A lime material incorporating aerated concrete waste and its preparation method

Abstract

This application relates to the field of building lime materials technology, specifically disclosing a lime material incorporating aerated concrete waste and its preparation method. The lime material incorporating aerated concrete waste comprises quicklime, composite recycled powder, metakaolin, lithium-based composite activator, modified nano-zinc oxide, hemihydrate gypsum, hydroxypropyl methylcellulose ether, and sodium carboxymethyl starch. The composite recycled powder is obtained by activating aerated concrete waste and waste clay brick powder with acetic acid solution and composite alkali solution. The modified nano-zinc oxide is obtained by modifying nano-zinc oxide with a silane coupling agent and trehalose. The lime material of this application can effectively utilize aerated concrete waste and waste clay brick powder; furthermore, through the synergistic innovation of the composite additive system, the setting strength and water resistance of the lime material are effectively improved.

Description

Technical Field

[0001] This application relates to the field of building lime materials technology, and more specifically, it relates to a lime material incorporating aerated concrete waste and its preparation method. Background Technology

[0002] Lime is an indispensable basic cementing material in the field of construction engineering. With its excellent plasticity, binding properties and compatibility with other building materials, it is widely used in wall plastering, masonry construction, foundation reinforcement and road base treatment, which is of great significance to ensuring the stability of building structures and construction results.

[0003] In existing technologies, limestone is mostly prepared using natural limestone as the core raw material, processed through calcination, digestion, and other processes. Some methods add industrial waste such as fly ash and slag to reduce production costs or improve specific properties. However, the current limestone formulation design is still mainly based on traditional raw materials, and the performance optimization direction is relatively singular, making it difficult to achieve a comprehensive improvement in strength, setting speed, and water resistance.

[0004] The sources of aerated concrete waste are diverse, including substandard materials and scraps generated during production due to dimensional deviations or substandard performance, as well as aerated concrete construction waste generated during building demolition. This type of waste is abundant, and due to its complex composition and irregular particle shape, current disposal methods primarily involve stockpiling or landfilling. This not only occupies significant land resources but also potentially causes dust pollution and impacts on soil and water environments, resulting in extremely low resource utilization rates. Simultaneously, existing lime materials generally suffer from insufficient setting strength and poor water resistance, limiting their application in demanding building scenarios. Therefore, how to effectively recycle and utilize aerated concrete waste while simultaneously improving the overall performance of lime materials to achieve the dual goals of solid waste resource utilization and building material performance upgrades has become a pressing technical challenge in the field of building lime materials. Summary of the Invention

[0005] In order to effectively recycle aerated concrete waste and improve the setting strength and water resistance of lime materials, this application provides a lime material containing aerated concrete waste and its preparation method.

[0006] This application provides a technical solution for using aerated concrete waste as a blend:

[0007] A mixture of aerated concrete waste and raw materials comprises the following parts by weight:

[0008] 50-60 parts quicklime;

[0009] 20-30 parts of composite recycled powder;

[0010] 5-10 parts of metakaolin;

[0011] 3-6 parts of lithium-based composite activator;

[0012] 1-3 parts of modified nano zinc oxide;

[0013] 3-6 parts hemihydrate gypsum;

[0014] Hydroxypropyl methylcellulose ether, 0.2-0.8 parts;

[0015] Sodium carboxymethyl starch 0.5-1.5 parts;

[0016] The composite recycled powder is obtained by activating aerated concrete waste and waste clay brick powder with acetic acid solution and composite alkali solution.

[0017] The modified nano zinc oxide was obtained by modifying nano zinc oxide with a silane coupling agent and trehalose.

[0018] By adopting the above technical solution, the core problems of insufficient setting strength and poor water resistance of lime materials are precisely solved through the synergistic effect of multiple components. Quicklime provides the basic cementitious skeleton, composite recycled powder acts as an active aggregate to replace part of the natural raw materials, and forms a reaction system with metakaolin and lithium-based composite activators. Modified nano zinc oxide optimizes the microstructure, and auxiliary materials such as hemihydrate gypsum and hydroxypropyl methylcellulose ether regulate the reaction rhythm. The synergistic effect of each component achieves a simultaneous upgrade in setting strength and water resistance.

[0019] Composite recycled powder can efficiently promote the resource utilization of aerated concrete waste. By compounding aerated concrete waste with waste clay brick powder to form composite recycled powder, not only is the environmental problem of waste dumping and landfilling solved, but also the components such as hydrated calcium silicate and activated alumina contained in the waste undergo a secondary reaction with lime hydration products, transforming the waste from a "passive filler" into an "active reactant." This reduces raw material costs while providing additional active support for strength improvement. Lithium-based composite activators inhibit alkali-aggregate reaction and accelerate CSH gel formation. Modified nano zinc oxide enhances interfacial bonding and blocks water penetration through chemical bonding and hydrophobic modification. The auxiliary additives balance setting speed and water retention. The three work synergistically to optimize the microstructure of lime, enabling hydration products to form a continuous and dense network structure, significantly improving setting strength and water resistance stability, meeting the needs of high-requirement building applications.

[0020] Optionally, the composite recycled powder is prepared using the following method:

[0021] (1) After mixing the aerated concrete waste and waste clay brick powder, microwave sintering is carried out at 250-300℃ for 15-25 minutes to obtain sintered material;

[0022] (2) Immerse the sintered material in acetic acid solution for 2-4 hours, drain it to obtain acid-etched material, immerse the acid-etched material in composite alkaline solution for 3-5 hours, wash it with deionized water until neutral, dry it at 80-100℃ until constant weight, grind it and pass it through a 100-mesh sieve, and take the sieve material to obtain composite recycled powder.

[0023] By adopting the above technical solution, after the aerated concrete waste and waste clay brick powder are compounded, they are modified by "microwave sintering-acid etching-alkali activation". On the one hand, the organic impurities in the waste are removed by microwave sintering, and the acid etching treatment increases the surface roughness of the particles and dissolves the inert coating layer, creating a channel for the release of active components. On the other hand, the silicate ions and carbonate ions in the composite alkali solution can efficiently activate the active SiO2 and Al2O3 components in the waste to be converted into reactive states. The complementary effect of the components of the composite aggregate (aerated concrete waste is rich in hydrated calcium silicate, and waste clay brick powder is rich in active alumina) further enhances the reactivity with lime hydration products, transforming the waste from a "passive filler" to an "active reactant". The Ca(OH)2 generated by quicklime hydration provides an alkaline environment for the system, which undergoes a secondary hydration reaction with the active SiO2 and Al2O3 released by the composite modified aggregate, generating a large amount of high-density C-(A)-SH gel and a small amount of ettringite. These products intertwine to form a continuous network structure, filling the internal pores, thereby effectively improving the setting strength and water resistance of the lime material.

[0024] Optionally, in step (1), the mass ratio of the aerated concrete waste to the waste clay brick powder is (2-3):1.

[0025] By adopting the above technical solution, the mass ratio design of aerated concrete waste and waste clay brick powder is conducive to achieving complementary components. Aerated concrete waste is rich in hydrated calcium silicate, and waste clay brick powder is rich in active alumina. The combination of the two can provide sufficient multi-element active components for secondary hydration reaction, promote the synergistic formation of C-(A)-SH gel and a small amount of ettringite, improve the stability of setting strength, and optimize the pore structure through the interweaving effect of multi-element hydration products, thereby enhancing water resistance.

[0026] Optionally, in step (2), the mass concentration of the acetic acid solution is 0.3%-0.9%, and the mass ratio of the sintering material to the acetic acid solution is 1:(12-15).

[0027] By adopting the above technical solution, the above proportion can uniformly acid etch the surface of the sintered material under mild conditions, which not only ensures the improvement of particle roughness to enhance the interfacial bonding force, but also avoids excessive corrosion that damages the internal structure of the powder, thus ensuring its supporting role as aggregate. Moderate acid etching can also create more reaction sites for subsequent alkali activation, promote the full release of active components, and lay a structural foundation for improving the setting strength and water resistance.

[0028] Optionally, in step (2), the solute of the composite alkaline solution is prepared by mixing glass and sodium carbonate in a mass ratio of (3-4):1, the mass concentration of the composite alkaline solution is 8%-12%, and the mass ratio of the acid etching material to the composite alkaline solution is 1:(10-12).

[0029] Optionally, the lithium-based composite activator is prepared by mixing lithium hydroxide, sodium sulfate and zeolite powder in a mass ratio of (2-3):(3-4):5.

[0030] By adopting the above technical solution, the above ratio enables the lithium-based composite activator to have strong activation, early strength effect and adsorption properties. Lithium ions lower the dehydration temperature of Ca(OH)2, accelerate the formation of CSH gel and inhibit the reaction of alkali aggregate, sodium sulfate improves the early setting strength, and zeolite powder adsorbs free ions to optimize the microstructure. The three work together to ensure that the lime material sets quickly and forms a high-strength skeleton, and also reduce water erosion and improve water resistance stability by inhibiting cracking and optimizing pore structure.

[0031] Optionally, the modified nano-zinc oxide is prepared using the following method:

[0032] A. Place the nano zinc oxide in a low-temperature plasma treatment instrument, introduce a mixture of argon and oxygen, with a volume ratio of argon to oxygen of (3-5):1, control the power to be 80-120W and the pressure to be 50-80Pa, and treat for 10-15 minutes to obtain activated nano zinc oxide.

[0033] B. Dissolve γ-aminopropyltriethoxysilane and trehalose in anhydrous ethanol and deionized water to obtain a composite modified solution;

[0034] C. Add activated nano zinc oxide to the composite modification solution, stir magnetically at 40-50℃ for 2-3 hours, then centrifuge to separate, collect the precipitate, wash with anhydrous ethanol 3-5 times, vacuum dry at 60-70℃ for 3-4 hours, grind through a 400-mesh sieve to obtain modified nano zinc oxide.

[0035] By adopting the above technical solution, the combined process of low-temperature plasma pretreatment and "γ-aminopropyltriethoxysilane + trehalose" composite modification solves the pain points of traditional nano zinc oxide agglomeration and modification failure in alkaline systems: plasma activation increases the number of hydroxyl groups on the surface of nano zinc oxide, thereby improving reactivity; γ-aminopropyltriethoxysilane enhances the interfacial bonding force with hydration products and composite recycled powder through chemical bonding, while trehalose assists in dispersion through hydrogen bonding and protects γ-aminopropyltriethoxysilane from decomposition by strong alkali; the modified nano zinc oxide not only acts as a crystal nucleus to promote the directional growth of CSH gel and improve coagulation strength, but also forms a dense hydrophobic layer to block water penetration, significantly improving water resistance.

[0036] Optionally, in step B, the mass ratio of γ-aminopropyltriethoxysilane, trehalose, anhydrous ethanol and deionized water is (4-5):1:(60-70):(30-40).

[0037] Optionally, in step C, the mass ratio of activated nano zinc oxide to composite modified liquid is 1:(8-10).

[0038] Secondly, this application provides a method for preparing lime material mixed with aerated concrete waste, using the following technical solution:

[0039] A method for preparing lime material mixed with aerated concrete waste includes the following steps:

[0040] S1. First, put quicklime and composite recycled powder into a mixer and stir at 300-350 rpm for 3-4 minutes. Then add metakaolin and lithium-based composite activator, adjust the speed to 350-400 rpm and stir for 2-3 minutes. Finally, add modified nano zinc oxide, hemihydrate gypsum, hydroxypropyl methylcellulose ether and sodium carboxymethyl starch, and stir at the same speed for 4-5 minutes to obtain a mixture.

[0041] S2. Place the mixture in an environment with a temperature of 20-30℃ and a humidity of 55%-65% for 72-96 hours, and stir it once every 12 hours during the period. After aging, use a vibrating screen to sieve it through a 60-mesh standard sieve. Take the material that passes through the sieve to obtain the lime material.

[0042] By adopting the above technical solution, the preparation process of segmented stirring and gradient aging can ensure that the raw materials are mixed evenly and the hydration reaction is sufficient: segmented stirring avoids the agglomeration of raw materials with different densities and activities, and ensures that the composite recycled powder, activator and modified nano zinc oxide are evenly dispersed in the system; the aging environment of 20-30℃ and 55%-65% and the timed stirring not only ensure that the quicklime is slowly digested to avoid volume expansion and cracking, but also promotes the full progress of the secondary hydration reaction, so that C-(A)-SH gel is fully generated and interwoven to form a dense structure; 60-mesh sieving removes coarse particles and agglomerates, further optimizes the particle size uniformity, and ultimately improves the consistency of the lime material's setting strength and water resistance.

[0043] In summary, this application has the following beneficial effects:

[0044] 1. This application, through innovative design and modification process of composite recycled powder, efficiently solves the dual technical challenges of low resource utilization rate of aerated concrete waste and insufficient setting strength of lime. This application abandons the traditional extensive utilization model of simple waste filling, scientifically compounding aerated concrete waste with waste clay brick powder, and then employing a composite modification treatment of microwave sintering, acid etching, and alkali activation: microwave sintering removes organic impurities from the waste, acid etching increases particle surface roughness and dissolves the inert coating layer, and composite alkali solution efficiently activates the active silicon and aluminum components in the waste into a reactive state. The compound recycled powder, through the complementary effect of its components, combines the hydrated calcium silicate rich in aerated concrete waste with the active alumina rich in waste clay brick powder, transforming the waste from a passive filler into an active reactant. It undergoes a secondary hydration reaction with the calcium hydroxide generated from the hydration of quicklime, producing a large amount of high-density gel and a small amount of ettringite. These products intertwine to form a continuous network structure, filling internal pores and significantly improving the setting strength of the lime. At the same time, the design significantly reduces the amount of aerated concrete waste, avoiding land occupation and environmental pollution problems caused by waste dumping and landfilling, and successfully achieving the dual goals of solid waste resource utilization and building material performance upgrade.

[0045] 2. This application addresses the core weakness of poor water resistance in lime materials through synergistic innovation in a composite additive system, while further enhancing setting strength and stability. This application innovatively employs a synergistic system of lithium-based composite activators, modified nano-zinc oxide, and auxiliary additives: the lithium-based composite activator, through a scientifically proportioned multi-component system, possesses strong activating properties, early strength effect, and adsorption capacity, accelerating gel formation, inhibiting alkali-aggregate reaction, and improving early strength; the modified nano-zinc oxide, after low-temperature plasma pretreatment and synergistic modification with a composite modifier, enhances the interfacial bonding with hydration products and composite recycled powder through chemical bonding, and forms a dense hydrophobic layer to block water penetration, effectively solving the problems of easy agglomeration and modification failure of traditional nano-zinc oxide in alkaline systems; the auxiliary additives synergistically regulate the setting rate and improve water retention, ensuring the full progress of the hydration reaction. The multi-components work synergistically from multiple dimensions, including activity activation, microstructure optimization, and reaction process regulation, to enable the lime hydration products to form a continuous and dense network structure. This not only improves the setting strength to a level suitable for high-requirement building scenarios, but also significantly enhances the water resistance.

[0046] 3. The production process of this application is simple and controllable, and can stably produce lime with high setting strength, excellent water resistance and stable volume. At the same time, it reduces energy consumption and cost in the production process, providing strong support for the industrial application of the technical solution and effectively solving the practical problems of large performance fluctuations and poor process adaptability in traditional lime production. Detailed Implementation

[0047] The present application will be further described in detail below with reference to the embodiments.

[0048] Example of preparation of composite recycled powder

[0049] Preparation Example 1

[0050] The composite recycled powder was prepared using the following method:

[0051] (1) After mixing aerated concrete waste and waste clay brick powder at a mass ratio of 2:1, microwave sintering is carried out at 250℃ for 25 minutes to obtain sintered material;

[0052] (2) Immerse the sintered material in an acetic acid solution with a mass concentration of 0.3% for 4 hours. The mass ratio of the sintered material to the acetic acid solution is 1:15. After immersion, remove the material and drain it to obtain the acid-etched material. Immerse the acid-etched material in a composite alkaline solution for 3 hours. The solute in the composite alkaline solution is glass and sodium carbonate prepared in a mass ratio of 3:1. The mass concentration of the composite alkaline solution is 12%. After immersion, remove the material and wash it with deionized water until neutral. Place it in an environment of 80°C and dry it to constant weight. After grinding, pass it through a 100-mesh sieve. Take the material that passes through the sieve to obtain the composite recycled powder.

[0053] Preparation Example 2

[0054] The composite recycled powder was prepared using the following method:

[0055] (1) After mixing aerated concrete waste and waste clay brick powder at a mass ratio of 2.5:1, microwave sintering was carried out at 275℃ for 20 min to obtain sintered material;

[0056] (2) The sintered material is immersed in an acetic acid solution with a mass concentration of 0.6% for 3 hours. The mass ratio of the sintered material to the acetic acid solution is 1:14. After immersion, the material is taken out and drained to obtain the acid-etched material. The acid-etched material is then immersed in a composite alkaline solution for 4 hours. The solute in the composite alkaline solution is glass and sodium carbonate prepared in a mass ratio of 3.5:1. The mass concentration of the composite alkaline solution is 10%. After immersion, the material is taken out and washed with deionized water until neutral. It is then dried at 90°C until constant weight. After grinding, it is passed through a 100-mesh sieve. The material passing through the sieve is the composite recycled powder.

[0057] Preparation Example 3

[0058] The composite recycled powder was prepared using the following method:

[0059] (1) After mixing aerated concrete waste and waste clay brick powder at a mass ratio of 3:1, microwave sintering is carried out at 300℃ for 15 minutes to obtain sintered material;

[0060] (2) Immerse the sintered material in an acetic acid solution with a mass concentration of 0.9% for 2 hours. The mass ratio of the sintered material to the acetic acid solution is 1:12. After immersion, remove the material and drain it to obtain the acid-etched material. Immerse the acid-etched material in a composite alkaline solution for 3 hours. The solute in the composite alkaline solution is glass and sodium carbonate prepared in a mass ratio of 4:1. The mass concentration of the composite alkaline solution is 8%. After immersion, remove the material and wash it with deionized water until neutral. Place it in an environment of 100°C and dry it to constant weight. Then grind it and pass it through a 100-mesh sieve. Take the material that passes through the sieve to obtain the composite recycled powder.

[0061] Preparation Example 4

[0062] The difference between the composite recycled powder and the preparation example 3 is that in this preparation example, the mass concentration of the acetic acid solution used in step (2) is 5%.

[0063] Preparation Example 5

[0064] The composite recycled powder differs from preparation example 3 in that step (2) was not performed in this preparation example. The specific preparation method is as follows:

[0065] (1) After mixing aerated concrete waste and waste clay brick powder at a mass ratio of 3:1, microwave sintering is carried out at 300℃ for 15 minutes to obtain sintered material; after grinding, the sintered material is passed through a 100-mesh sieve, and the material passing through the sieve is taken to obtain composite recycled powder.

[0066] Preparation example of modified nano zinc oxide

[0067] Preparation Example 6

[0068] Modified nano-zinc oxide was prepared using the following method:

[0069] A. Place nano zinc oxide in a low-temperature plasma treatment instrument, introduce a mixture of argon and oxygen with a volume ratio of argon to oxygen of 3:1, control the power at 80W and the pressure at 50Pa, and treat for 10 minutes to obtain activated nano zinc oxide.

[0070] B. Dissolve γ-aminopropyltriethoxysilane and trehalose in anhydrous ethanol and deionized water to obtain a composite modified solution; the mass ratio of γ-aminopropyltriethoxysilane, trehalose, anhydrous ethanol and deionized water is 4:1:60:40.

[0071] C. Add activated nano zinc oxide to the composite modification solution. The mass ratio of activated nano zinc oxide to composite modification solution is 1:8. Then, stir magnetically at 40℃ for 2 hours, then centrifuge to separate the precipitate, wash it 5 times with anhydrous ethanol, vacuum dry it at 60℃ for 3 hours, and grind it through a 400-mesh sieve to obtain modified nano zinc oxide.

[0072] Preparation Example 7

[0073] Modified nano-zinc oxide was prepared using the following method:

[0074] A. Place nano zinc oxide in a low-temperature plasma treatment instrument, introduce a mixture of argon and oxygen with a volume ratio of 4:1, control the power at 100W and the pressure at 65Pa, and treat for 12 minutes to obtain activated nano zinc oxide.

[0075] B. Dissolve γ-aminopropyltriethoxysilane and trehalose in anhydrous ethanol and deionized water to obtain a composite modified solution; the mass ratio of γ-aminopropyltriethoxysilane, trehalose, anhydrous ethanol and deionized water is 4.5:1:65:35.

[0076] C. Add activated nano zinc oxide to the composite modification solution at a mass ratio of 1:9. Then, stir magnetically at 45°C for 2.5 hours, centrifuge to separate the precipitate, wash it 5 times with anhydrous ethanol, vacuum dry it at 65°C for 3.5 hours, and grind it through a 400-mesh sieve to obtain modified nano zinc oxide.

[0077] Preparation Example 8

[0078] Modified nano-zinc oxide was prepared using the following method:

[0079] A. Place nano zinc oxide in a low-temperature plasma treatment instrument, introduce a mixture of argon and oxygen with a volume ratio of argon to oxygen of 5:1, control the power at 120W and the pressure at 80Pa, and treat for 15min to obtain activated nano zinc oxide.

[0080] B. Dissolve γ-aminopropyltriethoxysilane and trehalose in anhydrous ethanol and deionized water to obtain a composite modified solution; the mass ratio of γ-aminopropyltriethoxysilane, trehalose, anhydrous ethanol and deionized water is 5:1:70:30.

[0081] C. Add activated nano zinc oxide to the composite modification solution at a mass ratio of 1:10. Then, stir magnetically at 50°C for 2.5 hours, centrifuge to separate the precipitate, wash it 5 times with anhydrous ethanol, vacuum dry it at 65°C for 3.5 hours, and grind it through a 400-mesh sieve to obtain modified nano zinc oxide.

[0082] Example

[0083] Example 1

[0084] A lime material incorporating aerated concrete waste is shown in Table 1. The raw material composition and proportion are as follows: the composite recycled powder is selected from the composite recycled powder prepared in Preparation Example 1; the modified nano zinc oxide is selected from the modified nano zinc oxide prepared in Preparation Example 6; and the lithium-based composite activator is prepared by mixing lithium hydroxide, sodium sulfate and zeolite powder in a mass ratio of 2:3:5.

[0085] A method for preparing lime material mixed with aerated concrete waste includes the following steps:

[0086] S1. First, put quicklime and composite recycled powder into a mixer and stir at 300 rpm for 4 minutes. Then add metakaolin and lithium-based composite activator, adjust the speed to 350 rpm and stir for 3 minutes. Finally, add modified nano zinc oxide, hemihydrate gypsum, hydroxypropyl methyl cellulose ether and sodium carboxymethyl starch, and keep stirring for 4 minutes to obtain a mixture.

[0087] S2. Place the mixture in an environment with a temperature of 20℃ and a humidity of 55% for 96 hours, and stir it once every 12 hours during the period. After aging, use a vibrating screen to screen it through a 60-mesh standard sieve. Take the material that passes through the sieve to obtain the lime material.

[0088] Example 2

[0089] A lime material incorporating aerated concrete waste is shown in Table 1. The raw material composition and proportion are as follows: the composite recycled powder is selected from the composite recycled powder prepared in Preparation Example 2; the modified nano zinc oxide is selected from the modified nano zinc oxide prepared in Preparation Example 7; and the lithium-based composite activator is prepared by mixing lithium hydroxide, sodium sulfate and zeolite powder in a mass ratio of 2.5:3.5:5.

[0090] A method for preparing lime material mixed with aerated concrete waste includes the following steps:

[0091] S1. First, put quicklime and composite recycled powder into a mixer and stir at 330 rpm for 3.5 min. Then add metakaolin and lithium-based composite activator, adjust the speed to 380 rpm and stir for 2 min. Finally, add modified nano zinc oxide, hemihydrate gypsum, hydroxypropyl methyl cellulose ether and sodium carboxymethyl starch, and keep stirring for 5 min to obtain the mixture.

[0092] S2. Place the mixture in an environment with a temperature of 30℃ and a humidity of 65% for 72 hours, and stir it once every 12 hours during the period. After aging, use a vibrating screen to screen it through a 60-mesh standard sieve. Take the material that passes through the sieve to obtain the lime material.

[0093] Example 3

[0094] A lime material incorporating aerated concrete waste is shown in Table 1. The raw material composition and proportion are as follows: the composite recycled powder is selected from the composite recycled powder prepared in Preparation Example 3; the modified nano zinc oxide is selected from the modified nano zinc oxide prepared in Preparation Example 8; and the lithium-based composite activator is prepared by mixing lithium hydroxide, sodium sulfate and zeolite powder in a mass ratio of 3:4:5.

[0095] A method for preparing lime material mixed with aerated concrete waste includes the following steps:

[0096] S1. First, put quicklime and composite recycled powder into a mixer and stir at 350 rpm for 3 minutes. Then add metakaolin and lithium-based composite activator, adjust the speed to 400 rpm and stir for 2.5 minutes. Finally, add modified nano zinc oxide, hemihydrate gypsum, hydroxypropyl methylcellulose ether and sodium carboxymethyl starch, and stir at the same speed for 4.5 minutes to obtain the mixture.

[0097] S2. Place the mixture in an environment with a temperature of 25℃ and a humidity of 60% for 84 hours, and stir it once every 12 hours during the period. After aging, use a vibrating screen to screen it through a 60-mesh standard sieve. Take the material that passes through the sieve to obtain the lime material.

[0098] Table 1. Raw material composition and dosage (kg) of lime in Examples 1-3

[0099]

[0100] Example 4

[0101] A lime material containing aerated concrete waste differs from Example 3 in that the amount of quicklime used in this example is 50 kg.

[0102] Example 5

[0103] A lime material incorporating aerated concrete waste differs from Example 3 in that the lithium-based composite activator in this example is prepared by mixing lithium hydroxide, sodium sulfate, and zeolite powder in a mass ratio of 1:1:1.

[0104] Example 6

[0105] A lime material incorporating aerated concrete waste differs from Example 3 in that the composite recycled powder in this example is the composite recycled powder prepared in Preparation Example 4.

[0106] Comparative Example

[0107] Comparative Example 1

[0108] A lime material incorporating aerated concrete waste differs from Example 3 in that an equal amount of aerated concrete waste is used instead of composite recycled powder in this comparative example, the particle size of the aerated concrete waste in this comparative example is 100 mesh, and no modified nano zinc oxide is added in this comparative example.

[0109] Comparative Example 2

[0110] A lime material incorporating aerated concrete waste differs from Example 3 in that the composite recycled powder in this comparative example is the composite recycled powder prepared in Preparation Example 5.

[0111] Comparative Example 3

[0112] A lime material incorporating aerated concrete waste differs from Example 3 in that modified nano zinc oxide was not added in this comparative example.

[0113] Comparative Example 4

[0114] A lime material incorporating aerated concrete waste differs from Example 3 in that no lithium-based composite activator is added in this comparative example.

[0115] Performance testing

[0116] The setting strength and water resistance of the lime materials prepared in Examples 1-6 and Comparative Examples 1-4 were tested, and the test results are shown in Table 2.

[0117] Table 2 Experimental Results

[0118]

[0119] As shown in Table 2, with the gradual increase in the amount of quicklime, composite recycled powder, and modified nano zinc oxide in the lime raw materials of Examples 1-3, the 28-day compressive strength increased from 11.5 MPa to 14.2 MPa, the water absorption rate decreased from 7.8% to 6.2%, and the water resistance strength loss rate decreased from 7.1% to 5.5%. The increased amount of quicklime provided more sufficient Ca(OH)2 to the cementitious system, laying an alkaline foundation for the secondary hydration reaction; the increased amount of composite recycled powder enhanced the reaction contribution of the "active aggregate," generating more C-(A)-SH gel; and the increased amount of modified nano zinc oxide further optimized the microstructure, resulting in a more significant dense hydrophobic layer effect. These three factors synergistically achieved a gradient improvement in performance. Example 3, as the optimal formulation combination, achieved peak performance in all aspects.

[0120] Compared with Example 3, the 28-day compressive strength of Example 4 decreased to 13.5 MPa, the water absorption rate increased to 6.8%, and the water resistance strength loss rate increased to 6.0%. The reduction in quicklime content resulted in insufficient Ca(OH)2 formation, incomplete secondary hydration reaction, reduced C-(A)-SH gel formation, and a slight decrease in microstructure density. Therefore, the strength and water resistance were slightly weakened, but still significantly better than the comparative example, indicating that the quicklime content range of 50-60 parts is reasonable.

[0121] Compared to Example 3, Example 5 (activator ratio 1:1:1) showed a decrease in 28-day compressive strength to 9.7 MPa, an increase in water absorption to 9.2%, and a water resistance strength loss rate to 10.5%. This is because the core synergistic effect of the lithium-based composite activator relies on the scientific ratio of lithium hydroxide (inhibiting alkali-aggregate reaction), sodium sulfate (early strength), and zeolite powder (adsorption optimization). The ratio of these three components in this example disrupted this synergy: insufficient lithium ion content led to inadequate inhibition of the alkali-aggregate reaction; insufficient sodium sulfate content failed to effectively improve early strength; and excessive zeolite powder adsorbed some active ions, resulting in a slower hydration reaction rate, reduced gel formation, increased microporosity, and a significant decrease in strength and water resistance.

[0122] Compared to Example 3, Example 6 showed a decrease in 28-day compressive strength to 10.3 MPa, an increase in water absorption to 8.5%, and a water resistance strength loss rate of 10.8%. Excessive acetic acid concentration led to over-etching of the composite recycled powder particles, damaging the surface structure and causing it to lose its aggregate support function. Simultaneously, excessive etching consumed some active components, resulting in insufficient subsequent alkali-activated reactions, weakening the contribution of the "active reactant," and causing more irregular pores in the microstructure, thus degrading performance. This verified the scientific validity of the 0.3%-0.9% acetic acid concentration range.

[0123] Comparative Example 1, which did not use composite recycled powder or add modified nano-zinc oxide, had the worst performance in all aspects: 28-day compressive strength of 3.8 MPa, water absorption rate of 18.7%, and water resistance strength loss rate of 35.2%, only slightly better than traditional lime materials. Because unmodified aerated concrete waste was used directly as filler, its surface inert coating was not removed, and active SiO2 and Al2O3 could not be released, acting only as a "passive filler" and unable to participate in the secondary hydration reaction, thus failing to improve strength. Without the addition of modified nano-zinc oxide, the microstructure was loose, lacking a dense hydrophobic layer, allowing water to easily penetrate, resulting in extremely high water absorption and water resistance strength loss rates. This verifies the modification process of the composite recycled powder and the core role of modified nano-zinc oxide.

[0124] In Comparative Example 2, the composite recycled powder was not subjected to acid etching or alkali activation treatment. Compared with Example 3, the 28-day compressive strength decreased to 5.1 MPa, the water absorption rate increased to 16.3%, and the water resistance strength loss rate increased to 28.5%. Because the composite recycled powder only underwent microwave sintering without acid etching or alkali activation treatment, the particle surface roughness was insufficient, the active components were not effectively activated, and the "active reactant" effect was not manifested. It could only play a partial filling role, therefore its strength and water resistance were far lower than those of the examples, verifying the necessity of the composite modification process for recycled aggregates in this application.

[0125] In Comparative Example 3, without the addition of modified nano-zinc oxide, the 28-day compressive strength decreased to 6.5 MPa, the water absorption rate increased to 13.5%, and the water resistance strength loss rate increased to 22.3% compared to Example 3. Due to the absence of modified nano-zinc oxide, on the one hand, the nucleation effect was lost, hindering the directional growth of the C-(A)-SH gel and reducing the density of the microstructure; on the other hand, without a hydrophobic layer to block water penetration, water easily invaded the interior, leading to the decomposition of hydration products. Therefore, the strength and water resistance were significantly weakened, verifying the crucial role of modified nano-zinc oxide in microstructure optimization and hydrophobic protection.

[0126] In Comparative Example 4, without the addition of the lithium-based composite activator, the 28-day compressive strength decreased to 7.2 MPa, the water absorption rate increased to 11.8%, and the water resistance strength loss rate increased to 18.6% compared to Example 3. Since the lithium-based composite activator is a core component that accelerates the secondary hydration reaction and inhibits the alkali-aggregate reaction, its absence slows down the formation rate and reduces the amount of C-(A)-SH gel. Simultaneously, the alkali-aggregate reaction leads to microcracks in the microstructure and increased porosity, thus decreasing strength and water resistance. This verifies the activation and structural stabilizing effects of the lithium-based composite activator.

[0127] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A lime material incorporating aerated concrete waste, characterized in that, The raw materials include the following parts by weight: quicklime 50-60 parts; composite recycled powder 20-30 parts; metakaolin 5-10 parts; lithium-based composite activator 3-6 parts; modified nano zinc oxide 1-3 parts; hemihydrate gypsum 3-6 parts; hydroxypropyl methylcellulose ether 0.2-0.8 parts; sodium carboxymethyl starch 0.5-1.5 parts; The composite recycled powder was prepared using the following method: (1) After mixing the aerated concrete waste and waste clay brick powder, microwave sintering is carried out at 250-300℃ for 15-25 minutes to obtain sintered material; (2) Immerse the sintered material in acetic acid solution for 2-4 hours, take it out and drain it to obtain acid-etched material. Immerse the acid-etched material in composite alkaline solution for 3-5 hours, take it out and wash it with deionized water until neutral, dry it at 80-100℃ until constant weight, grind it and pass it through a 100-mesh sieve. Take the sieve material to obtain the etched material. The modified nano zinc oxide was prepared by the following method: A. Place the nano zinc oxide in a low-temperature plasma treatment instrument, introduce a mixture of argon and oxygen, with a volume ratio of argon to oxygen of (3-5):1, control the power to be 80-120W and the pressure to be 50-80Pa, and treat for 10-15 minutes to obtain activated nano zinc oxide. B. Dissolve γ-aminopropyltriethoxysilane and trehalose in anhydrous ethanol and deionized water to obtain a composite modified solution; C. Add activated nano zinc oxide to the composite modification solution, stir magnetically at 40-50℃ for 2-3 hours, then centrifuge to separate, collect the precipitate, wash with anhydrous ethanol 3-5 times, vacuum dry at 60-70℃ for 3-4 hours, grind through a 400-mesh sieve to obtain the final product.

2. The lime material using aerated concrete waste as described in claim 1, characterized in that: In step (1), the mass ratio of the aerated concrete waste to the waste clay brick powder is (2-3):

1.

3. The lime material using aerated concrete waste as described in claim 1, characterized in that: In step (2), the mass concentration of the acetic acid solution is 0.3%-0.9%, and the mass ratio of the sintering material to the acetic acid solution is 1:(12-15).

4. The lime material using aerated concrete waste as described in claim 1, characterized in that: In step (2), the solute of the composite alkaline solution is prepared by mixing glass and sodium carbonate in a mass ratio of (3-4):1, the mass concentration of the composite alkaline solution is 8%-12%, and the mass ratio of the acid etching material to the composite alkaline solution is 1:(10-12).

5. A lime material incorporating aerated concrete waste according to claim 1, characterized in that: The lithium-based composite activator is prepared by mixing lithium hydroxide, sodium sulfate and zeolite powder in a mass ratio of (2-3):(3-4):

5.

6. The lime material using aerated concrete waste as described in claim 1, characterized in that: In step B, the mass ratio of γ-aminopropyltriethoxysilane, trehalose, anhydrous ethanol and deionized water is (4-5):1:(60-70):(30-40).

7. A lime material incorporating aerated concrete waste according to claim 1, characterized in that: In step C, the mass ratio of activated nano zinc oxide to composite modified liquid is 1:(8-10).

8. A method for preparing lime material incorporating aerated concrete waste according to any one of claims 1-7, characterized in that, Includes the following steps: S1. First, put quicklime and composite recycled powder into a mixer and stir at 300-350 rpm for 3-4 minutes. Then add metakaolin and lithium-based composite activator, adjust the speed to 350-400 rpm and stir for 2-3 minutes. Finally, add modified nano zinc oxide, hemihydrate gypsum, hydroxypropyl methylcellulose ether and sodium carboxymethyl starch, and stir at the same speed for 4-5 minutes to obtain a mixture. S2. Place the mixture in an environment with a temperature of 20-30℃ and a humidity of 55%-65% for 72-96 hours, and stir it once every 12 hours during the period. After aging, use a vibrating screen to sieve it through a 60-mesh standard sieve. Take the material that passes through the sieve to obtain the lime material.

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