Process for the production of a crack-resistant aerated concrete

Abstract

The application belongs to the technical field of building materials, and particularly relates to a preparation process of anti-cracking aerated concrete. The process comprises the following steps: preparation of high-dispersibility wax layer basalt fiber; compounding of tea polyphenol-saponin compound and aluminum powder; compounding of concrete raw materials and initial setting curing. The surface modified basalt fiber is coated by preparing high-hardness paraffin wax, and the high-dispersibility wax layer basalt fiber is prepared, and a high content of the high-dispersibility wax layer basalt fiber is added into the concrete, which can prevent the agglomeration of the high content of the fiber in the early stage, avoid the influence on the fluidity of the concrete system, change the dispersibility of the basalt fiber in the later initial setting stage, make the basalt fiber have high adhesion, and effectively combine with the concrete matrix, so that the prepared aerated concrete has high fiber content, high mechanical property and low dry density.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of building materials, and particularly relates to a preparation process of anti-cracking aerated concrete. BACKGROUND

[0002] The aerated concrete mainly uses sand or fly ash as a siliceous component, and cement and quicklime as a calcareous base material, and is formed into a concrete product with a porous structure through high-temperature and high-pressure steam hardening. The special preparation process of the aerated concrete enables the aerated concrete to have advantages such as high porosity and low density, and the aerated concrete has excellent performance in fire prevention, heat preservation and sound insulation.

[0003] Although the high porosity of the aerated concrete brings characteristics such as small density and good heat preservation, it also leads to poor mechanical properties and brittleness, and cracks are easily generated in the process of production, transportation and use. Therefore, the mechanical properties of the aerated concrete need to be improved, and adding fibers to the aerated concrete is a simple and effective method to enhance the mechanical properties and structural stability.

[0004] Since the fibers need to be adhered to the concrete matrix to enhance the mechanical properties of the overall structure, the fibers need to have high adhesion. In order to prevent the fibers with high adhesion from affecting the fluidity of the concrete slurry in the early stage and increasing the dry density of the concrete by affecting the foaming, the amount of fibers added in the aerated concrete in the prior art is usually not more than 0.5%. The low content of fibers leads to poor strengthening effect of the fibers on the mechanical properties of the aerated concrete, and it is difficult to have high crack resistance. The characteristics of the fibers needing to have high adhesion also lead to the fact that the fibers cannot be surface modified in the prior art to increase the dispersibility of the fibers in the concrete matrix and reduce the agglomeration of the fibers with high content. Therefore, it is urgent to develop a method which can increase the content of fibers in the concrete to improve the mechanical properties, avoid the agglomeration of the fibers to increase the dry density, and also can not affect the adhesion between the fibers and the concrete matrix. SUMMARY

[0005] In order to solve the above technical defects, the application researches a preparation process of anti-cracking aerated concrete. The high-dispersibility wax-layer basalt fibers are added into the concrete system, which can avoid the agglomeration in the early stage, enhance the fluidity of the slurry, and change the surface adhesion in the initial setting stage, so that the fibers can be fully combined with the matrix. The prepared aerated concrete has high fiber content, high mechanical properties and low dry density.

[0006] A preparation process of anti-cracking aerated concrete, comprising the following steps:

[0007] S1: Preparation of high-dispersibility wax-layer basalt fibers

[0008] The No. 58 paraffin wax, Fischer-Tropsch wax, capric acid and stearic acid are melt compounded to obtain high-hardness paraffin wax, the basalt fiber surface is treated by using hydrogen peroxide aqueous solution, then the high-hardness paraffin wax is used for coating to obtain the basalt fiber coated with high-hardness paraffin wax, and then the basalt fiber coated with high-hardness paraffin wax is vacuum-impregnated by using polyethylene glycol 600 diacrylate, filtered and dried to obtain the basalt fiber with high-dispersibility wax layer;

[0009] S2: compounding of tea polyphenol-saponin complex and aluminum powder

[0010] The dry tea residue and soapnut powder are subjected to ultrasonic-microwave synergistic alcohol extraction, rotary evaporation extraction, and freeze drying to obtain a tea polyphenol-saponin complex, the tea polyphenol-saponin complex and triethyl citrate are dissolved in anhydrous ethanol, aluminum powder is added and stirred uniformly, and then drying is performed to obtain a composite gas generating agent;

[0011] S3: compounding of concrete raw materials and initial setting curing

[0012] The composite gas generating agent is dispersed in hot water to obtain a composite gas generating agent dispersion liquid, then the quartz sand and the basalt fiber with high-dispersibility wax layer are added into tap water and stirred uniformly, then the gypsum, cement and quicklime are sequentially added and stirred uniformly, then the foam stabilizer, polycarboxylic acid water reducing agent and the composite gas generating agent dispersion liquid are added and stirred to obtain an aerated concrete compound, which is poured into a mold for initial setting, and then transferred to an autoclave for autoclaving and curing to obtain the anti-cracking aerated concrete.

[0013] Further, the preparation of the basalt fiber with high-dispersibility wax layer in step S1 specifically includes the following steps:

[0014] S1.1: the No. 58 paraffin wax is placed in a container with a stirring device, 4-5wt% of Fischer-Tropsch wax, 5-6wt% of capric acid and 4-8wt% of stearic acid are added, nitrogen is introduced into the container to exhaust air, then the container is sealed and placed in an oil bath at 130-140℃, and magnetic stirring is performed at a speed of 600-800rpm for 2.5-3 hours to obtain high-hardness paraffin wax;

[0015] S1.2: the basalt fiber and hydrogen peroxide aqueous solution with a concentration of 25-30wt% are mixed in a container at a mass ratio of 1: (15-20), ultrasonic treatment is performed at an ultrasonic frequency of 25-30kHz for 25-30 minutes, then reflux reaction is performed at 100-105℃ and 200-250rpm for 3-4 hours, the mixture is cooled to room temperature, centrifugation is performed at a speed of 10000-11000rpm for 4-6 minutes, the precipitate is collected, washed with deionized water for 2-3 times, and then vacuum dried to constant weight to obtain the surface-modified basalt fiber;

[0016] S1.3: The surface modified basalt fiber and petroleum ether are mixed in a container at a mass ratio of 1: (2-3), ultrasonic treatment is performed at an ultrasonic frequency of 25-30 kHz for 8-10 minutes, and the temperature is raised to 50-55°C under stirring, then 3-4 wt% of high hardness paraffin is added, and stirring is continued for 1.5-2 hours, then the temperature is cooled to room temperature, the precipitate is collected by filtration, and vacuum drying is performed at 40-42°C for 16-20 hours to obtain a high hardness paraffin coated basalt fiber;

[0017] S1.4: Polyethylene glycol 600 diacrylate and PBS buffer are mixed at a mass ratio of 1: (45-50), and stirring is performed at a water bath temperature of 45-50°C until the solid is completely dissolved to obtain a modified solution, then the high hardness paraffin coated basalt fiber is immersed in the modified solution and added to a vacuum impregnation tank, vacuum impregnation is performed at 0.08-1 Pa for 15-20 minutes, then the precipitate is collected by filtration, and oven drying is performed at a temperature of 45-50°C until the weight is constant to obtain a high dispersion wax layer basalt fiber.

[0018] Further, the compounding of the tea polyphenol-saponin complex and aluminum powder in step S2 specifically includes the following steps:

[0019] S2.1: Dry tea residue and soapnut powder are added to an ultrasonic-microwave synergistic extractor at a mass ratio of 1: (0.75-0.8), and an ethanol aqueous solution with a concentration of 70-75% is added at a solid-liquid ratio of 1: (15-20) g / mL, the ultrasonic frequency is set to 40-45 kHz, the microwave power is set to 300-320 W, and the temperature is set to 60-65°C, and the mixture is treated for 20-25 minutes, then the extract is obtained by filtration, and the extract is subjected to rotary evaporation to remove the solvent to obtain an extract, the extract is dispersed in 15-20 times the volume of pure water, an equal volume of ethyl acetate is added for extraction, the precipitate is removed by filtration, and the water layer is obtained, then freeze-drying is performed at -50°C to -45°C to obtain a tea polyphenol-saponin complex;

[0020] S2.2: 3-5 parts by weight of the tea polyphenol-saponin complex and 1-1.5 parts by weight of triethyl citrate are dissolved in 15-20 parts by weight of anhydrous ethanol, then 40-50 parts by weight of aluminum powder is quickly added, stirring is performed at 35-40°C and 3500-4000 rpm for 15-20 minutes, then the mixture is dried in a fluidized bed dryer to obtain a composite gas generating agent.

[0021] Further, the compounding of the concrete raw materials and the initial setting curing in step S3 specifically include the following steps:

[0022] S3.1: 0.2-0.3 parts by weight of the composite gas generating agent is added to 5-10 parts by weight of hot water at 55-60°C and stirred uniformly to obtain a composite gas generating agent dispersion;

[0023] S3.2: 200-220 parts by weight of quartz sand and 2-2.5 parts by weight of high-dispersible wax-coated basalt fiber are added into 110-120 parts by weight of tap water and stirred for 1.5-2 minutes, then 12-15 parts by weight of gypsum, 100-110 parts by weight of cement and 50-55 parts by weight of quicklime are sequentially added and stirred for 2-2.5 minutes, then 0.1-0.2 parts by weight of foam stabilizer, 0.3-0.4 parts by weight of polycarboxylic acid water reducer and the composite gas-releasing agent dispersion liquid prepared in step S3.1 are added and stirred for 1.5-2 minutes to obtain an aerated concrete compound;

[0024] S3.3: The aerated concrete compound is poured into a mold, and initial setting is performed at 55-60℃ for 2-4 hours, and then the mold is transferred to an autoclave for autoclaving and curing at 180-185℃ and 1-1.2 MPa for 8-10 hours to obtain a crack-resistant aerated concrete.

[0025] Further, in step S1.2, the basalt fiber has a length of 4-6 mm, a single-fiber diameter of 10-15 μm and a density of 2000-2500 kg / m 3 .

[0026] Further, the PBS buffer in step S1.4 contains 4.3 mmol / L Na2HPO4, 1.4 mmol / L KH2PO4, 137 mmol / L NaCl and 2.7 mmol / L KCl, and has a pH of 7.2-7.4.

[0027] Further, in step S2.2, the fluidized bed dryer is dried by nitrogen hot air at 50-55℃.

[0028] Further, in step S3.2, the quicklime CaO has a content of 90-95%.

[0029] Further, in step S3.2, the foam stabilizer is prepared by mixing oleic acid, triethanolamine and deionized water at a mass ratio of 1: (3-4): (30-36).

[0030] The beneficial effects are: 1, the application first utilizes the hydrogen peroxide aqueous solution to treat the surface of basalt fiber, increases the number of hydroxyl groups on the surface, then utilizes high hardness paraffin to coat the surface modified basalt fiber, and is modified by polyethylene glycol 600 diacrylate through vacuum impregnation, high dispersibility wax layer basalt fiber is prepared, the high dispersibility wax layer basalt fiber is added in concrete, due to the high dispersibility caused by polyethylene glycol 600 diacrylate modification, it can be uniformly dispersed in the concrete system, in the case of high fiber content, the agglomeration phenomenon can be effectively avoided, the influence on the fluidity of the system during mixing can be reduced, the influence on the later foaming is avoided, the dry density of aerated concrete is prevented from being too large, when the concrete system enters the initial setting stage of heating, the wax layer of high dispersibility wax layer basalt fiber melts, the internal rough basalt fiber is exposed, the contact area with the concrete matrix is increased, the basalt fiber changes from high dispersibility to high adhesion, and SiO2, the main component, can participate in the hydration reaction in the alkaline matrix, further strengthening the adhesion strength with the concrete matrix, so that the crack resistance and compressive strength of the subsequent aerated concrete can be effectively improved.

[0031] 2, by adding a higher content of high dispersibility wax layer basalt fiber in concrete, the high content of fiber can be prevented from agglomerating in the early stage, the influence on the fluidity of the concrete system can be avoided, and the surface state of the basalt fiber can be changed in the later initial setting stage, so that the basalt fiber has high adhesion and is effectively combined with the concrete matrix, and the aerated concrete prepared has high fiber content, high mechanical properties and low dry density.

[0032] 3, the application prepares tea polyphenol-saponin complex, and coats the surface of aluminum powder by mixing with triethyl citrate to prepare a composite air-entraining agent, which is added into the subsequent concrete system, triethyl citrate can be hydrolyzed by contacting with alkali solution first, so that the aluminum powder has more time to be dispersed in the concrete system, the uniformity of foaming and the uniformity of cracks are increased, the mechanical properties of aerated concrete are improved, and the tea polyphenol-saponin complex can also assist the foam stabilizer to stabilize the foam when the aluminum powder foams, so that the dry density of aerated concrete is effectively reduced.

[0033] 4, the application melts and compounding paraffin, fischer-tropsch wax, capric acid and stearic acid, so that low-melting-point high-hardness paraffin can be prepared, which can be stably coated on the surface of basalt fiber in the subsequent process, the stability during mixing with the concrete system is improved, the wax layer is prevented from being damaged, so that the dispersing effect of high dispersibility wax layer basalt fiber can be effectively maintained, the basalt fiber is prevented from agglomeration, and the dry density of aerated concrete is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The preparation process flow chart of the anti-cracking aerated concrete used in the embodiments of the application. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be apparently and completely described in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0036] Embodiment 1

[0037] A preparation process of anti-cracking aerated concrete, as shown in the figure, specifically comprises the following steps: Figure 1

[0038] S1: Preparation of high-dispersibility wax-coated basalt fiber

[0039] S1.1: Put No. 58 paraffin into a container with a stirring device, add 4wt% Fischer-Tropsch wax, 5wt% decanoic acid and 4wt% stearic acid, introduce nitrogen into the container to exhaust air, then seal the container and place it in a 130℃ oil bath, and magnetically stir at a speed of 600rpm for 2.5 hours to obtain high-hardness paraffin;

[0040] S1.2: Mix basalt fibers with a length of 4mm, a single-fiber diameter of 10μm and a density of 2000kg / m 3 with a 25wt% hydrogen peroxide aqueous solution at a mass ratio of 1:15, and place them in a container, ultrasonic at a frequency of 25kHz for 25 minutes, then reflux at 100℃ and 200rpm for 3 hours, cool to room temperature, centrifuge at a speed of 10000rpm for 4 minutes, collect the precipitate, wash twice with deionized water, and then vacuum dry to constant weight to obtain surface-modified basalt fibers;

[0041] S1.3: Mix the surface-modified basalt fibers and petroleum ether at a mass ratio of 1:2, place them in a container, ultrasonic at a frequency of 25kHz for 8 minutes, heat to 50℃ under stirring, then add 3wt% high-hardness paraffin, continue to stir for 1.5 hours, then cool to room temperature, filter to collect the precipitate, and vacuum dry at 40℃ for 16 hours to obtain basalt fibers coated with high-hardness paraffin;

[0042] ​S1.4: Polyethylene glycol 600 diacrylate and PBS buffer were mixed at a mass ratio of 1:45, the PBS buffer contained 4.3 mmol / L Na2HPO4, 1.4 mmol / L KH2PO4, 137 mmol / L NaCl, 2.7 mmol / L KCl, and the pH was 7.2, and stirring was carried out at a water bath temperature of 45°C until the solids were completely dissolved to obtain a modified solution, then basalt fibers coated with high-hardness paraffin were immersed in the modified solution and added to a vacuum impregnation tank, vacuum impregnation was carried out at 0.08 Pa for 15 minutes, then the precipitate was filtered and placed in an oven to dry at a temperature of 45°C until the weight was constant to obtain high-dispersion wax-coated basalt fibers.

[0043] S2: Complexing of tea polyphenol-saponin complex and aluminum powder

[0044] S2.1: Dry tea residues and saponin powder were added to an ultrasonic-microwave synergistic extractor at a mass ratio of 1:0.75, and 70% ethanol aqueous solution was added at a solid-liquid ratio of 1:15 g / mL, the ultrasonic frequency was set to 40 kHz, the microwave power was 300 W, and the treatment was carried out at 60°C for 20 minutes, then the extract was filtered, the solvent was removed by rotary evaporation to obtain an extract, the extract was dispersed in 15 times the volume of pure water, an equal volume of ethyl acetate was added for extraction, the precipitate was removed after filtration, and the water layer was freeze-dried at -50°C to obtain a tea polyphenol-saponin complex;

[0045] S2.2: 3 parts by weight of tea polyphenol-saponin complex and 1 part by weight of triethyl citrate were dissolved in 15 parts by weight of anhydrous ethanol, then 40 parts by weight of aluminum powder was quickly added, stirring was carried out at 35°C and 3500 rpm for 15 minutes, then it was placed in a fluidized bed dryer and dried by 50°C nitrogen hot air to obtain a composite gas generating agent.

[0046] S3: Compounding of concrete raw materials and initial setting maintenance

[0047] S3.1: 0.2 parts by weight of the composite gas generating agent was added to 5 parts by weight of hot water at 55°C and stirred uniformly to obtain a composite gas generating agent dispersion;

[0048] S3.2: 200 parts by weight of quartz sand and 2 parts by weight of high-dispersion wax-coated basalt fibers were added to 110 parts by weight of tap water and stirred for 1.5 minutes, then 12 parts by weight of gypsum, 100 parts by weight of cement, and 50 parts by weight of quicklime with a CaO content of 90% were added and stirred for 2 minutes, then 0.1 parts by weight of a foam stabilizer prepared by mixing oleic acid, triethanolamine, and deionized water at a mass ratio of 1:3:30, 0.3 parts by weight of a polycarboxylic acid water reducer, and the composite gas generating agent dispersion prepared in step S3.1 were added, and the mixture was stirred for 1.5 minutes to obtain an aerated concrete compound;

[0049] S3.3: Pour the aerated concrete compound into a mold, and initiate setting at 55℃ for 2 hours, and then transfer to an autoclave for autoclaving at 180℃ and 1MPa for 10 hours to obtain the anti-cracking aerated concrete.

[0050] Example 2

[0051] A preparation process of an anti-cracking aerated concrete, as shown in Figure 1 , specifically comprising the following steps:

[0052] S1: Preparation of high-dispersibility wax-coated basalt fibers

[0053] S1.1: Put No. 58 paraffin wax into a container with stirring device, add 5wt% Fischer-Tropsch wax, 6wt% decanoic acid and 8wt% stearic acid, introduce nitrogen into the container to exhaust air, then seal the container and place it in a 130℃ oil bath, and magnetically stir at a speed of 600rpm for 2.5 hours to obtain high-hardness paraffin wax;

[0054] S1.2: Mix basalt fibers with a length of 4mm, a single-fiber diameter of 10μm and a density of 2000kg / m 3 , and a 25wt% hydrogen peroxide aqueous solution at a mass ratio of 1:20, and place them in a container, and ultrasonic at a frequency of 25kHz for 25 minutes, then reflux at 100℃ and 200rpm for 3 hours, cool to room temperature, and centrifuge at a speed of 10000rpm for 4 minutes, collect the precipitate, wash with deionized water for 2 times, and then vacuum dry to constant weight to obtain surface-modified basalt fibers;

[0055] S1.3: Mix the surface-modified basalt fibers and petroleum ether at a mass ratio of 1:3, and place them in a container, and ultrasonic at a frequency of 25kHz for 8 minutes, and heat to 50℃ under stirring, then add 3wt% high-hardness paraffin wax, continue to stir for 1.5 hours, then cool to room temperature, filter to collect the precipitate, and vacuum dry at 40℃ for 16 hours to obtain basalt fibers coated with high-hardness paraffin wax;

[0056] S1.4: Polyethylene glycol 600 diacrylate and PBS buffer were mixed at a mass ratio of 1:50, the PBS buffer contained 4.3 mmol / L Na2HPO4, 1.4 mmol / L KH2PO4, 137 mmol / L NaCl, 2.7 mmol / L KCl, and the pH was 7.2, and stirring was carried out at a water bath temperature of 45℃ until the solid was completely dissolved to obtain a modified solution, then basalt fibers coated with high-hardness paraffin were immersed in the modified solution and added to a vacuum impregnation tank, vacuum impregnation was carried out at 0.08 Pa for 15 minutes, then the precipitate was filtered and placed in an oven to dry at a temperature of 45℃ until the weight was constant to obtain high-dispersion wax-coated basalt fibers.

[0057] S2: Tea polyphenol-saponin complex and aluminum powder composite

[0058] S2.1: Dry tea residues and saponin powder were put into an ultrasonic-microwave synergistic extractor at a mass ratio of 1:0.8, and 70% ethanol aqueous solution was added at a solid-liquid ratio of 1:20 g / mL, the ultrasonic frequency was set to 40 kHz, the microwave power was 300 W, and the treatment was carried out at 60℃ for 20 minutes, then the extract was filtered, the solvent was removed by rotary evaporation to obtain an extract, the extract was dispersed in 15 times the volume of pure water, an equal volume of ethyl acetate was added for extraction, the precipitate was removed after filtration, and the water layer was freeze-dried at -50℃ to obtain a tea polyphenol-saponin complex;

[0059] S2.2: 5 parts by weight of tea polyphenol-saponin complex and 1.5 parts by weight of triethyl citrate were dissolved in 20 parts by weight of anhydrous ethanol, then 50 parts by weight of aluminum powder was quickly added, stirring was carried out at 35℃ and 3500 rpm for 15 minutes, then it was placed in a fluidized bed dryer and dried by 50℃ nitrogen hot air to obtain a composite gas generating agent.

[0060] S3: Compounding of concrete raw materials and initial setting maintenance

[0061] S3.1: 0.3 parts by weight of the composite gas generating agent was added to 10 parts by weight of hot water at 55℃ and stirred uniformly to obtain a composite gas generating agent dispersion;

[0062] S3.2: 220 parts by weight of quartz sand and 2.5 parts by weight of high-dispersion wax-coated basalt fibers were added to 120 parts by weight of tap water and stirred for 1.5 minutes, then 15 parts by weight of gypsum, 110 parts by weight of cement and 55 parts by weight of quicklime with a CaO content of 90% were added in sequence and stirred for 2 minutes, then 0.2 parts by weight of a foam stabilizer prepared by mixing oleic acid, triethanolamine and deionized water at a mass ratio of 1:4:36, 0.4 parts by weight of a polycarboxylic acid water reducer and the composite gas generating agent dispersion prepared in step S3.1 were added, and the mixture was stirred for 1.5 minutes to obtain an aerated concrete compound;

[0063] S3.3: Pour the aerated concrete compound into a mold, and initiate setting at 55℃ for 2 hours, and then transfer to an autoclave for autoclaving at 180℃ and 1 MPa for 10 hours to obtain the anti-cracking aerated concrete.

[0064] Example 3

[0065] A preparation process of an anti-cracking aerated concrete, as shown in Figure 1 , specifically comprising the following steps:

[0066] S1: Preparation of high-dispersibility wax-coated basalt fibers

[0067] S1.1: Put No. 58 paraffin wax into a container with a stirring device, add 4wt% Fischer-Tropsch wax, 5wt% decanoic acid and 4wt% stearic acid, introduce nitrogen into the container to exhaust air, then seal the container and place it in a 140℃ oil bath, and magnetically stir at a speed of 800 rpm for 3 hours to obtain high-hardness paraffin wax;

[0068] S1.2: Mix basalt fibers with a length of 6mm, a single-fiber diameter of 15μm and a density of 2500kg / m 3 , and a 30wt% hydrogen peroxide aqueous solution at a mass ratio of 1:15, and place them in a container, and ultrasonically treat at an ultrasonic frequency of 30kHz for 30 minutes, then reflux at 105℃ and 250rpm for 4 hours, cool to room temperature, and centrifuge at a speed of 11000rpm for 6 minutes, collect the precipitate, wash with deionized water for 3 times, and then vacuum dry to constant weight to obtain surface-modified basalt fibers;

[0069] S1.3: Mix the surface-modified basalt fibers and petroleum ether at a mass ratio of 1:2, and place them in a container, and ultrasonically treat at an ultrasonic frequency of 30kHz for 10 minutes, heat to 55℃ under stirring, then add 4wt% high-hardness paraffin wax, continue to stir for 2 hours, then cool to room temperature, filter to collect the precipitate, and vacuum dry at 42℃ for 20 hours to obtain basalt fibers coated with high-hardness paraffin wax;

[0070] S1.4: Polyethylene glycol 600 diacrylate and PBS buffer were mixed at a mass ratio of 1:45, the PBS buffer contained 4.3 mmol / L Na2HPO4, 1.4 mmol / L KH2PO4, 137 mmol / L NaCl, 2.7 mmol / L KCl, and the pH was 7.4, and stirring was carried out at a water bath temperature of 50°C until the solids were completely dissolved to obtain a modified solution, then the basalt fiber coated with high hardness paraffin was immersed in the modified solution and added to a vacuum impregnation tank, vacuum impregnation was carried out at 1 Pa for 20 minutes, then the precipitate was filtered and placed in an oven at a temperature of 50°C to dry to constant weight to obtain high-dispersion wax-coated basalt fiber.

[0071] S2: Tea polyphenol-saponin complex and aluminum powder composite

[0072] S2.1: Dry tea residues and saponin powder were added to an ultrasonic-microwave synergistic extractor at a mass ratio of 1:0.75, and 75% ethanol aqueous solution was added at a solid-liquid ratio of 1:15 g / mL, the ultrasonic frequency was set to 45 kHz, the microwave power was 320 W, and the treatment was carried out at 65°C for 25 minutes, then the extract was filtered, the extract was subjected to rotary evaporation to remove the solvent to obtain an extract, the extract was dispersed in 20 times the volume of pure water, an equal volume of ethyl acetate was added for extraction, the precipitate was removed after filtration, and the water layer was freeze-dried at -45°C to obtain a tea polyphenol-saponin complex;

[0073] S2.2: 3 parts by weight of tea polyphenol-saponin complex and 1 part by weight of triethyl citrate were dissolved in 15 parts by weight of anhydrous ethanol, then 40 parts by weight of aluminum powder was quickly added, stirring was carried out at 40°C and 4000 rpm for 20 minutes, then it was placed in a fluidized bed dryer and dried by 55°C nitrogen hot air to obtain a composite gas generating agent.

[0074] S3: Compounding of concrete raw materials and initial setting maintenance

[0075] S3.1: 0.2 parts by weight of the composite gas generating agent was added to 5 parts by weight of hot water at 60°C and stirred uniformly to obtain a composite gas generating agent dispersion;

[0076] S3.2: 200 parts by weight of quartz sand and 2 parts by weight of high-dispersion wax-coated basalt fiber were added to 110 parts by weight of tap water and stirred for 2 minutes, then 12 parts by weight of gypsum, 100 parts by weight of cement and 50 parts by weight of quicklime with a CaO content of 95% were added and stirred for 2.5 minutes, then 0.1 parts by weight of a foam stabilizer prepared by mixing oleic acid, triethanolamine and deionized water at a mass ratio of 1:3:30, 0.3 parts by weight of a polycarboxylic acid water reducer and the composite gas generating agent dispersion prepared in step S3.1 were added, and mixed and stirred for 2 minutes to obtain an aerated concrete compound;

[0077] S3.3: Pour the aerated concrete compound into a mold, allow it to set for 4 hours at 60℃, and then transfer it to an autoclave for autoclaving at 185℃ and 1.2MPa for 8 hours to obtain crack-resistant aerated concrete.

[0078] Comparative Example 1

[0079] The difference from Example 1 is that Comparative Example 1 removed steps S1.1 and S1.3, replaced the basalt fibers coated with high-hardness paraffin in step S1.4 with surface-modified basalt fibers to obtain highly dispersed basalt fibers, and then replaced the subsequent highly dispersed wax layer basalt fibers with an equal mass of highly dispersed basalt fibers. All other specific implementation methods are the same as in Example 1.

[0080] Comparative Example 2

[0081] The difference between Comparative Example 2 and Example 1 is that step S1 was removed, and the highly dispersed wax layer basalt fiber in step S3.2 was replaced with an equal mass of basalt fiber. All other specific implementation methods are the same as those in Example 1.

[0082] Comparative Example 3

[0083] The difference between Comparative Example 3 and Example 1 is that step S2 was removed and the subsequent composite gas-generating agent was replaced with an equal mass of aluminum powder. All other specific implementation methods are the same as those in Example 1.

[0084] Comparative Example 4

[0085] The difference between Comparative Example 4 and Example 1 is that step S1.1 was removed, and the subsequent high-hardness paraffin was replaced with an equal mass of No. 58 paraffin. All other specific implementation methods are the same as those in Example 1.

[0086] Autoclaved aerated concrete (AAC) samples prepared in Examples 1-3 and Comparative Examples 1-4 after normal curing for 28 days of equal quality were used as test samples. Dry density, splitting tensile strength, and compressive strength were tested according to the method of standard GB / T11969-2008 "Test Method for Performance of Autoclaved Aerated Concrete". Each test sample was tested three times, and the average value of the test data was taken. The test results are shown in Table 1.

[0087] Table 1: Dry density, splitting tensile strength, and compressive strength of the test samples

[0088]

[0089] From Table 1, Examples 1-3 and autoclaved aerated concrete block (GB / T11968-2006) standard, the anti-cracking aerated concrete prepared in the application has excellent performance, with low dry density, high splitting tensile strength and compressive strength.

[0090] From the data of Table 1, Example 1 and Comparative Example 1, when the basalt fiber surface is not coated with high-hardness paraffin, the dry density of the aerated concrete changes little, but the mechanical properties decrease significantly. This is because although the polyethylene glycol 600 dipropenoate modification can improve fiber dispersibility and reduce dry density by improving foaming efficiency, the basalt fiber cannot undergo surface roughness transformation during the initial setting stage due to the lack of high-hardness paraffin coating, resulting in poor bonding with the concrete matrix and causing a decrease in mechanical properties. From the data of Comparative Example 2, when the basalt fiber is not treated at all, adding 2 parts by weight of basalt fiber can significantly increase the dry density of the aerated concrete, which proves that the high-dispersibility wax-coated basalt fiber prepared in the application can enable the aerated concrete to have high fiber content and high mechanical properties while maintaining low dry density.

[0091] From the data of Table 1, Example 1 and Comparative Example 3, when the tea polyphenol-saponin complex is not mixed with triethyl citrate to coat the surface of aluminum powder, the dry density of the aerated concrete increases. This is because under the mixing time of Example 1, although the aluminum powder can be uniformly dispersed in the concrete system, it will be lost during stirring, and the generated bubbles will also be broken during stirring, resulting in a decrease in total gas generation and a decrease in foaming stability, leading to a decrease in porosity and an increase in dry density. The mechanical properties naturally increase with the dry density, and the dry density of the example is significantly smaller than that of the comparative example, which proves that coating the surface of aluminum powder with a tea polyphenol-saponin complex mixed with triethyl citrate can reduce the dry density of aerated concrete while maintaining mechanical properties.

[0092] From the data of Table 1, Example 1 and Comparative Example 4, replacing the high-hardness paraffin compounded from paraffin, Fischer-Tropsch wax, capric acid and stearic acid with ordinary paraffin increases the dry density of the aerated concrete, indicating that the basalt fibers are partially agglomerated in the system and the wax layer is damaged during mixing. This proves that the high-hardness paraffin prepared can prevent the wax layer from being damaged, thereby effectively maintaining the dispersing effect of the high-dispersibility wax-coated basalt fiber, preventing the agglomeration of basalt fibers, and reducing the dry density of the aerated concrete while maintaining mechanical properties.

[0093] The above embodiments are only illustrative of the principles of the present application and its efficacy, and are not intended to limit the present application. Any modification or change made by any person skilled in the art without departing from the spirit and scope of the present application shall be covered by the claims of the present application.

Claims

1. A process for the production of a crack resistant aerated concrete, characterized in that, Comprising the following steps: S1: Preparation of high dispersibility wax layer basalt fiber S1.1: Put No. 58 paraffin wax into a container with stirring device, add 4-5wt% Fischer-Tropsch wax, 5-6wt% decanoic acid and 4-8wt% stearic acid, exhaust air by blowing nitrogen into the container, then seal the container and place it in an oil bath at 130-140℃, and magnetically stir at a speed of 600-800rpm for 2.5-3 hours to obtain high hardness paraffin wax; S1.2: Mix basalt fiber and 25-30wt% hydrogen peroxide solution in a mass ratio of 1: (15-20) and place it in a container, ultrasonic at a frequency of 25-30kHz for 25-30 minutes, then reflux at 100-105℃ and 200-250rpm for 3-4 hours, cool to room temperature and centrifuge at a speed of 10000-11000rpm for 4-6 minutes, collect the precipitate, wash with deionized water for 2-3 times, then vacuum dry to constant weight to obtain surface modified basalt fiber; S1.3: Mix the surface modified basalt fiber and petroleum ether in a mass ratio of 1: (2-3) and place it in a container, ultrasonic at a frequency of 25-30kHz for 8-10 minutes, heat to 50-55℃ under stirring, then add 3-4wt% high hardness paraffin wax, continue to stir for 1.5-2 hours, then cool to room temperature, filter to collect the precipitate, and vacuum dry at 40-42℃ for 16-20 hours to obtain basalt fiber coated with high hardness paraffin wax; S1.4: Mix polyethylene glycol 600 diacrylate and PBS buffer in a mass ratio of 1: (45-50), stir until the solid is completely dissolved at a water bath temperature of 45-50℃ to obtain a modified solution, then immerse the basalt fiber coated with high hardness paraffin wax in the modified solution and add it into a vacuum impregnation tank, vacuum impregnate at 0.08-1Pa for 15-20 minutes, then filter to collect the precipitate, and dry in an oven at a temperature of 45-50℃ to constant weight to obtain high dispersibility wax layer basalt fiber; S2: Complexing of tea polyphenol-saponin complex and aluminum powder Ultrasonic-microwave synergistic alcohol extraction of dry tea residue and soapnut powder, rotary evaporation extraction, freeze drying to obtain tea polyphenol-saponin complex, dissolving tea polyphenol-saponin complex and triethyl citrate in anhydrous ethanol, adding aluminum powder and stirring uniformly, drying to obtain a composite gas generating agent; S3: Compounding of concrete raw materials and initial setting curing Disperse the composite gas generating agent in hot water to obtain a composite gas generating agent dispersion, then add quartz sand and high dispersibility wax layer basalt fiber into tap water and stir uniformly, then add gypsum, cement and quicklime in turn and stir uniformly, then add foam stabilizer, polycarboxylic acid water reducing agent and composite gas generating agent dispersion and stir to obtain aerated concrete compound, pour into a mold for initial setting, then transfer to a steam autoclave for steam curing to obtain anti-cracking aerated concrete.

2. A process for the production of a crack resistant aerated concrete according to claim 1, characterized in that, Step S2 of complexing tea polyphenol-saponin complex and aluminum powder, specifically comprising the following steps: S2.1: The dry tea residues and Gleditsia sinensis L. powder are put into an ultrasonic-microwave synergistic extractor at a mass ratio of 1:(0.75-0.8), and then 70-75% ethanol aqueous solution is added at a solid-liquid ratio of 1:(15-20) g / mL; the ultrasonic frequency is set to 40-45 kHz, the microwave power is set to 300-320 W, and the treatment is carried out at 60-65 °C for 20-25 minutes; the extraction liquid is obtained by filtration, and the extraction liquid is subjected to rotary evaporation to remove the solvent to obtain an extract; the extract is dispersed in 15-20 times the volume of pure water, and an equal volume of ethyl acetate is added for extraction; after the precipitate is removed by filtration, the water layer is obtained and subjected to freeze-drying at-50 °C to-45 °C to obtain a tea polyphenol-glycoside complex; S2.2: 3-5 parts by weight of the tea polyphenol-glycoside complex and 1-1.5 parts by weight of triethyl citrate are dissolved in 15-20 parts by weight of anhydrous ethanol, and then 40-50 parts by weight of aluminum powder is quickly added; stirring is carried out at 35-40 °C and 3500-4000 rpm for 15-20 minutes, and then the mixture is dried in a fluidized bed dryer to obtain a composite gas releasing agent.

3. A process for the production of a crack resistant aerated concrete according to claim 2, characterized in that, Step S3: The concrete raw materials are compounded and initial setting maintenance, specifically including the following steps: S3.1: 0.2-0.3 parts by weight of the composite gas releasing agent is added to 5-10 parts by weight of hot water at 55-60 °C and stirred uniformly to obtain a composite gas releasing agent dispersion; S3.2: 200-220 parts by weight of quartz sand and 2-2.5 parts by weight of high-dispersibility wax-coated basalt fiber are added to 110-120 parts by weight of tap water and stirred for 1.5-2 minutes, and then 12-15 parts by weight of gypsum, 100-110 parts by weight of cement, and 50-55 parts by weight of quicklime are sequentially added and stirred for 2-2.5 minutes; then 0.1-0.2 parts by weight of a foam stabilizer, 0.3-0.4 parts by weight of a polycarboxylate superplasticizer, and the composite gas releasing agent dispersion prepared in step S3.1 are added and stirred for 1.5-2 minutes to obtain an aerated concrete compound; S3.3: The aerated concrete compound is poured into a mold, and initial setting is carried out at 55-60 °C for 2-4 hours; then the mold is transferred to an autoclave, and autoclaving is carried out at 180-185 °C and 1-1.2 MPa for 8-10 hours to obtain a crack-resistant aerated concrete.

4. The process for preparing a crack-resistant aerated concrete according to claim 1, characterized in that, The basalt fibers in step S1.2 have a length of 4-6 mm, a filament diameter of 10-15 μm, and a density of 2000-2500 kg / m 3 .

5. The process for preparing a crack-resistant aerated concrete according to claim 1, characterized in that, The PBS buffer in step S1.4 contains 4.3 mmol / L Na2HPO4, 1.4 mmol / L KH2PO4, 137 mmol / L NaCl, and 2.7 mmol / L KCl, and has a pH of 7.2-7.

4.

6. The process for preparing a crack-resistant aerated concrete according to claim 2, characterized in that, The fluidized bed dryer in step S2.2 is dried by 50-55 °C nitrogen hot air.

7. The process for preparing a crack-resistant aerated concrete according to claim 3, characterized in that, The quicklime CaO in step S3.2 has a content of 90-95%.

8. The process for preparing a crack-resistant aerated concrete according to claim 3, characterized in that, The foam stabilizer in step S3.2 is prepared by mixing oleic acid, triethanolamine, and deionized water at a mass ratio of 1:(3-4):(30-36).

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