Autoclaved aerated concrete block and preparation process thereof

Abstract

The invention relates to the field of building materials, and particularly discloses an autoclaved aerated concrete block and a preparation process thereof. The autoclaved aerated concrete block is prepared from the following raw materials in parts by weight: 27 to 29 parts of coal gangue waste residues, 8.6 to 9.6 parts of concrete waste slurry, 7.2 to 8 parts of cement, 4.9 to 5.5 parts of quick lime, 1.5 to 1.9 parts of fly ash, 0.3 to 0.5 part of a water reducing agent, 0.2 to 0.4 part of a foaming agent, 34 to 37.5 parts of water, 2 to 2.5 parts of freeze-thaw resistant fibers and 1 to 1.5 parts of silanized rubber particles. The freeze-thaw resistant fibers are basalt fibers modified by chitosan / polyacrylic acid composite gel, and the chitosan / polyacrylic acid composite gel contains nano silicon dioxide. The aerated concrete block disclosed by the invention has relatively high compressive strength, meanwhile, the mass loss rate and the strength loss rate after freezing and thawing are reduced slightly, and the freezing and thawing cycle resistance is high.

Description

Technical Field

[0001] This application relates to the technical field of building materials, and more specifically, it relates to an autoclaved aerated concrete block and its preparation process. Background Art

[0002] The new type of wall material, aerated concrete block, is a new type of building material that is lightweight, porous, has good heat insulation and fire resistance, has a certain seismic resistance, is very plastic, and can be planed and sawn. Moreover, the greatest advantage of aerated concrete blocks is that they save land resources and do not waste a large amount of arable land. Their raw material sources are very extensive, and ash sand, slag, fly ash, coal gangue, etc. are all raw materials for making aerated concrete blocks.

[0003] In the prior art, the Chinese invention patent document with the application number CN2010102470501 discloses a fly ash aerated concrete block and its preparation method. The formula composition of the fly ash aerated concrete block is: 100 - 200 kg of cement, 350 - 380 kg of lime, 1350 - 1550 kg of fly ash, 1.4 - 1.5 kg of aluminum powder, 0.195 - 0.205 kg of foam stabilizer, and water added; and the preparation method is: raw material preparation - metering - stirring - pouring into the mold - static pre-curing - demolding - hoisting to the cutting part for cutting - autoclave curing in the autoclave - warehousing the finished product. The made block has a large number of pores and micropores inside, and has good heat insulation performance. However, due to its internal pore structure, the aerated concrete block meets various functions such as light weight, heat insulation, and sound absorption, but at the same time, it also has disadvantages such as low strength, high brittleness, and large water absorption. Especially in the cold environment in the north, after continuous alternating freezing and thawing of ice and snow, the compressive strength of the aerated concrete block often drops significantly, bringing great hidden dangers to the stability of the building wall. Summary of the Invention

[0004] In order to enhance the frost resistance of the aerated concrete block and enable it to meet the bearing requirements in cold regions, this application provides an autoclaved aerated concrete block and its preparation process.

[0005] In the first aspect, this application provides an autoclaved aerated concrete block, adopting the following technical solution: An autoclaved aerated concrete block, comprising the following raw materials in parts by weight: 27 - 29 parts of coal gangue waste residue, 8.6 - 9.6 parts of concrete waste slurry, 7.2 - 8 parts of cement, 4.9 - 5.5 parts of quicklime, 1.5 - 1.9 parts of fly ash, 0.3 - 0.5 parts of water reducing agent, 0.2 - 0.4 parts of foaming agent, 34 - 37.5 parts of water, 2 - 2.5 parts of freeze-thaw resistant fiber, and 1 - 1.5 parts of silanized rubber particles; The antifreeze-thaw fiber is a basalt fiber modified by a chitosan / polyacrylic acid composite gel, and the chitosan / polyacrylic acid composite gel contains nano silicon dioxide. The mass ratio of the basalt fiber, the chitosan / polyacrylamide composite gel and the nano silicon dioxide is 3:2-3:1-2.

[0006] By adopting the above technical scheme, coal gangue waste slag and concrete waste slurry are used as the main raw materials. The coal gangue waste slag is a mixture of crushed fine-grained and coarse-grained sandstone, shale, soft clay and ungrounded carbonaceous shale, which reduces the pollution of waste slag stacking to the environment, realizes the resource utilization of waste slag, and reduces production costs at the same time, improves the mechanical properties and durability of blocks. Concrete waste slurry is the wastewater generated by the mixing station during the production and cleaning process. The main components of these wastewaters include unhydrated cement and mineral admixtures, limestone powder, etc. Using them for the preparation of aerated concrete blocks can provide a reference for the recycling of waste slurry. In addition, the small particles of powder in the waste slurry can wrap the water, which can reduce the loss of free water and improve the water retention capacity of concrete. In addition, the powder particles in the waste slurry The particle grading of fly ash, quicklime, etc. is improved, filling is formed inside the concrete, and the compressive strength is enhanced. In addition, quicklime, fly ash, cement and other components are used as auxiliary raw materials for autoclaved aerated concrete blocks. Quicklime can provide effective calcium oxide for aerated concrete blocks, and it interacts with silicon dioxide and aluminum oxide in fly ash to generate hydrated calcium silicate and hydrated calcium aluminate, thereby improving the strength of the blocks. Quicklime can also be mixed with cement to ensure the stability of casting, accelerate the hardening of the body, and improve the performance of the body. The hydrated calcium silicate, hydrated calcium aluminate and other hydrates generated after cement hydration can improve the strength of the blocks, and the calcium hydroxide in the quicklime can be used as an alkaline activator to increase the alkalinity of the casting slurry, which is beneficial to the gasification of the foaming agent.

[0007] Basalt fiber can form a uniform and disordered support inside the aerated concrete block, thereby increasing the toughness of the aerated concrete block, significantly alleviating the internal stress of the concrete caused by temperature changes, and preventing the expansion of temperature cracks. At the same time, a large amount of basalt fiber evenly distributed in the aerated concrete block can reduce water precipitation and aggregate segregation on the surface of the block, reduce the content of microvoids, and reduce the original cracks of the concrete block. Its crack-blocking effect significantly improves the concrete's impermeability and freeze-thaw resistance. When the concrete is frozen and cracks are formed, the stress of the entangled fibers prevents the cracks from expanding continuously in the freeze-thaw environment, leading to its collapse.

[0008] The chitosan / polyacrylic acid composite gel is made from raw materials such as chitosan / polyacrylic acid. Functional groups such as amino and hydroxyl groups on the chitosan molecular chain can provide hydrogen bonds and electrostatic interactions, while polyacrylic acid can form ionic crosslinking with chitosan, enabling the composite gel to have good adhesiveness and firmly adhere to basalt fibers. The basalt fibers are bonded and fixed in multiple capillary fiber pores of the concrete block, improving the poor compatibility and bonding degree between the basalt fibers and the concrete slurry, effectively improving the bonding strength between the basalt fibers and the interior of the concrete block, filling the concrete block, improving the load-bearing mode of the basalt fibers between the concretes, and further enhancing the freeze-thaw resistance. Moreover, when the composite gel is mixed with cement, water, quicklime, etc., it can absorb a part of the mixed water and release it when needed, promoting the further hydration of cement particles. This effect helps to increase the density of the aerated concrete block and enhance the freeze-thaw resistance. In addition, the introduction of the composite gel can also improve the overlap of the basalt fibers with other raw materials in the concrete, strengthen the internal structure of the aerated concrete block, resist the stress and deformation generated during the freeze-thaw cycle, and enhance the durability of the aerated concrete block. Additionally, the chitosan and polyacrylic acid composite gel has flexibility and slipperiness, enabling the molecular chain to form a network structure during the stretching process, thus helping to disperse the stress of the overall material and having high toughness. Adding nano-silica into the chitosan / polyacrylic acid composite aerogel can increase the anchoring effect between the modified basalt fibers and the concrete block and enhance the interfacial bonding.

[0009] The compatibility between rubber powder and slurries such as cement is poor. When incorporated into concrete blocks, it will reduce the strength of the concrete. Therefore, the rubber particles are silanized and modified to improve the interfacial structure bonding between the rubber particles and the cement paste, thereby increasing the strength of the concrete block. Moreover, the rubber particles after silanization treatment are hydrophobic. When incorporated into the concrete block, microscopic air bubbles will form on the surface of the rubber particles. These bubbles play an air-entraining role in the concrete, improving the frost resistance of the concrete. In addition, the rubber particles have elasticity and are evenly distributed in the concrete block to form a telescopic particle group, which helps to reduce the elastic modulus of the block and improve the deformation ability.

[0010] Optionally, the mass ratio of the freeze-thaw resistant fibers to the silanized rubber particles is 2 - 2.5:1.5.

[0011] By adopting the above technical solution, there is a strong interfacial force between the rubber particles treated with silane coupling agent and the inorganic substances, and cracks are not easily formed when under pressure. The silane coupling agent can form a bonding layer of organic matrix - silane coupling agent - inorganic matrix between the inorganic concrete interface and the organic rubber interface, thereby improving the mechanical properties to a certain extent. The nano-silica deposited on the surface of the chitosan / polyacrylic acid composite gel has good filling effect, pozzolanic chemical reaction activity and hydration product nucleation effect, which can effectively improve the compressive and flexural strengths of the concrete, and at the same time enhance the interfacial bonding between the basalt fiber and the concrete.

[0012] Optionally, the chitosan / polyacrylic acid composite gel is prepared by the following method: Chitosan is added to the acrylic acid solution, ammonium persulfate and N,N-methylenebisacrylamide are added, the temperature is raised and stirred, and a hydrochloric acid dopamine solution with a pH of 8.5 is added. After stirring evenly, the chitosan / polyacrylic acid composite gel is prepared.

[0013] By adopting the above technical solution, under the initiation of ammonium persulfate, acrylic acid and chitosan undergo free radical polymerization with hydrochloric acid dopamine to form a double network structure with interaction. The chitosan molecular chain belongs to a semi-rigid molecular chain, making it semi-flexible and constituting the first network. After acrylic acid completely dissolves chitosan, under the free radical polymerization caused by ammonium persulfate, due to the presence of polydopamine, polyacrylic acid has good ductility, thus preparing a second network that is soft but not tough. The two networks are entangled with each other, endowing the composite gel with excellent mechanical properties. Since polydopamine and chitosan carry a large number of carboxyl, hydroxyl and phenolic hydroxyl groups, the composite gel has excellent adhesiveness, can firmly adhere to the surface of the basalt fiber, improve the bonding fastness between the basalt fiber and the components in the building block, and fix the basalt fiber in multiple capillary fiber pores of the building block, thereby improving the freeze-thaw resistance.

[0014] Optionally, the freeze-thaw resistant fiber is prepared by the following method: The basalt fiber is irradiated and activated, and a fly ash slurry is sprayed on its surface. After drying, it is used as a substrate. The carbon source gas is used to form nano-carbon on the substrate by chemical vapor deposition to obtain the pretreated basalt fiber. The mass ratio of the irradiated and activated basalt fiber to the fly ash slurry is 1:0.1 - 0.2, and the carbon source gas includes nitrogen, hydrogen and methane with a flow ratio of 4:1.5:1; The chitosan / polyacrylic acid composite gel is mixed with nano-silica, and the pretreated basalt fiber is added and mixed evenly to obtain the freeze-thaw resistant fiber.

[0015] By adopting the above technical solution, the irradiation can activate the basalt fiber, increasing the surface hydroxyl groups and roughness, promoting the adhesion of the fly ash slurry. After drying, a fly ash layer is formed on the surface of the irradiated basalt fiber. The fly ash contains non-metallic oxides such as alumina and silica, which can catalyze the graphitization of the carbon source to form graphene. Moreover, the silica particles with a rich oxygen-containing surface can enhance the adsorption of hydrocarbons at high temperatures and provide good opportunities for C-C bond connection and nucleation. Alumina can form nucleation sites for the growth of deposited nano-carbon through Al-O-C and Al-C bonds, promoting the growth of nano-carbon on the surface of the fly ash layer. The deposition of nano-carbon is a process of methane cracking with stepwise dehydrogenation and C-C bond connection. Hydrogen assists in the stepwise dehydrogenation of methane cracking. During the deposition of nano-carbon, hydrogen participates in the activation and stepwise dehydrogenation cracking reactions of the carbon-hydrogen bonds of the carbon source and carbon active groups, assisting in the activation and dissociation of the carbon-hydrogen bonds and promoting the growth of high-quality deposited nano-carbon. Nitrogen is used as a carrier gas to adjust the concentration and partial pressure of methane and hydrogen. The deposition of nano-carbon optimizes the microstructure of the basalt fiber surface to a certain extent. Moreover, nano-carbon has a large specific surface area, can bond with hydration products to generate more calcium silicate hydrate gel, promote the hydration reaction to make the hydration products more dense, significantly reduce the microcracks and micropores in the calcium silicate hydrate, reduce the micro-cracking at the initial stage of the freeze-thaw cycle of the block, and also improve the load-bearing capacity of the block. In addition, the deposition of nano-carbon can improve the interfacial bonding performance between the basalt fiber and the composite gel, which is beneficial to improving the mechanical properties of the block.

[0016] Optionally, the fly ash slurry comprises fly ash, polyvinyl alcohol and water with a mass ratio of 1:0.5 - 1:20 - 30.

[0017] By adopting the above technical solution, the fly ash contains abundant non-metallic oxides such as alumina, silica and magnesia, which can promote methane cracking and provide nucleation sites. Moreover, the oxygen-containing surface of the oxide particles has a high surface energy and a relatively negative hydrocarbon adsorption energy, which can improve the ability to capture hydrocarbon species and greatly accelerate the nucleation and growth process of deposited nano-carbon. Polyvinyl alcohol has a certain viscosity, which can increase the adhesion between the fly ash and the basalt fiber and prevent the fly ash layer from falling off, affecting the deposition of nano-carbon on the basalt fiber.

[0018] Optionally, the water reducing agent is selected from polycarboxylate water reducing agent or naphthalene series water reducing agent.

[0019] Optionally, the foaming agent comprises aluminum powder and tea saponin with a mass ratio of 1:0.5 - 1.

[0020] By adopting the above technical solution, tea saponin is a non-ionic surfactant that can significantly reduce the surface tension of liquids, contribute to foaming and foam stabilization, and has strong foaming ability, good foam stability, environmental protection and safety. Using aluminum powder and tea saponin as foaming agents can improve the pore structure of the product, and enhance the uniformity and strength.

[0021] Optionally, the fly ash is Class F Grade II fly ash, with a residue on a 45μm square-hole sieve of 8 - 12%, a water demand ratio of 95 - 98%, and a loss on ignition of 2 - 4.5%; The active calcium oxide content in the quicklime is ≥80%, the residue on a 0.08mm sieve is ≤10%, and the magnesium oxide content is ≤2%.

[0022] By adopting the above technical solution, the active components of fly ash are silica and alumina. After being mixed with cement and water, they can form a relatively stable cementitious material, thereby enabling the concrete to have relatively high strength. At the same time, more than 70% of the particles in fly ash are amorphous spherical glass bodies, which mainly play the role of ball bearings and lubricate in the concrete mixture, improving the workability of the concrete mixture. Moreover, fly ash and crushed stones form a reasonable grading, filling each other, effectively increasing the compactness of the concrete and further enhancing the compressive strength of the concrete; quicklime mainly provides effective calcium oxide for autoclaved aerated concrete blocks. Calcium oxide can react with silica, alumina, etc. in fly ash to form hydration products, and quicklime can also supply gas for the gas-forming agent. The heat released by lime and water can quickly harden the green body.

[0023] In a second aspect, the present application provides a preparation process for autoclaved aerated concrete blocks, adopting the following technical solution: A preparation process for autoclaved aerated concrete blocks includes the following steps: Mix the coal gangue waste residue, fly ash, quicklime, and cement evenly to obtain a dry mix; Mix the water reducer, foaming agent, concrete waste slurry, and water evenly, add anti-freeze and thawing fibers and silanized rubber particles, stir and disperse, and then add the dry mix and stir evenly to obtain a mixed slurry; Pour the mixed slurry into a mold, then carry out static curing, demolding, cutting, and steam curing to obtain autoclaved aerated concrete blocks.

[0024] By adopting the above technical solution, first mix the granular materials such as coal gangue waste residue and fly ash to prevent damage to the structures of the anti-freeze and thawing fibers and silane-modified rubber particles during the blending process, ensure the entanglement performance of the anti-freeze and thawing fibers, and enable the final aerated concrete blocks to have good structural strength.

[0025] In summary, the present application has the following beneficial effects: 1. Since this application uses anti-freeze-thaw fibers and silanized rubber particles in aerated concrete blocks, and the anti-freeze-thaw fibers are basalt fibers modified by chitosan / polyacrylic acid composite gel, the modified basalt fibers entangle and freeze-fill each other in the concrete blocks. During the process of concrete freezing and ice formation causing cracking, stress exists due to the entangled fibers, preventing the continuous expansion of cracks in the concrete under freeze-thaw environment and resulting in its collapse. At the same time, the adhesiveness of the chitosan / polyacrylic acid composite gel can fix the basalt fibers in the voids of the aerated concrete blocks, improving the bonding strength between the basalt fibers and the concrete, further enhancing the anti-freeze-thaw ability. The silanized rubber particles have a certain elasticity, can absorb the energy generated by concrete cracking, weaken the stress at the front of crack development, thus alleviating or even terminating crack propagation and improving the anti-freeze and anti-crack properties.

[0026] 2. In this application, it is preferably to use irradiation to treat the surface of basalt fibers to increase their roughness, and then spray fly ash slurry to form a fly ash layer on the irradiated basalt fibers. Utilize the non-metallic oxides in the fly ash layer to promote the gas-phase deposition of other carbon sources, and form nano-carbon on the basalt fibers containing the fly ash layer. The deposition of nano-carbon improves the surface denseness of the basalt fibers, improves their anti-tensile ability, and enhances their adhesion effect with the composite gel. Detailed implementation mode

[0027] The following examples further illustrate this application in detail.

[0028] Preparation examples I-II of chitosan / polyacrylic acid composite gel Preparation example I: Add 0.2 kg of chitosan to 0.3 kg of acrylic acid solution to obtain chitosan / acrylic acid solution, add 0.02 kg of ammonium persulfate and 0.01 kg of N,N-methylenebisacrylamide, heat up to 50 °C and stir for 20 min, add 0.1 kg of hydrochloric acid dopamine solution with a pH of 8.5 (prepared by adjusting the pH of the hydrochloric acid dopamine solution with sodium hydroxide with a pH of 10), stir evenly, and keep warm at 60 °C for 3 h to obtain chitosan / polyacrylic acid composite gel. The deacetylation degree of chitosan > 95%, selected from Xi'an Qiuhe Biology, product number 8718.

[0029] Preparation example II: The difference from preparation example I is that the hydrochloric acid dopamine solution is not added.

[0030] Preparation examples 1-10 of anti-freeze-thaw fibers Preparation example 1: Mix 0.3 kg of chitosan / polyacrylic acid composite gel with 0.2 kg of nano-silica, and then add 0.3 kg of basalt fibers, mix evenly to obtain anti-freeze-thaw fibers. The chitosan / polyacrylic acid composite gel is made from preparation example I, the length of the basalt fibers is 9 mm, selected from Jiangsu Kangdafu New Materials, product number 1250.

[0031] Preparation Example 2: 0.2 kg of chitosan / polyacrylic acid composite gel was mixed with 0.1 kg of nano-silica, and then 0.3 kg of basalt fiber was added and mixed evenly to obtain the freeze-thaw resistant fiber. The chitosan / polyacrylic acid composite gel was made from Preparation Example I. The length of the basalt fiber was 9 mm, selected from Jiangsu Kangdafu New Materials, and the product number was 1250.

[0032] Preparation Example 3: The difference from Preparation Example 1 was that the chitosan / polyacrylic acid composite gel was made from Preparation Example II.

[0033] Preparation Example 4: The difference from Preparation Example 1 was that nano-silica was not added.

[0034] Preparation Example 5: The difference from Preparation Example 1 was that the chitosan / polyacrylic acid composite gel was not added, and only 3 g of basalt fiber and 2 g of nano-silica were mixed to obtain the freeze-thaw resistant fiber.

[0035] Preparation Example 6: The difference from Preparation Example 1 was that the basalt fiber was subjected to a series of pretreatment. The specific preparation method was as follows: The basalt fiber was irradiated and activated with an irradiation dose of 400 kGy, and then a fly ash slurry was sprayed on its surface. After drying, it was used as a substrate. Nitrogen, hydrogen, and methane with a flow ratio of 40:15:1 were used as carbon source gases to deposit nano-carbon on the substrate. The specific method was: The substrate was placed in a tube furnace at a temperature, and nitrogen with a flow rate of 100 sccm was introduced. After the air in the tube furnace was exhausted, hydrogen with a flow rate of 37.5 sccm was introduced, and the temperature of the tube furnace was raised to 1080 °C within 120 min. Methane with a flow rate of 25 sccm was introduced, and after maintaining for 4 h, the introduction of hydrogen and methane was stopped, and the heating was stopped. After cooling to room temperature, the introduction of nitrogen was stopped, and the pretreated basalt fiber with nano-carbon deposited on its surface was obtained. The mass ratio of the fly ash slurry to the irradiated basalt fiber was 1:0.2, and the fly ash slurry contained 0.1 kg of fly ash, 0.1 kg of polyvinyl alcohol, and 3 kg of water. The fly ash was Class F Grade II fly ash, and the polyvinyl alcohol was Wanwei 2488. The length of the basalt fiber was 9 mm, selected from Jiangsu Kangdafu New Materials, and the product number was 1250; 0.3 kg of chitosan / polyacrylic acid composite gel was mixed with 0.2 kg of nano-silica, and then 0.3 kg of pretreated basalt fiber was added and mixed evenly to obtain the freeze-thaw resistant fiber. The chitosan / polyacrylic acid composite gel was made from Preparation Example I.

[0036] Preparation Example 7: The difference from Preparation Example 1 is that the basalt fibers are subjected to a series of pretreatment, and the specific preparation method is as follows: The basalt fibers are irradiated and activated with an irradiation dose of 400 KGy, and then a fly ash slurry is sprayed on their surface. After drying, it is used as a substrate. Nitrogen, hydrogen, and methane with a flow ratio of 40:15:1 are used as carbon source gases to deposit nano-carbon on the substrate. The specific method is as follows: The substrate is placed in a tube furnace at a temperature, nitrogen with a flow rate of 100 sccm is introduced. After the air in the tube furnace is exhausted, hydrogen with a flow rate of 37.5 sccm is introduced, and the temperature of the tube furnace is raised to 1080 °C within 120 min. Methane with a flow rate of 25 sccm is introduced. After maintaining for 4 h, the introduction of hydrogen and methane is stopped, and the heating is stopped. After cooling to room temperature, the introduction of nitrogen is stopped, and the pretreated basalt fibers with nano-carbon deposited on the surface are obtained. The mass ratio of the fly ash slurry to the irradiated basalt fibers is 1:0.1, and the fly ash slurry contains 0.1 kg of fly ash, 0.05 kg of polyvinyl alcohol, and 2 kg of water. The fly ash is Class F Grade II fly ash, the polyvinyl alcohol is Wanwei 2488, the length of the basalt fibers is 9 mm, selected from Jiangsu Kangdafu New Materials, and the product number is 1250; Mix 0.2 kg of chitosan / polyacrylic acid composite gel with 0.1 kg of nano-silica, and then add 0.3 kg of pretreated basalt fibers and mix evenly to obtain freeze-thaw resistant fibers. The chitosan / polyacrylic acid composite gel is prepared from Preparation Example I.

[0037] Preparation Example 8: The difference from Preparation Example 6 is that the basalt fibers are not irradiated and activated.

[0038] Preparation Example 9: The difference from Preparation Example 6 is that no fly ash slurry is sprayed on the irradiated and activated basalt fibers.

[0039] Preparation Example 10: The difference from Preparation Example 6 is that nano-carbon is not deposited on the irradiated and activated basalt fibers sprayed with fly ash slurry. Examples

[0040] The chemical composition of the coal gangue waste residue in the examples is shown in Table 1, and the chemical composition of the concrete waste slurry is shown in Table 2.

[0041] Table 1 Chemical Composition of Coal Gangue Waste Residue Table 2 Chemical Composition of Concrete Waste Slurry Example 1: An autoclaved aerated concrete block, the raw material dosage of which is shown in Table 3. Among them, the cement is P.O42.5 portland cement, the fly ash is Class F Grade II fly ash, the residue on a 45μm square-hole sieve is 12%, the water demand ratio is 98%, the loss on ignition is 4.5%, the content of active calcium oxide in quicklime is ≥80%, the residue on a 0.08mm sieve is ≤10%, the content of magnesium oxide is ≤2%, the water reducing agent is a polycarboxylate water reducing agent, the polycarboxylate water reducing agent is selected from Langfang Longteng New Materials, and the product number is PC-1050. The foaming agent includes aluminum powder and tea saponin with a mass ratio of 1:1. The freeze-thaw resistant fiber is made from Preparation Example 1. The preparation method of the silanized rubber particles is as follows: Mix methanol and the silane coupling agent KH570, adjust the pH to 10 with ammonia water, add rubber particles, heat to 90°C, stir for 4h and then filter, and dry at 90°C for 120min. The dosage of the silane coupling agent KH570 is 3wt% of the mass of the rubber particles. The rubber particles are selected from LingShou BaiXin New Materials Technology, and the product number is XJF-1, with a particle size of 40 mesh. The particle size of the coal gangue waste residue is 250μm, and its chemical composition is shown in Table 1. The concrete waste slurry is obtained by drying the waste slurry water from the concrete sedimentation tank of our company's mixing station, removing large particle impurities, etc., passing through a 100-mesh sieve to obtain waste slurry powder, and then adding water to the waste slurry powder to obtain a 5% concentration of concrete waste slurry, and its specific composition is shown in Table 2.

[0042] The preparation process of the above autoclaved aerated concrete block includes the following steps: Mix the coal gangue waste residue, fly ash, quicklime and cement, and stir evenly to obtain a dry mix. Mix the water reducing agent, foaming agent, concrete waste slurry and water evenly, add the freeze-thaw resistant fiber and silanized rubber particles, stir and disperse, and then add the dry mix and stir evenly to obtain a mixed slurry. Pour the mixed slurry into a mold, then carry out static curing at 40°C for 3h, demold, cut, and steam cure at 160°C and 1MPa for 10h to obtain the autoclaved aerated concrete block.

[0043] Table 3 Raw material dosage of autoclaved aerated concrete blocks in Examples 1-4 Example 2: An autoclaved aerated concrete block, which is different from that of Example 1 in that the cement is P.O42.5 portland cement, the fly ash is Class F Grade II fly ash, the residue on a 45μm square hole sieve is 12%, the water demand ratio is 98%, the loss on ignition is 4.5%, the content of active calcium oxide in quicklime is ≥80%, the residue on a 0.08mm sieve is ≤10%, the content of magnesium oxide is ≤2%, the water reducing agent is a naphthalene-based high-efficiency water reducing agent, selected from Shandong Xinfuman Chemical Technology, with the model number FND and the product number 29. The foaming agent includes aluminum powder and tea saponin with a mass ratio of 1:0.5. The freeze-thaw resistant fiber is made from Preparation Example 2. The preparation method of the silanized rubber particles is as follows: Mix methanol and the silane coupling agent KH570, adjust the pH to 10 with ammonia water, add rubber particles, heat to 90°C, stir for 4h and then filter, and dry at 90°C for 120min. The dosage of the silane coupling agent KH570 is 3wt% of the mass of the rubber particles. The rubber particles are selected from LingShou County BaiXin New Material Technology, with the product number XJF-1 and a particle size of 40 mesh. The particle size of the coal gangue waste residue is 250μm, and its chemical composition is shown in Table 1. The concrete waste slurry is obtained by drying the waste slurry water in the concrete sedimentation tank of our company's mixing station, removing large particle impurities, etc., passing through a 100-mesh sieve to obtain waste slurry powder, and then adding water to the waste slurry powder to obtain a 5% concentration of concrete waste slurry, and its specific composition is shown in Table 2.

[0044] The preparation process of the above autoclaved aerated concrete block includes the following steps: Mix the coal gangue waste residue, fly ash, quicklime and cement, and stir evenly to obtain a dry mix; Mix the water reducing agent, foaming agent, concrete waste slurry and water evenly, add the freeze-thaw resistant fiber and silanized rubber particles, stir and disperse, and then add the dry mix, and stir evenly to obtain a mixed slurry; Pour the mixed slurry into a mold, then carry out static curing at 40°C for 3h, demold, cut, and steam cure at 180°C and 2MPa for 8h to obtain the autoclaved aerated concrete block.

[0045] Examples 3-4: An autoclaved aerated concrete block, which is different from that of Example 1 in that the raw material dosage is shown in Table 1.

[0046] Example 5: An autoclaved aerated concrete block, which is different from that of Example 1 in that the freeze-thaw resistant fiber is made from Preparation Example 3.

[0047] Example 6: An autoclaved aerated concrete block, which is different from that of Example 1 in that the freeze-thaw resistant fiber is made from Preparation Example 6.

[0048] Example 7: An autoclaved aerated concrete block, which is different from that of Example 1 in that the freeze-thaw resistant fiber is made from Preparation Example 7.

[0049] Example 8: An autoclaved aerated concrete block, which is different from that of Example 6 in that the freeze-thaw resistant fiber is made from Preparation Example 8.

[0050] Example 9: An autoclaved aerated concrete block, which is different from that of Example 6 in that the freeze-thaw resistant fiber is made from Preparation Example 9.

[0051] Example 10: An autoclaved aerated concrete block, which is different from that of Example 6 in that the freeze-thaw resistant fiber is made from Preparation Example 10.

[0052] Comparative Example Comparative Example 1: An autoclaved aerated concrete block, which is different from that of Example 1 in that the freeze-thaw resistant fiber is made from Preparation Example 4.

[0053] Comparative Example 2: An autoclaved aerated concrete block, which is different from that of Example 1 in that the freeze-thaw resistant fiber is made from Preparation Example 5.

[0054] Comparative Example 3: An autoclaved aerated concrete block, which is different from that of Example 1 in that the freeze-thaw resistant fiber is only basalt fiber.

[0055] Comparative Example 4: An autoclaved aerated concrete block, which is different from that of Example 1 in that the rubber particles are not treated with silane.

[0056] Comparative Example 5: An autoclaved aerated concrete block, which is different from that of Example 1 in that silanized rubber is used to replace the freeze-thaw resistant fiber in equal mass.

[0057] Performance Detection Test Prepare autoclaved aerated concrete blocks according to the methods in the examples and comparative examples, and refer to the following method for freeze-thaw durability detection, and record the detection results in Table 4.

[0058] Cut the test concrete blocks into cube specimens of 10 cm × 10 cm × 10 cm, and conduct the test according to the rapid freezing method in the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" GB / T50082—2009. Take out the concrete and soak it in water at 24 °C, with the water surface 20 mm higher than the test block. Take it out after 4 days. At the end of freezing and melting, control the center temperature of the specimen at -17 ± 2 °C and 8 ± 2 °C respectively; each freeze-thaw cycle is completed within 2.5 - 4 hours, and the melting time is not less than 1 / 4 of the entire freeze-thaw cycle. After 100 freeze-thaw cycles, take out the stones respectively, dry the surface with a wet cloth, and measure their mass and compressive strength. Among them, the compressive strength is detected according to the "Test Methods for Properties of Autoclaved Aerated Concrete" GB / T11969-2020, and the loading speed is 0.5 MPa / S. The compressive strength loss rate is calculated according to the following formula: Compressive strength loss rate (%) = (P1 - P2) / P1 × 100%, where P1 is the 28-day compressive strength of the specimen before testing, and P2 is the compressive strength of the specimen after 100 freeze-thaw cycles. The mass loss rate is calculated according to the following formula: Mass loss rate (%) = (M1 - M2) / M1 × 100%, where M1 is the mass of the specimen before testing, and M2 is the mass of the specimen after 100 freeze-thaw cycles. And detect the flexural strength of the specimen before testing according to the "Test Methods for Properties of Autoclaved Aerated Concrete" GB / T11969-2020. Take 10 specimens for each example or comparative example, and the test results are averaged.

[0059] Table 4 Performance test results of autoclaved aerated concrete blocks Combined with the raw material dosages in Examples 1 - 4 and the data in Table 4, it can be seen that the freeze-thaw resistant fibers and silanized rubber particles prepared by a specific method can effectively improve the compressive strength and flexural strength of aerated concrete blocks, and significantly enhance the freeze-thaw resistance effect.

[0060] In Example 5, the freeze-thaw resistant fibers prepared in Preparation Example 3 are used. Compared with Preparation Example 1 in Example 1, the hydrochloric acid dopamine solution is not added to the chitosan / polyacrylic acid composite gel. It can be seen that the flexural strength of the aerated concrete block is reduced, and the freeze-thaw resistance effect is weakened.

[0061] In Examples 6 and 7, the freeze-thaw resistant fibers prepared in Preparation Example 6 and Preparation Example 7 are used respectively. Compared with Example 1, the basalt fibers are pretreated with fly ash slurry and nano-carbon. It can be seen that the compressive strength of the aerated concrete blocks prepared in Examples 6 and 7 is increased, the flexural strength is slightly improved, and the freeze-thaw resistance ability is further improved.

[0062] In Example 8, the freeze-thaw resistant fiber prepared in Preparation Example 8 was used. Compared with Preparation Example 6 in Example 6, the basalt fiber was not irradiated and activated. It can be seen that compared with the aerated concrete block prepared in Example 6, the compressive strength of the aerated concrete block prepared in Example 8 decreased slightly, and the freeze-thaw resistance ability weakened.

[0063] Compared with Example 6, in Example 9, the freeze-thaw resistant fiber prepared in Preparation Example 9 was used, in which fly ash slurry was not sprayed on the surface of the activated basalt fiber. It can be seen that the aerated concrete block prepared therefrom had a significant decrease in compressive strength compared with Example 6, and the loss rate of compressive strength after freeze-thaw cycles was relatively large, and the freeze-thaw resistance ability decreased significantly.

[0064] In Example 10, the freeze-thaw resistant fiber prepared in Preparation Example 10 was used. Compared with Preparation Example 6, nano-carbon was deposited therein. It can be seen that the compressive strength of the prepared aerated concrete block decreased, and the freeze-thaw resistance ability weakened.

[0065] In Comparative Example 1, the freeze-thaw resistant fiber prepared in Preparation Example 4 was used. Compared with Preparation Example 1 in Example 1, nano-silica was not added to the composite gel in Preparation Example 4. It can be seen that the compressive strength and flexural strength of the aerated concrete block prepared therefrom decreased, and the freeze-thaw resistance ability weakened.

[0066] Compared with Example 1, in Comparative Example 2, the freeze-thaw resistant fiber prepared in Preparation Example 5 was used. Compared with Preparation Example 1, chitosan / polyacrylic acid composite gel was not added, and basalt fiber and nano-silica were used as the freeze-thaw resistant fiber. Although the decrease in compressive strength was not large, the freeze-thaw resistance ability decreased significantly. In Comparative Example 3, only basalt fiber was used as the freeze-thaw resistant fiber. Compared with Example 1, the compressive strength of the aerated concrete block prepared in Comparative Example 3 decreased significantly, the flexural strength decreased, and the freeze-thaw resistance ability weakened.

[0067] In Comparative Example 4, the rubber particles were not silanized, and in Comparative Example 5, silanized rubber particles were used to replace the freeze-thaw resistant fiber in equal amount. Compared with Example 1, the mechanical strength of the aerated concrete block prepared in Comparative Example 4 decreased significantly. The tensile strength of the aerated concrete block prepared in Comparative Example 5 did not decrease significantly, but the freeze-thaw resistance ability and mechanical strength were inferior to those of Example 1.

[0068] This specific embodiment is only an explanation of the present application, and it does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. An autoclaved aerated concrete block, characterized in that, It comprises the following raw materials in parts by weight: 27 - 29 parts of coal gangue waste residue, 8.6 - 9.6 parts of concrete waste slurry, 7.2 - 8 parts of cement, 4.9 - 5.5 parts of quicklime, 1.5 - 1.9 parts of fly ash, 0.3 - 0.5 part of water reducing agent, 0.2 - 0.4 part of foaming agent, 34 - 37.5 parts of water, 2 - 2.5 parts of freeze-thaw resistant fiber and 1 - 1.5 parts of silanized rubber particles; The freeze-thaw resistant fiber is basalt fiber modified by chitosan / polyacrylic acid composite gel, and the chitosan / polyacrylic acid composite gel contains nano-silica, and the mass ratio of basalt fiber, chitosan / polyacrylamide composite gel and nano-silica is 3:2 - 3:1 - 2.

2. The autoclaved aerated concrete block according to claim 1, characterized in that: The mass ratio of the freeze-thaw resistant fiber to the silanized rubber particles is 2 - 2.5:1.

5.

3. The autoclaved aerated concrete block according to claim 1, wherein: The chitosan / polyacrylic acid composite gel is prepared by the following method: Chitosan is added to an acrylic acid solution, ammonium persulfate and N,N-methylenebisacrylamide are added, the temperature is raised and stirred, and a hydrochloric acid dopamine solution with a pH of 8.5 is added. After stirring evenly, the chitosan / polyacrylic acid composite gel is obtained.

4. The autoclaved aerated concrete block according to claim 3, wherein: The freeze-thaw resistant fiber is prepared by the following method: The basalt fiber is irradiated and activated, a fly ash slurry is sprayed on its surface, and after drying, it is used as a substrate. A nano-carbon is formed on the substrate by chemical vapor deposition using a carbon source gas. The pretreated basalt fiber is obtained. The mass ratio of the basalt fiber after irradiation activation to the fly ash slurry is 1:0.1 - 0.2, and the carbon source gas includes nitrogen, hydrogen and methane with a flow ratio of 4:1.5:1; The chitosan / polyacrylic acid composite gel is mixed with nano-silica, and the pretreated basalt fiber is added and mixed evenly to obtain the freeze-thaw resistant fiber.

5. The autoclaved aerated concrete block according to claim 4, characterized in that: The fly ash slurry contains fly ash, polyvinyl alcohol and water with a mass ratio of 1:0.5 - 1:20 - 30.

6. The autoclaved aerated concrete block according to claim 1, characterized in that: The water reducing agent is selected from polycarboxylate water reducing agent or naphthalene series water reducing agent.

7. The autoclaved aerated concrete block according to claim 1, characterized in that: The foaming agent includes aluminum powder and tea saponin with a mass ratio of 1:0.5 - 1.

8. The autoclaved aerated concrete block according to claim 1, characterized in that: The fly ash is Class F Grade II fly ash, the residue on a 45μm square hole sieve is 8 - 12%, the water demand ratio is 95 - 98%, and the loss on ignition is 2 - 4.5%; The content of active calcium oxide in the quicklime is ≥80%, the residue on a 0.08mm sieve is ≤10%, and the content of magnesium oxide is ≤2%.

9. The preparation process of the autoclaved aerated concrete block according to any one of claims 1-8, characterized in that: It includes the following steps: The coal gangue waste residue, fly ash, quicklime and cement are mixed evenly to obtain a dry mix; The water reducing agent, foaming agent, concrete waste slurry and water are mixed evenly, the freeze-thaw resistant fiber and silanized rubber particles are added, and after stirring and dispersing, the dry mix is added and stirred evenly to obtain a mixed slurry; The mixed slurry is cast and formed, and then subjected to static curing, demoulding, cutting and steam curing to obtain autoclaved aerated concrete blocks.

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