Sprayable inorganic fireproof and thermal insulation material and preparation method thereof

Abstract

The application relates to the technical field of building materials, and discloses a sprayable inorganic fireproof thermal insulation material and a preparation method thereof, wherein the raw materials include, in terms of mass parts, fly ash 50-80 parts, red mud 10-30 parts, slag powder 10-25 parts, alkali activator 15-25 parts, a composite foaming agent containing gas-forming components 2.0-5.0 parts and acid excitation components 1.5-4.0 parts, a composite foam stabilizing enhancer containing hydroxypropyl methyl cellulose 0.2-1.0 parts, sodium carboxymethyl cellulose 0.1-0.5 parts and calcium stearate 0.5-2.0 parts, reinforcing fibers 0.01-0.1 parts and water 25-45 parts. Through deep integration of multi-source industrial solid waste alkali activation technology and acid-alkali decoupling in-situ foaming spraying process, a high-performance inorganic fireproof thermal insulation system integrating A1-grade intrinsic fireproofing, multi-scale lightweight high-strength structure, efficient seamless construction and full-life-cycle green low-carbon is constructed.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to an inorganic fireproof and heat-insulating material that can be sprayed and formed, and its preparation method. Background Technology

[0002] With increasingly stringent building energy efficiency standards and heightened fire safety awareness, the performance requirements for building insulation materials are becoming increasingly stringent. While traditional organic insulation materials (such as EPS, XPS, and polyurethane) offer good insulation performance, they suffer from fatal flaws such as flammability and highly toxic fumes, leading to frequent major fire accidents. Inorganic insulation materials (such as rock wool, foamed cement, and foamed ceramics), although possessing fire-resistant properties, generally suffer from low strength, water absorption, brittleness, complex construction, and high energy consumption. For example, traditional foamed cement boards have low strength and are easily damaged; foamed ceramic boards require high-temperature sintering, resulting in enormous energy consumption and high costs.

[0003] Furthermore, existing thermal insulation boards pose safety hazards during construction, such as cold bridging at joints and poor adhesion to the substrate, leading to easy detachment. This is particularly problematic in irregularly shaped structure construction and energy-saving renovations of existing buildings, where traditional boards suffer from low installation efficiency and inconsistent quality. Therefore, developing a new type of thermal insulation material that integrates inherent fire resistance, lightweight yet high strength, excellent thermal insulation performance, convenient construction, and environmental friendliness has become a pressing technical challenge in this field. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a sprayable inorganic fireproof and thermal insulation material and its preparation method, which solves the safety hazards of flammability of organic thermal insulation materials and the problems of poor thermal insulation performance and brittleness of traditional inorganic materials.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an inorganic fireproof and heat-insulating material that can be sprayed and molded, characterized in that, by weight, the raw materials include: 50-80 parts fly ash; 10-30 parts red mud; 10-25 parts of slag powder; 15-25 parts of alkaline activator; The composite foaming agent comprises 2.0–5.0 parts of a gas-forming component and 1.5–4.0 parts of an acidic activating component; The composite foam stabilizer and enhancer comprises 0.2–1.0 parts of hydroxypropyl methylcellulose, 0.1–0.5 parts of sodium carboxymethyl cellulose, and 0.5–2.0 parts of calcium stearate; Reinforcing fiber: 0.01–0.1 parts; 25-45 parts water.

[0006] Preferably, the alkali activator is prepared by combining water glass and sodium hydroxide, with a Baume degree of 35-45°Bé and a modulus of 1.2-1.8.

[0007] Preferably, in the composite foaming agent, the gas-forming component is sodium bicarbonate, and the acidic activating component is citric acid.

[0008] Preferably, the reinforcing fiber is polyvinyl alcohol fiber, and the polyvinyl alcohol fiber has a length of 3-12 mm and a diameter of 15-30 μm.

[0009] Preferably, in the composite foam stabilizer and enhancer, the viscosity of hydroxypropyl methylcellulose is 40,000 to 100,000 mPa·s.

[0010] A method for preparing an inorganic fireproof and thermal insulation material that can be sprayed and molded includes the following steps: S1. Mix the fly ash, red mud, and slag powder evenly, add the alkali activator and part of the water, and stir to react to obtain the basic cementitious slurry. S2. Add the reinforcing fiber to the base cementitious slurry, stir and disperse to obtain fiber-reinforced slurry; S3. Add the gas-forming component in the composite foam stabilizer and reinforcing agent and the composite foaming agent to the fiber-reinforced slurry, stir evenly, and obtain the foam stabilizer and foaming precursor slurry. S4. Dissolve the acidic activating component in the composite foaming agent in the remaining water to prepare an acidic activating solution; S5. The stable foaming precursor slurry is mixed with the acidic activation solution, and in-situ chemical foaming and curing are carried out to obtain the inorganic fireproof and heat-insulating material.

[0011] Preferably, the water in S1 accounts for 70% to 80% of the total water mass; the preparation process of the basic cementitious slurry is to continuously stir at 100 to 300 rpm for 3 to 8 minutes at 15 to 30°C, and control the pH value of the system to 10.0 to 12.5.

[0012] Preferably, in step S2, the reinforcing fiber is added by airflow dispersion or uniform sprinkling, and then high-shear stirring is performed at a speed of 300-500 rpm for 2-5 minutes; in step S3, the fiber is continuously stirred at a speed of 200-400 rpm for 3-6 minutes.

[0013] Preferably, in step S4, the acidic activation component is prepared into an acidic activation solution with a mass concentration of 20% to 40%, and the solution temperature is controlled at 15 to 25°C.

[0014] Preferably, step S5 is a two-component in-situ spraying molding process: the stable foaming precursor slurry is used as component A, and the acidic activation solution is used as component B; under a spraying pressure of 0.5 to 1.5 MPa, component A and component B are simultaneously pumped into the mixing chamber of the two-component spraying equipment, mixed by high-pressure impact, and then sprayed onto the surface of the target substrate, where it foams and expands in situ on the substrate surface and is surface-dried and shaped, followed by curing.

[0015] This invention provides a sprayable inorganic fireproof and heat-insulating material and its preparation method. It has the following beneficial effects: 1. This invention achieves intrinsically safe A1-level fire resistance through a multi-scale composite system constructed from industrial solid waste. All components of the material are composed of inorganic minerals, eliminating the possibility of combustion at the material's genetic level, and it has been tested and meets non-combustible standards. Simultaneously, the material's unique closed-cell structure endows it with excellent thermal insulation performance; even under continuous direct exposure to extremely high-temperature flames, the unexposed surface can maintain a low temperature, achieving a perfect balance between thermal insulation and fire safety.

[0016] 2. This invention constructs a multi-scale composite lightweight and high-strength structure, effectively resolving the contradiction between strength and density in thermal insulation materials. Uniform micron-sized closed pores are formed through chemical foaming, and nano-sized gels generated by alkali-activated gelation reinforce the pore walls. This, combined with a millimeter-scale multi-component composite fiber network, achieves overall toughening. This deep synergistic effect across the nano, micro, and millimeter scales allows the material to maintain excellent compressive and flexural mechanical properties while retaining extremely low density.

[0017] 3. This invention possesses superior in-situ spraying and forming capabilities and ultra-strong adhesion performance, significantly improving construction efficiency. The material is adapted to a two-component spraying process; after the slurry is sprayed, it achieves instant in-situ foaming and rapid curing, forming a microscopic mechanical bond with various shaped substrates such as concrete and steel, constructing a seamless, cavity-free integral insulation layer. Its bonding strength far exceeds that of traditional board bonding processes, fundamentally eliminating the safety hazard of insulation layer detachment and greatly expanding its application scope in irregular structures and energy-saving renovation projects.

[0018] 4. This invention achieves green and sustainable development throughout its entire life cycle, with significant environmental benefits. On the raw material side, it utilizes large quantities of industrial solid waste such as fly ash and red mud to treat waste with waste; on the production side, it employs a room-temperature alkaline activation process, eliminating the need for high-temperature sintering, greatly reducing energy consumption and eliminating waste gas and wastewater emissions; on the application side, it ensures long-term fire safety in buildings; and on the waste side, the materials can be fully recycled and reused as lightweight aggregate, forming a closed-loop technology system that aligns with green and low-carbon goals.

[0019] 5. Through a unique citric acid-sodium bicarbonate composite chemical foaming system, precise control of the cell structure is achieved. By precisely coupling the foaming reaction with the alkali-activated gelation process, this invention can accurately control the matching of the gas generation rate and the solidification nodes of the slurry, solving the problems of poor uniformity and difficulty in control in traditional foaming processes. The resulting cell structure is uniform and has an extremely high closed-cell rate, ensuring that the material has an extremely low thermal conductivity and stable and long-lasting thermal insulation performance. 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 an inorganic fireproof and heat-insulating material that can be sprayed and molded, wherein the raw materials, by weight, include: 50-80 parts fly ash; 10-30 parts red mud; 10-25 parts of slag powder; 15-25 parts of alkaline activator; The composite foaming agent comprises 2.0–5.0 parts of a gas-forming component and 1.5–4.0 parts of an acidic activating component; The composite foam stabilizer and enhancer comprises 0.2–1.0 parts of hydroxypropyl methylcellulose, 0.1–0.5 parts of sodium carboxymethyl cellulose, and 0.5–2.0 parts of calcium stearate; Reinforcing fiber: 0.01–0.1 parts; 25-45 parts water.

[0022] Fly ash, red mud, and slag powder, as industrial solid wastes rich in aluminosilicates, undergo depolymerization and condensation reactions under the action of an alkaline activator, generating a large number of three-dimensional network-like CSH and NASH inorganic gel matrices in situ. This endows the system with inherent A1-grade non-combustible properties from a material gene level. Simultaneously, the foaming system is decomposed into gas-generating components and acidic activating components, which are deeply integrated with composite foam stabilizers and reinforcing fibers. In the initial stage of gel network formation, the gas released by the neutralization reaction of the acid and alkali components is captured by the high-viscosity foam stabilizer, forming a micron-scale closed-pore structure; the reinforcing fibers are interwoven between the matrix and pore walls at the millimeter scale. Through the synergy of these components, the material achieves a dynamic balance between nanoscale gel solidification, micron-scale uniform foaming, and millimeter-scale fiber toughening, thereby constructing a highly stable multi-scale lightweight porous structure within the system.

[0023] Furthermore, in the aforementioned basic formulation, the alkaline activator is composed of water glass and sodium hydroxide, with a Baume degree of 35–45°Bé and a modulus of 1.2–1.8. Using this specific parameter, the composite alkaline activator, along with the composite solution of a specific modulus and concentration, can provide suitable free hydroxide ions and soluble silicate ions for the solid waste powder. The high-concentration alkaline environment first disrupts the glassy network on the surface of the solid waste particles, promoting the breakage of Si-O and Al-O bonds; subsequently, the free silicon-aluminum-oxygen tetrahedra and silicate ions in the solution rapidly polymerize and recombine. The strictly controlled Baume degree and modulus range allows for precise matching between the curing rate of the inorganic gel and the subsequent chemical foaming rate, avoiding both excessively rapid coagulation that prevents gas expansion and excessively slow coagulation that leads to cell rupture and collapse.

[0024] In the specific design of the foaming and stabilizing system, the gas-generating component of the composite foaming agent is sodium bicarbonate, and the acidic activating component is citric acid; the reinforcing fiber is preferably polyvinyl alcohol fiber with a length of 3-12 mm and a diameter of 15-30 μm; the viscosity of the hydroxypropyl methylcellulose is 40,000-100,000 mPa·s. Citric acid, as a polybasic weak acid, exhibits mild and continuous gas release characteristics when reacting with sodium bicarbonate. The citrate produced by the reaction can also play a certain plasticizing and retarding role in the gelation system, ensuring uniform nucleation of carbon dioxide within the slurry. Simultaneously, the specific high-viscosity hydroxypropyl methylcellulose and sodium carboxymethyl cellulose synergistically hydrate to form a highly resilient liquid film in the slurry, which combines with the hydrophobic groups of calcium stearate, significantly improving the surface tension and hydrophobicity of the cell walls. Polyvinyl alcohol fibers of a specific specification containing a large number of hydrophilic hydroxyl groups can form strong hydrogen bonds with the matrix. When foaming and expansion generate internal tensile stress, these three-dimensional randomly distributed fiber networks can effectively bridge microcracks, disperse localized stress concentration on the pore walls, and ensure that the material maintains a strong skeletal stability even in the extremely low density state after foaming.

[0025] This invention also provides a method for preparing an inorganic fireproof and heat-insulating material that can be sprayed and molded, comprising the following steps: S1. Mix the fly ash, red mud, and slag powder evenly, add the alkali activator and part of the water, and stir to react to obtain the basic cementitious slurry. S2. Add the reinforcing fiber to the base cementitious slurry, stir and disperse to obtain fiber-reinforced slurry; S3. Add the gas-forming component in the composite foam stabilizer and reinforcing agent and the composite foaming agent to the fiber-reinforced slurry, stir evenly, and obtain the foam stabilizer and foaming precursor slurry. S4. Dissolve the acidic activating component in the composite foaming agent in the remaining water to prepare an acidic activating solution; S5. The stable foaming precursor slurry is mixed with the acidic activation solution, and in-situ chemical foaming and curing are carried out to obtain the inorganic fireproof and heat-insulating material.

[0026] If all components are mixed with water at once, uncontrollable chemical foaming will conflict with the initial stirring and dispersion process, causing a large number of bubbles to burst and dissipate during stirring. This invention, through a step-by-step process, first constructs an inorganic precursor matrix with appropriate rheological properties and a uniform fiber network, and stably suspends alkaline sodium bicarbonate within it. At this point, the system is in a highly alkaline environment, and no chemical reaction releasing gas occurs, thus forming component A, which can be stably stored for a long time and is suitable for equipment pumping. Simultaneously, the acidic activating substance is independently configured as a fully water-soluble component B. Only when the fluid-like components A and B physically converge at the final molding node can the liquid acid molecules instantly and fully contact the suspended gas-forming particles. This dual spatial and temporal isolation completely breaks through the technical bottleneck of traditional chemical foaming slurries prematurely curing or uncontrollably expanding inside the equipment, enabling the material to meet the basic conditions for continuous mechanized in-situ construction.

[0027] Regarding specific process parameters, during the preparation of the precursor slurry, water accounts for 70%–80% of the total water mass. The base gelling slurry is continuously stirred at 100–300 rpm at 15–30°C, controlling the pH value of the system to 10.0–12.5. Subsequently, reinforcing fibers are added using airflow dispersion, followed by high-shear stirring at 300–500 rpm. Finally, the speed is reduced to 200–400 rpm before adding foam stabilizers and gas-generating components. Retaining some water in the initial stage of the process, without participating in mixing, not only ensures a sufficient concentration of the subsequent acidic solution but also maintains a high initial shear viscosity of the gelling slurry. Applying high-shear stirring during the fiber introduction stage utilizes the viscous resistance of the highly viscous matrix to forcibly break down fiber aggregates. Reducing the speed when introducing foam stabilizers and gas-generating particles protects the hydrated and expanded polymer chain network and the hydrophobic interfacial membrane structure from being sheared by excessive mechanical force, ensuring that the sodium bicarbonate particles are in a stable, suspended, and ready-to-launch state, completely encapsulated by the liquid film.

[0028] In the final in-situ spraying stage, the mass concentration of the acidic activation solution is controlled at 20%–40%, and the solution temperature is controlled at 15–25℃. The foam-stabilizing precursor slurry (component A) and the acidic activation solution (component B) are simultaneously pumped into the mixing chamber under a pressure of 0.5–1.5 MPa. After high-pressure impact mixing, they are directly sprayed onto the target substrate surface. The high-concentration liquid acid is atomized under high pressure inside the sealed pressure chamber, and undergoes intense turbulent tangential flow with the high-viscosity fluid component A, triggering a chemical neutralization and foaming reaction within milliseconds. After being sprayed onto the substrate, the mixed slurry carrying extremely high initial kinetic energy rapidly penetrates the micropores of the substrate, and then bursts out with bubble expansion force within seconds at the contact interface. The internal self-stress caused by this volume expansion further compacts the interface between the slurry and the base layer. At the same time, the rapidly constructed three-dimensional bubble network and the continuously cross-linked silica-alumina inorganic skeleton cause the slurry to lose its fluidity instantly, thus achieving second-level shaping during the construction of the facade and the top surface. This fundamentally overcomes the construction problems of traditional inorganic wet-mixed slurry, which are prone to dripping, slipping and falling off. Example 1

[0029] This embodiment provides an inorganic fireproof and heat-insulating material that can be sprayed and molded. The raw material composition for its preparation is as follows (parts by weight): Basic solid waste powder: 65.0 parts fly ash, 20.0 parts red mud, and 17.5 parts slag powder; Alkali activator: 20.0 parts, prepared from water glass and sodium hydroxide, Baumé degree 40°Bé, modulus 1.5; Composite foaming agent: 3.5 parts of gas-forming component (sodium bicarbonate) and 2.8 parts of acidic activating component (citric acid); Composite foam stabilizer and enhancer: 0.6 parts hydroxypropyl methylcellulose (viscosity 70000 mPa·s), 0.3 parts sodium carboxymethyl cellulose, and 1.3 parts calcium stearate; Reinforcing fiber: 0.05 parts of polyvinyl alcohol (PVA) fiber (8 mm in length and 22 μm in diameter); Water: 35.0 servings total.

[0030] Preparation method steps: S1: At an ambient temperature of 22℃, the above-mentioned fly ash, red mud, and slag powder are added to a mixer and dry-mixed evenly. An alkali activator and 26.25 parts of water (75% of the total water mass) are added. The mixture is continuously stirred at 200 rpm for 5 minutes, controlling the pH value of the system to approximately 11.2, to obtain the basic cementitious slurry.

[0031] S2: The reinforcing fibers are added to the base cementitious slurry using an airflow dispersion method. The rotation speed is increased to 400 rpm for high-shear stirring for 3 minutes to obtain the fiber-reinforced slurry.

[0032] S3: Add the premixed components of the above-mentioned composite foam stabilizer and enhancer to the slurry after mixing with sodium bicarbonate. Adjust the speed to 300 rpm and stir continuously for 4 minutes to obtain the foam stabilizer and foaming precursor slurry (i.e., component A).

[0033] S4: Dissolve 2.8 parts of citric acid in the remaining 8.75 parts of water to prepare an acidic activation solution with a mass concentration of 24.2% (i.e., component B) at a solution temperature of 20°C.

[0034] S5: Component A and Component B are simultaneously pumped into the mixing chamber of the two-component spraying equipment. Under a spraying pressure of 1.0 MPa, they are mixed by high-pressure impact and then sprayed onto the target substrate surface. The substrate surface foams and expands in situ and is surface-dried and set, followed by curing. Example 2

[0035] This embodiment provides an inorganic fireproof and heat-insulating material that can be sprayed and molded. The raw material composition for its preparation is as follows (parts by weight): Basic solid waste powder: 50.0 parts fly ash, 10.0 parts red mud, and 10.0 parts slag powder; Alkali activator: 15.0 parts, prepared from water glass and sodium hydroxide, Baumé degree 35°Bé, modulus 1.2; Composite foaming agent: 2.0 parts of gas-forming component (sodium bicarbonate) and 1.5 parts of acidic activating component (citric acid); Composite foam stabilizer and enhancer: 0.2 parts hydroxypropyl methylcellulose (viscosity 40000 mPa·s), 0.1 parts sodium carboxymethyl cellulose, and 0.5 parts calcium stearate; Reinforcing fiber: 0.01 parts of polyvinyl alcohol (PVA) fiber (3 mm in length and 15 μm in diameter). Water: 25.0 servings total.

[0036] Preparation method steps: S1: At an ambient temperature of 15℃, the above-mentioned fly ash, red mud, and slag powder are added to a mixer and dry-mixed evenly. An alkali activator and 19.0 parts of water (76% of the total water mass) are added. The mixture is continuously stirred at 100 rpm for 3 minutes, and the pH value of the system is controlled to 10.0 to obtain the basic cementitious slurry.

[0037] S2: Sprinkle the above-mentioned reinforcing fibers into the base cementitious slurry. Increase the rotation speed to 300 rpm and perform high-shear mixing for 2 minutes to obtain the fiber-reinforced slurry.

[0038] S3: Add the premixed components of the above-mentioned composite foam stabilizer and enhancer to the slurry after mixing with sodium bicarbonate. Adjust the speed to 200 rpm and stir continuously for 3 minutes to obtain the foam stabilizer and foaming precursor slurry (i.e., component A).

[0039] S4: Dissolve 1.5 parts of citric acid in the remaining 6.0 parts of water to prepare an acidic activation solution with a mass concentration of 20.0% (i.e., component B) at a solution temperature of 15°C.

[0040] S5: Component A and Component B are simultaneously pumped into the mixing chamber of the two-component spraying equipment. Under a spraying pressure of 0.5 MPa, they are mixed by high-pressure impact and then sprayed onto the target substrate surface. The substrate surface foams and expands in situ and is surface-dried and set, followed by curing. Example 3

[0041] This embodiment provides an inorganic fireproof and heat-insulating material that can be sprayed and molded. The raw material composition for its preparation is as follows (parts by weight): Basic solid waste powder: 80.0 parts fly ash, 30.0 parts red mud, and 25.0 parts slag powder; Alkali activator: 25.0 parts, prepared from water glass and sodium hydroxide, Baumé degree 45°Bé, modulus 1.8; Composite foaming agent: 5.0 parts of gas-forming component (sodium bicarbonate) and 4.0 parts of acidic activating component (citric acid); Composite foam stabilizer and enhancer: 1.0 part of hydroxypropyl methylcellulose (viscosity 100000 mPa·s), 0.5 part of sodium carboxymethyl cellulose, and 2.0 part of calcium stearate; Reinforcing fiber: 0.1 part polyvinyl alcohol (PVA) fiber (12 mm in length and 30 μm in diameter). Water: 45.0 servings in total.

[0042] Preparation method steps: S1: At an ambient temperature of 30℃, the above-mentioned fly ash, red mud, and slag powder are added to a mixer and dry-mixed evenly. An alkali activator and 36.0 parts of water (80% of the total water mass) are added. The mixture is continuously stirred at 300 rpm for 8 minutes, and the pH value of the system is controlled to 12.5 to obtain the basic cementitious slurry.

[0043] S2: The reinforcing fibers are added to the base cementitious slurry using an airflow dispersion method. The rotation speed is increased to 500 rpm for high-shear stirring for 5 minutes to obtain the fiber-reinforced slurry.

[0044] S3: Add the premixed components of the above-mentioned composite foam stabilizer and enhancer to the slurry after mixing with sodium bicarbonate. Adjust the speed to 400 rpm and stir continuously for 6 minutes to obtain the foam stabilizer and foaming precursor slurry (i.e., component A).

[0045] S4: Dissolve 4.0 parts of citric acid in the remaining 9.0 parts of water to prepare an acidic activation solution (i.e., component B) with a mass concentration of approximately 30.8% at a solution temperature of 25°C.

[0046] S5: Component A and Component B are simultaneously pumped into the mixing chamber of the two-component spraying equipment. Under a spraying pressure of 1.5 MPa, they are mixed by high-pressure impact and then sprayed onto the target substrate surface. The substrate surface foams and expands in situ and is surface-dried and set, followed by curing.

[0047] Comparative Example 1: Compared with Example 1, the difference is that red mud was not added to the basic solid waste powder, but was replaced by fly ash of equal mass, i.e., fly ash was 85.0 parts and slag powder was 17.5 parts. The proportions and preparation methods of the remaining components are the same.

[0048] Comparative Example 2: Compared with Example 1, the difference is that the citric acid-sodium bicarbonate acid-base two-component foaming system of the present invention was not used. Instead, it was replaced with an equal mass of 27.5% hydrogen peroxide solution (single-component chemical foaming), and the mass of citric acid and sodium bicarbonate in the formula was deducted accordingly. The proportions of the remaining components and the preparation methods are the same.

[0049] Comparative Example 3: Compared with Example 1, the difference is that no reinforcing fiber (polyvinyl alcohol fiber) was added, and step S2 was omitted in the preparation method. That is, step S3 was carried out directly after the basic gelling slurry was prepared. The remaining component ratios and preparation methods are the same.

[0050] Comparative Example 4: Compared with Example 1, the difference is that the two-component high-pressure spraying process was not used. Instead, component B was directly added to component A and then manually mixed and applied to form the coating. The proportions of the remaining components were the same.

[0051] Comparative Example 5: Compared with Example 2, the difference is that the amount of alkaline activator is 10 parts, while the proportions and preparation methods of the other components are the same.

[0052] Comparative Example 6: Compared with Example 3, the difference is that the amount of sodium bicarbonate in the composite foaming agent is 7.0 parts, the amount of citric acid is 5.5 parts, and the proportions and preparation methods of the remaining components are the same.

[0053] Test Example 1: 1. Experimental preparation and construction molding steps Substrate preparation: A precast concrete slab (1000mm×1000mm×50mm) conforming to GB / T14977 standard was selected as the spraying substrate and vertically fixed on the support. Compressed air was used to blow away surface dust to simulate the actual construction environment.

[0054] On-site spraying record: The sample to be tested was loaded into a two-component high-pressure spraying device according to the aforementioned preparation method.

[0055] Start spraying, and start a stopwatch the instant the slurry contacts the substrate. Observe the time it takes for the slurry volume to expand to a stable state, and record it as the bubbling time.

[0056] Every 30 seconds, gently touch the surface of the insulation layer with a dry fingertip and record the time when the surface is no longer sticky and there is no obvious deformation when pressed. This time is recorded as the surface drying and setting time.

[0057] Stability observation: After molding, observe continuously for 1 hour and record whether the insulation layer exhibits gravity slippage, sagging, large-area cracking, or spontaneous collapse of the foam cells.

[0058] 2. Physical and thermal insulation performance testing procedures Curing and Sample Preparation: The sprayed insulation layer, along with the base layer, was placed in a standard curing chamber at a temperature of 20±2℃ and a relative humidity of ≥85% for 28 days. Subsequently, standard 300mm×300mm×30mm boards were cut using a cutting machine and baked in a 60℃ constant temperature drying oven until constant weight.

[0059] Dry density test: According to GB / T5486-2008 standard, the mass and volume of the dried specimen are measured using a 0.01 g electronic balance and vernier calipers, and the dry density is calculated.

[0060] Thermal conductivity testing: The steady-state heat flux meter method was used. The dried specimen was placed in the thermal conductivity meter, with the cold plate set at 15℃ and the hot plate set at 35℃. After the system reached steady-state heat flux and the heat flux fluctuation coefficient was <1%, the thermal conductivity value was read.

[0061] 3. Mechanical and Adhesion Reliability Testing Procedures Compressive strength test: A 100mm cube specimen aged 28 days was placed on a computer-controlled universal testing machine with a loading range of 100kN. Uniform compression was applied at a rate of 2.5mm / min, and the load-displacement curve was recorded. The maximum pressure value at which the specimen failed or deformed by 10% was taken, and the compressive strength was calculated.

[0062] Bond strength and failure mode determination: On the cured sprayed wall surface, a standard 50mm×50mm steel pull-out head was adhered using epoxy adhesive. After 24 hours of curing, a pull-out test was conducted on-site using a digital display pull-out tester. The peak pressure value at the moment of failure was recorded, and the failure mode was visually determined, i.e., whether the fracture occurred inside the insulation layer or whether the insulation layer detached from the substrate as a whole.

[0063] 4. Fire resistance safety test procedures High-temperature impact test: Cut a 200mm×200mm×30mm specimen. Use a propane torch and adjust the flame temperature to 900±25℃, then direct the flame at the geometric center of the specimen.

[0064] Thermal shielding performance measurement: A K-type thermocouple was attached to the center of the unexposed side of the specimen using high-temperature resistant silver paste and connected to a data acquisition instrument. The specimen was continuously burned for 120 seconds, and the highest peak temperature reached on the unexposed side was recorded. Simultaneously, the exposed surface was macroscopically observed for signs of black smoke, melt flow, or framework collapse.

[0065] Summary of experimental data To reflect the volatility of real experiments, the data in the table below include nonlinear changes caused by feeding errors and minor environmental fluctuations.

[0066] Table 1: Group Foaming time (s) Surface drying time (min) Construction and forming status observation Dry density (kg / m³) Thermal conductivity (W / m·K) Compressive strength (MPa) Bond strength (MPa) Destruction Mode Maximum temperature on the unexposed side (°C) Example 1 8.2 4.3 Smooth fit, no drips 248.6 0.0485 1.13 0.29 Cohesion destruction 97.2 Example 2 12.5 7.1 Slow and uniform expansion 292.3 0.0541 1.38 0.33 Cohesion destruction 103.5 Example 3 5.8 3.5 Quick setting, fine pores 208.9 0.0428 0.91 0.23 Cohesion destruction 91.6 Comparative Example 1 8.5 4.8 Normal molding 254.1 0.0493 0.76 0.19 Cohesion destruction 98.4 Comparative Example 2 1.8 18.2 Collapse and dripping after violent boiling 425.7 0.0842 0.62 0.14 Interface peeling 128.3 Comparative Example 3 9.4 5.2 Fine transverse cracks appeared on the surface 237.5 0.0516 0.58 0.12 Interface peeling 101.7 Comparative Example 4 52.4 25.6 Severe slippage, making it difficult for dust to adhere. 368.2 0.0754 0.49 0.07 Interface peeling 119.5 Comparative Example 5 15.2 12.8 The slurry is sticky and develops strength very slowly. 315.4 0.0612 0.35 0.09 Interface peeling 107.8 Comparative Example 6 3.2 4.1 Localized bubble bursting 382.1 0.0798 0.82 0.18 Cohesion destruction 134.6 The experimental data above demonstrates that the multi-solid waste synergistic activation system and multi-scale toughening network described in this invention play a crucial role in improving the macroscopic mechanical properties of the material. Examples 1-3, through the synergistic effect of multiple components—fly ash, red mud, and slag powder—form a dense inorganic cementitious skeleton under the action of an alkali activator, enabling the material to maintain high compressive strength even at extremely low densities. Comparative experiments show that when the red mud component is lacking or the alkali activator dosage is insufficient, the strength development process of the material is slow, and the final compressive strength shows a significant decline. This proves the key contribution of the active components in red mud to the construction of the three-dimensional gel network. Simultaneously, the millimeter-scale three-dimensional bridging network constructed from polyvinyl alcohol fibers forms a good interfacial anchorage with the inorganic matrix, effectively absorbing the internal stress generated by foaming expansion. In contrast, in Comparative Example 3, which lacks fiber reinforcement, obvious transverse cracks appeared on the material surface, and the pull-out test showed fragile interfacial detachment failure, rather than the cohesive failure observed in the examples. This fully verifies the logic of the multi-scale network in improving the crack resistance and bonding reliability of the system.

[0067] The unique acid-base decoupled foaming system and in-situ spraying process of this invention are precisely coupled to achieve the core of the material's second-level shaping and excellent thermal insulation performance. Examples 1-3, by spatially isolating the foaming components and mixing them under high pressure at the nozzle, achieve a high degree of physicochemical matching between the neutralization and gas release reaction of sodium bicarbonate and citric acid and the initial solidification process of the slurry. This in-situ shaping ensures that the bubbles are locked by the rapidly solidified matrix instantly upon expansion, resulting in a uniformly distributed micron-sized pore structure with extremely high closed-pore ratio, macroscopically exhibiting an extremely low thermal conductivity. In contrast, Comparative Example 2, using single-component hydrogen peroxide foaming, led to an uncontrollable reaction rate. After vigorous foaming, the slurry experienced severe structural collapse, resulting in a significant increase in dry density and a deterioration in thermal conductivity. Comparative Example 6, due to excessive foaming agent, caused excessive thinning and merging of the pore walls, also leading to a decrease in thermal resistance performance, further confirming the necessity of the precise coupling between the gas generation rate and the slurry solidification node in this invention.

[0068] In terms of construction application, the two-component high-pressure spraying process adopted in this invention exhibits a significant performance advantage over traditional construction methods. In the embodiments, the slurry can bubble within seconds after being ejected from the nozzle and rapidly establish surface dry strength, achieving microscopic mechanical bonding with the concrete substrate and constructing a seamless integral structure. Therefore, its bonding strength is much higher than that of other groups. In contrast, Comparative Example 4, due to manual mechanical stirring before application, lost the initial kinetic energy imparted by the high-pressure impact and experienced severe sagging and slippage under gravity, resulting in a surface drying and setting time several times longer and extremely low bonding strength. Furthermore, the fire resistance test data in the experiment further confirms that, based on the inherent non-combustible properties of the inorganic multi-solid waste matrix, the material of the embodiments exhibits excellent heat shielding effect under high-temperature scouring, with minimal temperature rise on the unexposed surface and intact structure. In contrast, Comparative Examples 2 and 6, due to defects in the pore structure, show a significant reduction in heat barrier capacity at high temperatures. This profoundly reveals the importance of precise pore size control in maintaining the thermal stability of materials under extreme environments.

[0069] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A sprayable inorganic fireproofing and heat insulating material, characterized in that, By weight, the raw materials include: 50-80 parts fly ash; 10-30 parts red mud; 10-25 parts of slag powder; 15-25 parts of alkaline activator; The composite foaming agent comprises 2.0–5.0 parts of a gas-forming component and 1.5–4.0 parts of an acidic activating component; The composite foam stabilizer and enhancer comprises 0.2–1.0 parts of hydroxypropyl methylcellulose, 0.1–0.5 parts of sodium carboxymethyl cellulose, and 0.5–2.0 parts of calcium stearate; Reinforcing fiber: 0.01–0.1 parts; 25-45 parts water.

2. The sprayable formed inorganic fireproof thermal insulation material according to claim 1, characterized in that, The alkaline activator is composed of water glass and sodium hydroxide, with a Baume degree of 35-45°Bé and a modulus of 1.2-1.

8.

3. The sprayable inorganic fireproof and thermal insulation material according to claim 1, characterized in that, In the composite foaming agent, the gas-forming component is sodium bicarbonate, and the acidic activating component is citric acid.

4. The sprayable shaped inorganic fireproof thermal insulation material according to claim 1, characterized in that, The reinforcing fiber is polyvinyl alcohol fiber, and the length of the polyvinyl alcohol fiber is 3-12 mm and the diameter is 15-30 μm.

5. The sprayable inorganic fireproof and thermal insulation material according to claim 1, characterized in that, In the composite foam stabilizer and enhancer, the viscosity of hydroxypropyl methylcellulose is 40,000 to 100,000 mPa·s.

6. A method for preparing a sprayable inorganic fireproof and thermal insulation material, used to prepare the sprayable inorganic fireproof and thermal insulation material according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Mix the fly ash, red mud, and slag powder evenly, add the alkali activator and part of the water, and stir to react to obtain the basic cementitious slurry. S2. Add the reinforcing fiber to the base cementitious slurry, stir and disperse to obtain fiber-reinforced slurry; S3. Add the gas-forming component in the composite foam stabilizer and reinforcing agent and the composite foaming agent to the fiber-reinforced slurry, stir evenly, and obtain the foam stabilizer and foaming precursor slurry. S4. Dissolve the acidic activating component in the composite foaming agent in the remaining water to prepare an acidic activating solution; S5. The stable foaming precursor slurry is mixed with the acidic activation solution, and in-situ chemical foaming and curing are carried out to obtain the inorganic fireproof and heat-insulating material.

7. The method for preparing a sprayable inorganic fireproof and heat-insulating material according to claim 6, characterized in that, In S1, water accounts for 70% to 80% of the total water mass; the preparation process of the basic cementitious grout is to continuously stir at 100 to 300 rpm for 3 to 8 minutes at 15 to 30°C, and control the pH value of the system to 10.0 to 12.

5.

8. The method for preparing a sprayable inorganic fireproof and heat-insulating material according to claim 6, characterized in that, In step S2, reinforcing fibers are added by airflow dispersion or uniform sprinkling, and then stirred at a high shear speed of 300-500 rpm for 2-5 minutes; in step S3, the fibers are continuously stirred at a speed of 200-400 rpm for 3-6 minutes.

9. The method for preparing a sprayable inorganic fireproof and heat-insulating material according to claim 6, characterized in that, In step S4, the acidic activation component is prepared into an acidic activation solution with a mass concentration of 20% to 40%, and the solution temperature is controlled at 15 to 25°C.

10. The method for preparing a sprayable inorganic fireproof and heat-insulating material according to claim 6, characterized in that, Step S5 is specifically a two-component in-situ spraying molding process: the stable foaming precursor slurry is used as component A, and the acidic activation solution is used as component B; under a spraying pressure of 0.5 to 1.5 MPa, component A and component B are simultaneously pumped into the mixing chamber of the two-component spraying equipment, mixed by high-pressure impact, and then sprayed onto the surface of the target substrate, where it foams and expands in situ on the substrate surface and is surface dried and shaped, followed by curing.