Autoclaved aerated concrete block based on all-solid waste material and preparation method of autoclaved aerated concrete block

Abstract

The invention relates to an autoclaved aerated concrete block based on an all-solid waste material and a preparation method thereof, and relates to the technical field of building material processing. Comprising the following components in parts by weight: 25-30 parts of an all-solid waste cementing material, 60-70 parts of construction waste micro powder, 0.05-0.1 part of aluminum powder, 0.02-0.06 part of a foam stabilizer and 60-70 parts of water, the all-solid waste cementing material is prepared from slag, fly ash, steel slag, desulfurized gypsum and red mud according to a mass ratio of (40-60): (20-35): (10-20): (5-15): (5-10); the construction waste micro powder is prepared from recycled concrete micro powder and brick powder according to a mass ratio of (60-70): (30-40). The dry density and compressive strength of the product prepared by the method can stably reach B07 and A5.0 grade standards, and the cost is lower.

Description

Technical Field

[0001] This invention relates to the field of building material processing technology, and in particular to an autoclaved aerated concrete block based on all solid waste materials and its preparation method. Background Technology

[0002] Autoclaved aerated concrete (AAC) is a new type of green wall material that is lightweight, high-strength, and possesses excellent thermal insulation, sound insulation, and fire resistance. Traditional AAC production relies primarily on natural resources; its calcareous materials are typically lime and cement, while its siliceous materials are mainly quartz sand. This production method presents two major problems: first, it consumes large quantities of non-renewable mineral resources such as limestone and natural quartz sand; second, the grinding process for quartz sand is energy-intensive and costly. Furthermore, the production of quicklime and cement involves significant carbon emissions, all of which contradict the current "dual-carbon" development strategy.

[0003] At the same time, my country's industrialization and urbanization processes have generated massive amounts of industrial solid waste (such as steel slag, ore slag, desulfurization gypsum, fly ash, and red mud) and construction demolition waste. If these solid wastes are not properly treated, they not only occupy vast amounts of land but also cause serious environmental pollution. Therefore, how to utilize these solid wastes on a large scale and with high added value, turning waste into treasure, is a major issue that urgently needs to be addressed by the building materials industry and the environmental protection sector. Summary of the Invention

[0004] The purpose of this invention is to address the above-mentioned problems by providing an autoclaved aerated concrete block based on all-solid waste materials and its preparation method.

[0005] The first aspect of this invention provides an autoclaved aerated concrete block based on all-solid waste materials, employing the following technical solution:

[0006] An autoclaved aerated concrete block based on all-solid waste materials comprises the following components by weight: 25-30 parts of all-solid waste cementitious material, 60-70 parts of construction waste powder, 0.05-0.1 parts of aluminum powder, 0.02-0.06 parts of foam stabilizer, and 60-70 parts of water; wherein the construction waste powder is obtained by crushing and grinding construction waste containing recycled concrete and bricks.

[0007] By adopting the above technical solution, all-solid-waste cementitious materials and construction waste powder are used to replace traditional cement and quartz sand, realizing the preparation of autoclaved aerated concrete blocks using all-solid-waste materials. The price of solid waste raw materials is much lower than that of cement, quicklime, and river sand. Furthermore, the replacement of river sand with construction waste powder eliminates the need for grinding energy consumption in the raw material processing, which will greatly reduce the production energy consumption and cost of the product. The concrete blocks using all-solid-waste cementitious materials alone have relatively low strength, mainly due to insufficient calcium ions in the system. Recycled concrete powder contains more calcium ions, but its silicon content is low. Recycled brick powder can make up for this deficiency. Therefore, by combining all-solid-waste cementitious materials, construction waste powder, and other functional additives, the strength of the blocks is improved.

[0008] Preferably, the solid waste cementitious material includes slag, fly ash, steel slag, desulfurized gypsum and red mud, and the mass ratio of each component is slag: fly ash: steel slag: desulfurized gypsum: red mud = (40-60): (20-35): (10-20): (5-15): (5-10).

[0009] Preferably, the specific surface area of ​​the solid waste cementitious material is not less than 500 m². 2 / kg.

[0010] Preferably, the construction waste powder is made by mixing recycled concrete powder and brick powder in a mass ratio of (60-70):(30-40).

[0011] Preferably, the specific surface area of ​​the construction waste powder is not less than 350 m². 2 / kg, with SiO2 content not less than 55%.

[0012] Preferably, the mixture comprises the following components by weight: 28 parts of solid waste cementitious material, 66 parts of construction waste powder, 0.08 parts of aluminum powder, 0.04 parts of foam stabilizer, and 60 parts of water; the solid waste cementitious material comprises the following components by weight: 50 parts of slag, 30 parts of fly ash, 15 parts of steel slag, 10 parts of desulfurized gypsum, and 7 parts of red mud; the construction waste powder comprises the following components by weight: 65 parts of recycled concrete powder and 35 parts of brick powder.

[0013] By adopting the above technical solution, steel slag and red mud in the solid waste cementitious material can produce a significant alkaline activation effect on the system. Steel slag provides the system with early strong alkalinity and calcium source, while red mud provides continuous alkalinity. The two work together to create an alkaline environment conducive to hydrothermal synthesis. This in-situ alkaline activation effect provided by the solid waste itself can effectively activate the activity of siliceous and calcareous raw materials in the system without the need to add additional alkaline activators. At the same time, it promotes the participation of calcium ions and silicon ions in the construction waste powder in the hydrothermal synthesis reaction in the whole system, ultimately enabling the blocks to obtain ideal strength.

[0014] A second aspect of the present invention provides a method for preparing the above-mentioned autoclaved aerated concrete blocks, which adopts the following technical solution:

[0015] A method for preparing autoclaved aerated concrete blocks based on all-solid waste materials includes the following steps:

[0016] S1. Weigh out the recycled concrete powder and brick powder according to the ratio, mix them, add water and stir to pre-wet the construction waste powder;

[0017] S2. Weigh the solid waste cementitious material and water according to the proportion and pour them into the pre-wetted construction waste powder obtained in S1, and stir to make a slurry.

[0018] S3. Weigh out aluminum powder and foam stabilizer according to the ratio, add them to the slurry prepared in S2, stir and pour into the mold. Place the slurry in the curing chamber with the mold to stand still and thicken due to gas generation.

[0019] S4. After the hardened embryo from S3 is cut into blocks of a specific size, the blocks are placed in an autoclave for curing. Once curing is complete, autoclaved aerated concrete blocks are obtained.

[0020] S5. Conduct quality testing on the finished product obtained in S4. Unqualified products are crushed and reused as construction waste powder material.

[0021] Preferably, in the above preparation method, the stirring time in step S2 is 2-3 minutes.

[0022] Preferably, in the above preparation method, in step S3, the stirring time after adding aluminum powder and foam stabilizer to the slurry is 30-40 seconds, and the gas generation and thickening time is 2-3 hours.

[0023] Preferably, in step S4, the curing conditions are: temperature 180–200℃, pressure 1.0–1.2 MPa, and curing time 10–12 h.

[0024] By adopting the above technical solution and optimizing the steps and parameters of the preparation method, concrete blocks with better performance can be obtained.

[0025] In summary, this application includes at least one of the following beneficial technical effects:

[0026] 1. By replacing traditional cement and quartz sand with all-solid-waste cementitious materials and construction waste powder, autoclaved aerated concrete (AAC) blocks can be prepared using all-solid-waste materials. The price of solid waste raw materials is much lower than that of cement, quicklime, and river sand. Furthermore, replacing river sand with construction waste powder eliminates the need for grinding energy in the raw material processing, which will greatly reduce the production energy consumption and cost of the product. The concrete blocks made solely with all-solid-waste cementitious materials have relatively low strength, mainly due to insufficient calcium ions in the system. Recycled concrete powder contains more calcium ions but less silicon, which can be compensated for by recycled brick powder. Therefore, the strength of the blocks is improved by combining all-solid-waste cementitious materials, construction waste powder, and other functional additives.

[0027] 2. The steel slag and red mud in the solid waste cementitious material can have a significant alkaline activation effect on the system. The steel slag provides the system with strong early alkalinity and calcium source, while the red mud provides continuous alkalinity. Together, they create an alkaline environment conducive to hydrothermal synthesis. This in-situ alkaline activation effect provided by the solid waste itself can effectively activate the activity of siliceous and calcareous raw materials in the system without the need for additional alkaline activators. At the same time, it promotes the participation of calcium and silicon ions in the construction waste powder in the hydrothermal synthesis reaction in the whole system, ultimately enabling the blocks to obtain ideal strength.

[0028] 3. The strong alkalinity of steel slag and red mud effectively stimulates the pozzolanic activity of fly ash and slag. Desulfurization gypsum regulates the reaction rate. Construction waste powder provides the main silicon source for the system and supplements the calcium source, ensuring that the hydrothermal synthesis reaction proceeds fully. The dry density and compressive strength of the final product can stably reach the B07 and A5.0 grade standards. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Modifications or equivalent substitutions made by those skilled in the art based on their understanding of the technical solutions of this invention, without departing from the spirit and scope of the invention, should all be covered within the protection scope of this invention.

[0030] The raw materials used in the following examples are from the following sources. Other conditions not specified are based on conventional conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0031] The sources of raw materials used in all embodiments of this application are as follows:

[0032] Slag originates from steel plants and has a specific surface area of ​​500–600 m². 2 / kg; fly ash originates from power plants, with a specific surface area of ​​500-600 m². 2 / kg, residue less than 15% on an 80μm square-hole sieve; steel slag originates from a steelmaking plant, with a specific surface area of ​​500–600 m² / kg. 2 / kg; Desulfurized gypsum is derived from power generation, with a calcium sulfate dihydrate content of not less than 95% and a specific surface area of ​​500-600 m². 2 / kg; the red mud originates from an alumina plant, with a specific surface area of ​​500–600 m². 2 / kg; Aluminum powder is purchased from the market, with an active aluminum content of not less than 85%; Quicklime is purchased from the market, with a CaO content of not less than 90%; Foam stabilizer uses soapberry powder, purchased from the market; Recycled concrete powder is obtained from building demolition, with a specific surface area of ​​350-400 m². 2 / kg; brick powder originates from building demolition, with a specific surface area of ​​350-400 m². 2 / kg.

[0033] I. Implementation Examples

[0034] Example 1

[0035] An autoclaved aerated concrete block based on all-solid waste materials comprises the following components by weight: 25 parts of all-solid waste cementitious material, 60 parts of construction waste powder, 0.05 parts of aluminum powder, 0.02 parts of foam stabilizer, and 60 parts of water; the all-solid waste cementitious material includes slag, fly ash, steel slag, desulfurized gypsum, and red mud, with the mass ratio of each component being slag:fly ash:steel slag:desulfurized gypsum:red mud = 60:20:10:5:5; the construction waste powder is obtained by crushing and grinding construction waste containing recycled concrete and bricks, and the construction waste powder is made by mixing recycled concrete powder and brick powder in a mass ratio of 60:40.

[0036] A method for preparing autoclaved aerated concrete blocks based on all-solid waste materials includes the following steps:

[0037] S1. Screening for SiO2 content of not less than 55% and specific surface area ≥ 350m². 2 / kg of recycled concrete powder is prepared for use. In this embodiment, the specific surface area of ​​the recycled concrete powder is 390m². 2 / kg, with a SiO2 content of 63%, weigh out the recycled concrete powder and brick powder according to the ratio, pour them into the mixer and stir for 1 minute. Then weigh out the water according to the ratio and add a small amount (the amount of water added should be enough to pre-wet the construction waste powder; in this example, it is 10% of the total water added). Continue stirring for 3 minutes to pre-wet the construction waste powder.

[0038] S2. Weigh out slag, fly ash, steel slag, desulfurization gypsum, and red mud according to the specified ratio and mix them to form a solid waste cementitious material. The specific surface area of ​​the solid waste cementitious material shall not be less than 500 m². 2 / kg, in this example it is 535m 2 / kg, pour all solid waste cementitious materials and remaining water into the pre-wetted construction waste powder prepared by S1, stir for 2 minutes to obtain slurry, and measure the consistency and specific gravity of the slurry;

[0039] S3. Weigh aluminum powder and foam stabilizer according to the ratio, add them to the slurry prepared in S2, continue stirring for 30 seconds and pour into the mold. Place the slurry in the curing room with the mold and let it stand for 2 hours to thicken and generate gas.

[0040] S4. After the hardened embryo from S3 is cut, it is formed into blocks of a specific size. In this embodiment, the size is designed to be 400mm*200mm*100mm. The blocks are placed in an autoclave for curing for 10 hours at a temperature of 180℃ and a pressure of 1.0MPa. After curing, the autoclaved aerated concrete blocks are obtained.

[0041] S5. Conduct quality testing on the finished product obtained in S4. Unqualified products are crushed and reused as construction waste powder material.

[0042] Example 2

[0043] An autoclaved aerated concrete block based on all-solid waste materials comprises the following components by weight: 30 parts of all-solid waste cementitious material, 70 parts of construction waste powder, 0.1 parts of aluminum powder, 0.06 parts of foam stabilizer, and 70 parts of water; the all-solid waste cementitious material includes slag, fly ash, steel slag, desulfurized gypsum, and red mud, with the mass ratio of each component being slag:fly ash:steel slag:desulfurized gypsum:red mud = 40:35:20:15:10; the construction waste powder is obtained by crushing and grinding construction waste containing recycled concrete and bricks, and the construction waste powder is made by mixing recycled concrete powder and brick powder in a mass ratio of 70:30.

[0044] A method for preparing autoclaved aerated concrete blocks based on all-solid waste materials includes the following steps:

[0045] S1. Screening for SiO2 content of not less than 55% and specific surface area ≥ 350m². 2 / kg of recycled concrete powder is prepared for use. In this embodiment, the specific surface area of ​​the recycled concrete powder is 375m². 2 / kg, with a SiO2 content of 56%, weigh out the recycled concrete powder and brick powder according to the ratio, pour them into the mixer and mix for 2 minutes. Then weigh out the water according to the ratio and add a small amount (the amount of water added should be enough to pre-wet the construction waste powder). Continue to mix for 2 minutes to pre-wet the construction waste powder.

[0046] S2. Weigh out slag, fly ash, steel slag, desulfurization gypsum, and red mud according to the specified ratio and mix them to form a solid waste cementitious material. The specific surface area of ​​the solid waste cementitious material shall not be less than 500 m². 2 / kg, in this example it is 540m 2 / kg, pour all solid waste cementitious materials and remaining water into the pre-wetted construction waste powder prepared by S1, stir for 3 minutes to obtain slurry, and measure the consistency and specific gravity of the slurry;

[0047] S3. Weigh out aluminum powder and foam stabilizer according to the ratio, add them to the slurry prepared in S2, continue stirring for 40 seconds and pour into the mold. Place the slurry in the curing room with the mold and let it stand still to generate gas and thicken for 3 hours.

[0048] S4. After the hardened embryo from S3 is cut, it is formed into blocks of a specific size. In this embodiment, the size is designed to be 400mm*200mm*100mm. The blocks are placed in an autoclave for curing for 12 hours at a temperature of 200℃ and a pressure of 1.2MPa. After curing, the autoclaved aerated concrete blocks are obtained.

[0049] S5. Conduct quality testing on the finished product obtained in S4. Unqualified products are crushed and reused as construction waste powder material.

[0050] Example 3

[0051] An autoclaved aerated concrete block based on all-solid waste materials comprises the following components by weight: 28 parts of all-solid waste cementitious material, 66 parts of construction waste powder, 0.08 parts of aluminum powder, 0.04 parts of foam stabilizer, and 60 parts of water; the all-solid waste cementitious material includes slag, fly ash, steel slag, desulfurized gypsum, and red mud, with the mass ratio of each component being slag:fly ash:steel slag:desulfurized gypsum:red mud = 50:30:15:10:7; the construction waste powder is obtained by crushing and grinding construction waste containing recycled concrete and bricks, and the construction waste powder is made by mixing recycled concrete powder and brick powder in a mass ratio of 65:35.

[0052] A method for preparing autoclaved aerated concrete blocks based on all-solid waste materials includes the following steps:

[0053] S1. Screening for SiO2 content of not less than 55% and specific surface area ≥ 350m². 2 / kg of recycled concrete powder is prepared for use. In this embodiment, the specific surface area of ​​the recycled concrete powder is 395m². 2 / kg, with a SiO2 content of 58%, weigh out the recycled concrete powder and brick powder according to the ratio, pour them into the mixer and mix for 2 minutes. Then weigh out the water according to the ratio and add a small amount (the amount of water added should be enough to pre-wet the construction waste powder). Continue to mix for 3 minutes to pre-wet the construction waste powder.

[0054] S2. Weigh out slag, fly ash, steel slag, desulfurization gypsum, and red mud according to the specified ratio and mix them to form a solid waste cementitious material. The specific surface area of ​​the solid waste cementitious material shall not be less than 500 m². 2 / kg, in this example it is 525m 2 / kg, pour all solid waste cementitious materials and remaining water into the pre-wetted construction waste powder prepared by S1, stir for 3 minutes to obtain slurry, and measure the consistency and specific gravity of the slurry;

[0055] S3. Weigh out aluminum powder and foam stabilizer according to the ratio, add them to the slurry prepared in S2, continue stirring for 40 seconds and pour into the mold. Place the slurry in the curing room with the mold and let it stand for 2.5 hours to thicken and generate gas.

[0056] S4. After the hardened embryo from S3 is cut, it is formed into blocks of a specific size. In this embodiment, the size is designed to be 400mm*200mm*100mm. The blocks are placed in an autoclave for curing for 11 hours at a curing temperature of 190℃ and a pressure of 1.0MPa. After curing, the autoclaved aerated concrete blocks are obtained.

[0057] S5. Conduct quality testing on the finished product obtained in S4. Unqualified products are crushed and reused as construction waste powder material.

[0058] Example 4

[0059] An autoclaved aerated concrete block based on all-solid waste materials comprises the following components by weight: 26 parts of all-solid waste cementitious material, 69 parts of construction waste powder, 0.07 parts of aluminum powder, 0.03 parts of foam stabilizer, and 65 parts of water; the all-solid waste cementitious material includes slag, fly ash, steel slag, desulfurized gypsum, and red mud, with the mass ratio of each component being slag:fly ash:steel slag:desulfurized gypsum:red mud = 55:25:13:12:10; the construction waste powder is obtained by crushing and grinding construction waste containing recycled concrete and bricks, and the construction waste powder is composed of recycled concrete powder and brick powder in a mass ratio of 62:33.

[0060] The preparation method of autoclaved aerated concrete blocks in this embodiment is basically the same as that in Example 3, and will not be repeated here.

[0061] Example 5

[0062] An autoclaved aerated concrete block based on all-solid waste materials comprises the following components by weight: 29 parts of all-solid waste cementitious material, 67 parts of construction waste powder, 0.09 parts of aluminum powder, 0.05 parts of foam stabilizer, and 69 parts of water; the all-solid waste cementitious material includes slag, fly ash, steel slag, desulfurized gypsum, and red mud, with the mass ratio of each component being slag:fly ash:steel slag:desulfurized gypsum:red mud = 45:32:17:13:6; the construction waste powder is obtained by crushing and grinding construction waste containing recycled concrete and bricks, and the construction waste powder is composed of recycled concrete powder and brick powder in a mass ratio of 67:33.

[0063] The preparation method of autoclaved aerated concrete blocks in this embodiment is basically the same as that in Example 3, and will not be repeated here.

[0064] Example 6

[0065] An autoclaved aerated concrete block based on all-solid waste materials comprises the following components by weight: 28 parts of all-solid waste cementitious material, 66 parts of construction waste powder, 0.08 parts of aluminum powder, 0.04 parts of foam stabilizer, and 60 parts of water; the all-solid waste cementitious material includes slag, fly ash, steel slag, desulfurized gypsum, and red mud, with the mass ratio of each component being slag:fly ash:steel slag:desulfurized gypsum:red mud = 30:10:5:3:2; the construction waste powder is obtained by crushing and grinding construction waste containing recycled concrete and bricks, and the construction waste powder is made by mixing recycled concrete powder and brick powder in a mass ratio of 65:35.

[0066] The preparation method of autoclaved aerated concrete blocks in this embodiment is basically the same as that in Example 3, and will not be repeated here.

[0067] Example 7

[0068] An autoclaved aerated concrete block based on all-solid waste materials comprises the following components by weight: 28 parts of all-solid waste cementitious material, 66 parts of construction waste powder, 0.08 parts of aluminum powder, 0.04 parts of foam stabilizer, and 60 parts of water; the all-solid waste cementitious material includes slag, fly ash, steel slag, desulfurized gypsum, and red mud, with the mass ratio of each component being slag:fly ash:steel slag:desulfurized gypsum:red mud = 70:15:25:20:15; the construction waste powder is obtained by crushing and grinding construction waste containing recycled concrete and bricks, and the construction waste powder is made by mixing recycled concrete powder and brick powder in a mass ratio of 65:35.

[0069] The preparation method of autoclaved aerated concrete blocks in this embodiment is basically the same as that in Example 3, and will not be repeated here.

[0070] Example 8

[0071] An autoclaved aerated concrete block based on all-solid waste materials comprises the following components by weight: 20 parts of all-solid waste cementitious material, 50 parts of construction waste powder, 0.02 parts of aluminum powder, 0.01 parts of foam stabilizer, and 40 parts of water; the all-solid waste cementitious material includes slag, fly ash, steel slag, desulfurized gypsum, and red mud, with the mass ratio of each component being slag:fly ash:steel slag:desulfurized gypsum:red mud = 50:30:15:10:7; the construction waste powder is obtained by crushing and grinding construction waste containing recycled concrete and bricks, and the construction waste powder is made by mixing recycled concrete powder and brick powder in a mass ratio of 50:20.

[0072] The preparation method of autoclaved aerated concrete blocks in this embodiment is basically the same as that in Example 3, and will not be repeated here.

[0073] Example 9

[0074] An autoclaved aerated concrete block based on all-solid waste materials comprises the following components by weight: 20 parts of all-solid waste cementitious material, 50 parts of construction waste powder, 0.02 parts of aluminum powder, 0.01 parts of foam stabilizer, and 40 parts of water; the all-solid waste cementitious material includes slag, fly ash, steel slag, desulfurized gypsum, and red mud, with the mass ratio of each component being slag:fly ash:steel slag:desulfurized gypsum:red mud = 50:30:15:10:7; the construction waste powder is obtained by crushing and grinding construction waste containing recycled concrete and bricks, and the construction waste powder is made by mixing recycled concrete powder and brick powder in a mass ratio of 80:15.

[0075] The preparation method of autoclaved aerated concrete blocks in this embodiment is basically the same as that in Example 3, and will not be repeated here.

[0076] II. Comparative Example

[0077] Comparative Example 1

[0078] An autoclaved aerated concrete block based on all-solid waste materials differs from Example 3 in that the all-solid waste cementitious material contains no red mud.

[0079] Specifically, it includes the following components by weight: 28 parts of all-solid-waste cementitious material, 66 parts of construction waste powder, 0.08 parts of aluminum powder, 0.04 parts of foam stabilizer, and 60 parts of water; the all-solid-waste cementitious material includes slag, fly ash, steel slag, and desulfurized gypsum, with the mass ratio of each component being slag:fly ash:steel slag:desulfurized gypsum = 50:30:15:10; the construction waste powder is obtained by crushing and grinding construction waste containing recycled concrete and bricks, and the construction waste powder is made by mixing recycled concrete powder and brick powder in a mass ratio of 65:35.

[0080] The preparation method of the concrete blocks in this comparative example is basically the same as that in Example 3, and will not be repeated here.

[0081] Comparative Example 2

[0082] An autoclaved aerated concrete block based on all-solid waste materials differs from Example 3 in that the all-solid waste cementitious material contains no steel slag.

[0083] Specifically, it includes the following components by weight: 28 parts of solid waste cementitious material, 66 parts of construction waste powder, 0.08 parts of aluminum powder, 0.04 parts of foam stabilizer, and 60 parts of water; the solid waste cementitious material includes slag, fly ash, desulfurized gypsum, and red mud, with the mass ratio of each component being slag:fly ash:desulfurized gypsum:red mud = 50:30:10:7; the construction waste powder is obtained by crushing and grinding construction waste containing recycled concrete and bricks, and the construction waste powder is made by mixing recycled concrete powder and brick powder in a mass ratio of 65:35.

[0084] The preparation method of the concrete blocks in this comparative example is basically the same as that in Example 3, and will not be repeated here.

[0085] Comparative Example 3

[0086] An autoclaved aerated concrete block based on all solid waste materials, which differs from Example 3 in that it does not contain construction waste powder.

[0087] Specifically, it includes the following components by weight: 28 parts of solid waste cementitious material, 0.08 parts of aluminum powder, 0.04 parts of foam stabilizer, and 60 parts of water; the solid waste cementitious material includes slag, fly ash, steel slag, desulfurized gypsum, and red mud, with the mass ratio of each component being slag:fly ash:steel slag:desulfurized gypsum:red mud = 50:30:15:10:7.

[0088] The preparation method of the concrete blocks in this comparative example is basically the same as that in Example 3, and will not be repeated here.

[0089] Comparative Example 4

[0090] An autoclaved aerated concrete block based on all solid waste materials, which differs from Example 3 in that the construction waste powder does not contain brick powder.

[0091] Specifically, it includes the following components by weight: 28 parts of all-solid-waste cementitious material, 66 parts of construction waste powder, 0.08 parts of aluminum powder, 0.04 parts of foam stabilizer, and 60 parts of water; the all-solid-waste cementitious material includes slag, fly ash, steel slag, desulfurized gypsum, and red mud, with the mass ratio of each component being slag:fly ash:steel slag:desulfurized gypsum:red mud = 50:30:15:10:7; the construction waste powder is obtained by crushing and grinding construction waste containing recycled concrete, and the mass percentage of recycled concrete powder in the construction waste powder is 65%.

[0092] The preparation method of the concrete blocks in this comparative example is basically the same as that in Example 3, and will not be repeated here.

[0093] Comparative Example 5

[0094] An autoclaved aerated concrete block based on all solid waste materials, which differs from Example 3 in that the construction waste powder does not contain recycled concrete powder.

[0095] Specifically, it includes the following components by weight: 28 parts of solid waste cementitious material, 66 parts of construction waste powder, 0.08 parts of aluminum powder, 0.04 parts of foam stabilizer, and 60 parts of water; the solid waste cementitious material includes slag, fly ash, steel slag, desulfurized gypsum, and red mud, with the mass ratio of each component being slag:fly ash:steel slag:desulfurized gypsum:red mud = 50:30:15:10:7; the construction waste powder is obtained by crushing and grinding construction waste containing bricks, and the mass percentage of brick powder in the construction waste powder is 35%.

[0096] The preparation method of the concrete blocks in this comparative example is basically the same as that in Example 3, and will not be repeated here.

[0097] Comparative Example 6

[0098] An autoclaved aerated concrete block based on all-solid waste materials differs from Example 3 in that the all-solid waste cementitious material contains no fly ash.

[0099] Specifically, it includes the following components by weight: 28 parts of solid waste cementitious material, 66 parts of construction waste powder, 0.08 parts of aluminum powder, 0.04 parts of foam stabilizer, and 60 parts of water; the solid waste cementitious material includes slag, steel slag, desulfurized gypsum, and red mud, with the mass ratio of each component being slag: steel slag: desulfurized gypsum: red mud = 50:15:10:7; the construction waste powder is obtained by crushing and grinding construction waste containing recycled concrete and bricks, and the construction waste powder is made by mixing recycled concrete powder and brick powder in a mass ratio of 65:35.

[0100] The preparation method of the concrete blocks in this comparative example is basically the same as that in Example 3, and will not be repeated here.

[0101] Comparative Example 7

[0102] An autoclaved aerated concrete block based on all-solid waste materials, which differs from Example 3 in that the all-solid waste cementitious material contains no slag.

[0103] Specifically, it includes the following components by weight: 28 parts of solid waste cementitious material, 66 parts of construction waste powder, 0.08 parts of aluminum powder, 0.04 parts of foam stabilizer, and 60 parts of water; the solid waste cementitious material includes fly ash, steel slag, desulfurized gypsum, and red mud, with the mass ratio of each component being fly ash: steel slag: desulfurized gypsum: red mud = 30:15:10:7; the construction waste powder is obtained by crushing and grinding construction waste containing recycled concrete and bricks, and the construction waste powder is made by mixing recycled concrete powder and brick powder in a mass ratio of 65:35.

[0104] The preparation method of the concrete blocks in this comparative example is basically the same as that in Example 3, and will not be repeated here.

[0105] Comparative Example 8

[0106] An autoclaved aerated concrete block based on all solid waste materials comprises the following components by weight: 13 parts cement, 2 parts gypsum, 20 parts quicklime, 0.07 parts aluminum powder, 0.05 parts foam stabilizer, 65 parts river sand, and 60 parts water.

[0107] The preparation method of autoclaved aerated concrete blocks in this comparative example is as follows: Weigh all components except aluminum powder and foam stabilizer according to the proportion, pour each component into a mixer, stir for 3 minutes to obtain slurry, and measure the consistency and specific gravity of the slurry; Weigh aluminum powder and foam stabilizer according to the proportion, add them to the prepared slurry, continue stirring for 40 seconds, pour into a mold, and place the slurry with the mold in a curing chamber for static gas generation and thickening for 2.5 hours; Cut the hardened preform into blocks of a specific size. The size of this comparative example is designed to be 400mm*200mm*100mm. Place the blocks in an autoclave for curing for 11 hours at a curing temperature of 190℃ and a pressure of 1.0MPa. After curing, the autoclaved aerated concrete blocks are obtained.

[0108] III. Performance Test Experiments and Results

[0109] After preparing the autoclaved aerated concrete blocks for each group according to the above process, the dry density, compressive strength and frost resistance (including the mass loss rate and strength loss rate after freezing) were tested according to the relevant provisions in GB / T11968-2020 Autoclaved Aerated Concrete Blocks. The cost of autoclaved aerated concrete blocks with different mix proportions and preparation processes was calculated. The performance test results and costs are shown in Table 1.

[0110] Table 1. Comparison of performance and cost of concrete blocks in different groups

[0111]

[0112] As shown in the table, in terms of performance, Examples 1-5 are within the mix proportion range protected by this application. The compressive strength of the concrete blocks within this mix proportion range is all above 5.0 MPa, and the dry density is all less than 750 kg / m³. 3 All meet the requirements of grade A5.0 / B07, have excellent antifreeze properties, and have a mass loss rate of 2.02% to 2.47% and a strength loss rate of 11.2% to 12.3% after freezing.

[0113] The components of Examples 6-9 are basically the same as those of this application, but the proportions are outside the scope of protection of this application. The compressive strength and dry density of Examples 6 and 7 still meet the requirements of A5.0 / B07 grade. The frost resistance of Examples 6-7 is not much different from that of Examples 1-5. The compressive strength of Example 8 meets A5.0, while the compressive strength of Example 9 does not meet A5.0. The dry density of Examples 8 and 9 does not meet the B07 grade. Example 8 has excellent frost resistance with a mass loss rate of 1.65% and a strength loss rate of 10.2% after freezing. Example 9 has poor frost resistance with a mass loss rate of 3.01% and a strength loss rate of 13.6% after freezing.

[0114] In the comparative examples, the compressive strength of comparative examples 1-7 was between 3.15 and 4.96 MPa, which was significantly lower than that of the example, and the frost resistance was poor (the mass loss rate after freezing was concentrated between 2.76% and 3.64%, and the strength loss rate after freezing was about 12.6% to 15.2%).

[0115] Comparative Example 1 (without red mud): The alkali activation system was not sustained enough, the fly ash / slag was not fully dissolved, the amount of tobermorite generated was reduced, resulting in a decrease in strength.

[0116] Comparative Example 2 (without steel slag): Insufficient alkaline environment in the early stage reduced the gas generation rate of aluminum powder, resulting in uneven bubble structure and affecting thermal conductivity and strength.

[0117] Comparative Example 3 (without construction waste powder): The main silicon source and secondary calcium source are lost, the hydration products of the cementitious material have poor interweaving properties, the drying shrinkage value increases, and the strength decreases.

[0118] Comparative Examples 4-5 (Missing Micropowder Components in Construction Waste): Insufficient supply of SiO2 / calcium ions, accumulation of unreacted Ca(OH)2 or reduced CSH gel formation, resulting in decreased strength and durability.

[0119] Comparative Examples 6-7 (Missing Solid Waste Cementitious Material Components): The absence of fly ash / slag leads to a decrease in slurry workability, excessive casting consistency, or a reduced rate of increase in strength in the later stages.

[0120] Therefore, the overall performance of the concrete blocks prepared in Examples 1-5 is better than that in Examples 6-9 and Comparative Examples 1-8. This is because in the solid waste cementitious materials, steel slag provides strong alkalinity to activate the activity of fly ash / slag, and red mud continuously replenishes alkalinity. The two work together to promote the generation of hydration products such as tobermorite, thereby improving strength. The calcium-silicon complementarity of construction waste powder (recycled concrete powder + brick powder) optimizes the pore structure and the stability of hydration products, ensuring frost resistance. In addition, the price of solid waste raw materials is low, and the construction waste powder replaces river sand, saving grinding energy consumption and directly reducing production costs.

[0121] In terms of cost, the costs of Examples 1-9 range from 82.5 to 89.7 yuan / m². 3 It is economically viable, with costs for comparison examples 1-7 ranging from 85.9 to 87.2 yuan / m². 3 Some comparative examples (e.g., comparative example 3) have a much higher cost than the examples. Comparative example 8 is a common concrete block mix in the prior art, which has a high cost.

[0122] In summary, the autoclaved aerated concrete (AAC) blocks provided by this method use all-solid-waste cementitious materials and construction waste powder to replace traditional cement and quartz sand, achieving the preparation of AAC blocks using all-solid-waste materials. The price of solid waste raw materials is much lower than that of cement, quicklime, and river sand. Furthermore, the replacement of river sand with construction waste powder eliminates grinding energy consumption in the raw material processing, greatly reducing the production energy consumption and cost of the product. Through the combination of all-solid-waste cementitious materials, construction waste powder, and other functional additives, the strength of the blocks is improved.

[0123] For autoclaved aerated concrete blocks, superior performance is usually reflected in low dry density (which helps reduce the self-weight of buildings, etc.), high compressive strength (ensuring structural load-bearing capacity), good frost resistance (low mass loss rate and strength loss rate after freezing, adapting to different environments), and relatively low cost. Based on comprehensive judgment, Example 3 is the optimal embodiment of this application, which not only meets the requirement that the dry density and compressive strength of the product can stably reach the B07 and A5.0 grade standards, but also has a low cost.

Claims

1. An autoclaved aerated concrete block based on all-solid waste materials, characterized in that: It comprises the following components by weight: 25-30 parts of solid waste cementitious material, 60-70 parts of construction waste powder, 0.05-0.1 parts of aluminum powder, 0.02-0.06 parts of foam stabilizer, and 60-70 parts of water; the construction waste powder is obtained by crushing and grinding construction waste containing recycled concrete and bricks.

2. The autoclaved aerated concrete block based on all-solid waste materials according to claim 1, characterized in that: The solid waste cementitious material includes slag, fly ash, steel slag, desulfurized gypsum and red mud, and the mass ratio of each component is slag: fly ash: steel slag: desulfurized gypsum: red mud = (40~60): (20~35): (10~20): (5~15): (5~10).

3. The autoclaved aerated concrete block based on all-solid waste materials according to claim 1, characterized in that: The specific surface area of ​​the solid waste cementitious material is not less than 500 m². 2 / kg.

4. The autoclaved aerated concrete block based on all-solid waste materials according to claim 1, characterized in that: The construction waste powder is made by mixing recycled concrete powder and brick powder in a mass ratio of (60-70):(30-40).

5. The autoclaved aerated concrete block based on all-solid waste materials according to claim 1, characterized in that: The specific surface area of ​​the construction waste powder is not less than 350m². 2 / kg, with SiO2 content not less than 55%.

6. The autoclaved aerated concrete block based on all-solid waste materials according to claim 1, characterized in that: It includes the following components by weight: 28 parts of solid waste cementitious material, 66 parts of construction waste powder, 0.08 parts of aluminum powder, 0.04 parts of foam stabilizer, and 60 parts of water; The solid waste cementitious material includes slag, fly ash, steel slag, desulfurized gypsum and red mud, with the mass ratio of each component being slag: fly ash: steel slag: desulfurized gypsum: red mud = 50:30:15:10:7; the construction waste powder is made by mixing recycled concrete powder and brick powder in a mass ratio of 65:

35.

7. A method for preparing autoclaved aerated concrete blocks based on all-solid waste materials according to any one of claims 1-6, characterized in that: Includes the following steps: S1. Weigh out the recycled concrete powder and brick powder according to the ratio, mix them, add water and stir to pre-wet the construction waste powder; S2. Weigh the solid waste cementitious material and water according to the proportion and pour them into the pre-wetted construction waste powder obtained in S1, and stir to make a slurry. S3. Weigh out aluminum powder and foam stabilizer according to the ratio, add them to the slurry prepared in S2, stir and pour into the mold. Place the slurry in the curing chamber with the mold to stand still and thicken due to gas generation. S4. After the hardened embryo from S3 is cut into blocks of a specific size, the blocks are placed in an autoclave for curing. Once curing is complete, autoclaved aerated concrete blocks are obtained. S5. Conduct quality testing on the finished product obtained in S4. Unqualified products are crushed and reused as construction waste powder material.

8. The preparation method according to claim 7, characterized in that: In step S2, the stirring time is 2 to 3 minutes.

9. The preparation method according to claim 7, characterized in that: In step S3, the stirring time after adding aluminum powder and foam stabilizer to the slurry is 30-40 seconds, and the gas generation and thickening time is 2-3 hours.

10. The preparation method according to claim 7, characterized in that: In step S4, the curing conditions are: temperature 180–200℃, pressure 1.0–1.2 MPa, and curing time 10–12 h.

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