A lightweight autoclaved aerated concrete block

Abstract

The application discloses a light autoclaved aerated concrete block and relates to the technical field of concrete blocks.The light autoclaved aerated concrete block comprises the following raw materials: cement, lime, base material, modified palygorskite, calcium sulfate dihydrate, aluminum paste, foam stabilizer and deionized water.In the application, the fibrous structure of the modified palygorskite can form a network framework in the slurry, fill the internal pores and block the capillary channels, so that the overall structural compactness and surface strength of the block are improved, and the drying shrinkage and water absorption are reduced.The alkyl benzene sulfonic acid sodium in the foam stabilizer can reduce the surface tension of the slurry and promote the generation of a large number of bubbles.Nano silicon dioxide can form a rigid support framework in the bubble liquid film to prevent the bubbles from merging or breaking.Polyvinyl alcohol forms an elastic protective film on the bubble surface, prolongs the bubble life, greatly improves the block closed porosity, guarantees the light weight of the block, reduces the drying shrinkage due to the uniformity of the pores, and improves the impermeability and overall strength.

Description

Technical Field

[0001] This invention relates to the field of concrete block technology, and in particular to a lightweight autoclaved aerated concrete block. Background Technology

[0002] Concrete blocks are man-made building blocks made primarily of cement, aggregates, and water.

[0003] Existing lightweight autoclaved aerated concrete (AAC) blocks not only have compressive strength sufficient for non-load-bearing filling (far inferior to ordinary concrete), but also exhibit weak impact and abrasion resistance, easily chipping or breaking under external forces, making them unsuitable for high-load building scenarios. Their porous structure also presents significant durability limitations; prolonged contact with moisture leads to water absorption, resulting in softening and slight volume expansion. Furthermore, long-term exposure to the natural environment can cause surface weathering and powdering, affecting the overall service life of the wall. Therefore, this invention provides a lightweight autoclaved aerated concrete (AAC) block. Summary of the Invention

[0004] The main objective of this invention is to provide a high-strength, impermeable concrete block for use in a lightweight autoclaved aerated concrete block.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] This invention provides a lightweight autoclaved aerated concrete (AAC) block, which comprises the following raw materials: 12-15 parts cement, 10-13 parts lime, 30-35 parts base material, 1.5-2 parts modified palygorskite, 1.5-2 parts calcium sulfate dihydrate, 0.2-0.24 parts aluminum powder paste, 0.001-0.002 parts foam stabilizer, and 28-32 parts deionized water;

[0007] The preparation of the lightweight autoclaved aerated concrete blocks includes the following steps:

[0008] S1. Add cement, lime, base material, modified palygorskite and calcium sulfate dihydrate into the reactor and stir. Set the speed to 150 rpm and stir for 3 minutes. Add deionized water and foam stabilizer and stir. Set the speed to 200 rpm and stir for 5-8 minutes. Control the temperature at 25-30℃. Add aluminum powder paste and stir. Set the speed to 200 rpm and stir for 2 minutes to obtain the slurry.

[0009] S2. Apply release agent to the mold, add slurry into the mold, use a vibrating table to vibrate and vent the air, set the frequency to 50Hz, vibration amplitude to 0.5mm, vibrate and vent for 30-60 seconds, place the mold in a constant temperature and humidity room with a temperature of 25-30℃ and humidity ≥90% for 4-5 hours, remove the mold to obtain the brick blank;

[0010] S3. Place the brick blanks into an autoclave and heat them to 190-200℃ at a heating rate of 15℃ / h. Set the pressure to 1.2-1.3MPa and let them stand at a constant temperature for 10-12 hours. After the standing period, cool the autoclave to 80℃ at a cooling rate of ≤15℃ / h. Remove the brick blanks and let them cool naturally to 25℃ to obtain lightweight autoclaved aerated concrete blocks.

[0011] The cement is P.O42.5 grade Portland cement;

[0012] The effective CaO of the lime is ≥85%, and the fineness is ≤200 mesh;

[0013] Lime is a key alkaline activator and calcium supplement in cementitious systems. Its effective calcium oxide component can provide sufficient calcium for the formation of tobermorite crystals during autoclaving. On the other hand, it can create a strongly alkaline environment in the slurry, activate the gas-generating reaction of aluminum powder, and promote the combination of aluminum powder and hydroxide ions to release hydrogen gas. In addition, the slaking reaction of lime can moderately increase the slurry temperature, promote the early hydration process, assist the green body to solidify quickly, and can also work synergistically with calcium sulfate dihydrate to regulate the hydration rate, avoiding premature thickening of the slurry due to excessive cement hydration, which would hinder the normal gas generation of aluminum powder.

[0014] Calcium sulfate dihydrate has a fineness of ≤200 mesh;

[0015] Calcium sulfate dihydrate primarily serves to retard and regulate setting. It can effectively slow down the hydration rate of tricalcium aluminate in cement, preventing the slurry from thickening and clumping due to excessively vigorous early hydration reactions, and allowing sufficient time for aluminum powder to generate gas. During autoclaving, calcium sulfate dihydrate can also participate in the hydration reaction to generate hydrate products such as ettringite, filling the micropores inside the blocks and improving structural density. At the same time, calcium sulfate dihydrate can inhibit the excessive slaking of lime, reducing microcracks caused by uneven volume expansion of the green body, thus balancing the stability of the green body during molding and its later mechanical properties.

[0016] Furthermore, the preparation of the aluminum powder paste includes the following steps: adding deionized water into the reaction vessel and stirring at a speed of 200 rpm, adding aluminum powder and stirring at a speed of 200 rpm for 3-5 minutes to obtain the aluminum powder paste;

[0017] The mass ratio of aluminum powder to deionized water is 1:12.

[0018] Aluminum powder purity ≥ 98%, particle size ≤ 325 mesh.

[0019] Aluminum powder is a key gas-generating component for achieving the lightweight and porous core characteristics of building blocks. To prevent agglomeration of aluminum powder, it is mixed with water to form a paste before being added to the slurry. In the strongly alkaline environment of the slurry, the aluminum powder reacts with hydroxide ions to release hydrogen gas. After being stabilized by a foam stabilizer, this hydrogen gas forms uniform and fine bubbles in the slurry, ultimately constructing a porous structure with a high closed-cell rate in the green body, reducing the dry density of the building blocks to a lightweight level. At the same time, these closed cells also improve the thermal insulation performance of the building blocks. Furthermore, the water dispersed in the aluminum powder paste must be included in the total water volume to ensure a stable water-cement ratio and to avoid interfering with the hydration process of the cementitious material.

[0020] Furthermore, the base material is either fly ash or quartz sand.

[0021] The silica content of fly ash is ≥50%, and the silica content of quartz sand is ≥90%.

[0022] Furthermore, the release agent is a mixture of silicone oil and water;

[0023] The volume ratio of the silicone oil to water is 1:10.

[0024] Furthermore, the preparation of the modified palygorskite includes the following steps:

[0025] A1. Add palygorskite to a pulverizer and pulverize it at 3000 rpm for 20-30 minutes. Pass the pulverized material through a 200-mesh sieve to obtain palygorskite powder. Add the palygorskite powder to a constant temperature oven and dry it at 105℃ for 2 hours to obtain dried palygorskite powder.

[0026] A2. Add deionized water and dried palygorskite powder to the reactor and stir. Set the stirring speed to 200 rpm and stir for 5-8 minutes. Add sodium hexametaphosphate and stir. Set the reactor temperature to 50-60℃ and stir at 200 rpm for 1 hour. Heat the reactor to 70-80℃ and add sodium stearate. Maintain the temperature at 70-80℃ and stir at 200 rpm for 2 hours to obtain a suspension.

[0027] A3. Add the suspension to a vacuum filter and filter. Set the vacuum level to 0.06-0.08 MPa, turn on the vacuum pump, and filter for 10-20 minutes. Remove the filtrate, collect the solid, and wash the solid with deionized water 3-4 times to obtain a moist solid. Place the moist solid in a constant temperature oven to dry. Set the temperature to 80℃ and dry for 4 hours to obtain a dry solid. Place the dry solid in a pulverizer to pulverize. Set the speed to 3500 rpm and pulverize for 15-20 minutes. Pass the pulverized solid through a 325-mesh sieve to obtain modified palygorskite.

[0028] Furthermore, the mass ratio of dried palygorskite powder to deionized water in A2 is 1:2-3;

[0029] The solid in A3 is washed with deionized water until the pH value is reduced to 7.

[0030] Furthermore, the mass ratio of the dried palygorskite powder, sodium hexametaphosphate, and sodium stearate is 1:0.02-0.03:0.01-0.02.

[0031] Furthermore, the preparation of the foam stabilizer includes the following steps:

[0032] B1. Add deionized water to the reaction vessel and stir. Heat the temperature to 80°C and set the speed to 250 rpm. Add polyvinyl alcohol and stir for 30 minutes to obtain a polyvinyl alcohol solution.

[0033] B2. Add deionized water and nano-silica to an ultrasonic disperser and disperse for 30 minutes at a power of 300W. Add sodium alkylbenzene sulfonate and stir for 15 minutes at a speed of 300rpm. Add polyvinyl alcohol solution and stir for 20 minutes at a speed of 300rpm to obtain a foam stabilizer.

[0034] Furthermore, the mass ratio of deionized water to polyvinyl alcohol in B1 is 10-15:1.

[0035] Furthermore, the mass ratio of deionized water, nano-silica, polyvinyl alcohol solution, and sodium alkylbenzene sulfonate in B2 is 9:0.6:5.2:1.

[0036] The particle size of nano-silica is 20-50nm, and the specific surface area is ≥300m² / g.

[0037] The degree of alcoholysis of polyvinyl alcohol is 88%.

[0038] The present invention has the following beneficial effects:

[0039] 1. In this invention, modified palygorskite is added. Its fibrous structure can form a network skeleton in the slurry, filling the internal pores and blocking the capillary channels, which not only improves the overall structural density and surface strength of the block, but also reduces the drying shrinkage rate and water absorption rate. Sodium hexametaphosphate gives palygorskite excellent dispersibility, ensuring that it is evenly distributed in the slurry and avoiding local agglomeration that affects performance. The organic modification of sodium stearate enhances the interfacial bonding ability between palygorskite and cement matrix, while its micro-expansion characteristics can compensate for the volume shrinkage during the hydration and drying stages, synergistically improving the impermeability and crack resistance of the block.

[0040] 2. In this invention, the added foam stabilizer is the core auxiliary material to ensure the uniformity and stability of bubbles. The components in the foam stabilizer work synergistically to achieve the formation, stabilization and shape preservation of bubbles. Among them, sodium alkylbenzene sulfonate can reduce the surface tension of the slurry and promote the generation of a large number of bubbles; nano silica forms a rigid support skeleton in the bubble liquid film to prevent bubbles from merging or breaking; polyvinyl alcohol forms an elastic protective film on the bubble surface to extend the foam life. The combination of the three can control the bubble particle size within a small range, greatly improve the closed-cell rate of the block, and at the same time suppress the generation of large bubbles and interconnected pores. This not only ensures the lightweight characteristics of the block, but also reduces the drying shrinkage rate due to the uniformity of pores, thereby improving impermeability and overall strength.

[0041] 3. In this invention, aluminum powder and foam stabilizer work synergistically. Aluminum powder releases hydrogen in the alkaline environment provided by the cementing system, providing a gas source for the formation of pores in the blocks. The foam stabilizer specifically addresses the problem of uncontrolled bubble generation from aluminum powder. Sodium alkylbenzene sulfonate reduces the surface tension of the slurry, promoting the generation of a large number of bubbles. Nano-silica forms a rigid skeleton in the bubble liquid film to prevent bubble coalescence. Polyvinyl alcohol forms an elastic protective film to extend the foam life. The three components work together with aluminum powder to control the bubble particle size within a small and uniform range, significantly improving the closed-cell rate. This not only ensures the lightweight thermal insulation performance of the blocks but also reduces interconnected pores due to the uniform pore distribution, indirectly reducing the drying shrinkage rate. Detailed Implementation

[0042] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0043] It should be noted that all raw materials used in the following experiments are commercially available.

[0044] Example 1: A lightweight autoclaved aerated concrete block, comprising the following raw materials: 12 parts cement, 10 parts lime, 30 parts base material, 1.5 parts modified palygorskite, 1.5 parts calcium sulfate dihydrate, 0.2 parts aluminum powder paste, 0.001 parts foam stabilizer and 28 parts deionized water.

[0045] The preparation of lightweight autoclaved aerated concrete blocks includes the following steps:

[0046] S1. Add cement, lime, base material, modified palygorskite and calcium sulfate dihydrate into the reactor and stir. Set the speed to 150 rpm and stir for 3 minutes. Add deionized water and foam stabilizer and stir. Set the speed to 200 rpm and stir for 5-8 minutes. Control the temperature at 25-30℃. Add aluminum powder paste and stir. Set the speed to 200 rpm and stir for 2 minutes to obtain the slurry.

[0047] S2. Apply release agent to the mold, add slurry into the mold, use a vibrating table to vibrate and vent the air, set the frequency to 50Hz, vibration amplitude to 0.5mm, vibrate and vent for 30-60 seconds, place the mold in a constant temperature and humidity room with a temperature of 25-30℃ and humidity ≥90% for 4-5 hours, remove the mold to obtain the brick blank;

[0048] S3. Place the brick blanks into an autoclave and heat them to 190-200℃ at a heating rate of 15℃ / h. Set the pressure to 1.2-1.3MPa and let them stand at a constant temperature for 10-12 hours. After the standing period, cool the autoclave to 80℃ at a cooling rate of ≤15℃ / h. Remove the brick blanks and let them cool naturally to 25℃ to obtain lightweight autoclaved aerated concrete blocks.

[0049] The preparation of aluminum powder paste includes the following steps: adding deionized water into the reaction vessel and stirring at a speed of 200 rpm, adding aluminum powder and stirring at a speed of 200 rpm for 3-5 minutes to obtain aluminum powder paste;

[0050] The mass ratio of aluminum powder to deionized water is 1:12.

[0051] The base material is either fly ash or quartz sand.

[0052] The release agent is a mixture of silicone oil and water;

[0053] The volume ratio of silicone oil to water is 1:10.

[0054] The preparation of modified palygorskite includes the following steps:

[0055] A1. Add palygorskite to a pulverizer and pulverize it at 3000 rpm for 20-30 minutes. Pass the pulverized material through a 200-mesh sieve to obtain palygorskite powder. Add the palygorskite powder to a constant temperature oven and dry it at 105℃ for 2 hours to obtain dried palygorskite powder.

[0056] A2. Add deionized water and dried palygorskite powder to the reactor and stir. Set the stirring speed to 200 rpm and stir for 5-8 minutes. Add sodium hexametaphosphate and stir. Set the reactor temperature to 50-60℃ and stir at 200 rpm for 1 hour. Heat the reactor to 70-80℃ and add sodium stearate. Maintain the temperature at 70-80℃ and stir at 200 rpm for 2 hours to obtain a suspension.

[0057] A3. Add the suspension to a vacuum filter and filter. Set the vacuum level to 0.06-0.08 MPa, turn on the vacuum pump, and filter for 10-20 minutes. Remove the filtrate, collect the solid, and wash the solid with deionized water 3-4 times to obtain a moist solid. Place the moist solid in a constant temperature oven to dry. Set the temperature to 80℃ and dry for 4 hours to obtain a dry solid. Place the dry solid in a pulverizer to pulverize. Set the speed to 3500 rpm and pulverize for 15-20 minutes. Pass the pulverized solid through a 325-mesh sieve to obtain modified palygorskite.

[0058] The mass ratio of dried palygorskite powder to deionized water in A2 is 1:2-3;

[0059] In A3, the solid was washed with deionized water until the pH value was reduced to 7.

[0060] The mass ratio of dried palygorskite powder, sodium hexametaphosphate, and sodium stearate is 1:0.02-0.03:0.01-0.02.

[0061] The preparation of foam stabilizers includes the following steps:

[0062] B1. Add deionized water to the reaction vessel and stir. Heat the temperature to 80°C and set the speed to 250 rpm. Add polyvinyl alcohol and stir for 30 minutes to obtain a polyvinyl alcohol solution.

[0063] B2. Add deionized water and nano-silica to an ultrasonic disperser and disperse for 30 minutes at a power of 300W. Add sodium alkylbenzene sulfonate and stir for 15 minutes at a speed of 300rpm. Add polyvinyl alcohol solution and stir for 20 minutes at a speed of 300rpm to obtain a foam stabilizer.

[0064] The mass ratio of deionized water to polyvinyl alcohol in B1 is 10-15:1.

[0065] The mass ratio of deionized water, nano-silica, polyvinyl alcohol solution, and sodium alkylbenzene sulfonate in B2 is 9:0.6:5.2:1.

[0066] Example 2: A lightweight autoclaved aerated concrete block, comprising the following raw materials: 13.5 parts cement, 11.5 parts lime, 32.5 parts base material, 1.75 parts modified palygorskite, 1.75 parts calcium sulfate dihydrate, 0.22 parts aluminum powder paste, 0.0015 parts foam stabilizer, and 30 parts deionized water;

[0067] The preparation of lightweight autoclaved aerated concrete blocks includes the following steps:

[0068] S1. Add cement, lime, base material, modified palygorskite and calcium sulfate dihydrate into the reactor and stir. Set the speed to 150 rpm and stir for 3 minutes. Add deionized water and foam stabilizer and stir. Set the speed to 200 rpm and stir for 5-8 minutes. Control the temperature at 25-30℃. Add aluminum powder paste and stir. Set the speed to 200 rpm and stir for 2 minutes to obtain the slurry.

[0069] S2. Apply release agent to the mold, add slurry into the mold, use a vibrating table to vibrate and vent the air, set the frequency to 50Hz, vibration amplitude to 0.5mm, vibrate and vent for 30-60 seconds, place the mold in a constant temperature and humidity room with a temperature of 25-30℃ and humidity ≥90% for 4-5 hours, remove the mold to obtain the brick blank;

[0070] S3. Place the brick blanks into an autoclave and heat them to 190-200℃ at a heating rate of 15℃ / h. Set the pressure to 1.2-1.3MPa and let them stand at a constant temperature for 10-12 hours. After the standing period, cool the autoclave to 80℃ at a cooling rate of ≤15℃ / h. Remove the brick blanks and let them cool naturally to 25℃ to obtain lightweight autoclaved aerated concrete blocks.

[0071] The preparation of aluminum powder paste includes the following steps: adding deionized water into the reaction vessel and stirring at a speed of 200 rpm, adding aluminum powder and stirring at a speed of 200 rpm for 3-5 minutes to obtain aluminum powder paste;

[0072] The mass ratio of aluminum powder to deionized water is 1:12.

[0073] The base material is either fly ash or quartz sand.

[0074] The release agent is a mixture of silicone oil and water;

[0075] The volume ratio of silicone oil to water is 1:10.

[0076] The preparation of modified palygorskite includes the following steps:

[0077] A1. Add palygorskite to a pulverizer and pulverize it at 3000 rpm for 20-30 minutes. Pass the pulverized material through a 200-mesh sieve to obtain palygorskite powder. Add the palygorskite powder to a constant temperature oven and dry it at 105℃ for 2 hours to obtain dried palygorskite powder.

[0078] A2. Add deionized water and dried palygorskite powder to the reactor and stir. Set the stirring speed to 200 rpm and stir for 5-8 minutes. Add sodium hexametaphosphate and stir. Set the reactor temperature to 50-60℃ and stir at 200 rpm for 1 hour. Heat the reactor to 70-80℃ and add sodium stearate. Maintain the temperature at 70-80℃ and stir at 200 rpm for 2 hours to obtain a suspension.

[0079] A3. Add the suspension to a vacuum filter and filter. Set the vacuum level to 0.06-0.08 MPa, turn on the vacuum pump, and filter for 10-20 minutes. Remove the filtrate, collect the solid, and wash the solid with deionized water 3-4 times to obtain a moist solid. Place the moist solid in a constant temperature oven to dry. Set the temperature to 80℃ and dry for 4 hours to obtain a dry solid. Place the dry solid in a pulverizer to pulverize. Set the speed to 3500 rpm and pulverize for 15-20 minutes. Pass the pulverized solid through a 325-mesh sieve to obtain modified palygorskite.

[0080] The mass ratio of dried palygorskite powder to deionized water in A2 is 1:2-3;

[0081] In A3, the solid was washed with deionized water until the pH value was reduced to 7.

[0082] The mass ratio of dried palygorskite powder, sodium hexametaphosphate, and sodium stearate is 1:0.02-0.03:0.01-0.02.

[0083] The preparation of foam stabilizers includes the following steps:

[0084] B1. Add deionized water to the reaction vessel and stir. Heat the temperature to 80°C and set the speed to 250 rpm. Add polyvinyl alcohol and stir for 30 minutes to obtain a polyvinyl alcohol solution.

[0085] B2. Add deionized water and nano-silica to an ultrasonic disperser and disperse for 30 minutes at a power of 300W. Add sodium alkylbenzene sulfonate and stir for 15 minutes at a speed of 300rpm. Add polyvinyl alcohol solution and stir for 20 minutes at a speed of 300rpm to obtain a foam stabilizer.

[0086] The mass ratio of deionized water to polyvinyl alcohol in B1 is 10-15:1.

[0087] The mass ratio of deionized water, nano-silica, polyvinyl alcohol solution, and sodium alkylbenzene sulfonate in B2 is 9:0.6:5.2:1.

[0088] Example 3: A lightweight autoclaved aerated concrete block, comprising the following raw materials: 15 parts cement, 13 parts lime, 35 parts base material, 2 parts modified palygorskite, 2 parts calcium sulfate dihydrate, 0.24 parts aluminum powder paste, 0.002 parts foam stabilizer and 32 parts deionized water.

[0089] The preparation of lightweight autoclaved aerated concrete blocks includes the following steps:

[0090] S1. Add cement, lime, base material, modified palygorskite and calcium sulfate dihydrate into the reactor and stir. Set the speed to 150 rpm and stir for 3 minutes. Add deionized water and foam stabilizer and stir. Set the speed to 200 rpm and stir for 5-8 minutes. Control the temperature at 25-30℃. Add aluminum powder paste and stir. Set the speed to 200 rpm and stir for 2 minutes to obtain the slurry.

[0091] S2. Apply release agent to the mold, add slurry into the mold, use a vibrating table to vibrate and vent the air, set the frequency to 50Hz, vibration amplitude to 0.5mm, vibrate and vent for 30-60 seconds, place the mold in a constant temperature and humidity room with a temperature of 25-30℃ and humidity ≥90% for 4-5 hours, remove the mold to obtain the brick blank;

[0092] S3. Place the brick blanks into an autoclave and heat them to 190-200℃ at a heating rate of 15℃ / h. Set the pressure to 1.2-1.3MPa and let them stand at a constant temperature for 10-12 hours. After the standing period, cool the autoclave to 80℃ at a cooling rate of ≤15℃ / h. Remove the brick blanks and let them cool naturally to 25℃ to obtain lightweight autoclaved aerated concrete blocks.

[0093] The preparation of aluminum powder paste includes the following steps: adding deionized water into the reaction vessel and stirring at a speed of 200 rpm, adding aluminum powder and stirring at a speed of 200 rpm for 3-5 minutes to obtain aluminum powder paste;

[0094] The mass ratio of aluminum powder to deionized water is 1:12.

[0095] The base material is either fly ash or quartz sand.

[0096] The release agent is a mixture of silicone oil and water;

[0097] The volume ratio of silicone oil to water is 1:10.

[0098] The preparation of modified palygorskite includes the following steps:

[0099] A1. Add palygorskite to a pulverizer and pulverize it at 3000 rpm for 20-30 minutes. Pass the pulverized material through a 200-mesh sieve to obtain palygorskite powder. Add the palygorskite powder to a constant temperature oven and dry it at 105℃ for 2 hours to obtain dried palygorskite powder.

[0100] A2. Add deionized water and dried palygorskite powder to the reactor and stir. Set the stirring speed to 200 rpm and stir for 5-8 minutes. Add sodium hexametaphosphate and stir. Set the reactor temperature to 50-60℃ and stir at 200 rpm for 1 hour. Heat the reactor to 70-80℃ and add sodium stearate. Maintain the temperature at 70-80℃ and stir at 200 rpm for 2 hours to obtain a suspension.

[0101] A3. Add the suspension to a vacuum filter and filter. Set the vacuum level to 0.06-0.08 MPa, turn on the vacuum pump, and filter for 10-20 minutes. Remove the filtrate, collect the solid, and wash the solid with deionized water 3-4 times to obtain a moist solid. Place the moist solid in a constant temperature oven to dry. Set the temperature to 80℃ and dry for 4 hours to obtain a dry solid. Place the dry solid in a pulverizer to pulverize. Set the speed to 3500 rpm and pulverize for 15-20 minutes. Pass the pulverized solid through a 325-mesh sieve to obtain modified palygorskite.

[0102] The mass ratio of dried palygorskite powder to deionized water in A2 is 1:2-3;

[0103] In A3, the solid was washed with deionized water until the pH value was reduced to 7.

[0104] The mass ratio of dried palygorskite powder, sodium hexametaphosphate, and sodium stearate is 1:0.02-0.03:0.01-0.02.

[0105] The preparation of foam stabilizers includes the following steps:

[0106] B1. Add deionized water to the reaction vessel and stir. Heat the temperature to 80°C and set the speed to 250 rpm. Add polyvinyl alcohol and stir for 30 minutes to obtain a polyvinyl alcohol solution.

[0107] B2. Add deionized water and nano-silica to an ultrasonic disperser and disperse for 30 minutes at a power of 300W. Add sodium alkylbenzene sulfonate and stir for 15 minutes at a speed of 300rpm. Add polyvinyl alcohol solution and stir for 20 minutes at a speed of 300rpm to obtain a foam stabilizer.

[0108] The mass ratio of deionized water to polyvinyl alcohol in B1 is 10-15:1.

[0109] The mass ratio of deionized water, nano-silica, polyvinyl alcohol solution, and sodium alkylbenzene sulfonate in B2 is 9:0.6:5.2:1.

[0110] Comparative Example 1: The difference between this comparative example and Example 1 is that:

[0111] In this comparative example, no release agent was applied to the mold.

[0112] Comparative Example 2: The difference between this comparative example and Example 1 is that:

[0113] This comparative example does not contain foam stabilizers.

[0114] Comparative Example 3 differs from Example 1 in that:

[0115] This comparative example does not contain modified palygorskite.

[0116] Performance testing: The concrete blocks prepared in Examples 1, 2, 3, Comparative Examples 1, 2, and 3 were tested.

[0117] Performance testing: The relevant properties of the lightweight autoclaved aerated concrete block samples provided in Examples 1-3 and Comparative Examples 1-3 were tested respectively, and the test data are recorded in Table 1 below:

[0118]

[0119] Based on the above data, the following conclusions can be drawn:

[0120] (1) The through-face cracks of Examples 1-3 are far superior to those of Comparative Examples 1-3. The key point is that the Examples avoid the generation of through-face cracks by applying a release agent in the mold, and the release agent forms a uniform and dense isolation film on the inner wall of the mold during the molding and demolding process.

[0121] (2) The mass loss after 15 freeze-thaw cycles in Examples 1-3 is far better than that in Comparative Examples 1-3. The key point is that the examples add a foam stabilizer, which can increase the closed-cell rate of the blocks and reduce the number of interconnected pores. The closed-cell structure can prevent a large amount of water from penetrating, thereby reducing mass loss.

[0122] (3) The drying shrinkage rate of Examples 1-3 is far better than that of Comparative Examples 1-3. The key point is that the examples added modified palygorskite.

[0123] Through the above demonstration, the present invention is significantly superior to the control group in terms of through-face cracks, mass loss after 15 freeze-thaw cycles, and drying shrinkage rate, thus verifying the advanced nature and rationality of the preparation process.

[0124] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0125] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A lightweight autoclaved aerated concrete block, characterized in that, The lightweight autoclaved aerated concrete blocks comprise the following raw materials: 12-15 parts cement, 10-13 parts lime, 30-35 parts base material, 1.5-2 parts modified palygorskite, 1.5-2 parts calcium sulfate dihydrate, 0.2-0.24 parts aluminum powder paste, 0.001-0.002 parts foam stabilizer, and 28-32 parts deionized water; The preparation of the lightweight autoclaved aerated concrete blocks includes the following steps: S1. Add cement, lime, base material, modified palygorskite and calcium sulfate dihydrate into the reactor and stir. Add deionized water and foam stabilizer and stir. Add aluminum powder paste and stir to obtain slurry. S2. Apply release agent to the mold, add slurry into the mold, use a vibrating table to vibrate and vent the air, after venting, let the mold stand, remove the mold, and obtain the brick blank; S3. Place the brick blanks into an autoclave and heat them to 190-200℃ at a heating rate of 15℃ / h. Set the pressure to 1.2-1.3MPa and let them stand at a constant temperature for 10-12 hours. After the standing time is over, cool the autoclave to 80℃ at a cooling rate of ≤15℃ / h. Remove the brick blanks and let them cool naturally to 25℃ to obtain lightweight autoclaved aerated concrete blocks. The preparation of the modified palygorskite includes the following steps: A1. Add palygorskite to a pulverizer and pulverize it to obtain palygorskite powder. Add the palygorskite powder to a constant temperature oven and dry it to obtain dried palygorskite powder. A2. Add deionized water and dried palygorskite powder to the reaction vessel and stir. Add sodium hexametaphosphate and stir. Add sodium stearate and stir to obtain a suspension. A3. Add the suspension to a vacuum filter for filtration, turn on the vacuum pump, filter out the filtrate, collect the solid, wash the solid with deionized water to obtain a wet solid, put the wet solid into a constant temperature oven to dry to obtain a dry solid, and put the dry solid into a pulverizer to pulverize to obtain modified palygorskite. The preparation of the foam stabilizer includes the following steps: B1. Add deionized water to the reaction vessel and stir, then add polyvinyl alcohol and stir to obtain a polyvinyl alcohol solution; B2. Deionized water and nano-silica are added to an ultrasonic disperser for dispersion, sodium alkylbenzene sulfonate is added and stirred, and polyvinyl alcohol solution is added and stirred to obtain a foam stabilizer.

2. The lightweight autoclaved aerated concrete block according to claim 1, characterized in that, The preparation of the aluminum powder paste includes the following steps: Deionized water was added to the reaction vessel and stirred, then aluminum powder was added and stirred to obtain an aluminum powder paste. The mass ratio of aluminum powder to deionized water is 1:

12.

3. The lightweight autoclaved aerated concrete block according to claim 1, characterized in that, The base material is either fly ash or quartz sand.

4. The lightweight autoclaved aerated concrete block according to claim 1, characterized in that, The release agent is a mixture of silicone oil and water; The volume ratio of the silicone oil to water is 1:

10.

5. The lightweight autoclaved aerated concrete block according to claim 1, characterized in that, The mass ratio of dried palygorskite powder to deionized water in A2 is 1:2-3.

6. The lightweight autoclaved aerated concrete block according to claim 1, characterized in that, The mass ratio of the dried palygorskite powder, sodium hexametaphosphate, and sodium stearate is 1:0.02-0.03:0.01-0.

02.

7. The lightweight autoclaved aerated concrete block according to claim 1, characterized in that, The mass ratio of deionized water to polyvinyl alcohol in B1 is 10-15:

1.

8. The lightweight autoclaved aerated concrete block according to claim 1, characterized in that, The mass ratio of deionized water, nano-silica, polyvinyl alcohol solution, and sodium alkylbenzene sulfonate in B2 is 9:0.6:5.2:1.

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