Solid waste ultra-light conductive heating foam concrete and preparation method thereof

Abstract

The application relates to the technical field of building materials, and particularly discloses a solid waste super-light conductive heating foam concrete and a preparation method thereof. Fly ash, desulfurization gypsum and sulphoaluminate cement are stirred and mixed to form a mixed material A; 30-degree warm water, a dispersing agent and short-cut carbon fibers are sequentially put into a container, and are uniformly dispersed through ultrasonic dispersion to obtain a mixed material B; the mixed material B is slowly added into the dry mixed material A, and continues to be stirred until the fibers are uniformly dispersed to obtain a conductive slurry C; finally, manganese dioxide and hydrogen peroxide are added, and continuous stirring is carried out until the slurry is fully foamed, so that the super-light conductive heating foam concrete is obtained. The foam concrete not only realizes the reduction, resource utilization and harmless treatment of solid waste, but also endows the material with unique conductive heating performance, so that the foam concrete has a wide application prospect in the fields of building thermal insulation, ground snow melting, road maintenance and the like.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, specifically to a solid waste ultralight conductive heating foam concrete and its preparation method. Background Technology

[0002] In the construction industry, traditional building material production is energy-intensive and generates significant carbon emissions, contradicting the "dual carbon" goals. Developing green and low-carbon building materials is not only an inevitable trend for industry transformation but also a key path to improving building energy efficiency and reducing environmental impact. Foamed concrete, as a lightweight insulation material, is widely used in building insulation layers and infill structures due to its advantages such as low thermal conductivity, good sound insulation, and convenient construction. Currently, foamed concrete primarily consists of inorganic non-metallic materials such as cement, desulfurized gypsum, and slag powder. These materials are inherently poor conductors of electricity, and their porous internal structure further blocks electron migration paths, resulting in overall insulating properties. With the rapid development of new building engineering fields such as intelligent buildings, road snow and ice melting, and structural health monitoring, higher demands are placed on the functionality of building materials. There is an urgent need for integrated foamed concrete materials that combine thermal insulation, lightweight high strength, and electrical conductivity to meet the needs of specific application scenarios.

[0003] Patent application CN105859233A discloses a method for preparing lightweight insulating foamed concrete using wet-process and dry-process undisturbed desulfurized gypsum as the main cementing material, combined with slag powder, a small amount of cement, and lime powder, under alkaline activation. This technology, using undisturbed desulfurized gypsum as the main cementing material, eliminates the need for calcination. Through scientific proportioning and chemical foaming processes, the material possesses advantages such as high strength, low thermal conductivity, and low shrinkage, making it suitable for building insulation structures. However, its raw materials are inherently poor conductors of electricity. Although the system contains small amounts of slag and steel slag-like components, under alkaline activation, the metal ions are highly dispersed, failing to form a continuous conductive path, and the porous structure within the material further blocks electron migration pathways. Patent application CN120328955A discloses an ultra-low density foamed concrete and its preparation method. The main components of this process are cement, steel slag, lightweight aggregates, and foaming agents, all of which are inherently poor conductors of electricity. Although steel slag was added to the formula, its metallic activity was passivated by the alkaline environment and no continuous conductive path was formed, so it still exhibited insulating properties overall.

[0004] To address the aforementioned issues, this invention, based on a high solid waste content, utilizes a fly ash-desulfurized gypsum-sulfoaluminate cement composite cementitious system design, combined with a foaming process involving the construction and optimization of short-cut carbon fiber conductive networks. The aim is to develop a foamed concrete that combines ultra-lightweight properties, high solid waste utilization, and stable electrical conductivity and heating capabilities, providing a new path for the resource utilization of industrial solid waste and the development of intelligent building materials. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the purpose of this invention is to provide a solid waste ultralight conductive heating foam concrete and its preparation method, so as to solve the problems mentioned in the background art.

[0006] The present invention solves the technical problem by adopting the following technical solution: This invention provides a solid waste ultralight conductive and heating foam concrete and its preparation method, comprising the following raw materials in parts by weight: The content of fly ash is 650-750 parts by weight, the content of desulfurized gypsum is 450-550 parts by weight, the content of sulfoaluminate cement is 350-500 parts by weight, the content of water is 450-550 parts by weight, the content of foam stabilizer is 3-5 parts by weight, the content of water reducer is 3-6 parts by weight, the content of dispersant is 3-6 parts by weight, the content of hydrogen peroxide is 50-70 parts by weight, the content of manganese dioxide is 0.6-1.0 parts by weight, and the content of chopped carbon fiber is 4-12 parts by weight.

[0007] Preferably, the fly ash is Grade I fly ash; the water requirement ratio is 95%-97%, the loss on ignition is 1.5%-2%; the fineness is 10%-12% residue on a 45 μm square hole sieve, and the strength activity index is 75%-80%.

[0008] Preferably, the cement is PO52.5 sulfoaluminate cement; the water-reducing agent is polycarboxylate superplasticizer; and the water is 30-degree warm water.

[0009] Preferably, the foam stabilizer is calcium stearate, which is an industrial grade 1 product and has a fineness that passes through a 200-mesh sieve.

[0010] Preferably, the dispersant is hydroxyethyl cellulose with a viscosity of 3400-5000 mPa·s and a pH of 5.5-8.5 for a 1% aqueous solution.

[0011] Preferably, the hydrogen peroxide is industrial-grade hydrogen peroxide with a mass concentration of 30%.

[0012] Preferably, the foaming catalyst is manganese dioxide with a purity of not less than 99% and a fineness that passes through a 100-mesh sieve.

[0013] Furthermore, the chopped carbon fibers are polyacrylonitrile-based carbon fibers with a length of 6 mm and a resistivity of no more than 1.5 × 10⁻⁶. -3 Ω·cm.

[0014] The polyacrylonitrile-based carbon fiber has also undergone optimization and improvement treatment. The specific improvement method is as follows: S1: Add 2-3 parts of β-cyclodextrin, 1-2 parts of silane coupling agent KH550, and 3-5 parts of modified nano-attapulgite clay agent to 4-7 parts of chitosan solution with a mass fraction of 2-4%, stir thoroughly to obtain the improved solution; S2: Polyacrylonitrile-based carbon fiber and modified liquid are ultrasonically modified at a weight ratio of 3:(5-7), ultrasonic power 350-400W, ultrasonic for 2 hours. After ultrasonication, filter and dry.

[0015] The preparation method of the modified nano-attapulgite clay agent is as follows: S1a: Place nano-attapulgite in a muffle furnace and calcine at 300-400℃ for 2-3 hours. After cooling, grind through a 200-mesh sieve. Add the sieved nano-attapulgite to a lanthanum-based liquid at a mass ratio of 1:(8-10), and ultrasonically disperse for 30 minutes at an ultrasonic power of 200-300W to obtain an attapulgite dispersion. S1b: Ball mill the attapulgite dispersion and ball milling agent at a weight ratio of (8-11):5 until fully milled at a speed of 1000-1500 r / min for 2 hours. After milling, filter and dry to obtain a modified nano-attapulgite agent. The lanthanum-based liquid is prepared by mixing lanthanum oxide, a sodium dodecylbenzenesulfonate solution with a mass fraction of 8-12%, and citric acid at a weight ratio of (2-3):5:(1-2). The ball milling agent is a mixture of silicon carbide whiskers, carbon nanotubes and boron nitride in a weight ratio of (3-5):2:(1-3) and sintered for 1 hour at a sintering temperature of 350-400℃. After sintering, the ball milling agent is obtained.

[0016] This invention provides a solid waste ultralight conductive and heating foam concrete and its preparation method, comprising the following steps: Step (1) Put fly ash, desulfurized gypsum and cement into a mixer in sequence and mix until uniform to obtain mixed dry material A; Step (2) Place 30-degree warm water, dispersant and short-cut carbon fibers into a container in sequence, and disperse them by ultrasonication until uniform to obtain mixture B; Step (3) Slowly add mixture B to the dry mixture A and continue stirring to ensure uniform fiber dispersion to obtain conductive paste C; Step (4) Add manganese dioxide to conductive slurry C, stir briefly, then slowly add hydrogen peroxide and continue stirring until the slurry is fully foamed to obtain conductive foam slurry D; Step (5) Apply release agent evenly to the inner surface of the steel mold, then pour foam slurry D evenly into the steel mold, let it stand, demold, and place it in a standard curing room for curing. After curing, the solid waste ultra-lightweight conductive heating foam concrete as described in claims 1-8 can be obtained.

[0017] Preferably, the stirring rate in step (1) is 60-65 r / min and the stirring time is 2-3 min; the ultrasonic dispersion frequency in step (2) is 20-40 kHz and the dispersion time is 2-3 min; the stirring rate in step (3) is 80-100 r / min and the stirring time is 3-4 min; and the stirring rate after adding hydrogen peroxide in step (4) is 60-65 r / min and the stirring time is 1-2 min.

[0018] Preferably, the static curing time in step (5) is 24-36 hours; the curing conditions of the standard curing room are: temperature controlled at 20±2℃, humidity greater than or equal to 95%.

[0019] Compared with the prior art, the present invention has the following beneficial effects: This invention represents an innovation in the high-value and functionalization of solid waste: while maintaining the total proportion of fly ash and desulfurized gypsum in the cementitious materials at over 70%, short-cut carbon fibers are introduced to successfully prepare a novel type of foamed concrete with conductive and heating functions. This expands its application range in building heating, road snow melting, and other fields, realizing a transformation from a single insulation material to a multifunctional intelligent material. The incorporated short-cut carbon fibers are uniformly distributed in the foamed concrete matrix, forming an effective spatial conductive network, endowing the material with significant conductivity and electrothermal conversion capabilities. When electricity is applied, the material can generate heat rapidly and uniformly.

[0020] This invention, while providing new functions, still retains a dry density of 400-500 kg / m³. 3 Its ultra-lightweight properties and mechanical properties with a 28-day compressive strength ≥1.0 MPa achieve a balance between functionalization and lightweight high strength.

[0021] This invention improves the treatment of polyacrylonitrile-based short-cut carbon fibers. An improved solution is prepared using chitosan solution, β-cyclodextrin, silane coupling agent KH550, and modified nano-attapulgite clay agent. The carbon fibers are then modified by ultrasonic treatment, effectively reducing the surface energy of the carbon fibers and minimizing electrostatic adsorption and entanglement between fibers. Simultaneously, amino active sites are introduced onto the carbon fiber surface, significantly improving the interfacial compatibility between the carbon fibers and the fly ash-desulfurized gypsum-sulfoaluminate cement composite cementitious system. Combined with the physical barrier effect of the modified nano-attapulgite clay agent, carbon fiber agglomeration in the slurry is effectively prevented, ensuring uniform dispersion of the carbon fibers in the foamed concrete matrix. This lays a solid foundation for the formation of a continuous and stable three-dimensional conductive network, thereby significantly improving the conductivity and electrothermal conversion efficiency of the foamed concrete. The resulting material possesses uniform and stable heating performance, meeting the needs of special applications such as building heating and road snow melting.

[0022] Among them, the modified nano-attapulgite agent, after modification with lanthanum-based liquid and ball milling, has optimized surface charge and adsorption properties. This not only further assists in the dispersion of carbon fibers but also forms a transitional interface layer between the carbon fibers and the cementitious matrix, reducing interface defects and enhancing the interfacial bonding force between the carbon fibers and the matrix. Simultaneously, its rod-shaped high specific surface area structure synergistically reinforces the carbon fibers, effectively constraining the early and late shrinkage of the foamed concrete, improving the dimensional stability of the material, and reducing shrinkage cracking, while ensuring the dry density of the foamed concrete remains at 400-500 kg / m³. 3 While maintaining its ultra-lightweight properties, it also ensures a 28-day compressive strength of ≥1.0 MPa, achieving a balance between ultra-lightweight, high-strength, and conductive heating functions.

[0023] Furthermore, the modified nano-attapulgite agent also possesses certain thixotropic and thickening properties, which can synergistically stabilize the pores generated by hydrogen peroxide foaming with hydroxyethyl cellulose dispersant, preventing pore coalescence and collapse, ensuring a uniform pore structure in the foamed concrete, and balancing ultra-lightweight properties with good thermal insulation performance. Simultaneously, the doping modification of lanthanum oxide in the lanthanum-based liquid can inhibit the migration of harmful ions within the cementing system, reducing the risk of hydration product degradation. Combined with the synergistic effect of silicon carbide whiskers, carbon nanotubes, and boron nitride in the ball milling agent, the continuity of the conductive network is further optimized, improving the material's durability and extending its service life in long-term service scenarios such as structural health monitoring and road snow melting. Based on achieving a total proportion of fly ash and desulfurized gypsum exceeding 70% and promoting the high-value utilization of industrial solid waste, this invention, through the synergistic effect of the above-mentioned modified system, successfully upgrades foamed concrete from a single thermal insulation material into a multifunctional intelligent material with ultra-lightweight, high strength, stable electrical conductivity and thermal conductivity, and good durability. This expands the application scope of foamed concrete and provides a new path for the resource utilization of industrial solid waste and the development of intelligent building materials. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to specific examples. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] This embodiment of a solid waste ultralight conductive and heating foam concrete and its preparation method includes the following raw materials in parts by weight: The composition of the cementitious material is as follows: fly ash content is 650-750 parts by weight; desulfurized gypsum content is 450-550 parts by weight; sulfoaluminate cement content is 350-500 parts by weight; water content is 450-550 parts by weight; foam stabilizer content is 3-5 parts by weight; water-reducing agent content is 3-6 parts by weight; dispersant content is 3-6 parts by weight; hydrogen peroxide content is 50-70 parts by weight; manganese dioxide content is 0.6-1.0 parts by weight; and chopped carbon fiber content is 4-12 parts by weight. The sum of the mass of fly ash and desulfurized gypsum accounts for 70%-80% of the total mass of the cementitious material.

[0026] The fly ash in this embodiment is Grade I fly ash; the water requirement ratio is 95%-97%, the loss on ignition is 1.5%-2%; the fineness is 10%-12% residue on a 45μm square hole sieve, and the strength activity index is 75%-80%.

[0027] The cement used in this example is PO52.5 sulfoaluminate cement; the water-reducing agent is polycarboxylate superplasticizer; and the water is 30-degree warm water.

[0028] The foam stabilizer in this embodiment is calcium stearate, which is an industrial grade 1 product and its fineness passes through a 200-mesh sieve.

[0029] The dispersant in this embodiment is hydroxyethyl cellulose with a viscosity of 3400-5000 mPa·s and a pH of 5.5-8.5 for a 1% aqueous solution.

[0030] The hydrogen peroxide in this embodiment is an industrial-grade hydrogen peroxide with a mass concentration of 30%.

[0031] The foaming catalyst in this embodiment is manganese dioxide with a purity of not less than 99% and a fineness that passes through a 100-mesh sieve.

[0032] In this embodiment, the chopped carbon fiber is polyacrylonitrile-based carbon fiber with a length of 6 mm and a resistivity of no more than 1.5 × 10⁻⁶ mm. -3 Ω·cm.

[0033] The method for preparing fly ash-desulfurized gypsum ultralightweight foamed concrete in this embodiment includes the following steps: Step (1) Put fly ash, desulfurized gypsum and cement into a mixer in sequence and mix until uniform to obtain mixed dry material A; Step (2) Place 30-degree warm water, dispersant and short-cut carbon fibers into a container in sequence, and disperse them by ultrasonication until uniform to obtain mixture B; Step (3) Slowly add mixture B to the dry mixture A and continue stirring to ensure uniform fiber dispersion to obtain conductive paste C; Step (4) Add manganese dioxide to conductive slurry C, stir briefly, then slowly add hydrogen peroxide and continue stirring until the slurry is fully foamed to obtain conductive foam slurry D; Step (5) Apply release agent evenly to the inner surface of the steel mold, then pour foam slurry D evenly into the steel mold, let it stand, demold, and place it in a standard curing room for curing. After curing, the solid waste ultra-lightweight conductive heating foam concrete as described in claims 1-8 can be obtained.

[0034] In this embodiment, the stirring rate in step (1) is 60-65 r / min and the stirring time is 2-3 min; the ultrasonic dispersion frequency in step (2) is 20-40 kHz and the dispersion time is 2-3 min; the stirring rate in step (3) is 80-100 r / min and the stirring time is 3-4 min; and the stirring rate after adding hydrogen peroxide in step (4) is 60-65 r / min and the stirring time is 1-2 min.

[0035] In step (5) of this embodiment, the static curing time is 24-36 hours; the curing conditions of the standard curing room are: temperature controlled at 20±2℃, humidity greater than or equal to 95%.

[0036] Example 1: This example of solid waste ultralight conductive heating foam concrete consists of the following components by weight: 700 parts fly ash, 500 parts desulfurized gypsum, 400 parts cement, 500 parts mixing water, 3.2 parts foam stabilizer, 3.2 parts water-reducing agent, 48 parts hydrogen peroxide, 0.8 parts manganese dioxide, 3.2 parts dispersant, and 6.5 parts chopped carbon fiber. The fly ash is Grade I fly ash; the water requirement ratio is 95%-97%, the loss on ignition is 1.5%-2%; the fineness is 10%-12% residue on a 45 μm square-hole sieve, and the strength activity index is 75%-80%. The cement type is PO52.5 sulfoaluminate cement; the water-reducing agent is polycarboxylate high-efficiency water-reducing agent; the water is 30°C warm water. The foam stabilizer is calcium stearate, an industrial Grade I product, with a fineness passing through a 200-mesh sieve. The dispersant is hydroxyethyl cellulose with a viscosity of 3400-5000 mPa·s and a pH of 5.5-8.5 for a 1% aqueous solution. The hydrogen peroxide is 30% industrial-grade hydrogen peroxide. The foaming catalyst is manganese dioxide with a purity of not less than 99% and a fineness passing through a 100-mesh sieve. The chopped carbon fibers are polyacrylonitrile-based carbon fibers with a length of 6 mm and a resistivity not exceeding 1.5 × 10⁻⁶. -3 Ω·cm.

[0037] The method for preparing ultralightweight conductive and heating foamed concrete from solid waste in this embodiment includes the following steps: Step (1): Put 700 parts fly ash, 500 parts desulfurized gypsum and 400 parts cement into a mixer in sequence, and mix at a speed of 60-65 r / min for 2 minutes until uniform to obtain mixed dry material A; Step (2): Place 500 parts of 30-degree warm water, 3.2 parts of dispersant and 6.5 parts of short-cut carbon fiber into a container and ultrasonically disperse them at a frequency of 20-40kHz for 2 minutes until they are uniform, to obtain mixture B; Step (3): Slowly add mixture B to the dry mixture A, and continue stirring at a rate of 80-100 r / min for 3 minutes until a uniform viscous slurry is formed, thus obtaining conductive slurry C; Step (4): Add 0.8 parts of manganese dioxide to conductive slurry C, stir briefly, then slowly add 48 parts of hydrogen peroxide, and stir at a rate of 62 r / min for 2 min until the slurry is fully foamed to obtain conductive foam slurry D. Step (5): Apply release agent evenly to the inner surface of the steel mold, then pour foam slurry D evenly into the steel mold, let it stand for 24 hours to cure, then demold and place it in a standard curing room for curing. The curing conditions are: temperature controlled at 20±2℃ and humidity greater than or equal to 95%.

[0038] To conduct basic performance tests on the solid waste ultralight conductive and heating foam concrete prepared in the example, the casting mold used in this example is 100 mm × 100 mm × 100 mm for compressive strength and dry density testing, and 40 mm × 40 mm × 160 mm for conductivity and heating testing. The steel mold has the characteristics of high rigidity, not easy to deform, precise size and uniform heat conduction, which can effectively ensure the dimensional stability of the specimen and avoid damage to the foam structure during demolding.

[0039] The dry density of the specimens was tested according to GB / T 5486-2008 Test Method for Performance of Inorganic Rigid Thermal Insulation Products, the compressive strength was tested according to GB / T 50081-2019 Standard Test Method for Physical and Mechanical Properties of Concrete, and the heat generation and resistivity were tested according to ASTM C1876 Standard Test Method for Volume Resistivity or Volume Conductivity of Concrete. The performance indicators were determined after 28 days of curing.

[0040] Example 2: The solid waste ultralight conductive heating foam concrete of this example is composed of the following components in parts by weight: 700 parts fly ash, 500 parts desulfurized gypsum, 400 parts cement, 500 parts mixing water, 3.3 parts foam stabilizer, 3.2 parts water-reducing agent, 48 parts hydrogen peroxide, 0.8 parts manganese dioxide, 3.2 parts dispersant, and 10.8 parts short-cut carbon fiber.

[0041] The preparation method of solid waste ultralight conductive heating foam concrete in this embodiment is the same as that in Example 1.

[0042] The mold dimensions, dry density performance test, compressive strength test, resistivity and heating temperature test methods for the solid waste ultralight conductive heating foam concrete in this embodiment are the same as those in Embodiment 1.

[0043] Example 3: The solid waste ultralight conductive heating foam concrete of this example is composed of the following components in parts by weight: 652 parts fly ash, 500 parts desulfurized gypsum, 448 parts cement, 500 parts mixing water, 3.2 parts foam stabilizer, 3.2 parts water-reducing agent, 48 parts hydrogen peroxide, 0.8 parts manganese dioxide, 3.2 parts dispersant, and 4.3 parts short-cut carbon fiber.

[0044] The preparation method of solid waste ultralight conductive heating foam concrete in this embodiment is the same as that in Example 1.

[0045] The mold dimensions, dry density performance test, compressive strength test, resistivity and heating temperature test methods for the solid waste ultralight conductive heating foam concrete in this embodiment are the same as those in Embodiment 1.

[0046] Comparative Example 4: The solid waste ultralight conductive heating foam concrete of this embodiment is composed of the following components in parts by weight: 700 parts fly ash, 500 parts desulfurized gypsum, 646 parts cement, 530 parts mixing water, 3.2 parts foam stabilizer, 3.2 parts water-reducing agent, 48 parts hydrogen peroxide, 0.8 parts manganese dioxide, 3.2 parts dispersant, and 6.5 parts chopped carbon fiber.

[0047] The preparation method of solid waste ultralight conductive heating foam concrete in this embodiment is the same as that in Example 1.

[0048] The mold dimensions, dry density performance test, compressive strength test, resistivity and heating temperature test methods for the solid waste ultralight conductive heating foam concrete in this embodiment are the same as those in Embodiment 1.

[0049] The compressive strength of the solid waste ultralight conductive heating foam concrete of Examples 1 to 3 was tested and is shown in Table 1.

[0050] Table 1 Compressive strength of ultralightweight conductive and heating foam concrete made from solid waste The dry densities of the solid waste ultralight conductive heating foam concrete of Examples 1 to 3 are shown in Table 2 after testing.

[0051] Table 2 Dry density of solid waste ultralight conductive heating foam concrete The resistivity of the solid waste ultralight conductive heating foam concrete of Examples 1 to 3 was tested and is shown in Table 3.

[0052] Table 3 Resistivity of Ultralight Conductive and Heating Foamed Concrete from Solid Waste The temperature rise values ​​of the solid waste ultralight conductive heating foam concrete of Examples 1 to 3 after being energized for 1 hour at voltages of 20V, 30V and 40V are shown in Table 4.

[0053] Table 4. Temperature rise performance of solid waste ultralight conductive heating foam concrete (°C / h) Therefore, analysis of the performance data from the embodiments and comparative examples shows that this invention, using fly ash and desulfurized gypsum as core raw materials, has a solid waste content exceeding 70% of the total cementitious material, far higher than the industry average. This effectively solves the environmental problem of industrial solid waste accumulation and conforms to the circular economy principles of "reduction, reuse, and resource recovery." The dry density is as low as 400-500 kg / m³. 3 It has a strength approximately 30% that of ordinary concrete, a 28-day compressive strength > 1 MPa, and meets the structural requirements for building components such as roof insulation and non-load-bearing partitions, significantly reducing the building's self-weight and minimizing foundation reinforcement and construction costs. By introducing short-cut carbon fibers to construct a conductive network, its 28-day resistivity is as low as 200 Ω•m, and the material temperature can rise by 2-15℃ after 1 hour of energization. It possesses both active heating and passive insulation properties and can replace traditional underfloor heating backfill materials.

[0054] Optimization example; Based on Example 2, the polyacrylonitrile-based carbon fiber of the present invention has been further optimized and improved. The specific improvement method is as follows: S1: Add 2.5 parts of β-cyclodextrin, 1.5 parts of silane coupling agent KH550, and 4 parts of modified nano-attapulgite clay agent to 5.5 parts of chitosan solution with a mass fraction of 3%, stir thoroughly, and obtain the improved solution; S2: Ultrasonic treatment is carried out with polyacrylonitrile-based carbon fiber and modified liquid at a weight ratio of 3:6. Ultrasonic power is 375W, and ultrasonic treatment is carried out for 2 hours. After ultrasonic treatment, the mixture is filtered and dried.

[0055] The preparation method of the modified nano-attapulgite clay agent is as follows: S1a: Nano-attapulgite clay was placed in a muffle furnace and calcined at 350℃ for 2.5h. After cooling, it was ground through a 200-mesh sieve. The sieved nano-attapulgite clay was added to a lanthanum-based liquid at a mass ratio of 1:9 and ultrasonically dispersed for 30min at an ultrasonic power of 250W to obtain an attapulgite clay dispersion. S1b: The attapulgite clay dispersion and ball milling agent were ball milled thoroughly at a weight ratio of 9:5 at a ball milling speed of 1250r / min for 2h. After ball milling, the mixture was filtered and dried to obtain a modified nano-attapulgite clay agent. The lanthanum-based liquid was prepared by mixing lanthanum oxide, 10% sodium dodecylbenzenesulfonate solution, and citric acid at a weight ratio of 2.5:5:1.5. The ball milling agent was prepared by blending silicon carbide whiskers, carbon nanotubes, and boron nitride at a weight ratio of 4:2:2 and sintering for 1h at a sintering temperature of 375℃ to obtain the ball milling agent.

[0056] As can be seen from the above performance tests, the performance of the polyacrylonitrile-based carbon fiber of the present invention has been comprehensively and synergistically improved after optimization and improvement treatment.

[0057] The foregoing provides a detailed description of a solid waste-based ultralightweight conductive and heating foam concrete and its preparation method, using specific embodiments to illustrate the relationship between the material composition, preparation process, and performance of this patent application. The detailed description of the embodiments aims to help readers accurately grasp the core design logic of this material: "high-value utilization of solid waste - ultralightweight structure - conductive and heating function," understand the synergistic effect of industrial solid wastes such as fly ash and desulfurized gypsum in the cementitious system, and the regulatory mechanism of functional components such as chopped carbon fibers and manganese dioxide on the material's conductivity and heating performance. Furthermore, for those skilled in the art, based on the core ideas of this invention, the raw material ratio, foaming parameters, and curing conditions can be adaptively adjusted according to different application scenarios: for example, for heating needs in frigid regions, the amount of chopped carbon fibers can be appropriately increased to improve heating efficiency; for filling needs in high-rise buildings, the ratio of hydrogen peroxide to foam stabilizer can be optimized to further reduce dry density. It should be noted that the embodiments listed in this specification are merely demonstrations of typical application scenarios and should not be considered as limiting the scope of protection of this invention. Without departing from the principles of this invention, any technical improvements based on conductive and heating foam concrete made from solid waste materials fall within the scope of protection of this invention.

Claims

1. A solid waste ultralightweight conductive and heating foam concrete, characterized in that, Raw materials, by weight, include: The composition of the cementitious material is as follows: fly ash content is 650-750 parts by weight; desulfurized gypsum content is 450-550 parts by weight; sulfoaluminate cement content is 350-500 parts by weight; water content is 450-550 parts by weight; foam stabilizer content is 3-5 parts by weight; water-reducing agent content is 3-6 parts by weight; dispersant content is 3-6 parts by weight; hydrogen peroxide content is 50-70 parts by weight; manganese dioxide content is 0.6-1.0 parts by weight; and chopped carbon fiber content is 4-12 parts by weight. The sum of the mass of fly ash and desulfurized gypsum accounts for 70%-80% of the total mass of the cementitious material.

2. The solid waste ultralight conductive heating foam concrete according to claim 1, characterized in that, The fly ash is grade I fly ash; the water requirement ratio is 95%-97%, the loss on ignition is 1.5%-2%; the fineness is 10%-12% residue on a 45 μm square hole sieve, and the strength activity index is 75%-80%.

3. The solid waste ultralightweight conductive heating foam concrete according to claim 1, characterized in that, The cement is grade 52.5 sulfoaluminate cement; the water-reducing agent is polycarboxylate high-efficiency water-reducing agent; the water is 30-degree warm water; the foam stabilizer is calcium stearate, which is an industrial grade I product with a fineness passing through a 200-mesh sieve; the dispersant is hydroxyethyl cellulose with a viscosity of 3400-5000 mPa·s and a pH of 5.5-8.5 for a 1% aqueous solution; the hydrogen peroxide is industrial grade hydrogen peroxide with a mass concentration of 30%.

4. The solid waste ultralightweight conductive heating foam concrete according to claim 1, characterized in that, The foaming catalyst is manganese dioxide with a purity of not less than 99% and a fineness of not less than 100 mesh; the chopped carbon fibers are polyacrylonitrile-based carbon fibers with a length of 6 mm and a resistivity of not more than 1.5 × 10⁻⁶. -3 Ω·cm.

5. The solid waste ultralightweight conductive and heating foam concrete according to claim 4, characterized in that, The polyacrylonitrile-based carbon fiber has also undergone optimization and improvement treatment. The specific improvement method is as follows: S1: Add 2-3 parts of β-cyclodextrin, 1-2 parts of silane coupling agent KH550, and 3-5 parts of modified nano-attapulgite clay agent to 4-7 parts of chitosan solution with a mass fraction of 2-4%, stir thoroughly to obtain the improved solution; S2: Polyacrylonitrile-based carbon fiber and modified liquid are ultrasonically modified at a weight ratio of 3:(5-7), ultrasonic power 350-400W, ultrasonic for 2 hours. After ultrasonication, filter and dry.

6. The solid waste ultralightweight conductive and heating foam concrete according to claim 5, characterized in that, The preparation method of the modified nano-attapulgite clay agent is as follows: S1a: Place the nano-attapulgite in a muffle furnace and calcine it at 300-400℃ for 2-3 hours. After cooling, grind it through a 200-mesh sieve. Add the sieved nano-attapulgite to a lanthanide liquid at a mass ratio of 1:(8-10). Disperse it ultrasonically for 30 minutes with an ultrasonic power of 200-300W to obtain an attapulgite dispersion. S1b: Attapulgite dispersion and ball milling agent are ball milled at a weight ratio of (8-11):5 until fully milled. The ball milling speed is 1000-1500 r / min and the ball milling time is 2 h. After the ball milling is completed, the mixture is filtered and dried to obtain modified nano-attapulgite agent.

7. The solid waste ultralightweight conductive heating foam concrete according to claim 6, characterized in that, The lanthanum solution is prepared by mixing lanthanum oxide, sodium dodecylbenzenesulfonate solution (8-12% by mass), and citric acid in a weight ratio of (2-3):5:(1-2).

8. The solid waste ultralight conductive heating foam concrete according to claim 6, characterized in that, The ball milling agent is a mixture of silicon carbide whiskers, carbon nanotubes and boron nitride in a weight ratio of (3-5):2:(1-3) and sintered for 1 hour at a sintering temperature of 350-400℃. After sintering, the ball milling agent is obtained.

9. The solid waste ultralightweight conductive heating foam concrete as described in any one of claims 1-8, characterized in that, Includes the following steps: Step (1) Put fly ash, desulfurized gypsum and cement into a mixer in sequence and mix until uniform to obtain mixed dry material A; Step (2) Place 30-degree warm water, dispersant and short-cut carbon fibers into a container in sequence, and disperse them by ultrasonication until uniform to obtain mixture B; Step (3) Slowly add mixture B to the dry mixture A and continue stirring to ensure uniform fiber dispersion to obtain conductive paste C; Step (4) Add manganese dioxide to conductive slurry C, stir briefly, then slowly add hydrogen peroxide and continue stirring until the slurry is fully foamed to obtain conductive foam slurry D; Step (5) Apply release agent evenly to the inner surface of the steel mold, then pour foam slurry D evenly into the steel mold, let it stand, demold, and place it in a standard curing room for curing. After curing, the solid waste ultra-lightweight conductive heating foam concrete as described in claims 1-8 can be obtained.

10. The method for preparing ultralightweight conductive and heating foamed concrete from solid waste according to claim 9, characterized in that, The stirring rate in step (1) is 60-65 r / min and the stirring time is 2-3 min; the ultrasonic dispersion frequency in step (2) is 20-40 kHz and the dispersion time is 2-3 min; the stirring rate in step (3) is 80-100 r / min and the stirring time is 3-4 min; the stirring rate after adding hydrogen peroxide in step (4) is 60-65 r / min and the stirring time is 1-2 min; the static curing time in step (5) is 24-36 hours; the curing conditions in the standard curing room are: temperature controlled at 20±2℃ and humidity greater than or equal to 95%.

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