Light thermal insulation foam concrete based on industrial solid waste and forming process thereof

Abstract

The invention relates to the technical field of lightweight concrete, in particular to lightweight thermal insulation foam concrete based on industrial solid waste and a forming process thereof, and the lightweight thermal insulation foam concrete is prepared from the following raw materials: a modified industrial solid waste admixture, a cementing material, a composite foam system, a modified packaging phase change material, an additive and water; according to the invention, all the components and the process steps form a synergetic and complementary overall scheme; the compatibility and reaction activity among the raw materials are improved through multi-step modification treatment of the modified industrial solid waste admixture, and the interface defects in the hydration process are reduced; due to the stable pore structure of the composite foam system, stress concentration caused by uneven pores is avoided; the phase change effect of the modified packaging phase change material can counteract part of hydration shrinkage stress; the mixing uniformity of the raw materials is ensured through segmented stirring, internal bubbles and gaps are reduced through cooperation of layered pouring and slight vibration, and the cracking risk caused by temperature stress is reduced through slow heating and cooling in gradient maintenance.

Description

Technical Field

[0001] This invention relates to the field of lightweight concrete technology, specifically to lightweight thermal insulation foam concrete based on industrial solid waste and its molding process. Background Technology

[0002] As the construction industry transforms towards green, low-carbon, energy-efficient, and high-performance directions, thermal insulation materials, as a core component of building energy conservation, have become a key focus for performance optimization and resource utilization improvement. Foamed concrete, with its advantages of being lightweight, providing thermal insulation, and sound insulation, is widely used in building insulation and filling applications. However, existing foamed concrete products still have many problems that urgently need to be addressed.

[0003] Currently, cement is the primary cementitious material in the raw material system of foamed concrete. This not only results in high costs but also consumes a large amount of mineral resources and generates significant carbon emissions, which is inconsistent with the concept of green development. Meanwhile, the accumulation of solid waste such as steel slag, mineral slag, and red mud generated in industrial production is enormous. The indiscriminate dumping of this solid waste not only occupies land resources but also risks damaging the ecological environment due to heavy metal leakage and dust pollution. Therefore, how to achieve the resource utilization of industrial solid waste has become a major challenge for the industry.

[0004] In terms of thermal insulation performance, traditional foamed concrete mainly relies on internal pores to achieve thermal insulation. The thermal insulation mechanism is simple, the thermal conductivity is difficult to further reduce, and the problem of excessive heat transfer during temperature changes is easy to occur, which cannot meet the needs of high-precision thermal insulation scenarios.

[0005] Therefore, developing a foamed concrete that can achieve efficient utilization of industrial solid waste while possessing excellent lightweight thermal insulation, mechanical properties, and volume stability has become an urgent need in the field of building insulation materials, and is of great significance for promoting the green transformation of the construction industry and the resource utilization of industrial solid waste. Summary of the Invention

[0006] The purpose of this invention is to provide lightweight thermal insulation foam concrete based on industrial solid waste and its molding process.

[0007] To achieve the above objectives, the present invention provides the following technical solution: Lightweight thermal insulation foam concrete based on industrial solid waste is prepared from the following raw materials in parts by weight: 55-65 parts modified industrial solid waste admixture, 25-30 parts cementitious material, 4-6 parts composite foam system, 3-5 parts modified encapsulated phase change material, 1.0-2.0 parts admixture, and 28-35 parts water. The modified industrial solid waste admixture is made by mixing steel slag, ore slag and red mud in a mass ratio of 4:3:1, followed by mechanical grinding, low-temperature plasma pretreatment, chemical activation and composite modification. The composite foam system is made by mixing composite foaming agent and high-efficiency foam stabilizer in a mass ratio of 9:1, followed by ultrasonic emulsification pretreatment.

[0008] As a further technical solution, the preparation steps of the modified encapsulated phase change material are as follows: Preparation of S1 paraffin-graphite composite phase change material: Paraffin and modified graphite are mixed at a mass ratio of 9:1, heated to 62-68℃, and stirred at 200-250r / min for 20-30min until the paraffin is completely melted and mixed evenly. After cooling to room temperature, the mixture is pulverized to obtain a paraffin-graphite composite phase change material with a particle size of 55-95μm. S2 Microcapsule Encapsulation: Using the paraffin-graphite composite phase change material prepared in step S1 as the core material and melamine resin as the wall material, the microcapsules are encapsulated using interfacial polymerization at a core-to-wall ratio of 3:1. The core material is dispersed in deionized water, and 0.8%-1.2% of Tween-80 by weight of the core material is added as an emulsifier. The emulsification is carried out for 30 minutes. Melamine resin prepolymer is added as a wall material precursor. The pH of the system is adjusted to 8.2-8.8, the temperature is controlled at 62-68℃, and the reaction is carried out for 2.2-2.8 hours. After cooling, filtration, and drying, phase change microcapsules are obtained with a particle size of 1.5-4.5 μm. S3 Surface Modification: The phase change microcapsules prepared in step S2 are added to a 1.2%-1.4% (by mass) solution of silane coupling agent KH-560, ultrasonically dispersed for 22-28 min at an ultrasonic power of 280-320 W, and then dried at 80 °C for 1.2-1.8 h to obtain the modified encapsulated phase change material.

[0009] As a further technical solution, the modified graphite preparation method is as follows: graphite is placed in a 1.5%-2.5% ethanol solution of silane coupling agent KH-570, ultrasonically dispersed for 25-35 minutes, ultrasonic power 300-350W, dispersion temperature 28-32℃, and then dried at 90-100℃ for 2-3 hours to obtain modified graphite. The volume ratio of ethanol to water in the ethanol solution of silane coupling agent KH-570 is 9:1. As a further technical solution, the parameters of the mechanical grinding are as follows: steel balls are used as the grinding medium, the mass ratio of steel balls to mixed solid waste is 5:1, the grinding speed is 320-380 r / min, the grinding time is 2.0-2.8 h, and impurities are removed by passing the grinding material through a 200-mesh sieve.

[0010] As a further technical solution, the parameters of the low-temperature plasma pretreatment are: plasma power 160-200W, treatment time 15-18min, and treatment atmosphere is argon.

[0011] As a further technical solution, the composite activator used in the chemical activation is made by mixing water glass with a modulus of 1.65-1.75 and a solid content of 28.5%-29.5% with desulfurized gypsum at a mass ratio of 2:1. The amount of composite activator added is 3.5%-4.5% of the mass of the mixed solid waste powder after mechanical grinding. The curing conditions for chemical activation are constant temperature curing at 85-95℃ for 12-15 hours.

[0012] As a further technical solution, the composite modifier used in the composite modification is prepared by mixing silane coupling agent KH-550 and polycarboxylic acid dispersant at a mass ratio of 3:2. The amount of composite modifier added is 1.2%-1.8% of the mass of the chemically activated solid waste powder. The parameters of the composite modification are stirring at a speed of 520-580 r / min for 32-38 min, and then cooling to room temperature after stirring.

[0013] As a further technical solution, the composite foaming agent is prepared by mixing sodium dodecyl sulfate and plant protein foaming agent at a mass ratio of 3:2, and the high-efficiency foam stabilizer is prepared by mixing modified silicone resin polyether microemulsion and hydroxypropyl methylcellulose ether at a mass ratio of 2:1; the parameters of the ultrasonic emulsification pretreatment are: ultrasonic power 280-320W, ultrasonic time 16-20min, and emulsification temperature 32-38℃.

[0014] As a further technical solution, the cementitious material is made by mixing P·O42.5 grade ordinary Portland cement and slag Portland cement in a mass ratio of 1:1; the admixture is made by mixing liquid polyester-type polycarboxylate high-efficiency water-reducing agent, citric acid, and organosilicon waterproofing agent in a mass ratio of 3:2:1, wherein the solid content of the liquid polyester-type polycarboxylate high-efficiency water-reducing agent is 30%.

[0015] A molding process for lightweight insulating foamed concrete from industrial solid waste includes the following steps: S1: Raw material pretreatment, drying the modified industrial solid waste admixture, cementitious materials, and additives to a moisture content of ≤0.3%; S2: Segmented mixing. First, the modified industrial solid waste admixture, cementitious materials, and additives are mixed at 200-280 r / min for 6-10 min to form a dry mixture. Then, a preset amount of water is added to the dry mixture, and it is mixed at 450-480 r / min for 12-14 min to form a cement slurry. Finally, nano-silica dispersion is added to the cement slurry and mixed evenly. Then, the composite foam system is slowly added at 150-250 r / min and mixed for 4-5 min to form a foamed concrete slurry. The amount of the nano-silica aqueous dispersion added is 0.06-0.09 parts, and the concentration is 1.2%-1.8%. S3: Layered pouring. The foamed concrete slurry is poured into the pre-set mold in two layers. Each layer is 120-140mm thick. After each layer is poured, it is slightly vibrated at a frequency of 50Hz for 12-14s. After standing for 25-30 minutes, the next layer is poured. S4: Gradient curing. First, place the poured slurry in an environment of 22-24℃ and 88%-95% humidity for 7-10 hours until initial setting. Then, raise the temperature to 52-58℃ at a rate of 6-7℃ / h and maintain the temperature for 12-15 hours. Afterward, lower the temperature to room temperature at a rate of 4-5℃ / h and continue curing in an environment of 20-24℃ and 88%-95% humidity for 2-34 days. S5: Demolding and post-processing: Remove the mold and repair surface defects of the foamed concrete. Let it stand at room temperature for 4-5 days to obtain the finished product.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention uses steel slag, mineral slag, and red mud mixed in a specific ratio to prepare a modified industrial solid waste admixture. Mechanical grinding optimizes particle size distribution, achieving uniform and fine solid waste particles, laying a structural foundation for subsequent modification. Low-temperature plasma pretreatment activates active sites on the surface of solid waste particles, improving their physicochemical properties and enhancing their interaction with other raw materials. Chemical activation, through the action of a composite activator, further enhances the hydration activity of the solid waste, promoting its full participation in the hydration reaction to generate stable hydration products. Composite modification, through the synergistic effect of silane coupling agents and polycarboxylic acid dispersants, optimizes the dispersibility and compatibility of solid waste particles, preventing particle agglomeration. Because this multi-step modified industrial solid waste admixture replaces some cement and other cementitious materials, it not only achieves high-value utilization of industrial solid waste and reduces the environmental pressure caused by solid waste stockpiling, but also lowers the raw material cost of foamed concrete. Simultaneously, the modified solid waste admixture works synergistically with the cementitious materials, ensuring the structural density of the finished product and solving the performance degradation problem caused by the direct addition of traditional solid waste.

[0017] 2. The composite foam system combines a composite foaming agent with a high-efficiency foam stabilizer, along with ultrasonic emulsification pretreatment. This allows the foaming agent to form uniform and fine microbubbles, while the foam stabilizer forms a protective film on the bubble surface, effectively inhibiting bubble breakage and merging. This creates a uniformly distributed closed-pore structure within the concrete, significantly reducing the material's dry density for a lightweight effect. Furthermore, the closed pores hinder heat transfer, improving the basic insulation performance. The modified encapsulated phase change material uses a paraffin-graphite composite phase change material as its core. The addition of graphite enhances the core material's thermal conductivity, making heat transfer during the phase change process more efficient. Microencapsulation technology avoids paraffin leakage. The surface-modified phase change microcapsules have good compatibility with the concrete matrix and can absorb or release heat through the latent heat of phase change when the temperature changes, forming a dual insulation mechanism of porous insulation and phase change heat storage, further reducing the thermal conductivity. Meanwhile, phase change microcapsules, as functional fillers, can fill the tiny pores inside the matrix and form a dense composite structure with modified industrial solid waste admixtures and cementitious materials. Combined with segmented mixing, layered pouring and gradient curing processes, the raw materials are mixed more evenly, the hydration reaction is more complete, and the internal stress distribution is more balanced. Thus, while improving the thermal insulation performance, the compressive strength of the material is guaranteed, solving the technical problems of traditional foamed concrete that it is difficult to achieve both lightweight and high strength and that the thermal insulation mechanism is singular.

[0018] 3. The components and process steps of this invention form a synergistic and complementary overall solution: the multi-step modification treatment of the modified industrial solid waste admixture improves the compatibility and reactivity between raw materials and reduces interface defects during hydration; the stable pore structure of the composite foam system avoids stress concentration caused by uneven pore size; the phase change effect of the modified encapsulated phase change material can offset some of the hydration shrinkage stress; segmented stirring ensures the uniformity of raw material mixing; layered casting combined with slight vibration reduces internal air bubbles and voids; and gradient curing reduces the risk of cracking caused by temperature stress through slow heating and cooling. The synergistic effect of these treatments effectively inhibits the shrinkage deformation of foamed concrete during preparation and use, reduces the volume shrinkage rate, avoids cracking, hollowing, and other problems, and improves the volume stability and durability of the material. Attached Figure Description

[0019] Figure 1 This is a comparison chart of the linear shrinkage rates of the example and the comparative example over 7 days. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] This invention provides a lightweight thermal insulation foamed concrete based on industrial solid waste, prepared from the following raw materials in parts by weight: 55-65 parts modified industrial solid waste admixture, 25-30 parts cementitious material, 4-6 parts composite foam system, 3-5 parts modified encapsulated phase change material, 1.0-2.0 parts additive, and 28-35 parts water. A nano-silica aqueous dispersion is also added to assist in the preparation. This invention achieves efficient utilization of industrial solid waste through a rational combination of raw materials and optimization of various preparation process parameters, while simultaneously endowing the foamed concrete with excellent lightweight thermal insulation properties and mechanical stability.

[0022] Raw material description: Modified industrial solid waste admixtures: The modified industrial solid waste admixture is made by mixing steel slag, ore slag and red mud in a mass ratio of 4:3:1, and then sequentially undergoing mechanical grinding, low-temperature plasma pretreatment, chemical activation and composite modification.

[0023] The preferred parameters for mechanical grinding are: steel balls as the grinding medium, a mass ratio of steel balls to mixed solid waste of 5:1, a grinding speed of 320-380 r / min, a grinding time of 2.0-2.8 h, and impurities removed by passing the material through a 200-mesh sieve after grinding.

[0024] The preferred parameters for low-temperature plasma pretreatment are plasma power of 160-200W, treatment time of 15-18min, and argon atmosphere.

[0025] The composite activator used for chemical activation is made by mixing water glass with a modulus of 1.65-1.75 and a solid content of 28.5%-29.5% with desulfurized gypsum at a mass ratio of 2:1. The amount of composite activator added is 3.5%-4.5% of the mass of the mixed solid waste powder after mechanical grinding. The curing conditions for chemical activation are constant temperature curing at 85-95℃ for 12-15 hours.

[0026] The composite modifier used in the composite modification is made by mixing silane coupling agent KH-550 and polycarboxylic acid dispersant at a mass ratio of 3:2. The amount of composite modifier added is 1.2%-1.8% of the mass of the chemically activated solid waste powder. The parameters for composite modification are stirring at a speed of 520-580 r / min for 32-38 min, and then cooling to room temperature after stirring.

[0027] Cementing materials: The cementitious material is made by mixing ordinary Portland cement of P-O42.5 grade and slag Portland cement in a mass ratio of 1:1, and commercially available products known to those skilled in the art can be used.

[0028] Composite foam system: The composite foam system is made by mixing a composite foaming agent and a high-efficiency foam stabilizer at a mass ratio of 9:1, followed by ultrasonic emulsification pretreatment.

[0029] The composite foaming agent is prepared by mixing sodium dodecyl sulfate and plant protein foaming agent at a mass ratio of 3:2, and the high-efficiency foam stabilizer is prepared by mixing modified silicone resin polyether microemulsion and hydroxypropyl methylcellulose ether at a mass ratio of 2:1. The preferred parameters for ultrasonic emulsification pretreatment are ultrasonic power of 280-320W, ultrasonic time of 16-20min, and emulsification temperature of 32-38℃.

[0030] Modified encapsulated phase change materials: The preparation steps of the modified encapsulated phase change material are as follows: Preparation of paraffin-graphite composite phase change material: Paraffin and modified graphite are mixed at a mass ratio of 9:1, heated to 62-68℃, and stirred at 200-250r / min for 20-30min until the paraffin is completely melted and the mixture is uniform. After cooling to room temperature, the mixture is pulverized to obtain a paraffin-graphite composite phase change material with a particle size of 55-95μm.

[0031] Microcapsule encapsulation: Using the paraffin-graphite composite phase change material prepared in step 1 as the core material and melamine resin as the wall material, the microcapsules were encapsulated using interfacial polymerization at a core-to-wall ratio of 3:1. The core material was dispersed in deionized water, and 0.8%-1.2% of Tween-80 by weight of the core material was added as an emulsifier. The emulsification was carried out for 30 minutes. Melamine resin prepolymer was added as a wall material precursor. The pH of the system was adjusted to 8.2-8.8, the temperature was controlled at 62-68℃, and the reaction was carried out for 2.2-2.8 hours. After cooling, filtration, and drying, phase change microcapsules with a particle size of 1.5-4.5 μm were obtained.

[0032] Surface modification: The phase change microcapsules prepared in step 2 are added to a 1.2%-1.4% (by mass) solution of silane coupling agent KH-560, ultrasonically dispersed for 22-28 min at an ultrasonic power of 280-320 W, and then dried at 80 °C for 1.2-1.8 h to obtain the modified encapsulated phase change material.

[0033] The modified graphite is prepared by placing graphite in a 1.5%-2.5% ethanol solution of silane coupling agent KH-570, ultrasonically dispersing it for 25-35 minutes at an ultrasonic power of 300-350W and a dispersion temperature of 28-32℃, and then drying it at 90-100℃ for 2-3 hours to obtain modified graphite. The volume ratio of ethanol to water in the ethanol solution of silane coupling agent KH-570 is 9:1.

[0034] Additives: The admixture is made by mixing liquid polyester-type polycarboxylate high-efficiency water-reducing agent, citric acid, and organosilicon waterproofing agent in a mass ratio of 3:2:1. The liquid polyester-type polycarboxylate high-efficiency water-reducing agent has a solid content of 30%, and commercially available products well known to those skilled in the art can be used.

[0035] Other auxiliary materials: Ordinary industrial water is used; the concentration of the nano-silica aqueous dispersion is 1.2%-1.8%, and commercially available products familiar to those skilled in the art can be used.

[0036] The molding process of lightweight thermal insulation foam concrete based on industrial solid waste includes the following steps: Raw material pretreatment: The modified industrial solid waste admixture, cementitious materials, and additives are dried to a moisture content of ≤0.3%.

[0037] Segmented mixing: First, mix the modified industrial solid waste admixture, cementitious material, and additives at 200-280 r / min for 6-10 min to make a dry mix. Then, add the preset amount of water to the dry mix and mix at 450-480 r / min for 12-14 min to make a cement slurry. Finally, add nano-silica dispersion to the cement slurry and mix evenly. Then, slowly add the composite foam system at 150-250 r / min and mix for 4-5 min to make foamed concrete slurry.

[0038] Layered pouring: The foamed concrete slurry is poured into the pre-set mold in two layers, each layer being 120-140mm thick. After each layer is poured, it is gently vibrated at a frequency of 50Hz for 12-14 seconds and left to stand for 25-30 minutes before pouring the next layer.

[0039] Gradient curing: First, place the poured grout in an environment of 22-24℃ and 88%-95% humidity for 7-10 hours until initial setting. Then, raise the temperature to 52-58℃ at a rate of 6-7℃ / h and maintain the temperature for 12-15 hours. Afterward, cool the grout to room temperature at a rate of 4-5℃ / h and continue curing in an environment of 20-24℃ and 88%-95% humidity for 2-34 days.

[0040] Demolding and post-processing: Remove the mold and repair any defects on the surface of the foamed concrete. Let it stand at room temperature for 4-5 days to obtain the finished product.

[0041] The lightweight thermal insulation foam concrete based on industrial solid waste provided by this invention realizes the resource utilization of industrial solid waste by using modified industrial solid waste admixtures, reducing production costs. At the same time, the synergistic effect of the composite foam system and the modified encapsulated phase change material endows the material with excellent lightweight thermal insulation performance. The molding process is simple and controllable, the product quality is stable, and it is suitable for various scenarios such as building insulation.

[0042] To further illustrate the present invention, the following detailed description is provided through the examples and comparative examples.

[0043] Example 1: Prepare the raw materials by weight as follows: 55 parts modified industrial solid waste admixture, 25 parts cementitious material, 4 parts composite foam system, 3 parts modified encapsulation phase change material, 1.0 part additive, 28 parts water; 0.06 parts nano silica aqueous dispersion, concentration 1.2%.

[0044] Among them, the preparation parameters of modified industrial solid waste admixtures are as follows: Mechanical grinding: The mass ratio of steel balls to mixed solid waste is 5:1, the grinding speed is 320 r / min, the grinding time is 2.0 h, and the ground material is passed through a 200 mesh sieve.

[0045] Low-temperature plasma pretreatment: plasma power 160W, treatment time 15min, treatment atmosphere is argon.

[0046] Chemical activation: The amount of composite activator added is 3.5% of the mass of the mixed solid waste powder after mechanical grinding, and the curing conditions are constant temperature curing at 85℃ for 12 hours.

[0047] Composite modification: The amount of composite modifier added is 1.2% of the mass of the chemically activated solid waste powder, the stirring speed is 520 r / min, and the stirring time is 32 min.

[0048] Preparation parameters of composite foam system: ultrasonic emulsification pretreatment: ultrasonic power 280W, ultrasonic time 16min, emulsification temperature 32℃.

[0049] Preparation parameters for modified encapsulated phase change materials: Paraffin-graphite composite phase change material: heating temperature 62℃, stirring speed 200r / min, stirring time 20min, particle size after pulverization 55μm.

[0050] Microcapsule encapsulation: Tween-80 was added at 0.8% of the core material mass, the system pH was 8.2, the reaction temperature was 62℃, the reaction time was 2.2h, and the microcapsule particle size was 1.5μm.

[0051] Surface modification: The amount of silane coupling agent KH-560 solution added was 1.2% of the mass of the phase change microcapsules, the ultrasonic dispersion time was 22 min, the ultrasonic power was 280 W, and the drying time was 1.2 h.

[0052] Parameters for preparing modified graphite: 1.5% concentration of silane coupling agent KH-570 in ethanol solution, 25 min ultrasonic dispersion time, 300 W ultrasonic power, 28 ℃ dispersion temperature, 90 ℃ drying temperature, and 2 h drying time.

[0053] The molding process includes: Raw material pretreatment: The modified industrial solid waste admixture, cementitious materials, and additives are dried to a moisture content of ≤0.3%.

[0054] Segmented mixing: First, the modified industrial solid waste admixture, cementitious material, and additives are mixed at 200 r / min for 6 min to make a dry mixture. Then, 28 parts of water are added to the dry mixture and it is mixed at 450 r / min for 12 min to make a cement slurry. Finally, 0.06 parts of nano silica dispersion are added to the cement slurry and mixed evenly. Then, 4 parts of composite foam system are slowly added at 150 r / min and mixed for 4 min to make foamed concrete slurry.

[0055] Layered pouring: The foamed concrete slurry is poured into the pre-set mold in two layers, each layer is 120mm thick. After each layer is poured, it is slightly vibrated at a frequency of 50Hz for 12s. After standing for 25 minutes, the next layer is poured.

[0056] Gradient curing: First, place the poured slurry in an environment of 22℃ and 88% humidity for 7 hours until initial setting. Then, raise the temperature to 52℃ at a rate of 6℃ / h and keep it at a constant temperature for 12 hours. After that, lower the temperature to room temperature at a rate of 4℃ / h and continue to cure in an environment of 20℃ and 88% humidity for 2 days.

[0057] Demolding and post-processing: Remove the mold and repair surface defects of the foamed concrete. Let it stand at room temperature for 4 days to obtain the finished product.

[0058] Example 2: Prepare the raw materials by weight as follows: 65 parts modified industrial solid waste admixture, 30 parts cementitious material, 6 parts composite foam system, 5 parts modified encapsulation phase change material, 2.0 parts additive, 35 parts water; 0.09 parts nano silica aqueous dispersion, concentration 1.8%.

[0059] Among them, the preparation parameters of modified industrial solid waste admixtures are as follows: Mechanical grinding: The mass ratio of steel balls to mixed solid waste is 5:1, the grinding speed is 380 r / min, the grinding time is 2.8 h, and the ground material is passed through a 200 mesh sieve.

[0060] Low-temperature plasma pretreatment: plasma power 200W, treatment time 18min, treatment atmosphere is argon.

[0061] Chemical activation: The amount of composite activator added is 4.5% of the mass of the mixed solid waste powder after mechanical grinding, and the curing conditions are constant temperature curing at 95℃ for 15 hours.

[0062] Composite modification: The amount of composite modifier added is 1.8% of the mass of the chemically activated solid waste powder, the stirring speed is 580 r / min, and the stirring time is 38 min.

[0063] Preparation parameters of composite foam system: ultrasonic emulsification pretreatment: ultrasonic power 320W, ultrasonic time 20min, emulsification temperature 38℃.

[0064] Preparation parameters for modified encapsulated phase change materials: Paraffin-graphite composite phase change material: heating temperature 68℃, stirring speed 250r / min, stirring time 30min, particle size after pulverization 95μm.

[0065] Microcapsule encapsulation: Tween-80 was added at 1.2% of the core material mass, the system pH was 8.8, the reaction temperature was 68℃, the reaction time was 2.8h, and the microcapsule particle size was 4.5μm.

[0066] Surface modification: The amount of silane coupling agent KH-560 solution added was 1.4% of the mass of the phase change microcapsules, the ultrasonic dispersion time was 28 min, the ultrasonic power was 320 W, and the drying time was 1.8 h.

[0067] Parameters for preparing modified graphite: 2.5% concentration of silane coupling agent KH-570 ethanol solution, ultrasonic dispersion time 35 min, ultrasonic power 350 W, dispersion temperature 32 ℃, drying temperature 100 ℃, drying time 3 h.

[0068] The molding process includes: Raw material pretreatment: The modified industrial solid waste admixture, cementitious materials, and additives are dried to a moisture content of ≤0.3%.

[0069] Segmented mixing: First, the modified industrial solid waste admixture, cementitious material, and additives are mixed at 280 r / min for 10 min to make a dry mixture. Then, 35 parts of water are added to the dry mixture and it is mixed at 480 r / min for 14 min to make a cement slurry. Finally, 0.09 parts of nano silica dispersion are added to the cement slurry and mixed evenly. Then, 6 parts of composite foam system are slowly added at 250 r / min and mixed for 5 min to make foamed concrete slurry.

[0070] Layered pouring: The foamed concrete slurry is poured into the pre-set mold in two layers, each layer is 140mm thick. After each layer is poured, it is slightly vibrated at a frequency of 50Hz for 14s. After standing for 30 minutes, the next layer is poured.

[0071] Gradient curing: First, place the poured slurry in an environment of 24℃ and 95% humidity for 10 hours until initial setting, then raise the temperature to 58℃ at a rate of 7℃ / h and keep it at a constant temperature for 15 hours, then lower the temperature to room temperature at a rate of 5℃ / h and continue to cure in an environment of 24℃ and 95% humidity for 34 days.

[0072] Demolding and post-processing: Remove the mold and repair surface defects of the foamed concrete. Let it stand at room temperature for 5 days to obtain the finished product.

[0073] Example 3: Prepare the raw materials by weight as follows: 60 parts modified industrial solid waste admixture, 28 parts cementitious material, 5 parts composite foam system, 4 parts modified encapsulation phase change material, 1.5 parts additive, 32 parts water; 0.07 parts nano silica aqueous dispersion, concentration 1.5%.

[0074] Among them, the preparation parameters of modified industrial solid waste admixtures are as follows: Mechanical grinding: The mass ratio of steel balls to mixed solid waste is 5:1, the grinding speed is 350 r / min, the grinding time is 2.4 h, and the ground material is passed through a 200 mesh sieve.

[0075] Low-temperature plasma pretreatment: plasma power 180W, treatment time 16min, treatment atmosphere is argon.

[0076] Chemical activation: The amount of composite activator added is 4.0% of the mass of the mixed solid waste powder after mechanical grinding, and the curing conditions are constant temperature curing at 90℃ for 13 hours.

[0077] Composite modification: The amount of composite modifier added is 1.5% of the mass of the chemically activated solid waste powder, the stirring speed is 550 r / min, and the stirring time is 35 min.

[0078] Preparation parameters of composite foam system: ultrasonic emulsification pretreatment: ultrasonic power 300W, ultrasonic time 18min, emulsification temperature 35℃.

[0079] Preparation parameters for modified encapsulated phase change materials: Paraffin-graphite composite phase change material: heating temperature 65℃, stirring speed 220r / min, stirring time 25min, particle size after pulverization 75μm.

[0080] Microcapsule encapsulation: Tween-80 was added at 1.0% of the core material mass, the system pH was 8.5, the reaction temperature was 65℃, the reaction time was 2.5h, and the microcapsule particle size was 3.0μm.

[0081] Surface modification: The amount of silane coupling agent KH-560 solution added was 1.3% of the mass of the phase change microcapsules, the ultrasonic dispersion time was 25 min, the ultrasonic power was 300 W, and the drying time was 1.5 h.

[0082] Parameters for preparing modified graphite: 2.0% concentration of silane coupling agent KH-570 in ethanol solution, 30 min ultrasonic dispersion time, 320 W ultrasonic power, 30 °C dispersion temperature, 95 °C drying temperature, and 2.5 h drying time.

[0083] The molding process includes: Raw material pretreatment: The modified industrial solid waste admixture, cementitious materials, and additives are dried to a moisture content of ≤0.3%.

[0084] Segmented mixing: First, the modified industrial solid waste admixture, cementitious material, and additives are mixed at 240 r / min for 8 min to make a dry mixture. Then, 32 parts of water are added to the dry mixture and it is mixed at 460 r / min for 13 min to make a cement slurry. Finally, 0.07 parts of nano silica dispersion are added to the cement slurry and mixed evenly. Then, 5 parts of composite foam system are slowly added at 200 r / min and mixed for 4.5 min to make foamed concrete slurry.

[0085] Layered pouring: The foamed concrete slurry is poured into the pre-set mold in two layers, each layer is 130mm thick. After each layer is poured, it is slightly vibrated at a frequency of 50Hz for 13s. After standing for 28 minutes, the next layer is poured.

[0086] Gradient curing: First, place the poured slurry in an environment of 23℃ and 92% humidity for 8 hours until initial setting, then raise the temperature to 55℃ at a rate of 6.5℃ / h and keep it at a constant temperature for 13 hours, then lower the temperature to room temperature at a rate of 4.5℃ / h and continue to cure in an environment of 22℃ and 92% humidity for 18 days.

[0087] Demolding and post-processing: Remove the mold and repair surface defects of the foamed concrete. Let it stand at room temperature for 4.5 days to obtain the finished product.

[0088] Comparative Example 1: The preparation method of Example 3 was used, except that modified industrial solid waste admixtures were not used; instead, an equal amount of P-O42.5 grade ordinary Portland cement was used. All other raw materials and preparation parameters were the same as in Example 3.

[0089] Comparative Example 2: The preparation method of Example 3 was used, except that the composite foam system was replaced with a single sodium dodecyl sulfate foaming agent, and ultrasonic emulsification pretreatment was not performed. All other raw materials and preparation parameters were the same as in Example 3.

[0090] Comparative Example 3: The preparation method of Example 3 was used, except that no modified encapsulation phase change material was added. All other raw materials and preparation parameters were the same as in Example 3.

[0091] Comparative Example 4: The preparation method of Example 3 was used, except that the modified industrial solid waste admixture was only mechanically ground, without low-temperature plasma pretreatment, chemical activation, or composite modification. All other raw materials and preparation parameters were the same as in Example 3.

[0092] Experiment 1: Lightweight thermal insulation performance test: 1.1 Experimental Objective: The dry density and thermal conductivity of the foamed concrete in Examples 1-3 and Comparative Examples 1-4 were tested to verify the effects of modified industrial solid waste admixtures, composite foam systems, modified encapsulated phase change materials, and modification processes on the lightweight thermal insulation performance of foamed concrete. Dry density reflects the lightweight characteristics of the material, and thermal conductivity reflects the thermal insulation performance of the material. Both are core performance indicators of lightweight thermal insulation foamed concrete.

[0093] 1.2 Experimental Principle: The dry density of the prepared foamed concrete specimens was tested by weighing the specimens after drying and calculating the dry density by weighing the specimens and measuring their mass and volume. The thermal conductivity of the specimens was tested by the protective hot plate method. The thermal resistance was calculated by measuring the heat flux density, temperature difference between the two sides and the size of the specimens during steady-state heat transfer, and then the thermal conductivity was derived to directly reflect the heat insulation capacity of the material.

[0094] 1.3 Experimental Instruments and Equipment: Test instruments: electronic balance (accuracy 0.001g), forced-air drying oven (temperature control accuracy ±2℃), vernier calipers (accuracy 0.01mm), protective hot plate thermal conductivity meter (heat flux density resolution ≤0.01W / m). 2 Temperature resolution ≤0.01℃), diamond cutting saw (cutting accuracy ±1mm), dryer (built-in silica gel desiccant).

[0095] 1.4 Test Methods: Specimen Preparation: The foamed concrete products prepared in Examples 1-3 and Comparative Examples 1-4 were cut into 100mm×100mm×100mm dry density standard specimens and 300mm×300mm×50mm thermal conductivity standard specimens using a diamond saw. Three parallel specimens were prepared for each group. All specimens had to meet the following requirements: smooth surface, no cracks, no missing edges or corners; dimensional deviation of dry density specimens ≤ ±2mm; dimensional deviation of thermal conductivity specimens ≤ ±3mm (length / width) and ≤ ±1mm (thickness). After molding, the specimens were placed in a standard curing chamber (temperature 20±2℃, humidity 95%±5%) for curing for 28 days.

[0096] Dry density test: ① Place the dry density specimen in a forced-air drying oven, set the temperature to 105℃±5℃, and dry until constant weight (two consecutive weighings with an interval of 2 hours, and the mass change ≤0.1%). After taking it out, immediately place it in a desiccator to cool to room temperature (cooling time ≥2 hours to avoid the specimen absorbing moisture). ② Weigh each specimen using an electronic balance, accurate to 0.001g; ③ Use vernier calipers to measure the length, width, and height of the specimen. Measure three points at different locations in each direction and take the average value as the actual size of the specimen (accurate to 0.1 mm). Calculate the volume of the specimen (volume = length × width × height, accurate to 1 cm).3 ); ④ Dry density calculation: Dry density ρ = specimen mass m / specimen volume V. Calculate the dry density of each specimen, and take the average of 3 parallel specimens as the final dry density, accurate to 1 kg / m³. 3 If the dry density of a single specimen deviates from the average value by more than 10%, the integrity of the specimen must be rechecked, and damaged or out-of-tolerance specimens must be removed. The average value of the remaining valid specimens should be taken. If there are fewer than two valid specimens, new specimens must be prepared for testing.

[0097] Thermal conductivity test: ① The thermal conductivity specimens need to be cured simultaneously with the dry density specimens for 28 days. After being taken out, they are placed in a forced-air drying oven and dried at 105℃±5℃ until constant weight (same as the drying standard for dry density specimens). After cooling to room temperature, they are ready for use. ② Use vernier calipers to select 5 evenly spaced measurement points along the thickness direction of the specimen, measure the thickness value, and take the average value as the average thickness d of the specimen (accurate to 0.1 mm). Ensure that the thickness uniformity deviation of the specimen is ≤2%; if the deviation exceeds the standard, the specimen needs to be recut. ③ Place the specimen flat in the center of the hot plate of the protective hot plate thermal conductivity meter, ensuring that the specimen is completely in contact with the hot and cold plates without bubbles or gaps (if necessary, apply thermal conductive paste to the edge of the specimen to assist in the fit, but avoid contaminating the test area with thermal conductive paste). ④ Set the average test temperature to 25℃ (which is in line with the conventional test temperature for building insulation materials), start the instrument, and wait for the test system to reach a steady state: heat flux density fluctuation ≤2% / h, temperature difference fluctuation on both sides of the specimen ≤0.1℃ / h, and continue to be stable for 2 hours. Then record the heat flux density q, temperature difference ΔT on both sides of the specimen, and heating area A. ⑤ Thermal resistance calculation: Calculate the thermal resistance of the specimen using the formula R=qΔT (R is the thermal resistance, unit m). 2 • K / W; ΔT is the temperature difference between the two sides of the specimen, in K; q is the heat flux density, in W / m³ 2 ); ⑥ Thermal conductivity calculation: Calculate the thermal conductivity using the formula λ=Rd (λ is the thermal conductivity, in W / (m·K); d is the average thickness of the specimen, in m). ⑦ Each specimen was tested twice, and the deviation between the two test results was ≤3%. The average value was taken as the thermal conductivity of the specimen. The average value of three parallel specimens was then taken as the final thermal conductivity, accurate to 0.001 W / (m·K). The results are as follows: Table 1

[0098] The data from Experiment 1 show that the foamed concrete in Examples 1-3 all exhibit excellent lightweight thermal insulation performance, with a dry density of 350 kg / m³. 3The thermal conductivity values ​​are all below 0.07 W / (m·K), indicating that the technical solution of the present invention can achieve good lightweight thermal insulation effect within the range of parameter values.

[0099] Comparing Example 3 and Comparative Example 1, it can be seen that Comparative Example 1 did not use modified industrial solid waste admixtures. After replacing them with an equal amount of ordinary Portland cement, the dry density increased from 317.1 kg / m³. 3 Increased to 486.3 kg / m 3 The thermal conductivity increased from 0.056 W / (m·K) to 0.108 W / (m·K), resulting in a significant decrease in performance. This is because the modified industrial solid waste admixture undergoes multiple modifications, including mechanical grinding and low-temperature plasma pretreatment, leading to optimized particle size distribution and a rich internal pore structure. This effectively reduces the overall density of the material, while the pore structure hinders heat transfer, improving insulation performance. In contrast, ordinary silicate cement has a high density and a dense structure, resulting in increased dry density and deteriorated insulation performance.

[0100] Comparing Example 3 and Comparative Example 2, it can be seen that Comparative Example 2, which uses a single foaming agent and does not undergo ultrasonic emulsification pretreatment, has a dry density of 317.1 kg / m³. 3 Increased to 376.8 kg / m 3 The thermal conductivity increased from 0.056 W / (m·K) to 0.083 W / (m·K), indicating a significant decrease in performance. This is because the composite foam system of this invention is composed of a composite foaming agent and a high-efficiency foam stabilizer. After ultrasonic emulsification pretreatment, the foam is uniform, fine, and highly stable, forming uniformly distributed closed pores within the concrete, significantly reducing dry density and improving insulation performance. In contrast, foam produced by a single foaming agent is uneven in size, has poor stability, and is prone to breakage during preparation, resulting in an unreasonable pore structure, increased dry density, and decreased insulation performance.

[0101] Comparing Example 3 and Comparative Example 3, it can be seen that without the addition of the modified encapsulated phase change material, the thermal conductivity of Comparative Example 3 increased from 0.056 W / (m·K) to 0.079 W / (m·K), and the insulation performance decreased significantly. This is because the modified encapsulated phase change material has excellent latent heat of phase change performance, absorbing or releasing heat when the temperature changes, hindering internal temperature conduction and improving the insulation effect; without this component, the material relies solely on its porous structure for insulation, resulting in a significant reduction in insulation capacity.

[0102] Comparing Example 3 and Comparative Example 4, it can be seen that the modified industrial solid waste admixture in Comparative Example 4 only underwent mechanical grinding without subsequent modification processes, and its dry density was 317.1 kg / m³. 3 Increased to 414.2 kg / m 3The thermal conductivity increased from 0.056 W / (m·K) to 0.095 W / (m·K), resulting in a significant decrease in performance. This is because: low-temperature plasma pretreatment improves the surface activity of solid waste particles, chemical activation enhances the hydration activity of solid waste, composite modification optimizes particle dispersibility, and the synergistic effect of multi-step modification allows the modified industrial solid waste admixture to fully realize its lightweight insulation potential; solid waste particles that have only undergone mechanical grinding have low surface activity and insufficient hydration, failing to form a reasonable pore structure, leading to deteriorated material performance.

[0103] Experiment 2: Mechanical Properties and Volume Stability Tests 2.1 Experimental Objective: The compressive strength and volume shrinkage rate of the foamed concrete in Examples 1-3 and Comparative Examples 1-4 were tested to verify the effects of modified industrial solid waste admixtures, composite foam systems, modified encapsulated phase change materials, and modification processes on the mechanical properties and volume stability of foamed concrete. Compressive strength reflects the load-bearing capacity of the material, and volume shrinkage rate reflects the volume stability of the material. Both are key performance indicators in the practical application of foamed concrete.

[0104] 2.2 Experimental Principle: The compressive strength of standard cubic specimens was tested using a pressure testing machine. Axial pressure was applied until the specimen failed, and the maximum pressure at failure was recorded to calculate the compressive strength. A non-contact concrete shrinkage deformation tester was used to measure the length change of the specimens at different ages under standard curing conditions and calculate the linear shrinkage rate (there is no clear standard for testing the volume shrinkage rate of foamed concrete, but the linear shrinkage rate can reflect the volume stability equivalently), which directly reflects the volume deformation characteristics of the material.

[0105] 2.3 Experimental Instruments and Equipment: Test instruments: Compression testing machine (range 0-200kN, force accuracy ±1%, adjustable loading rate 0.1-10MPa / s), non-contact concrete shrinkage deformation tester (measuring range 0-5mm, accuracy 0.001mm), electronic balance (accuracy 0.001g), forced-air drying oven (temperature control accuracy ±2℃), vernier caliper (accuracy 0.01mm), standard curing chamber (temperature 20±2℃, humidity 95%±5%), diamond cutting saw (cutting accuracy ±1mm), specimen grinding machine (surface flatness deviation ≤0.05mm).

[0106] 2.4 Test Methods: Specimen preparation: The foamed concrete products prepared in Examples 1-3 and Comparative Examples 1-4 were cut into standard compressive strength specimens of 100mm×100mm×100mm and standard linear shrinkage specimens of 100mm×100mm×515mm using a diamond saw. Three parallel specimens were prepared for each group. After grinding, the surface flatness deviation of the compressive strength specimens was ≤0.1mm, and the perpendicularity deviation of adjacent surfaces was ≤0.5°. The parallelism deviation of the two end faces of the shrinkage specimens was ≤0.1mm, and the length deviation was ≤±2mm.

[0107] Compressive strength test: ① Place the compressive strength test specimen in a standard curing chamber and cure for 28 days. After curing, take it out and wipe the surface of the specimen clean with a damp cloth to ensure that there are no loose particles, oil stains and moisture residue. ② Place the specimen in the center on the pressure plate of the pressure testing machine, adjust the position of the specimen to ensure that the axis of the specimen coincides with the loading axis of the pressure machine, and avoid eccentric compression (calibration can be assisted by the specimen positioning device). ③ When the compressive strength of foamed concrete is ≤5MPa, the loading rate is set to 0.2-0.5MPa / s. In this test, a uniform loading rate of 0.3MPa / s is used until the specimen fails (obvious cracks, disintegration, or pressure drop of ≥30%), and the maximum failure pressure is recorded. ④ Compressive strength calculation: Compressive strength f = maximum failure pressure F / specimen compression area A (compression area A = 0.1m × 0.1m = 0.01m) 2 Calculate the compressive strength of each specimen, and take the average value of 3 parallel specimens as the final compressive strength, accurate to 0.01 MPa; if the value of a single specimen deviates from the average value by more than 15%, discard the data and take the average value of the remaining specimens; if there are less than 2 valid specimens remaining, specimens need to be prepared and tested again.

[0108] Linear shrinkage rate test: ① After the shrinkage specimen is formed, it should be demolded within 24 hours under standard curing conditions (to avoid the curing time being too long and affecting the initial length measurement). Immediately after demolding, the initial length L0 of the specimen should be measured with a non-contact concrete shrinkage deformation tester (accurate to 0.001 mm). Permanent measurement points should be marked on both ends of the specimen (using a marking pen that does not affect the performance of the specimen). ② Place the specimen in the standard curing chamber for continued curing. At 7d, 14d, and 28d, remove the specimen and measure the lengths L1 (7d), L1 (14d), and L3 (28d) at the original measurement points. Keep the ambient temperature at 20±2℃ during measurement to avoid temperature fluctuations affecting the measurement accuracy. ③ Calculation of linear shrinkage rate at each age: 7-day linear shrinkage rate ε1 = (L0 - L1) / L0 × 100%; 14-day linear shrinkage rate ε1 = (L0 - L1) / L0 × 100%; 28-day linear shrinkage rate ε3 = (L0 - L3) / L0 × 100%; ④ The average shrinkage rate of three parallel specimens at each age was taken as the final shrinkage rate for that age, accurate to 0.01%. If the shrinkage rate of a single specimen deviates from the average by more than 20%, the specimen should be checked for cracks or deformation. Abnormal specimens should be removed, and the remaining values ​​should be averaged. The 28-day linear shrinkage rate was used as the core evaluation index, and the shrinkage development trend was reflected by the 7-day and 14-day data. The results are as follows: Table 2

[0109] The data from Experiment 2 show that the foamed concrete in Examples 1-3 all exhibited good mechanical properties and volume stability, with 28-day compressive strength all above 3.0 MPa and 28-day linear shrinkage rate all below 0.20%.

[0110] Comparing Example 3 and Comparative Example 1, it can be seen that in Comparative Example 1, without the modified industrial solid waste admixture, after replacing it with an equal amount of ordinary Portland cement, the 28-day compressive strength increased from 3.70 MPa to 4.50 MPa, but the 28-day linear shrinkage rate increased from 0.16% to 0.30%, resulting in a significant decrease in volume stability. This is because ordinary Portland cement undergoes significant shrinkage deformation during hydration, leading to an increase in the overall linear shrinkage rate of the material. In contrast, the modified industrial solid waste admixture has mild hydration activity, and its internal pore structure can alleviate hydration shrinkage stress, effectively reducing the linear shrinkage rate. Although its compressive strength is slightly lower than that of the pure cement system, it can still meet the load-bearing requirements of lightweight insulation applications, and its volume stability is superior.

[0111] Comparing Example 3 and Comparative Example 2, it can be seen that Comparative Example 2, which used a single foaming agent and did not undergo ultrasonic emulsification pretreatment, showed a significant decrease in performance: the 28-day compressive strength dropped from 3.70 MPa to 2.80 MPa, and the 28-day linear shrinkage rate increased from 0.16% to 0.26%. This is because the foam produced by the single foaming agent is uneven and has poor stability, resulting in an unreasonable distribution of pores within the concrete, with numerous interconnected and large pores, reducing the material's structural density and mechanical properties. Simultaneously, the unstable foam is prone to rupture during hardening, causing internal stress concentration, exacerbating linear shrinkage, and leading to poor volume stability.

[0112] Comparing Example 3 and Comparative Example 3, it can be seen that without the addition of the modified encapsulated phase change material, the 28-day compressive strength of Comparative Example 3 decreased from 3.70 MPa to 3.00 MPa, while the 28-day linear shrinkage rate increased from 0.16% to 0.24%, indicating a decline in performance. This is because the microcapsule particles of the modified encapsulated phase change material can fill the tiny pores inside the concrete, optimizing the internal structure and improving structural density, thereby increasing compressive strength. Simultaneously, the phase change expansion effect of the microcapsules during temperature changes can offset some of the hydration shrinkage, reducing the linear shrinkage rate. Without this component, the internal structural density of the material is insufficient, and shrinkage stress cannot be effectively offset, leading to a decrease in mechanical properties and volume stability.

[0113] Comparing Example 3 and Comparative Example 4, it can be seen that the modified industrial solid waste admixture in Comparative Example 4, which only underwent mechanical grinding without subsequent modification, showed a significant deterioration in performance, with its 28-day compressive strength decreasing from 3.70 MPa to 2.50 MPa and its 28-day linear shrinkage rate increasing from 0.16% to 0.34%. This is because the industrial solid waste particles subjected only to mechanical grinding have low surface activity and weak interfacial bonding with cementitious materials, making them unable to effectively participate in the hydration reaction to form stable hydration products. This results in a loose internal structure and insufficient mechanical properties. Simultaneously, the unmodified solid waste particles exhibit poor dispersibility and are prone to agglomeration, leading to uneven internal stress, exacerbating linear shrinkage, and significantly reducing volumetric stability.

[0114] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0115] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. Lightweight thermal insulation foam concrete based on industrial solid waste, characterized in that, It is prepared from the following raw materials in parts by weight: 55-65 parts modified industrial solid waste admixture, 25-30 parts cementitious material, 4-6 parts composite foam system, 3-5 parts modified encapsulated phase change material, 1.0-2.0 parts additive, and 28-35 parts water; The modified industrial solid waste admixture is made by mixing steel slag, ore slag and red mud in a mass ratio of 4:3:1, followed by mechanical grinding, low-temperature plasma pretreatment, chemical activation and composite modification. The composite foam system is made by mixing composite foaming agent and high-efficiency foam stabilizer in a mass ratio of 9:1, followed by ultrasonic emulsification pretreatment.

2. The lightweight thermal insulation foamed concrete according to claim 1, characterized in that, The preparation steps of the modified encapsulated phase change material are as follows: Preparation of S1 paraffin-graphite composite phase change material: Paraffin and modified graphite are mixed at a mass ratio of 9:1, heated to 62-68℃, and stirred at 200-250r / min for 20-30min until the paraffin is completely melted and mixed evenly. After cooling to room temperature, the mixture is pulverized to obtain a paraffin-graphite composite phase change material with a particle size of 55-95μm. S2 Microcapsule Encapsulation: Using the paraffin-graphite composite phase change material prepared in step S1 as the core material and melamine resin as the wall material, the microcapsules are encapsulated using interfacial polymerization at a core-to-wall ratio of 3:

1. The core material is dispersed in deionized water, and 0.8%-1.2% of Tween-80 by weight of the core material is added as an emulsifier. The emulsification is carried out for 30 minutes. Melamine resin prepolymer is added as a wall material precursor. The pH of the system is adjusted to 8.2-8.8, the temperature is controlled at 62-68℃, and the reaction is carried out for 2.2-2.8 hours. After cooling, filtration, and drying, phase change microcapsules are obtained with a particle size of 1.5-4.5 μm. S3 Surface Modification: The phase change microcapsules prepared in step S2 are added to a 1.2%-1.4% (by mass) solution of silane coupling agent KH-560, ultrasonically dispersed for 22-28 min at an ultrasonic power of 280-320 W, and then dried at 80 °C for 1.2-1.8 h to obtain the modified encapsulated phase change material.

3. The lightweight thermal insulation foamed concrete according to claim 2, characterized in that, The modified graphite is prepared by placing graphite in a 1.5%-2.5% ethanol solution of silane coupling agent KH-570, ultrasonically dispersing it for 25-35 minutes at an ultrasonic power of 300-350W and a dispersion temperature of 28-32℃, and then drying it at 90-100℃ for 2-3 hours to obtain modified graphite. The volume ratio of ethanol to water in the ethanol solution of silane coupling agent KH-570 is 9:

1.

4. The lightweight thermal insulation foamed concrete according to claim 1, characterized in that, The parameters for the mechanical grinding are as follows: steel balls are used as the grinding medium, the mass ratio of steel balls to mixed solid waste is 5:1, the grinding speed is 320-380 r / min, the grinding time is 2.0-2.8 h, and impurities are removed by passing the material through a 200-mesh sieve after grinding.

5. The lightweight thermal insulation foamed concrete according to claim 1, characterized in that, The parameters for the low-temperature plasma pretreatment are: plasma power 160-200W, treatment time 15-18min, and treatment atmosphere is argon.

6. The lightweight thermal insulation foamed concrete according to claim 1, characterized in that, The chemical activation uses a composite activator made by mixing water glass with a modulus of 1.65-1.75 and a solid content of 28.5%-29.5% with desulfurized gypsum at a mass ratio of 2:

1. The amount of composite activator added is 3.5%-4.5% of the mass of the mixed solid waste powder after mechanical grinding. The curing conditions for chemical activation are constant temperature curing at 85-95℃ for 12-15 hours.

7. The lightweight thermal insulation foamed concrete according to claim 1, characterized in that, The composite modifier used in the composite modification is prepared by mixing silane coupling agent KH-550 and polycarboxylic acid dispersant at a mass ratio of 3:

2. The amount of composite modifier added is 1.2%-1.8% of the mass of the chemically activated solid waste powder. The parameters for composite modification are stirring at a speed of 520-580 r / min for 32-38 min, and then cooling to room temperature after stirring.

8. The lightweight thermal insulation foamed concrete according to claim 1, characterized in that, The composite foaming agent is prepared by mixing sodium dodecyl sulfate and plant protein foaming agent at a mass ratio of 3:2, and the high-efficiency foam stabilizer is prepared by mixing modified silicone resin polyether microemulsion and hydroxypropyl methylcellulose ether at a mass ratio of 2:

1. The parameters of the ultrasonic emulsification pretreatment are: ultrasonic power 280-320W, ultrasonic time 16-20min, and emulsification temperature 32-38℃.

9. The lightweight thermal insulation foamed concrete according to claim 1, characterized in that, The cementitious material is made by mixing P·O42.5 grade ordinary Portland cement and slag Portland cement in a mass ratio of 1:1; the admixture is made by mixing liquid polyester-type polycarboxylate high-efficiency water-reducing agent, citric acid, and organosilicon waterproofing agent in a mass ratio of 3:2:1, wherein the solid content of the liquid polyester-type polycarboxylate high-efficiency water-reducing agent is 30%.

10. A molding process for lightweight thermal insulation foamed concrete from industrial solid waste according to any one of claims 1-9, characterized in that, Includes the following steps: S1: Raw material pretreatment, drying the modified industrial solid waste admixture, cementitious materials, and additives to a moisture content of ≤0.3%; S2: Segmented mixing. First, the modified industrial solid waste admixture, cementitious materials, and additives are mixed at 200-280 r / min for 6-10 min to form a dry mixture. Then, a preset amount of water is added to the dry mixture, and it is mixed at 450-480 r / min for 12-14 min to form a cement slurry. Finally, nano-silica dispersion is added to the cement slurry and mixed evenly. Then, the composite foam system is slowly added at 150-250 r / min and mixed for 4-5 min to form a foamed concrete slurry. The amount of the nano-silica aqueous dispersion added is 0.06-0.09 parts, and the concentration is 1.2%-1.8%. S3: Layered pouring. The foamed concrete slurry is poured into the pre-set mold in two layers. Each layer is 120-140mm thick. After each layer is poured, it is slightly vibrated at a frequency of 50Hz for 12-14s. After standing for 25-30 minutes, the next layer is poured. S4: Gradient curing. First, place the poured slurry in an environment of 22-24℃ and 88%-95% humidity for 7-10 hours until initial setting. Then, raise the temperature to 52-58℃ at a rate of 6-7℃ / h and maintain the temperature for 12-15 hours. Afterward, lower the temperature to room temperature at a rate of 4-5℃ / h and continue curing in an environment of 20-24℃ and 88%-95% humidity for 2-34 days. S5: Demolding and post-processing: Remove the mold and repair surface defects of the foamed concrete. Let it stand at room temperature for 4-5 days to obtain the finished product.

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