A steam-free fast-hardening early-strength solid waste-based foam concrete and a preparation method thereof

Abstract

The application belongs to the technical field of building materials, and relates to a steam-curing-free fast-hardening and early-strength type solid waste-based foam concrete and a preparation method thereof.The foam concrete comprises the following components in parts by weight: solid waste-based cementing material 30-50 parts, fine aggregate 20-40 parts, polyester fiber 0.5-2 parts, foam stabilizer 0.1-0.5 parts, steam-curing-free self-prepared curing agent 1-3 parts, water 25-40 parts, and foaming agent 1-5 parts.The total utilization rate of solid waste in the application is higher than 80%, the land occupation and environmental pollution problems caused by solid waste storage are greatly reduced, and efficient recycling of resources is achieved;compared with traditional foam concrete, the apparent density of the foam concrete is less than 600kg / m 3 , the 3d compressive strength is greater than or equal to 2.5MPa, and the 28d compressive strength is greater than or equal to 7.8MPa;and the foam concrete does not need to be steam-cured, the process is simple, the energy consumption cost is reduced, and the foam concrete can be adapted to various engineering construction and service environments.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology and relates to a fast-hardening, early-strength solid waste-based foamed concrete that does not require autoclaving and has a preparation method thereof. Background Technology

[0002] Foamed concrete, as a lightweight, heat-insulating, and sound-insulating new type of building material, is widely used in engineering fields such as wall filling, roof insulation, and roadbed backfilling. Traditional foamed concrete mostly uses cement as the main binder, which not only consumes a large amount of mineral resources, but also has high carbon emissions during the production process, which is inconsistent with the concept of green and low-carbon development.

[0003] With the increasing volume of industrial solid waste emissions year by year, how to achieve efficient resource utilization of solid waste has become a focus of industry attention. Industrial solid wastes such as blast furnace slag powder, fly ash, and recycled construction waste powder are rich in active components such as silicon and aluminum, possessing the potential to be used as cementing materials or aggregates. However, current methods for preparing foamed concrete using solid waste generally suffer from problems such as low early strength, slow setting speed, and the need for steam curing, limiting its engineering application. Steam curing not only increases energy consumption and production costs but may also lead to internal structural defects in the concrete, affecting its later performance stability.

[0004] Furthermore, existing solid waste-based foamed concrete suffers from drawbacks such as difficulty in balancing strength and lightweight properties, poor volume stability, and susceptibility to cracking. Therefore, developing a foamed concrete that requires no steam curing, exhibits rapid hardening and early strength, has stable performance, and can absorb large quantities of solid waste is of great significance for promoting the green transformation of building materials and reducing the pressure of solid waste disposal. Summary of the Invention

[0005] To address the shortcomings of the existing technology, this invention provides a non-steam-cured, fast-hardening, early-strength solid waste-based foamed concrete and its preparation method.

[0006] To achieve the above objectives, the specific technical solution is as follows: This invention provides a non-steam-curing, fast-hardening, early-strength solid waste-based foamed concrete, comprising the following components in parts by weight: Solid waste-based binder 30-50 parts, fine aggregate 20-40 parts, polyester fiber 0.5-2 parts, foam stabilizer 0.1-0.5 parts, self-made curing agent without steam curing 1-3 parts, water 25-40 parts, foaming agent 1-5 parts; The solid waste-based cementitious material is prepared from the following raw materials: blast furnace slag powder, fly ash, gypsum dihydrate, and activator; The self-made curing agent without steam curing is prepared from the following raw materials: water, triethanolamine, polycarboxylate superplasticizer mother liquor, glycerol, silicone defoamer, sodium gluconate, anhydrous sodium sulfate, lithium silicate aqueous solution, and sodium carboxymethyl cellulose.

[0007] The core cementitious material of this invention, "solid waste-based binder," and the fine aggregates both utilize a large amount of industrial solid waste (such as blast furnace slag, fly ash, carbide slag, recycled construction waste powder, furnace slag, tailings sand, etc.). The total utilization rate of solid waste exceeds 80%, which significantly reduces the land occupation and environmental pollution problems caused by solid waste storage, realizes the efficient recycling of resources, and conforms to the concept of green and low-carbon development.

[0008] The solid waste-based binder used in this invention is the core cementing component of foamed concrete, replacing traditional cement. It is prepared from blast furnace slag powder, fly ash, gypsum dihydrate, and an activator, and forms the basis for achieving solid waste cementing, rapid hardening, and early strength. Blast furnace slag powder is rich in calcium, silicon, and aluminum active components, and its glassy structure is easily activated. The hydration reaction can generate a large amount of calcium silicate hydrate (CSH) and calcium aluminate hydrate (CAH) gels. Fly ash, being a siliceous and aluminous solid waste, provides the core silicon and aluminum source for the pozzolanic reaction, reacting with Ca(OH)2 in the hydration products to generate CSH gel, supplementing the strength of the cementing system. Gypsum dihydrate (CaSO4·2H2O) provides SO4. 2- The hydrated material reacts with the aluminum phase to form ettringite (AFt), while simultaneously regulating the setting time of the cementitious system to prevent the hydration reaction from being too fast or too slow. These three raw materials achieve complementary activity, while the activator rapidly and efficiently triggers the hydration of solid waste and the reaction with pozzolanic ash. The hydration reaction quickly generates CSH and CAH gels and ettringite crystals. The gels form a three-dimensional network structure, and the ettringite crystals fill the pores and intertwine, collectively constituting the strength framework of the foamed concrete, achieving the core foundation for high 3D strength.

[0009] This invention further optimizes the material system through a specially formulated "self-made curing agent that eliminates the need for steam curing," simplifying the process and reducing energy costs. Triethanolamine, as an organic alcohol amine early-strength agent, has N and O atoms in its molecule that interact with Ca through lone pairs of electrons. 2+ Al 3+ It forms complexes, alters the form of ions in solution, accelerates the dissolution of solid waste cementitious materials and the nucleation and crystallization of hydration products, promotes the rapid formation of CSH gel and ettringite crystals, and further enhances 3-day early strength; anhydrous sodium sulfate provides SO4. 2- It reacts secondaryly with the aluminum and calcium phases in the cementitious material to form ettringite, supplementing early strength. Glycerol is a polyol-based water-retaining agent, and sodium carboxymethyl cellulose (CMC) is a high-molecular-weight thickening and water-retaining agent. Together, they form a breathable and water-retaining film on the surface of the foamed concrete, preventing excessive evaporation of internal moisture and ensuring the moisture required for the hydration reaction of the cementitious material. The polycarboxylate superplasticizer disperses the cementitious material powder particles through steric hindrance and electrostatic repulsion, releasing the encapsulated free water, reducing the water-cement ratio, making the slurry more uniform and delicate, and allowing for a more complete hydration reaction; Li in the lithium silicate aqueous solution... + With SiO3 2-It can react with Ca 2+ The reaction generates calcium silicate salt gel, which fills the micropores inside the concrete, improving the density and bond strength of the paste. Simultaneously, Li... + It can promote the formation and stabilization of CSH gel. Organosilicon defoamers can quickly eliminate harmful large air bubbles generated during slurry preparation, avoiding internal structural defects caused by large air bubbles; at the same time, the defoamer and foam stabilizer work synergistically, without destroying the effective foam prepared by the foaming agent, ensuring the lightweight characteristics of foamed concrete, making the internal pores mainly composed of fine effective foam, with very few harmful large air bubbles, and improving the uniformity of strength.

[0010] The polyester fiber in the formula of this invention works synergistically with the shrinkage-reducing components (such as sodium sulfate solution, triethanolamine and polycarboxylic acid) and water-retaining components (such as sodium carboxymethyl cellulose) in the "self-made curing agent without steam curing" to reduce the drying shrinkage of concrete, inhibit or compensate for shrinkage stress, thereby improving the volume stability of foamed concrete, reducing its cracking risk, ensuring the stability of later performance, and improving the volume stability and crack resistance of the product.

[0011] The foamed concrete of this invention achieves high strength while maintaining low density, thus achieving a good balance between lightweight and strength. Its apparent density is less than 600 kg / m³. 3 It is a lightweight material with excellent thermal insulation properties. This overcomes the shortcomings of existing technologies where it is difficult to balance strength and lightweight properties in solid waste-based foamed concrete, thus broadening its application range.

[0012] Furthermore, the solid waste-based binder is prepared from raw materials comprising the following components by weight: 40-60 parts blast furnace slag powder, 20-35 parts fly ash, 10-20 parts dihydrate gypsum, and 3-8 parts activator.

[0013] Preferably, the blast furnace slag powder has an activity level of not less than S95 after 28 days and a specific surface area of ​​not less than 400 m². 2 / kg.

[0014] Preferably, the main indicators of the fly ash are as follows: strength activity index (28 days) not less than 70%, fineness (45μm square hole sieve residue) not greater than 30%, water demand ratio not greater than 105%, and loss on ignition not greater than 10%.

[0015] Preferably, the main requirements for the dihydrate gypsum are: calcium sulfate dihydrate (CaSO4·2H2O) content not less than 75%, pH value not less than 6.0, and fineness (residue on a 45μm square hole sieve) not greater than 10%.

[0016] Furthermore, the preparation method of the solid waste-based cementitious material is as follows: a powder with a moisture content ≤0.5% and a fineness of 550–650 μm is prepared. 2An activator is injected into a mixture of blast furnace slag, fly ash, and dihydrate gypsum powder per kg, and then the mixture is ground until the specific surface area of ​​the powder reaches 700–750 m². 2 / kg, mix well.

[0017] Specifically, the preparation method of the solid waste-based cementitious material includes the following steps: A1: Add blast furnace slag, fly ash, and dihydrate gypsum with a moisture content ≤0.5% to a vertical roller mill or ball mill, respectively, and add 0.03–0.05% grinding aid. Grind each to a specific surface area of ​​400–450 m². 2 / kg, to obtain pre-ground powder of blast furnace slag, fly ash and dihydrate gypsum; A2: Mix the pre-ground powders of blast furnace slag, fly ash, and dihydrate gypsum according to the formula ratio, and put them into an ultrafine ball mill or stirred mill. Use 3-5mm zirconia balls as the grinding media, and grind until the specific surface area is 550-650m². 2 At a concentration of / kg, the activator is evenly sprayed into the mill, and grinding continues until the specific surface area of ​​the mixed powder reaches 700-750m². 2 / kg; A3: The ground cementitious material is passed through an airflow homogenization chamber and pneumatically stirred with compressed air for at least 4 hours to obtain solid waste-based cementitious material.

[0018] The solid waste-based binder of this invention is prepared by precision grinding, ultrafine grinding, and homogenization of blast furnace slag powder, fly ash, dihydrate gypsum, and activator. The staged grinding process enhances reactivity, utilizing the mechanical force of grinding to ensure full contact and uniform mixing between the activator and the solid waste powder. This achieves a synergistic effect of mechanical activation and chemical activation, allowing the activator to rapidly and efficiently trigger the hydration and pozzolanic reactions of the solid waste, quickly generating CSH and CAH gels and ettringite crystals. The gels form a three-dimensional network structure, and the ettringite crystals fill the pores and intertwine, collectively constituting the strength framework of the foamed concrete, which is the core foundation for achieving 3D high strength.

[0019] Furthermore, the grinding aid is selected from one or a mixture of two of triethanolamine and ethylene glycol.

[0020] Furthermore, the self-made curing agent without steam curing is prepared from raw materials comprising the following components in parts by weight: 90-105 parts water, 2-5 parts triethanolamine, 6-10 parts polycarboxylate superplasticizer mother liquor, 1-4 parts glycerol, 0.1-0.3 parts silicone defoamer, 0.6-1 parts sodium gluconate, 3-6 parts anhydrous sodium sulfate, 3-7 parts lithium silicate aqueous solution, and 1-3 parts sodium carboxymethyl cellulose (CMC); the concentration of the polycarboxylate superplasticizer mother liquor is 20 wt.%; and the concentration of the lithium silicate aqueous solution is 20 wt.%.

[0021] Preferably, the silicone defoamer is a polyether-modified silicone defoamer, such as PS-310 defoamer produced by Shandong Puniao Water Treatment Technology Co., Ltd.

[0022] Polyether-modified silicone defoamers can more quickly eliminate harmful large bubbles generated during slurry preparation, avoiding internal structural defects caused by large bubbles.

[0023] Furthermore, the method for preparing the self-made curing agent without steaming includes the following steps: B1: Dissolve sodium carboxymethyl cellulose in 50-70 parts of water at 40-45°C by stirring to obtain a sodium carboxymethyl cellulose solution; dissolve glycerol and sodium gluconate in 25-35 parts of water at 10-20°C by stirring to obtain an alcohol-sugar solution; dissolve anhydrous sodium sulfate in 6-12 parts of water at 40-45°C by stirring, and then cool to room temperature to obtain a sodium sulfate solution. B2: Cool the sodium carboxymethyl cellulose solution to below 30°C, and add alcohol-sugar solution, sodium sulfate solution, triethanolamine and polycarboxylate superplasticizer mother liquor in sequence while stirring. Stir to dissolve and obtain mixture one. B3: Under stirring, add the lithium silicate aqueous solution to mixture one and disperse by ultrasonication to obtain mixture two; B4: Premix the silicone defoamer with 1-3 parts of water to form an emulsion. Then, add the emulsion to the mixture while stirring. After stirring and letting stand, you will get the self-made curing agent that does not require steaming.

[0024] Furthermore, the activator is a ternary composite activator, prepared from raw materials comprising the following components by weight: 50-60 parts of sulfate activating component, 25-35 parts of alkaline activating component, and 10-20 parts of functional synergistic component; The preparation method of the sulfate-activated component is as follows: anhydrous calcium sulfoaluminate and anhydrous gypsum are mixed at a mass ratio of 20-40:40-80, calcined at 800-900℃ for 25-35 minutes, cooled to 100-150℃ for 30 minutes, and then ground to a specific surface area ≥450m². 2 / kg; The alkaline activating component is prepared by: removing free water from carbide slag and mixing the same mass of water glass at a high speed of 2000-3000 r / min to form an alkaline carrier with a "core-shell" structure. The preparation method of the functional synergistic component is as follows: MgO expanding agent, powdered polycarboxylate shrinkage agent and nano-SiO2 in a mass ratio of 50-60:1-5:40-50 are placed in a mixer, and 0.3-0.7% of sodium tripolyphosphate dispersant (the total mass of MgO expanding agent, powdered polycarboxylate shrinkage agent and nano-SiO2) is added. The mixture is mixed for 10-15 minutes under high-speed shear at 2500-3500 r / min to allow the nanoparticles to fully depolymerize and adsorb onto the surface of MgO particles to form functional microspheres.

[0025] Compared with existing solid waste-based foamed concrete, which suffers from low early strength and slow setting, this invention, through the synergistic effect of a "ternary composite activator" and a "self-made curing agent without steam curing," greatly stimulates the early activity of the cementitious material. Its product achieves a compressive strength of over 2.5 MPa after 3 days and over 7.8 MPa after 28 days, exhibiting excellent rapid-hardening and early-strength properties, thus meeting the engineering requirements for rapid-hardening and early-strength applications.

[0026] The functional synergistic components introduced into the activator in this invention work synergistically with the polyester fibers in the formula and the shrinkage-reducing and water-retaining components in the "self-made curing agent without steam curing" to further reduce the drying shrinkage of concrete, inhibit or compensate for shrinkage stress, thereby improving the volume stability of foamed concrete, reducing its cracking risk, ensuring the stability of later performance, and improving the volume stability and crack resistance of the product.

[0027] Preferably, the MgO expanding agent is a multi-scale MgO expanding agent, that is, it contains nano, micro, and millimeter-sized particles, which can achieve different activities and expansion properties.

[0028] Furthermore, the preparation method of the ternary composite activator is as follows: the sulfate activating component, the alkaline activating component and the functional synergistic component are put into a mixer, and stirred at a speed of 80-120 r / min for 3-8 min under the conditions of 40-50℃ and dry nitrogen protection, then stirred at a speed of 150-200 r / min for 8-15 min, and finally stirred at a speed of 100-140 r / min for 3-8 min.

[0029] Furthermore, the foaming agent is one or both of animal protein foaming agents and / or plant protein foaming agents; preferably, it is a composite foaming agent composed of animal protein foaming agents and plant protein foaming agents in a mass ratio of 2:1 to 3.

[0030] Furthermore, the foam stabilizer is one or both of sodium dodecyl sulfate and sodium fatty alcohol polyoxyethylene ether sulfate; preferably, it is a composite foam stabilizer composed of sodium dodecyl sulfate and sodium fatty alcohol polyoxyethylene ether sulfate in a mass ratio of 1:1 to 2.

[0031] Furthermore, the fine aggregate is selected from one or more of fly ash, recycled construction waste powder, slag, and tailings sand; preferably, the recycled construction waste powder has a particle size ≤0.15mm, and the slag and tailings sand have a particle size of 0.075~2.36mm.

[0032] Furthermore, the polyester fiber has a length of 6–12 mm, a diameter of 15–30 μm, and a tensile strength ≥350 MPa.

[0033] This invention also provides a method for preparing the above-mentioned autoclaved, fast-setting, early-strength solid waste-based foamed concrete, comprising the following steps: S1: Put solid waste-based binder, fine aggregate, and polyester fiber into a mixer and dry mix for 2-3 minutes until uniform to form a dry mix. S2: Add the self-made curing agent and 17.5-32 parts of water to the dry mixture, stir for 4-6 minutes to obtain the composite slurry; S3: Mix the foaming agent with the remaining water and stir to achieve an apparent density of 30–60 kg / m³. 3 Stable bubbles; S4: Add foam to the composite slurry, and add foam stabilizer at the same time. Stir at 30-40 r / min for 1-2 minutes to mix and form foam concrete slurry. S5: Pour the foamed concrete slurry into the mold, let it stand naturally for 12-24 hours before demolding, and then cure it naturally at 20±5℃ and relative humidity ≥70% until the specified age.

[0034] Traditional foamed concrete often requires autoclaving to improve early strength. This invention achieves autoclaving-free curing through a specially formulated "self-made curing agent without autoclaving" and an optimized material system. This simplifies the process and reduces energy costs. Performance requirements can be achieved by natural curing under normal temperature (20±5℃) and high humidity (≥70%) conditions. It eliminates the need for investment in autoclaves and other equipment and steam energy consumption, significantly reducing production energy consumption and costs. The process is simpler and easier to apply on-site.

[0035] The beneficial effects of this invention are: The autoclaved, rapid-hardening, early-strength solid waste-based foamed concrete provided by this invention has a total solid waste utilization rate of over 80%, significantly reducing land occupation and environmental pollution problems caused by solid waste storage, and achieving efficient resource recycling; compared with traditional foamed concrete, this foamed concrete has an apparent density of less than 600 kg / m³. 3 It has a 3-day compressive strength ≥2.5MPa and a 28-day compressive strength ≥7.8MPa; and it does not require steam curing, has a simple process, reduces energy consumption costs, and can be adapted to various engineering construction and service environments. Attached Figure Description

[0036] Figure 1This is a photograph of a fast-hardening, early-strength solid waste-based foamed concrete prepared according to Embodiment 1 of the present invention. Detailed Implementation

[0037] Unless otherwise specified, the instruments, reagents, and materials used in the following embodiments are all conventional instruments, reagents, and materials already available in the prior art and can be obtained through legitimate commercial channels. Unless otherwise specified, the experimental methods and detection methods used in the following embodiments are all conventional experimental methods and detection methods already available in the prior art.

[0038] Anhydrous calcium sulfoaluminate is a rapid-hardening sulfoaluminate cement with a strength grade of 42.5, produced by Shandong Yunhe New Material Co., Ltd., with a specific surface area of ​​≥350 m². 2 / kg, setting time: initial setting ≥25min, final setting ≤180min; Anhydrous gypsum is a high-strength, premium-grade anhydrous gypsum produced by Taian Aohui New Decorative Materials Co., Ltd. Calcium carbide slag is produced by Shandong Lutai Environmental Protection Building Materials Co., Ltd., with a CaO content ≥45% and a specific surface area ≥350m². 2 / kg of powdery substance; The water glass is sodium silicate with a modulus range of 2.0 to 3.3 and a purity of 99.9%, provided by Shandong Longhui Chemical Co., Ltd. MgO expanding agent is a magnesium oxide expanding agent for hydraulic concrete produced by Shandong Yihexin Materials Technology Co., Ltd. It has a magnesium oxide (MgO) content greater than 85%, a fineness (residue on a 0.08mm square-hole sieve) not greater than 10%, and a free calcium oxide (f-CaO) content not greater than 2%. The powdered polycarboxylate shrinkage reducer is an early-strength powdered shrinkage reducer produced by Shandong Gaoqiang Building Materials Co., Ltd., with a water reduction rate ≥25%, chloride ion content ≤0.03%, total alkali content ≤10.0%, and pH value: 6.0~8.0; Nano-SiO2 is the HN series nano-silica produced by Shandong Hainan High-Tech Materials Co., Ltd., with an average particle size of 10-30 nm, purity ≥99.5%, and specific surface area of ​​200-300 m². 2 / g; Sodium tripolyphosphate is an industrial-grade sodium tripolyphosphate produced by Shandong Xinheng Chemical Co., Ltd., with a purity of 95%. Triethanolamine is an industrial-grade triethanolamine produced by Jinan Huifengda Chemical Co., Ltd., with a purity of 99%. Polycarboxylate superplasticizer mother liquor (20%) is a light yellow to brownish-brown viscous liquid superplasticizer produced by Shandong Jufu Chemical Technology Co., Ltd., with a solid content of 20%±1% and a water reduction rate of 25%~40%. Glycerol: Premium grade glycerol produced by Shandong Jinyueyuan New Materials Co., Ltd., with a content of 99.5%; The silicone defoamer (polyether modified) is PS-310 defoamer produced by Shandong Puniao Water Treatment Technology Co., Ltd., with a pH value of 5.0-8.0, a solid content of 10%, and a viscosity of 2000-4000 mPa·s. Sodium gluconate: a white or pale yellow crystalline powder with a purity of 99% produced by Shandong Kaixiang Biotechnology Co., Ltd. Anhydrous sodium sulfate is an industrial-grade sodium sulfate produced by Shandong Yukang Chemical Co., Ltd., with a purity of 98%. The lithium silicate aqueous solution (20%) is a colorless, transparent, slightly viscous liquid produced by Shandong Suihua Biotechnology Co., Ltd., with a SiO2 content of 19.0-21.0%, a Li2O content of 2.0-2.2%, a modulus M (SiO2 / Li2O) of 4.8±0.2, a pH value of 10.0-12.0, and a relative density (20℃) of 1.17-1.19 g / ml. Sodium carboxymethyl cellulose (CMC) is an industrial-grade cellulose produced by Shandong Hengnuo Cellulose Co., Ltd. The foam stabilizer is composed of sodium dodecyl sulfate and sodium fatty alcohol polyoxyethylene ether sulfate in a mass ratio of 1:1.3; The composite foaming agent is composed of animal protein foaming agent and plant protein foaming agent in a mass ratio of 2:1; The particle size of recycled construction waste powder is 0–0.6 mm; The particle size of slag and tailings sand is 0.075 to 2.36 mm.

[0039] Preparation of ternary composite activators: (1) Anhydrous calcium sulfoaluminate and anhydrous gypsum are mixed at a mass ratio of 1:2, calcined at 850℃ for 30 min, cooled to 120℃ for 30 min, and then ground to a specific surface area ≥450 m². 2 / kg, yielding sulfate-activated components; (2) Dry the carbide slag at 105°C to remove free water, and then stir it with an equal mass of water glass in a high-speed mixer so that the water glass is uniformly loaded on the porous surface of the carbide slag to form an alkaline carrier with a "core-shell" structure, i.e., an alkaline activating component. (3) Place MgO expanding agent, powdered polycarboxylate shrinkage agent and nano SiO2 in a three-dimensional vortex mixer with a mass ratio of 55:3:45, add sodium tripolyphosphate dispersant of 0.5% of the total mass of MgO expanding agent, powdered polycarboxylate shrinkage agent and nano SiO2, and mix for 15 min under high-speed shear at 3000 r / min to fully depolymerize the nanoparticles and adsorb them on the surface of MgO particles to form functional microspheres, i.e. functional synergistic components; (4) By weight, 55 parts of sulfate activating component, 30 parts of alkaline activating component and 15 parts of functional synergistic component are put into a temperature-controlled mixer; the temperature is controlled at 45℃ and dry nitrogen is introduced for protection; first at low speed for 5 minutes, then at high speed for 10 minutes, and finally at low speed for 5 minutes to obtain the ternary composite activator.

[0040] Preparation of homemade curing agent without steaming: The product, by weight, is prepared from 100 parts water, 3.0 parts triethanolamine, 8.0 parts polycarboxylate superplasticizer mother liquor (20%), 2.5 parts glycerol, 0.2 parts silicone defoamer (polyether modified), 0.8 parts sodium gluconate, 4.0 parts anhydrous sodium sulfate, 5.0 parts lithium silicate aqueous solution (20%), and 1.5 parts sodium carboxymethyl cellulose (CMC). The specific preparation method is as follows: (1) Heat 60 parts of water to 40°C, and slowly sprinkle in sodium carboxymethyl cellulose powder while stirring. Control the sprinkling speed to avoid clumping. After adding, continue stirring at 700 rpm for 30 minutes until CMC is completely dissolved and a transparent viscous solution is formed, i.e. sodium carboxymethyl cellulose solution. (2) Mix glycerol and sodium gluconate in a container, add 30 parts of cold water at 10°C, and stir until sodium gluconate is completely dissolved to obtain an alcohol-sugar solution; (3) Add anhydrous sodium sulfate to 9 parts of 40°C warm water, stir to dissolve, and cool to room temperature to prepare sodium sulfate solution; (4) Cool the sodium carboxymethyl cellulose solution from step (1) to 20°C, and add alcohol-sugar solution, sodium sulfate solution, triethanolamine and polycarboxylate superplasticizer mother liquor in sequence while stirring. Continue stirring for 10 minutes to ensure that the components are fully miscible. (5) While stirring continuously, slowly add lithium silicate aqueous solution (20%), and after the addition is complete, treat with an ultrasonic disperser for 10 min (frequency 40 kHz) to obtain a mixture; (6) Premix the silicone defoamer with 1 part water to make an emulsion; then slowly add it to the above mixture while stirring, continue stirring for 15 minutes, and let it stand for 24 hours to obtain the self-made curing agent that does not require steaming.

[0041] The above substances were used in the embodiments and comparative examples of the present invention.

[0042] The performance testing of the autoclaved, fast-hardening, early-strength solid waste-based foamed concrete prepared in the embodiments or comparative examples of this invention was carried out in accordance with JG / T 266-2011 "Foamed Concrete for Building". Other unspecified indicators were tested and evaluated in accordance with relevant building materials industry standards.

[0043] Example 1: This embodiment provides a non-steam-curing, fast-hardening, early-strength solid waste-based foamed concrete and its preparation method, as detailed below: The autoclaved, fast-setting, early-strength solid waste-based foamed concrete comprises the following components by weight: 30 parts solid waste-based binder, 20 parts fine aggregate, 0.5 parts polyester fiber, 0.1 parts foam stabilizer, 1 part self-made curing agent without steam curing, 25 parts water, and 1 part composite foaming agent; The fine aggregate is a single component of recycled construction waste powder; The solid waste-based cementitious material, by weight percentage, is prepared from 40% blast furnace slag powder, 35% fly ash, 20% dihydrate gypsum, and 5% ternary composite activator. The specific preparation method is as follows: (1) Dry the blast furnace slag, fly ash, and dihydrate gypsum separately until the moisture content is ≤0.5%; (2) Blast furnace slag, fly ash, and dihydrate gypsum were respectively fed into a ball mill, and 0.04% of grinding aid (a mixture of triethanolamine and ethylene glycol in a mass ratio of 1:1) was added. The mixtures were then ground to a specific surface area of ​​400-450 m². 2 / kg; (3) Mix the pre-ground slag powder, fly ash, and dihydrate gypsum according to the formula ratio, and put them into an ultrafine ball mill. The grinding media should be 3-5mm zirconia balls. When the ultrafine grinding is carried out for 50 minutes, the fineness of the powder reaches about 600 μm. 2 At a concentration of / kg, the metered ternary composite activator is evenly sprayed into the mill; grinding continues until the specific surface area of ​​the mixed powder reaches 700-750m². 2 / kg; (4) The ground cementitious material is passed through an airflow homogenization chamber and pneumatically stirred for 5 hours using compressed air to obtain solid waste-based cementitious material.

[0044] The preparation method of the non-steam-cured, fast-hardening, early-strength solid waste-based foamed concrete includes the following steps: S1: Put solid waste-based binder, fine aggregate, and polyester fiber into a mixer and dry mix for 2 minutes until uniform to form a dry mix. S2: Add the self-made curing agent and 20 parts of water to the dry mixture, stir for 4 minutes to obtain the composite slurry; S3: Mix the foaming agent with the remaining water and stir to produce an apparent density of 30 kg / m³. 3 Stable bubbles; S4: Add foam to the composite slurry, and add foam stabilizer at the same time. Stir at 30 r / min for 1 min to obtain foamed concrete slurry. S5: Pour the foamed concrete slurry into the mold, let it stand naturally for 12 hours before demolding, and then cure it naturally at room temperature and relative humidity of 80±10% until the specified age. See the attached document for details of the test specimens. Figure 1 .

[0045] Performance test results: Solid waste utilization rate 82%, apparent density 480 kg / m³ 3 It has a 3-day compressive strength of 2.5 MPa, a 28-day compressive strength of 7.8 MPa, a volume shrinkage rate of 0.8%, no defects such as cracking or honeycombing, and good workability.

[0046] Example 2 This embodiment provides a non-steam-curing, fast-hardening, early-strength solid waste-based foamed concrete and its preparation method, as detailed below: The autoclaved, fast-setting, early-strength solid waste-based foamed concrete comprises the following components by weight: 38 parts of solid waste-based binder, 28 parts of fine aggregate, 1.0 part of polyester fiber, 0.3 parts of foam stabilizer, 2 parts of self-made curing agent without steam curing, 32 parts of water, and 3 parts of composite foaming agent; The fine aggregate is composed of recycled construction waste powder and tailings sand in a mass ratio of 1:1. The solid waste-based binder is prepared by weight percentage from 48% blast furnace slag powder, 30% fly ash, 14% dihydrate gypsum, and 8% ternary composite activator, with the specific preparation method being the same as in Example 1.

[0047] The preparation method of the steam-curing, fast-hardening, early-strength solid waste-based foamed concrete differs from that in Example 1 in that: dry mixing for 2.5 minutes, slurry mixing for 5 minutes, and the apparent density of the foam is 45 kg / m³. 3 Mix and mold for 1.5 minutes, let stand naturally for 24 hours to demold, and cure at room temperature until the specified age.

[0048] Performance test results: Solid waste utilization rate 85%, apparent density 520 kg / m³ 3 The 3-day compressive strength is 2.9 MPa, the 28-day compressive strength is 8.4 MPa, the volume shrinkage rate is 0.6%, there is no cracking, the foam is evenly distributed, and the surface of the finished product is smooth.

[0049] Example 3 This embodiment provides a non-steam-curing, fast-hardening, early-strength solid waste-based foamed concrete and its preparation method, as detailed below: The autoclaved, fast-setting, early-strength solid waste-based foamed concrete comprises the following components by weight: 45 parts solid waste-based binder, 35 parts fine aggregate, 1.5 parts polyester fiber, 0.4 parts foam stabilizer, 2.5 parts self-made curing agent without steam curing, 36 parts water, and 4 parts composite foaming agent; The fine aggregate is composed of recycled construction waste powder, slag and tailings sand in a mass ratio of 1:1:1. The solid waste-based binder is prepared by weight percentage from 55% blast furnace slag powder, 25% fly ash, 12% dihydrate gypsum, and 8% ternary composite activator, with the specific preparation method being the same as in Example 1.

[0050] The preparation method of the steam-curing, fast-hardening, early-strength solid waste-based foamed concrete differs from that in Example 1 in that: dry mixing for 3 minutes, slurry mixing for 6 minutes, and the apparent density of the foam is 55 kg / m³. 3 Mix and mold for 2 minutes, let stand naturally for 20 hours to demold, and cure at room temperature until the specified age.

[0051] Performance test results: Solid waste utilization rate 88%, apparent density 570 kg / m³ 3 It has a 3d compressive strength of 3.2MPa, a 28d compressive strength of 8.9MPa, a volume shrinkage rate of 0.5%, optimal mechanical properties, and excellent volume stability, making it suitable for high-strength engineering requirements.

[0052] Example 4 This embodiment provides a non-steam-curing, fast-hardening, early-strength solid waste-based foamed concrete and its preparation method, as detailed below: The autoclaved, fast-setting, early-strength solid waste-based foamed concrete comprises the following components by weight: 50 parts solid waste-based binder, 40 parts fine aggregate, 2.0 parts polyester fiber, 0.5 parts foam stabilizer, 3 parts self-made curing agent without steam curing, 40 parts water, and 5 parts composite foaming agent; The fine aggregate is a single component of tailings sand; The solid waste-based binder is prepared by weight percentage from 60% blast furnace slag powder, 20% fly ash, 12% dihydrate gypsum, and 8% ternary composite activator, with the specific preparation method being the same as in Example 1.

[0053] The preparation method of the steam-curing, fast-hardening, early-strength solid waste-based foamed concrete differs from that in Example 1 in that: dry mixing for 3 minutes, slurry mixing for 6 minutes, and the apparent density of the foam is 60 kg / m³. 3 Mix and mold for 2 minutes, let stand naturally for 24 hours to demold, and cure at room temperature until the specified age.

[0054] Performance test results: Solid waste utilization rate 86%, apparent density 590 kg / m³ 3 It has a 3d compressive strength of 3.1MPa, a 28d compressive strength of 8.7MPa, and a volume shrinkage rate of 0.55%. It has high strength and good compactness, making it suitable for heavy-load scenarios such as roadbed backfilling and foundation pit support.

[0055] Example 5 This embodiment provides a non-steam-curing, fast-hardening, early-strength solid waste-based foamed concrete and its preparation method, as detailed below: The autoclaved, fast-setting, early-strength solid waste-based foamed concrete comprises the following components by weight: 42 parts solid waste-based binder, 32 parts fine aggregate, 1.2 parts polyester fiber, 0.3 parts foam stabilizer, 2 parts self-made curing agent without steam curing, 34 parts water, and 3.5 parts composite foaming agent; The fine aggregate is composed of fly ash and recycled construction waste powder in a mass ratio of 2:1. The solid waste-based binder is prepared by weight percentage from 50% blast furnace slag powder, 30% fly ash, 15% dihydrate gypsum, and 5% ternary composite activator, with the specific preparation method being the same as in Example 1.

[0056] The preparation method of the steam-curing, fast-hardening, early-strength solid waste-based foamed concrete differs from that in Example 1 in that: dry mixing for 2.5 minutes, slurry mixing for 5 minutes, and the apparent density of the foam is 48 kg / m³. 3 Mix and mold for 1.5 minutes, let stand naturally for 18 hours to demold, and cure at room temperature until the specified age.

[0057] Performance test results: Solid waste utilization rate 87%, apparent density 540 kg / m³ 3 It has a 3d compressive strength of 2.8MPa, a 28d compressive strength of 8.2MPa, and a volume shrinkage rate of 0.65%. Its overall performance is well-balanced and it is suitable for common building applications such as wall filling and roof insulation.

[0058] Comparative Example 1 This comparative example provides a foamed concrete and its preparation method, as detailed below: The foamed concrete described herein does not contain a ternary composite activator; instead, it uses traditional sodium hydroxide (NaOH) as a single alkaline activator at a dosage of 4% of the mass of the cementitious material. The remaining components, proportions, and preparation methods are consistent with those in Example 1.

[0059] Performance test results: 3-day compressive strength: 1.1 MPa (far below the 2.5 MPa requirement); 28-day compressive strength: 4.2 MPa; volume shrinkage rate: 1.5%; Early strength growth was extremely slow, making demolding difficult within 24 hours of molding, and later strength development was slow, with obvious shrinkage cracks in the finished product. This is because the lack of synergistic effect from a ternary composite activator prevents the efficient activation of the solid waste material's activity, thus failing to achieve the goal of "rapid hardening and early strength".

[0060] Comparative Example 2 This comparative example provides a foamed concrete and its preparation method, as detailed below: The foamed concrete does not contain any self-made curing agent that requires no autoclaving; it is mixed using only ordinary tap water and, after molding, is placed directly in the air to air dry naturally. The remaining components and proportions are consistent with those in Example 1.

[0061] This comparative example uses the conventional water curing method: that is, the specimens are directly immersed in water after final setting.

[0062] The performance test results are as follows: 3-day compressive strength: 0.8 MPa; 28-day compressive strength: 3.5 MPa; Phenomenon: Poor slurry fluidity and severe bleeding during molding. Due to the lack of water-retaining components, surface moisture evaporates rapidly, forcing the hydration reaction to stop, resulting in extremely poor early strength and later strength far below the requirements of the invention. It is evident that, compared to the example, the self-made curing agent without steam curing is crucial for achieving natural curing at room temperature and ensuring sufficient hydration reaction; its absence will lead to the failure of the entire system.

[0063] Comparative Example 3 This comparative example provides a foamed concrete and its preparation method, as detailed below: The foamed concrete described herein does not contain any solid waste-based binder; it directly uses P.O42.5 ordinary Portland cement as the sole cementing material, with a dosage equivalent to the total mass of binder and activator in Example 1. The remaining components, proportions, and preparation methods are consistent with those in Example 1.

[0064] Performance test results: Solid waste utilization rate: 12% (containing only a small amount of fine aggregate); 3-day compressive strength: 2.2 MPa; 28-day compressive strength: 6.5 MPa; Although the specimens prepared in the comparative example showed some early strength, the solid waste content was extremely low, resulting in poor environmental benefits. Furthermore, the cement usage was high, leading to high costs, and the 28-day strength was still lower than that of the embodiments of this invention. The core of this invention lies in replacing cement with a highly active solid waste-based binder. This comparative example demonstrates that, under the same cost or cost control conditions, the solid waste-based binder outperforms the traditional pure cement system.

[0065] Comparative Example 4 This comparative example provides a foamed concrete and its preparation method, as detailed below: The foamed concrete uses a binary composite activator, which is the same as the ternary composite activator in Example 1, but with the sulfate activating component removed, retaining only the alkaline activating component and the functional synergistic component, while keeping the total dosage unchanged. The remaining components, proportions, and preparation methods are consistent with those in Example 1.

[0066] The performance test results are as follows: 3-day compressive strength: 1.5 MPa; 28-day compressive strength: 5.8 MPa; Observations: Early strength improvement is weak, lacking the support of rapid growth of needle-like ettringite crystals, and the system framework forms slowly. Later strength growth is also significantly affected, and the overall performance drops sharply. Compared with Example 1, the sulfate-activated component is the core contributor to early strength; its absence will completely fail to achieve the "fast hardening" target.

[0067] Comparative Example 5 This comparative example provides a foamed concrete and its preparation method, as detailed below: The foamed concrete described above replaces the self-made curing agent that does not require autoclaving with a single water-retaining agent containing only sodium carboxymethyl cellulose (CMC), with the dosage remaining unchanged. The remaining components, proportions, and preparation methods are consistent with those in Example 1.

[0068] Performance test results: 3-day compressive strength: 1.8 MPa; 28-day compressive strength: 6.2 MPa. While the specimens from this comparative example showed some water retention, alleviating surface cracking, the slurry fluidity was poor, and internal hydration was incomplete. The lack of synergistic effects from early-strength agents, water-reducing agents, and defoamers resulted in low early strength and poor workability. Therefore, the multi-functional synergy of self-made, autoclaved aerated concrete (SAC) curing agents is crucial for improving overall performance; a single function will limit both construction and early-stage performance.

[0069] The above comparative examples clearly demonstrate that the present invention achieves the comprehensive technical advantages of "high-value utilization of solid waste, no steam curing, rapid hardening and early strength, and lightweight and high strength" through the synergistic effect of three core materials: solid waste-based binder, ternary composite activator, and self-made curing agent that does not require steam curing. The absence or simplification of any key component will lead to a significant decline in product performance.

[0070] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A type of autoclaved, fast-setting, early-strength solid waste-based foamed concrete, characterized in that, Includes the following components in parts by weight: Solid waste-based binder 30-50 parts, fine aggregate 20-40 parts, polyester fiber 0.5-2 parts, foam stabilizer 0.1-0.5 parts, self-made curing agent without steam curing 1-3 parts, water 25-40 parts, foaming agent 1-5 parts; The solid waste-based cementitious material is prepared from the following raw materials: blast furnace slag powder, fly ash, gypsum dihydrate, and activator; The self-made curing agent without steam curing is prepared from the following raw materials: water, triethanolamine, polycarboxylate superplasticizer mother liquor, glycerol, silicone defoamer, sodium gluconate, anhydrous sodium sulfate, lithium silicate aqueous solution, and sodium carboxymethyl cellulose.

2. The autoclaved, fast-setting, early-strength solid waste-based foamed concrete according to claim 1, characterized in that, The solid waste-based binder is prepared from raw materials comprising the following components by weight: 40-60 parts blast furnace slag powder, 20-35 parts fly ash, 10-20 parts dihydrate gypsum, and 3-8 parts activator. And / or, the self-made curing agent without steam curing is prepared from raw materials comprising the following components in parts by weight: 90-105 parts water, 2-5 parts triethanolamine, 6-10 parts polycarboxylate superplasticizer mother liquor, 1-4 parts glycerol, 0.1-0.3 parts silicone defoamer, 0.6-1 parts sodium gluconate, 3-6 parts anhydrous sodium sulfate, 3-7 parts lithium silicate aqueous solution, and 1-3 parts sodium carboxymethyl cellulose; the concentration of the polycarboxylate superplasticizer mother liquor is 20 wt.%; and the concentration of the lithium silicate aqueous solution is 20 wt.%.

3. The autoclaved, fast-setting, early-strength solid waste-based foamed concrete according to claim 1 or 2, characterized in that, The preparation method of the solid waste-based cementitious material is as follows: The material has a moisture content ≤0.5% and a powder fineness of 550–650 μm. 2 An activator is injected into a mixture of blast furnace slag, fly ash, and dihydrate gypsum powder per kg, and then the mixture is ground until the specific surface area of ​​the powder reaches 700–750 m². 2 / kg, mix well.

4. The autoclaved, rapid-hardening, early-strength solid waste-based foamed concrete according to claim 1 or 2, characterized in that, The method for preparing the self-made curing agent without steaming includes the following steps: B1: Dissolve sodium carboxymethyl cellulose in 50-70 parts of water at 40-45°C by stirring to obtain a sodium carboxymethyl cellulose solution; dissolve glycerol and sodium gluconate in 25-35 parts of water at 10-20°C by stirring to obtain an alcohol-sugar solution; dissolve anhydrous sodium sulfate in 6-12 parts of water at 40-45°C by stirring, and then cool to room temperature to obtain a sodium sulfate solution. B2: Cool the sodium carboxymethyl cellulose solution to below 30°C, and add alcohol-sugar solution, sodium sulfate solution, triethanolamine and polycarboxylate superplasticizer mother liquor in sequence while stirring. Stir to dissolve and obtain mixture one. B3: Under stirring, add the lithium silicate aqueous solution to mixture one and disperse by ultrasonication to obtain mixture two; B4: Premix the silicone defoamer with 1-3 parts water to form an emulsion. Then, add the emulsion to the mixture while stirring. After stirring and letting stand, you will get the self-made curing agent that does not require steaming.

5. The autoclaved, rapid-hardening, early-strength solid waste-based foamed concrete according to claim 3, characterized in that, The activator is a ternary composite activator, prepared from raw materials comprising the following components by weight: 50-60 parts of sulfate activating component, 25-35 parts of alkaline activating component, and 10-20 parts of functional synergistic component. The preparation method of the sulfate-activated component is as follows: anhydrous calcium sulfoaluminate and anhydrous gypsum are mixed at a mass ratio of 20-40:40-80, calcined at 800-900℃ for 25-35 minutes, cooled to 100-150℃ for 30 minutes, and then ground to a specific surface area ≥450m². 2 / kg; The alkaline activating component is prepared by: removing free water from carbide slag and mixing the same mass of water glass at a high speed of 2000-3000 r / min to form an alkaline carrier with a "core-shell" structure. The preparation method of the functional synergistic component is as follows: MgO expanding agent, powdered polycarboxylate shrinkage agent and nano-SiO2 in a mass ratio of 50-60:1-5:40-50 are placed in a mixer, and 0.3-0.7% of sodium tripolyphosphate dispersant (the total mass of MgO expanding agent, powdered polycarboxylate shrinkage agent and nano-SiO2) is added. The mixture is mixed for 10-15 min under high-speed shear at 2500-3500 r / min to form functional microspheres.

6. The autoclaved, rapid-hardening, early-strength solid waste-based foamed concrete according to claim 5, characterized in that, The preparation method of the ternary composite activator is as follows: the sulfate activating component, the alkaline activating component and the functional synergistic component are put into a mixer, and stirred at a speed of 80-120 r / min for 3-8 min under the conditions of 40-50℃ and dry nitrogen protection, then stirred at a speed of 150-200 r / min for 8-15 min, and finally stirred at a speed of 100-140 r / min for 3-8 min.

7. The autoclaved, rapid-hardening, early-strength solid waste-based foamed concrete according to claim 1 or 2, characterized in that, The foaming agent is one or two of animal protein foaming agents and / or plant protein foaming agents; and / or, the foam stabilizer is one or two of sodium dodecyl sulfate and sodium fatty alcohol polyoxyethylene ether sulfate.

8. The autoclaved, rapid-hardening, early-strength solid waste-based foamed concrete according to claim 7, characterized in that, The foaming agent is a composite foaming agent composed of animal protein foaming agent and plant protein foaming agent in a mass ratio of 2:1 to 3; the foam stabilizer is a composite foam stabilizer composed of sodium dodecyl sulfate and sodium fatty alcohol polyoxyethylene ether sulfate in a mass ratio of 1:1 to 2.

9. The autoclaved, fast-setting, early-strength solid waste-based foamed concrete according to claim 1 or 2, characterized in that, The fine aggregate is selected from one or more of fly ash, recycled construction waste powder, slag, and tailings sand; the recycled construction waste powder has a particle size ≤0.15mm, and the slag and tailings sand have a particle size of 0.075~2.36mm; the polyester fiber has a length of 6~12mm, a diameter of 15~30μm, and a tensile strength ≥350MPa.

10. A method for preparing non-steam-cured, fast-hardening, early-strength solid waste-based foamed concrete as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1: Put solid waste-based binder, fine aggregate, and polyester fiber into a mixer and dry mix for 2-3 minutes until uniform to form a dry mix. S2: Add the self-made curing agent and 17.5-32 parts of water to the dry mixture, stir for 4-6 minutes to obtain the composite slurry; S3: Mix the foaming agent with the remaining water and stir to achieve an apparent density of 30–60 kg / m³. 3 Stable bubbles; S4: Add foam to the composite slurry, and add foam stabilizer at the same time. Stir at 30-40 r / min for 1-2 minutes to mix and form foam concrete slurry. S5: Pour the foamed concrete slurry into the mold, let it stand naturally for 12-24 hours before demolding, and then cure it naturally at 20±5℃ and relative humidity ≥70% until the specified age.

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