 2.5% of the mass of bisphenol A diglycidyl ether; (2) The intermediate product obtained in step (1) is mixed with 1% boric acid solution at a mass ratio of 1:20, heated to 70°C, and kept at normal pressure for 10 min, then distilled under reduced pressure for 10 min, heated to 80°C, and kept at normal pressure for 10 min, then distilled under reduced pressure for 10 min again, heated to 90°C, and kept at normal pressure for 10 min, and distilled under reduced pressure until the liquid is in a state of being drawn into a filament, to obtain a boron phenolic epoxy resin; (3) 1 g of graphene oxide is dispersed in 400 ml of deionized water, ultrasonic dispersion is performed for 30-45 min, then transferred into a high-pressure homogenizer at 200 MPa, and 3 cycles are performed to obtain a dispersion liquid, and vacuum freeze-drying is performed to obtain pretreated graphene oxide; (4) 100 mg of the pretreated graphene oxide is mixed with 100 ml of N,N-dimethylformamide and stirred uniformly, ultrasonic dispersion is performed for 2 h to obtain a dispersion liquid, 5 g of the boron phenolic epoxy resin is added thereto and stirred uniformly, 0.1-0.2 g of 10% sodium hydroxide solution is added dropwise, heated to 70°C and kept for 5-6 h of reaction, the mixed solution is sequentially washed with DMF and deionized water, centrifuged, and dried to obtain functionalized graphene oxide; (5) The polypropylene fiber is placed in an oxygen plasma cabin at 150 W for 5 min to obtain an activated polypropylene fiber; (6) The activated polypropylene fiber is immersed in a 0.5 wt% functionalized graphene oxide dispersion liquid, ultrasonic treatment is performed for 20-30 min, the fiber is taken out and hot-pressed by a hot-pressing roller, the linear pressure of the hot-pressing roller is controlled to be 0.5-1.0 MPa, the roller speed is controlled to be 0.5-1.0 m / min, and the temperature is controlled to be 120°C, and then the fiber is placed in a vacuum drying box at 60°C for drying for 4 h to obtain a functionalized graphene oxide modified polypropylene fiber.

[0032] The composite foaming agent is prepared from the following raw materials by weight: 55 kg of soybean protein, 7 kg of hydroxypropyl methyl cellulose, 7 kg of dodecyl dimethyl betaine, 4 kg of modified nano silicon dioxide, 2 kg of calcium gluconate, 12 kg of metakaolin powder, and 2 kg of polyether modified siloxane.

[0033] The modified nano silicon dioxide is prepared by the following method: (a) Anhydrous ethanol and deionized water are mixed at a volume ratio of 9:1 to obtain a mixed solvent, and 1 g of nano silicon dioxide is added thereto at a ratio of 1 g:50 ml, ultrasonic dispersion is performed for 30 min to obtain a nano silicon dioxide suspension; (b) adding silane coupling agent KH560 dropwise to the above nano-silica suspension, after the dropwise addition is completed, adjusting the pH value of the reaction system to 4-6 with dilute hydrochloric acid, heating to 70-80°C, magnetic stirring reaction for 2-3h, after the reaction is completed, centrifugal separation and washing the precipitate with anhydrous ethanol for 3-5 times, drying to obtain modified nano-silica. The amount of silane coupling agent KH560 is 5% of the amount of nano-silica.

[0034] A method for preparing the thermal insulation foam concrete as described above, comprising the following steps: A, preparing modified polypropylene fibers; B, preparing a composite foaming agent; C, adding cement, fly ash, diatomite, and polycarboxylic acid water reducing agent into a forced mixer, dry mixing at a speed of 300-500 rpm for 5-8 minutes until uniform, slowly adding 70% of the total water amount into the dry mixture, continuing to stir for 2-3 minutes to form a base slurry; D, premixing the remaining 30% water with the composite foaming agent, processing for 1 minute at 8000 rpm with a high-speed emulsifier to form a foaming liquid; E, injecting the foaming liquid into the base slurry at a uniform speed, at the same time increasing the stirring speed to 800-1000 rpm, continuing to stir for 3-5 minutes until the slurry volume expands to 2-2.5 times the original volume, forming a uniform foam slurry, finally adding modified polypropylene fibers, reducing the stirring speed to 200-300 rpm, and continuing to stir for 1-2 minutes until the fibers are uniformly dispersed to obtain a foam slurry; F, pouring and demolding the mixed slurry, and curing to obtain the thermal insulation foam concrete.

[0035] Comparative Example 1 A thermal insulation foam concrete, whose raw material composition and preparation method are basically the same as those of Example 1, with the only difference being that the polypropylene fibers are not modified.

[0036] Comparative Example 2 A thermal insulation foam concrete, whose raw material composition and preparation method are basically the same as those of Example 1, with the only difference being that the composite foaming agent is replaced by a single soy protein foaming agent.

[0037] Comparative Example 3 A thermal insulation foam concrete, whose raw material composition and preparation method are basically the same as those of Example 1, with the only difference being that the modified nano-silica in the composite foaming agent is replaced by ordinary nano-silica.

[0038] Comparative Example 4 A thermal insulation foam concrete, whose raw material composition and preparation method are basically the same as those of Example 1, with the only difference being that the polypropylene fibers are not modified, and the composite foaming agent is replaced by a single soy protein foaming agent.

[0039] Performance test The performance test was conducted on the foam concrete prepared in Examples 1-3 and Comparative Examples 1-4, and the test standard referred to JG / T 266-2011 "Foam Concrete". The results are shown in Table 1 below.

[0040] Table 1 Performance test results It can be seen from the results in Table 1 above that the compressive strength and flexural strength of the thermal insulation foam concrete prepared in Examples 1-3 are significantly higher than those of Comparative Examples 1-4, which indicates that the foam concrete prepared in the present application is added with modified polypropylene fibers, and the functionalized graphene oxide formed on the surface thereof has a stable three-dimensional network structure, which significantly improves the interfacial adhesion between the fibers and the cement matrix, inhibits crack propagation, improves brittleness, and improves the mechanical properties of the concrete. The thermal conductivity and water absorption of the thermal insulation foam concrete prepared in Examples 1-3 are significantly lower than those of Comparative Examples 1-4, which is because the soybean protein, hydroxypropyl methyl cellulose and dodecyl dimethyl betaine in the composite foaming agent form a composite foam stabilizing system, the modified nano silicon dioxide forms a nano reinforced film at the bubble interface, inhibits foam merging and rupture, thereby forming a uniform closed pore structure, and reduces the thermal conductivity. The synergistic effect of the composite foaming agent and the modified polypropylene fiber significantly reduces the thermal conductivity of the concrete; the modified polypropylene fiber enhances the integrity of the cement matrix and reduces internal defects; the composite foaming agent optimizes the pore structure and reduces the connected pores, thereby reducing the water absorption. The present application significantly improves the mechanical properties, thermal insulation performance and durability of the foam concrete by introducing functionalized graphene oxide modified polypropylene fibers and special composite foaming agents.

[0041] It should be noted that the above examples are only part of the preferred modes of implementing the present application, but not all. Obviously, based on the above examples of the present application, all other examples obtained by those of ordinary skill in the art without creative labor should be within the scope of protection of the present application.

Claims

1. A thermal insulation foam concrete, characterized in that: The invention is prepared from the following raw materials in parts by weight: 100-150 parts of cement, 30-50 parts of fly ash, 50-80 parts of diatomaceous earth, 1-3 parts of modified polypropylene fiber, 3-6 parts of composite foaming agent, 1-2 parts of polycarboxylic acid water reducer, and 70-110 parts of water; the modified polypropylene fiber is functionalized graphene oxide modified polypropylene fiber.

2. The thermal insulation foam concrete according to claim 1, characterized in that The functionalized graphene oxide modified polypropylene fiber is prepared by the following method: (1) Bisphenol A diglycidyl ether and formaldehyde are mixed according to a molar ratio, and an appropriate amount of n-butanol solvent is added to completely dissolve the mixture. The mixed solution is magnetically stirred and heated to 70°C, and then an appropriate amount of ammonia catalyst is added. The mixture is stirred and heated to 80-85°C. After the mixture is kept at this temperature for 2 hours, the temperature is lowered and the solvent is removed by vacuum distillation to obtain an intermediate product. (2) The intermediate product obtained in step (1) was mixed with 1% boric acid solution in a mass ratio, heated to 70°C and kept at room temperature for 10 minutes, and then distilled under reduced pressure for 10 minutes, then heated to 80°C and kept at room temperature for 10 minutes, and then distilled under reduced pressure for another 10 minutes, and then heated to 90°C and kept at room temperature for 10 minutes, and distilled under reduced pressure until the liquid was in a drawing state, thereby obtaining a boron novolac epoxy resin; (3) Dispersing graphene oxide in deionized water, ultrasonically dispersing for 30-45 min, and then transferring to a high-pressure homogenizer at 200 MPa for 3 cycles to obtain a dispersion, which was then freeze-dried in vacuum to obtain pretreated graphene oxide; (4) The pretreated graphene oxide and N,N-dimethylformamide were mixed in proportion and stirred evenly, and ultrasonically dispersed for 2 hours to obtain a dispersion, to which boron phenolic epoxy resin was added and stirred evenly, and then an appropriate amount of 10% sodium hydroxide solution was added dropwise, and the mixture was heated to 70°C and kept warm for 5-6 hours. The mixed solution was washed with DMF and deionized water in turn, centrifuged, and dried to obtain functionalized graphene oxide; (5) The polypropylene fiber was placed in an oxygen plasma chamber at 150W for 5 minutes to obtain activated polypropylene fiber; (6) The activated polypropylene fiber was immersed in a 0.5 wt% functionalized graphene oxide dispersion and ultrasonically treated for 20-30 min. The fiber was then taken out and hot-pressed and composited using a hot pressing roller. The line pressure of the hot pressing roller was controlled to be 0.5-1.0 MPa, the roller speed was 0.5-1.0 m / min, and the temperature was 120 °C. The fiber was then placed in a vacuum drying oven at 60 °C and dried for 4 h to obtain functionalized graphene oxide modified polypropylene fiber.

3. The thermal insulation foam concrete according to claim 2, characterized in that In the step (1), the molar ratio of bisphenol A diglycidyl ether to formaldehyde is 1:1.1; and the amount of ammonia water used is 2-3% of the mass of bisphenol A diglycidyl ether.

4. The thermal insulation foam concrete according to claim 2, characterized in that The mass ratio of the intermediate product to the 1% boric acid solution in step (2) is 1:

20.

5. The thermal insulation foam concrete according to claim 2, characterized in that: In step (3), the mass ratio of graphene oxide to deionized water is 1:

400.

6. The thermal insulation foam concrete according to claim 2, characterized in that: In the step (4), the amount ratio of the pretreated graphene oxide, N,N-dimethylformamide, boron phenolic epoxy resin and sodium hydroxide solution is 100 mg: 100 ml: 5 g: 0.1-0.2 g.

7. The thermal insulation foam concrete according to claim 1, characterized in that: The composite foaming agent is prepared from the following raw materials in parts by weight: 50-60 parts of soy protein, 6-8 parts of hydroxypropyl methylcellulose, 6-8 parts of dodecyl dimethyl betaine, 3-5 parts of modified nano silicon dioxide, 1-3 parts of calcium gluconate, 10-15 parts of high-density terrestrial micropowder, and 1-3 parts of polyether modified silicone.

8. The thermal insulation foam concrete according to claim 7, characterized in that: The modified nano-silica is prepared by the following method: (a) Anhydrous ethanol and deionized water were prepared in a volume ratio of 9:1 to obtain a mixed solvent, nano-silica was added in a ratio of 1 g:50 ml, and ultrasonic dispersion was performed for 30 minutes to obtain a nano-silica suspension; (b) adding a silane coupling agent KH560 dropwise to the nano-silica suspension, adjusting the pH of the reaction system to 4-6 with dilute hydrochloric acid, heating to 70-80° C., and reacting with magnetic stirring for 2-3 h. After the reaction is completed, centrifuging and washing the precipitate with anhydrous ethanol 3-5 times, and drying to obtain modified nano-silica.

9. The thermal insulation foam concrete according to claim 7, characterized in that: The amount of the silane coupling agent KH560 is 5% of the amount of nano-silicon dioxide.

10. A method for preparing the thermal insulation foam concrete according to any one of claims 1 to 9, characterized in that: The following steps are involved: A, preparation of modified polypropylene fiber; B, preparing a composite foaming agent; C. Add cement, fly ash, diatomaceous earth, and polycarboxylate water reducer into a forced mixer and dry mix at 300-500 rpm for 5-8 minutes until uniform. Slowly add 70% of the total water to the dry mixture and continue stirring for 2-3 minutes to form a base slurry. D. Premix the remaining 30% water with the composite foaming agent and process it in a high-speed emulsifier at 8000 rpm for 1 minute to form a foaming liquid; E. Inject the foaming liquid into the base slurry at a uniform speed, while increasing the stirrer speed to 800-1000 rpm. Continue stirring for 3-5 minutes until the slurry volume expands to 2-2.5 times its original volume to form a uniform foam slurry. Finally, add the modified polypropylene fiber, reduce the speed to 200-300 rpm, and continue stirring for 1-2 minutes until the fibers are evenly dispersed to obtain a foam slurry. F. Casting, demoulding and curing the mixed slurry to obtain thermal insulation foam concrete.

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