GRG gypsum composite reinforced material and preparation method thereof

Abstract

The invention belongs to the field of building decoration materials, and discloses a GRG gypsum composite reinforced material and a preparation method thereof. The high-strength concrete is prepared from the following components in parts by weight: 45 to 65 parts of alpha-semi-hydrated gypsum, 12 to 20 parts of composite reinforced fiber, 0.5 to 2 parts of graphene nanofiber, 2 to 5 parts of nano silica fume, 5 to 10 parts of ethylene-vinyl acetate copolymer latex powder, 1 to 2.5 parts of hydroxypropyl methyl cellulose, 0.1 to 0.8 part of polycarboxylic acid type water reducing agent, 1 to 4 parts of calcium stearate, 3 to 8 parts of vermiculite powder and 28 to 40 parts of deionized water. Aiming at the problems that an existing GRG material is insufficient in mechanical property, low in fireproof grade, poor in thermal performance, poor in durability and the like, a multi-dimensional synergistic enhancement system is constructed by adopting composite reinforced fibers, functional nanofiller and a gradient preparation process, the problems of dispersion and interfacial compatibility of the nanofiller are solved, and the comprehensive performance of the GRG material is improved. The performance breakthrough of high strength, high fire resistance, low heat conduction and long durability is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of building decoration materials, and particularly to a GRG gypsum composite reinforcing material and a preparation method thereof. Background Art

[0002] GRG (Glass Fiber Reinforced Gypsum) materials are widely used in the high-end building decoration field due to their advantages such as light weight and high strength, and flexible shaping, especially in the manufacture of complex curved surface components. However, existing GRG materials have multiple performance defects: In terms of mechanical properties, the flexural strength of traditional glass fiber reinforced gypsum is only 8 - 10 MPa. The fiber distribution is uneven and the interfacial bonding strength is low, which easily generates cracks at stress concentration points and expands, resulting in an increased risk of component failure.

[0003] In terms of fire resistance, most products only meet the B1-level standard. The flame retardant mechanism relies on the endothermic dehydration of gypsum, but it is easy to form molten dripping objects at high temperatures, which cannot meet the fire resistance requirements of A-level non-combustible materials for high-rise buildings.

[0004] The defects in thermal performance are manifested as a relatively high thermal conductivity (≥0.25 W / m·K), and the heat insulation ability is 20% - 30% lower than that of traditional materials. This is due to the unreasonable pore structure and low interfacial thermal resistance, resulting in easy heat conduction.

[0005] Among the durability indicators, the water absorption rate of the material is as high as 15% - 20%. Under freeze-thaw cycles (≤300 times), the pore structure is easily damaged, the mass loss exceeds 5%, and the compressive strength attenuation reaches more than 30%. This is directly related to the high pore connectivity and insufficient impermeability performance.

[0006] Although existing modification technologies have tried to add single fibers or ordinary fillers, there are three major limitations: a single reinforcement mechanism is difficult to achieve the coordinated improvement of multi-dimensional properties; nano-fillers are prone to agglomeration due to high surface energy and have insufficient dispersibility; there is a lack of chemical bonding at the fiber-matrix interface, and the compatibility problem has not been solved, so the reinforcing phase efficiency cannot be fully exerted.

[0007] Based on the above technical defects, existing GRG materials are already difficult to meet the requirements of modern buildings for high performance and functional integration. Therefore, it is urgent to develop a new GRG material system to achieve a breakthrough improvement in the key properties of the material through multi-scale reinforcement networks, pore structure optimization, and interface control technologies. Summary of the Invention

[0008] The present invention aims to provide a GRG gypsum composite reinforcing material and its preparation method, aiming at the problems of insufficient mechanical properties, low fire protection level, poor thermal performance and durability defects of existing GRG materials. Through the adoption of composite reinforcing fibers, functional nano-fillers and gradient preparation processes, a multi-dimensional synergistic reinforcement system is constructed to solve the problems of nano-filler dispersion and interfacial compatibility, and achieve performance breakthroughs in high strength, high fire resistance, low thermal conductivity and long durability.

[0009] To achieve the above object, the present invention provides the following technical solutions: The technical solution provided by the present invention is: a GRG gypsum composite reinforcing material, including by weight: 45-65 parts of α-hemihydrate gypsum, 12-20 parts of composite reinforcing fibers, 0.5-2 parts of graphene nanofibers, 2-5 parts of nano-silica fume, 5-10 parts of ethylene-vinyl acetate copolymer latex powder, 1-2.5 parts of hydroxypropyl methylcellulose, 0.1-0.8 parts of polycarboxylate superplasticizer, 1-4 parts of calcium stearate, 3-8 parts of vermiculite powder, and 28-40 parts of deionized water; The composite reinforcing fibers are a mixed fiber of basalt fibers and aramid fibers, with a mass ratio of 3:1, both surface-modified with KH-560 silane coupling agent, fiber length 5-8 mm, and diameter 10-15 μm; The graphene nanofibers are prepared by chemically reducing graphene oxide with 3-5 layers, with a transverse size of 5-10 μm, and the surface is coated with dopamine; The vermiculite powder is expanded vermiculite crushed by air flow to a particle size of 20-50 μm, and the surface is treated with NDZ-201 titanate coupling agent. Further, the purity of α-hemihydrate gypsum is ≥97%, the calcium oxide content is ≥93%, the standard consistency water consumption is 24%-30%, and the specific surface area is 450-500 m² / kg.

[0010] Further, the average particle size of the nano-silica fume is 10-20 nm, the SiO2 content is ≥95%, the pozzolanic activity index is ≥90%, and the surface is treated with stearic acid.

[0011] Further, it also includes 1-3% of magnesium hydroxide flame retardant based on the total amount, with a particle size of 3-8 μm, and the surface is coated with stearic acid.

[0012] A preparation method of a GRG gypsum composite reinforcing material includes the following steps: S1: Fiber pretreatment, mixing basalt fibers and aramid fibers according to a mass ratio of 3:1, adding a 2-3% KH-560 silane coupling agent ethanol solution (1.5-2.5% of the total fiber mass), ultrasonically treating at 70-80 °C for 15-20 min (power 300-400 W, frequency 40 kHz), and drying to a moisture content ≤0.2% to obtain composite reinforcing fibers; S2: Graphene dispersion. Disperse graphene nanofibers in deionized water, add 0.1 - 0.3% polyvinylpyrrolidone (PVP) as a dispersant, and treat it with an ultrasonic homogenizer (power 500 - 600W, frequency 20kHz) for 20 - 30 min to obtain a graphene suspension with an absolute Zeta potential ≥ 40 mV; S3: Functional powder blending. Put α - hemihydrate gypsum, nano - silica fume, ethylene - vinyl acetate copolymer latex powder, hydroxypropyl methylcellulose, polycarboxylate superplasticizer, calcium stearate, vermiculite powder, and magnesium hydroxide into a double - planetary mixer, mix at a speed of 400 - 500 r / min for 20 - 30 min, and pass through a 120 - mesh sieve; S4: Slurry preparation. Add the graphene suspension and the remaining deionized water to the mixed powder, and stir with a high - speed disperser at a speed of 500 - 600 r / min for 8 - 10 min to make the slurry fluidity reach 200 - 220 mm; S5: Fiber dispersion and forming. Add the pretreated composite reinforcing fibers, disperse at a speed of 800 - 1000 r / min for 10 - 15 min to ensure that the fiber dispersion uniformity ≥ 99%; inject the slurry into a mold preheated to 50 - 60 °C, and vibrate on a vibrating platform with a frequency of 60 - 80 Hz and an amplitude of 0.5 - 0.8 mm for 30 - 45 s; S6: Gradient curing. Conduct low - temperature initial setting (stand still at 18 - 22 °C, humidity 90 - 95% for 3 - 4 h), medium - temperature strengthening (constant - temperature curing at 70 ± 5 °C for 6 - 8 h), high - temperature crystallization (microwave - assisted heating curing at 90 ± 5 °C for 2 - 3 h, microwave power 300 - 500W), and natural curing (normal temperature and normal humidity environment for 96 h) in sequence. Furthermore, in S1, the drying conditions are a temperature of 85 - 95 °C and a time of 40 - 50 min to form a uniform coupling agent coating layer on the fiber surface. Furthermore, in the high - temperature crystallization stage of S6, microwave - assisted heating is combined with traditional heat conduction to control the directional growth of gypsum crystals along the crystal plane, and the crystal aspect ratio ≤ 3:1.

[0013] The beneficial effects of this technical solution are: (1) The synergistic improvement of high strength and heat preservation performance breaks through the bottlenecks of load-bearing and energy conservation of traditional materials. Through the innovative design of a three-dimensional composite reinforcement system and a multi-scale heat insulation network, this technology has achieved a double breakthrough in mechanical properties and thermal performance. The materials selected are basalt fiber (high strength) and aramid fiber (high toughness) compounded in a ratio of 3:1 to form a "rigid-flexible combination" mechanical skeleton. The flexural strength can reach 17 - 20 MPa (only 8 - 10 MPa for traditional GRG), which is 100% - 150% higher than that of single-fiber reinforcement, meeting the high load-bearing requirements of large-span and thin-walled components. At the same time, graphene nanofibers (with 3 - 5 layers) and airflow-crushed vermiculite powder (with a particle size of 20 - 50 μm) are introduced. The former forms a "molecular glue" through dopamine coating, generating chemical covalent bonds with the gypsum matrix (the interfacial binding energy is increased by 115%). The latter constructs a "microporous heat insulation layer" with a porous structure. The two work together to reduce the thermal conductivity to 0.13 - 0.16 W / m・K (0.28 W / m・K for traditional materials), meeting the A-level heat preservation standard, and can replace the traditional heat insulation layer, combining the functions of decoration and energy conservation. In addition, nano-silica fume (with a particle size of 10 - 20 nm) and microwave-assisted crystallization process promote the directional growth of gypsum crystals (aspect ratio ≤ 3:1), increasing the density to over 98%, and the compressive strength can reach up to 62.4 MPa, strengthening the material integrity from the microstructural level.

[0014] (2) Utilizing the gradient flame retardant mechanism of magnesium hydroxide flame retardant and vermiculite powder, combined with the carbonization barrier effect of graphene nanofibers, this technology breaks through the fire protection bottleneck of traditional GRG materials. Magnesium hydroxide (with a particle size of 3 - 8 μm) decomposes endothermically above 340°C (endothermic value ≥ 1300 kJ / kg), reducing the surface temperature of the material by 20 - 30°C and diluting the concentration of combustible gases released. Vermiculite powder forms a porous structure (average pore diameter of 5 - 10 μm) after airflow crushing, expanding and blocking the pores at high temperatures, reducing the oxygen permeability from 20% to less than 8% and inhibiting the combustion reaction. Graphene nanofibers form a carbonization barrier layer during combustion, preventing the diffusion of heat and smoke. Under the triple action, the oxygen index of the material is increased to 32.5% - 34.2% (26% for traditional materials), and the fire resistance limit is ≥ 3 hours (1.5 hours for traditional materials), meeting the GB8624 - 2012 A1-level non-combustible standard, filling the gap in the application of traditional GRG materials (B1 level) in the core area of super high-rise buildings. In addition, the flame retardant system uses the compounding of inorganic hydroxides and natural minerals, avoiding the release of toxic gases from halogen flame retardants, which is in line with the development trend of green building materials.

[0015] (3) Through interface modification technology and gradient preparation process, breakthroughs have been achieved in the aspects of water resistance, freeze-thaw resistance and production efficiency of the material. Calcium stearate and titanate coupling agent are used to hydrophobically modify the gypsum matrix and vermiculite powder respectively, forming a single-molecule hydrophobic film (contact angle ≥ 90°). The water absorption rate is reduced from 18.5% to 7.2% - 8.0%, significantly reducing the risks of mold erosion and softening caused by water intrusion. The synergistic effect of surface silane coupling agent treatment (KH-560) of composite reinforcing fibers and dense crystal structure (porosity ≤ 12%) increases the number of freeze-thaw cycles to 450 - 550 times (traditional ≤ 300 times), adapting to the climatic conditions in cold regions (such as Northeast and Northwest China). In the preparation process, ultrasonic homogenization and dispersion technology (Zeta potential ≥ 40mV) solves the problem of nano-filler agglomeration, and the material homogeneity is improved by 60%. The gradient curing process (low-temperature initial setting → medium-temperature strengthening → high-temperature crystallization) shortens the total curing period to 96 hours (traditional 7 days). Combined with microwave-assisted crystallization (energy utilization rate increased by 30%), the production efficiency is increased by 40%. At the same time, by optimizing the vibration molding parameters (frequency 60 - 80Hz), the slurry density is ensured to be ≥ 98%, reducing internal defects from the source. The above technologies extend the service life of the material in harsh environments such as humidity and high-low temperature cycles by more than 2 times, with both engineering applicability and industrial production advantages. Description of the Drawings

[0016] Figure 1 Key parameter and performance comparison of each embodiment of a GRG gypsum composite reinforcing material and its preparation method proposed by the present invention; Figure 2 Comparison table between the embodiments of a GRG gypsum composite reinforcing material and its preparation method proposed by the present invention and the prior art; Detailed Description of the Invention

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0018] The specific implementation process is as follows: Example 1: Please refer to Figure 1-2 , a technical solution provided by the present invention: a GRG gypsum composite reinforcing material and its preparation method, including 55.0 parts of α-hemihydrate gypsum. High-purity raw materials with a purity of 97.2% and a calcium oxide content of 93.5% are selected. Its standard consistency water consumption is 26%, and the specific surface area is 480m² / kg, ensuring the hydration activity and early strength of the cementitious system; 12.0 parts of basalt fiber and 4.0 parts of aramid fiber form a composite reinforcing fiber, and the mass ratio of the two is 3:1. The basalt fiber is an alkali-free type with a diameter of 12 μm and a length of 6 mm, and is treated with an ethanol solution of KH-560 silane coupling agent with a concentration of 2.0% (the volume ratio of ethanol to water is 9:1, and the pH value of the solution is adjusted to 9.0); the aramid fiber is para-aramid with a diameter of 13 μm and a length of 7 mm, and together with the basalt fiber constitutes a mechanical reinforcing framework; 1.0 part of graphene nanofiber, which is few-layer graphene with 3 - 5 layers, has a lateral size of 5 - 8 μm, and the surface is coated with dopamine to form a polydopamine coating with a thickness of 10 - 15 nm to improve the interfacial compatibility with the gypsum matrix; 3.0 parts of nano-silica fume, with an average particle size of 15 nm and a SiO₂ content of 96%, is treated with stearic acid, and the modification degree reaches 85% to improve the dispersibility and pozzolanic activity in aqueous slurries; 5.0 parts of vermiculite powder, which is obtained by air-flow pulverization of expanded vermiculite to a particle size of 20 - 50 μm, and then treated with NDZ-201 titanate coupling agent, and the dosage of the coupling agent is 2% of the mass of the vermiculite powder to impart surface hydrophobicity; The functional additives include: 7.0 parts of ethylene-vinyl acetate copolymer latex powder (glass transition temperature -15 °C, solid content 98%), 1.5 parts of hydroxypropyl methylcellulose (substitution degree 1.2, viscosity of 2% aqueous solution 5000 mPa・s), 0.5 part of polycarboxylate superplasticizer (solid content 30%, water reduction rate 25%), 2.0 parts of calcium stearate (particle size 5 μm, fatty acid content ≥99%), 2.0 parts of magnesium hydroxide flame retardant (particle size 5 μm, treated with stearic acid, coating rate 90%); 35.0 parts of deionized water, with a conductivity ≤10 μS / cm, to avoid the influence of impurities on the hydration reaction; The preparation method is as follows: S1: Pretreatment of composite reinforcing fiber. Put basalt fiber and aramid fiber into a high-speed mixer according to a mass ratio of 3:1, premix at a speed of 200 r / min for 5 minutes to make the two fibers evenly dispersed; configure an ethanol solution of KH-560 silane coupling agent with a concentration of 2.0%, and evenly spray it onto the fiber surface according to the dosage of 1.8% of the total fiber mass, and make the coupling agent fully infiltrate the fiber through high-speed stirring; transfer the infiltrated fiber into a 75 °C constant-temperature blast drying oven, and dry it at a hot air circulation rate of 1.5 m / s for 45 minutes until the moisture content on the fiber surface ≤0.15% to form a uniform silane coupling agent coating layer to enhance the interfacial bonding force between the fiber and the gypsum matrix; S2: Graphene nanofiber dispersion Add 1.0 part of graphene nanofibers to 10 parts of deionized water, and add 0.02 part of polyvinylpyrrolidone (PVP) with a molecular weight of 40,000 as a dispersant. Treat it with a JYD-650 ultrasonic homogenizer (power 550W, frequency 20kHz) for 25 minutes. During this period, control the water temperature ≤ 30°C through circulating cooling water to avoid the oxidation of graphene caused by high temperature. After detection by a Zeta potential analyzer, the potential value of the dispersion liquid is -45mV, and the absolute value ≥ 40mV, forming a stable graphene suspension to ensure the uniform dispersion of nanosheets without agglomeration; S3: Functional powder blending Put α-hemihydrate gypsum, nano-silica fume, ethylene-vinyl acetate copolymer latex powder, hydroxypropyl methylcellulose, polycarboxylate superplasticizer, calcium stearate, vermiculite powder, and magnesium hydroxide into an SDS-10 double planetary mixer. First, mix at a low speed of 200r / min for 5 minutes to make the components initially contact, and then increase the speed to 450r / min and mix at a high speed for 20 minutes. Through strong shearing action, the powders are uniformly dispersed. Finally, the particle size distribution D90 of the powders ≤ 75μm; After mixing, pass through a 120-mesh stainless steel sieve to remove the undispersed coarse particles to ensure the uniformity of the slurry; S4: Slurry preparation Add the prepared graphene suspension and the remaining 25 parts of deionized water to the mixed powders, start a high-speed disperser (rotation speed 550r / min) and stir for 8 minutes. During this period, monitor the slurry temperature ≤ 40°C in real time to avoid the premature curing of ethylene-vinyl acetate copolymer latex powder due to high temperature; Stir until the fluidity of the slurry reaches 210mm (tested according to the GB / T2419 standard) to form a uniform slurry with good construction performance; S5: Fiber dispersion and forming Add the pretreated composite reinforcing fibers in 3 times (with an interval of 1 minute each time), gradually increase the stirring speed to 900r / min, and disperse for 12 minutes. Detect the fiber dispersion state through a laser particle size analyzer. Stop stirring when the fiber particle size of ≥ 99% is in the range of 5 - 8mm to ensure the uniform distribution of fiber filaments; Inject the slurry into an aluminum mold preheated to 55°C (the inner wall is coated with methyl silicone oil release agent), and place it on a ZDP-60 vibration platform (frequency 70Hz, amplitude 0.6mm) and vibrate for 40 seconds until the surface bubble escape rate ≤ 5 bubbles / 10cm² to eliminate internal pores and improve the density; S6: Gradient curing process Low-temperature initial setting: Move the mold into a constant temperature and humidity chamber (temperature 20°C, humidity 92%), and let it stand for 3.5 hours until the slurry loses plasticity (Vicat hardness ≥ 30HV) to form an initial structural strength; Medium-temperature strengthening: Transfer it to a 70°C constant temperature oven for curing for 7 hours. During this period, turn on forced ventilation (wind speed 0.5m / s) to promote the film formation of ethylene-vinyl acetate copolymer latex powder inside the material and enhance the toughness of the matrix; High-temperature crystallization: Transfer it into a microwave-assisted curing box (power 400W, frequency 2.45GHz), cure it at 90°C for 2.5 hours, and use an infrared thermometer to monitor the surface temperature of the mold in real time, controlling the temperature fluctuation ≤ ±2°C. Utilize microwave energy to promote the oriented growth of gypsum crystals along the (020) crystal plane; Natural curing: After demolding, place the specimens in a normal temperature environment (25°C, humidity 60%) for 96 hours. Spray water twice a day during this period to keep the surface moist, ensuring the full hydration of gypsum and crystal development; Key performance characteristics: Observed by scanning electron microscope, the dispersion uniformity of graphene nanofibers in the gypsum matrix is ≥98%. An obvious chemical bonding structure can be seen at the fiber-matrix interface, and the interfacial bonding force is tested to reach 32.8 J / m². X-ray diffraction analysis shows that the gypsum crystals mainly grow in an oriented manner along the (020) crystal plane, with a crystal aspect ratio of 2.5:1 and a porosity ≤ 12%, endowing the material with excellent mechanical properties and durability.

[0019] Example 2: Please refer to Figure 1-2 , a technical solution provided by the present invention: A GRG gypsum composite reinforcing material and its preparation method. In this example, the content of graphene nanofibers is adjusted on the basis of Example 1 to enhance the thermal conductivity. The specific components are as follows: Including, 55.0 parts of α-hemihydrate gypsum, with a purity of 97.2%, a calcium oxide content of 93.5%, a standard consistency water demand of 26%, and a specific surface area of 480 m² / kg; 12.0 parts of basalt fiber and 4.0 parts of aramid fiber, with a mass ratio of 3:1. The fiber specifications and treatment processes are the same as those in Example 1; 2.0 parts of graphene nanofibers, with 3 - 5 layers, a lateral size of 5 - 8 μm, and dopamine coating treatment (coating thickness 10 - 15 nm); 3.0 parts of nano-silica fume, with an average particle size of 15 nm, a SiO2 content of 96%, and stearic acid modification (modification degree 85%); 5.0 parts of vermiculite powder, with a particle size of 20 - 50 μm, and NDZ-201 titanate treatment (coupling agent dosage 2%); Functional additives: 7.0 parts of ethylene-vinyl acetate copolymer latex powder, 1.5 parts of hydroxypropyl methyl cellulose, 0.5 part of polycarboxylate-based water reducer, 2.0 parts of calcium stearate, 2.0 parts of magnesium hydroxide flame retardant, with the same specifications as in Example 1; 36.0 parts of deionized water. Due to the increase in graphene content, the water volume is appropriately increased to maintain the stability of the water-gypsum ratio, and the conductivity ≤ 10 μS / cm; The preparation method is adjusted as follows (the rest is the same as in Example 1): Adjust S2 in Example 1: For the dispersion of graphene nanofibers, to ensure the dispersion stability of a high content of graphene, increase the dosage of the dispersant PVP to 0.06 parts (3% of the mass of graphene). Adopt a two-step dispersion method: first, ultrasonically treat for 15 minutes at a power of 600W to break up the graphene aggregates, and then reduce the power to 500W and treat for another 15 minutes to avoid local overheating causing sheet stacking. Observed by transmission electron microscopy, the interlayer spacing of the graphene sheets remains at 1.2nm, without obvious agglomeration. The Zeta potential of the dispersion liquid is detected to be -48mV, and the stability is further improved compared to Example 1. Adjust S5 in Example 1: For fiber dispersion, due to the increase in graphene content, the interaction between the nano-fillers and the fibers during stirring is enhanced. Increase the stirring speed to 1000r / min and extend the dispersion time to 15 minutes. Ensure the synergistic dispersion of graphene and the composite reinforcing fibers through high-intensity shearing. Detected by a laser particle size analyzer, the dispersion uniformity of the fibers and nano-fillers is ≥98.5%. Key performance characteristics: The high content of graphene nanofibers forms a denser nano-sheet network in the gypsum matrix, significantly reducing the heat conduction efficiency through the phonon scattering effect. The thermal conductivity is reduced by 7.1% compared to Example 1, reaching 0.13W / m・K. At the same time, the interfacial synergistic strengthening effect between graphene and the composite reinforcing fibers increases the flexural strength to 19.5MPa, verifying the superposition effect of nano-filler and fiber reinforcement.

[0020] Example 3: Please refer to Figure 1-2 , a technical solution provided by the present invention: A GRG gypsum composite reinforcing material and its preparation method. In this example, with the goal of improving mechanical properties, increase the dosage of the composite reinforcing fibers and adjust the filler ratio. The specific components are as follows: Including, 55.0 parts of α-hemihydrate gypsum, with the same specification as in Example 1; 15.0 parts of basalt fiber and 5.0 parts of aramid fiber, with a mass ratio of 3:1. The fiber diameters are 12μm and 13μm respectively, and the length is 6 - 7mm. Treated with 2.5% KH-560 silane coupling agent (the treatment process is the same as in Example 1, but the dosage of the coupling agent is increased to adapt to the high fiber content); 1.0 part of graphene nanofibers, with the same specification and treatment process as in Example 1; 3.0 parts of nano-silica fume, with the same specification as in Example 1; 3.0 parts of vermiculite powder, with a particle size of 20 - 50μm, treated with NDZ-201 titanate coupling agent (coupling agent dosage 2%). Due to the increase in fiber content, appropriately reduce the vermiculite powder to balance the total volume; Functional additives: 7.0 parts of ethylene-vinyl acetate copolymer latex powder, 1.5 parts of hydroxypropyl methylcellulose, 0.5 part of polycarboxylate superplasticizer, 2.0 parts of calcium stearate, 2.0 parts of magnesium hydroxide flame retardant, with the same specifications as in Example 1; 35.0 parts of deionized water, with conductivity ≤ 10 μS / cm; The preparation method is adjusted as follows (the rest is the same as in Example 1): Adjust S1 in Example 1: For fiber pretreatment to ensure the surface modification effect at a high fiber content, increase the dosage of silane coupling agent to 2.5% of the total fiber mass, raise the treatment temperature to 80 °C, and extend the drying time to 50 minutes, so that the coupling agent can react more fully with the hydroxyl groups on the fiber surface to form a uniform and dense coating layer; Adjust S5 in Example 1: Fiber dispersion and forming adopt a three-stage dispersion process: First, premix at a low speed of 300 r / min for 3 minutes to make the fibers preliminarily wet and dispersed; then disperse at a medium speed of 600 r / min for 5 minutes to break the fiber bundle structure and form a single-filament trend; finally, disperse at a high speed of 1000 r / min for 10 minutes to achieve complete single-filament of the fibers. After detection, the dispersion uniformity ≥ 99.5%; when vibration forming, increase the frequency to 75 Hz and extend the time to 45 seconds to ensure the slurry density at a high fiber content, and the measured density reaches 98.5%; Key performance characteristics: The total amount of composite reinforcing fibers is increased to 20 parts (accounting for 18%), forming a denser three-dimensional reinforcement network. The compressive strength is increased to 62.4 MPa, and the flexural strength reaches 20.1 MPa, meeting the high load-bearing requirements of large-span GRG components; however, due to the increase in the micro-porosity between fibers to 13.5%, the number of freeze-thaw cycles is slightly reduced to 480 times, and it can be further optimized by adjusting the dosage of calcium stearate or superhydrophobic modification of the fiber surface in the future.

[0021] Example 4: Please refer to Figure 1-2 , a technical solution provided by the present invention: A GRG gypsum composite reinforcing material and its preparation method. In this example, improving the fire resistance performance is the core, increasing the dosage of flame retardant and adjusting related components, specifically as follows: Including, 55.0 parts of α-hemihydrate gypsum, with the same specifications as in Example 1; 12.0 parts of basalt fiber and 4.0 parts of aramid fiber, with a mass ratio of 3:1, with the same specifications and treatment processes as in Example 1; 0.5 part of graphene nanofiber. Due to the increase in the proportion of flame retardant, appropriately reduce the graphene dosage to balance the filler volume; 3.0 parts of nano-silica fume, with the same specifications as in Example 1; 5.0 parts of vermiculite powder, with the same specifications as in Example 1; Functional additives: 7.0 parts of ethylene-vinyl acetate copolymer latex powder, 1.5 parts of hydroxypropyl methylcellulose, 0.5 part of polycarboxylate superplasticizer, with the same specifications as in Example 1; 3.0 parts of calcium stearate (1.0 part more than in Example 1 to enhance hydrophobicity); 3.0 parts of magnesium hydroxide flame retardant (particle size 5 μm, treated with stearic acid coating, coating rate 90%, 1.0 part more than in Example 1); 35.0 parts of deionized water, with conductivity ≤ 10 μS / cm; The preparation method is adjusted as follows (the rest is the same as in Example 1): Adjust S3 in Example 1: For the blending of functional powders, the feeding order of "flame retardant first and then fiber" is adopted: First, put the magnesium hydroxide flame retardant and vermiculite powder into the blender and premix at a speed of 300 r / min for 10 minutes to form an interfacial synergistic effect between the stearic acid coating layer on the surface of the flame retardant and the titanate coupling agent layer of the vermiculite powder; then add other powder components, and extend the blending time to 30 minutes to ensure that the flame retardant is evenly dispersed and fully combined with the filler; Adjust S6 in Example 1: In the medium-temperature strengthening stage of the curing process, the humidity is increased to 85% to promote the formation of a continuous hydrophobic film of calcium stearate on the surface and internal pores of the material, offsetting the influence brought by the hygroscopicity of the magnesium hydroxide flame retardant. After the water absorption test, the water absorption of Example 4 is controlled at 8.0%, still meeting the requirements of high-performance GRG materials; Key performance features: The magnesium hydroxide flame retardant and vermiculite powder form a "heat absorption - heat insulation" dual flame retardant system: Magnesium hydroxide decomposes above 340 °C to absorb heat and release water vapor, reducing the matrix temperature; the porous structure of vermiculite powder inhibits oxygen penetration and flame spread, increasing the oxygen index to 34.2% and extending the fire resistance limit to 3.75 hours, meeting the GB8624-2012 A1 class non-combustible standard, and is applicable to the core area of high-rise buildings with strict fire performance requirements.

[0022] Please refer to Figure 1-2 : Influence of graphene content (Example 2 vs Example 1): In Example 2, the graphene nanofibers are increased from 1.0 part to 2.0 parts. By constructing a denser nanosheet network, the thermal conductivity decreases from 0.14 W / m・K to 0.13 W / m・K (a 7% decrease), proving that the phonon scattering effect of graphene increases with the increase of content; at the same time, the flexural strength is increased to 19.5 MPa (↑7%), due to the interfacial synergistic strengthening effect between graphene and the composite reinforcing fiber. However, too high a content leads to an increase in the dosage of the dispersant and the ultrasonic time, and it is necessary to balance performance and cost in industrialization; Breakthrough of fiber content (Example 3 vs Example 1): Example 3: The total amount of composite reinforcing fibers was increased from 16 parts to 20 parts (↑25%). The flexural / compressive strength was increased to 20.1 MPa / 62.4 MPa respectively (↑10% / 13%). Due to the increased density of the three-dimensional fiber network, the load transfer efficiency was significantly improved. However, the micro-porosity between fibers increased from 12% to 13.5%, resulting in a slight decrease in the number of freeze-thaw cycles (480 times vs 500 times). This can be improved by hydrophobic modification of the fiber surface or optimization of the vibration compaction process in the future; Synergistic effect of flame retardant compounding (Example 4 vs Example 1): In Example 4, the amount of magnesium hydroxide was increased from 2.0 parts to 3.0 parts (↑50%), and the amount of calcium stearate was increased simultaneously (3.0 parts vs 2.0 parts). The oxygen index was increased to 34.2% (↑5%), and the fire resistance limit was extended to 3.75 h (↑15%). A dual flame retardant mechanism of "endothermic decomposition of magnesium hydroxide + heat insulation and oxygen barrier of vermiculite" was formed. Although the reduction of graphene content by half led to a slight increase in the thermal conductivity (0.16 W / m・K), the water absorption rate was still controlled at 8.0%, proving that calcium stearate effectively offset the hygroscopicity effect of the flame retardant; Synergistic effect of preparation process adjustment: Optimization of graphene dispersion process (Example 2): By increasing the amount of PVP (0.06 parts) and extending the ultrasonic time (30 min), the agglomeration problem of high-content graphene was solved. The absolute value of the Zeta potential of the dispersion liquid increased from 45 mV to 48 mV, ensuring the uniform distribution of nanosheets and laying a foundation for improving the thermal conductivity; Fiber dispersion and forming strengthening (Example 3): The three-stage dispersion process (low-speed premixing → medium-speed de-bundling → high-speed single-filamentation) increased the fiber dispersion uniformity from 99% to 99.5%. Combined with high-frequency vibration (75 Hz), the density reached 98.5%, and finally a breakthrough in mechanical properties was achieved; Curing humidity control (Example 4): The humidity in the medium-temperature stage was increased to 85%, which promoted the formation of a continuous hydrophobic film of calcium stearate on the pore surface. The water absorption rate was only 8.0% (close to 7.2% in Example 1), balancing the hygroscopicity risk brought by the addition of the flame retardant.

[0023] Advantages compared with the prior art: Mechanical properties: The flexural strength is 18.2 MPa (8.5 MPa in the prior art), which is more than twice that of traditional GRG, meeting the bearing requirements of large-span and thin-walled components and reducing the reinforcement or thickening design; Thermal performance: The thermal conductivity is 0.14 W / m・K (0.28 W / m・K in the prior art), which can directly replace part of the insulation layer, reducing building energy consumption and costs; Fire resistance performance: The oxygen index is 32.5% (26% in the prior art), and the fire resistance limit is 3.25 h (1.5 h in the prior art), meeting the non-combustible standard of Class A1, filling the gap in the fire protection field of existing GRG materials for high-rise buildings; Durability performance: The water absorption rate is 7.2% (18.5% in the prior art), and it can withstand 500 freeze-thaw cycles (200 cycles in the prior art), adapting to harsh environments such as severe cold and humidity, and the service life is increased by more than 2 times; Each embodiment realizes the directional optimization of performance by precisely adjusting the core components (graphene, fiber, flame retardant) and the supporting process: Taking Embodiment 1 as a benchmark, the synergistic strengthening mechanism of composite reinforcing fiber + nano filler + gradient curing is verified; Embodiments 2-4 respectively strengthen the thermal conductivity, mechanical properties, and fire resistance performance, demonstrating the scalability and flexibility of the technical solution of the present invention; Compared with the prior art, the present invention breaks through the performance bottleneck of traditional GRG materials through "biomimetic interface modification + multi-dimensional functional fillers + precise process control", achieving comprehensive superiority in key indicators such as mechanics, thermal engineering, fire protection, and durability, and has significant industrial application value.

[0024] The above are only embodiments of the present invention. Specific technical solutions or common knowledge such as characteristics well known in the art are not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be based on the content of its claims, and the specific implementation manners described in the specification can be used to interpret the content of the claims.

Claims

1. A GRG gypsum composite reinforced material, characterized in that: The composition comprises, by weight: 45-65 parts of α-hemihydrate gypsum, 12-20 parts of composite reinforcing fiber, 0.5-2 parts of graphene nanofiber, 2-5 parts of nano silica fume, 5-10 parts of ethylene-vinyl acetate copolymer latex powder, 1-2.5 parts of hydroxypropyl methylcellulose, 0.1-0.8 parts of polycarboxylic acid water reducer, 1-4 parts of calcium stearate, 3-8 parts of vermiculite powder, and 28-40 parts of deionized water; The composite reinforcing fiber is a mixed fiber of basalt fiber and aramid fiber, with a mass ratio of 3:1, both of which are surface-modified with KH-560 silane coupling agent, with a fiber length of 5-8 mm and a diameter of 10-15 μm; The graphene nanofibers are made of 3-5 layers of graphene oxide through chemical reduction, with a lateral size of 5-10 μm and a surface coated with dopamine; The vermiculite powder is expanded vermiculite that is pulverized by air flow to a particle size of 20-50 μm, and the surface is treated with NDZ-201 titanate coupling agent.

2. The GRG gypsum composite reinforced material according to claim 1, characterized in that: The α-hemihydrate gypsum has a purity of ≥97%, a calcium oxide content of ≥93%, a standard consistency water consumption of 24%-30%, and a specific surface area of ​​450-500m² / kg.

3. The GRG gypsum composite reinforced material according to claim 1, characterized in that: The nano silica fume has an average particle size of 10-20 nm, a SiO2 content of ≥95%, a volcanic ash activity index of ≥90%, and a surface modified by stearic acid.

4. The GRG gypsum composite reinforced material according to claim 1, characterized in that: It also includes 1-3% of the total amount of magnesium hydroxide flame retardant, with a particle size of 3-8μm and a surface coated with stearic acid.

5. A method for preparing the GRG gypsum composite reinforced material according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1: fiber pretreatment, basalt fiber and aramid fiber are mixed in a mass ratio of 3:1, 2-3% KH-560 silane coupling agent ethanol solution (1.5-2.5% of the total mass of the fiber) is added, ultrasonic treatment is performed at 70-80°C for 15-20min (power 300-400W, frequency 40kHz), and dried to a moisture content of ≤0.2% to obtain a composite reinforced fiber; S2: Graphene dispersion: graphene nanofibers are dispersed in deionized water, 0.1-0.3% polyvinyl pyrrolidone (PVP) is added as a dispersant, and an ultrasonic homogenizer (power 500-600W, frequency 20kHz) is used for 20-30min to obtain a graphene suspension with an absolute value of Zeta potential ≥40mV; S3: functional powder blending: put α-hemihydrate gypsum, nano silica fume, ethylene-vinyl acetate copolymer latex powder, hydroxypropyl methylcellulose, polycarboxylic acid water reducer, calcium stearate, vermiculite powder and magnesium hydroxide into a double planetary mixer, mix at a speed of 400-500r / min for 20-30min, and pass through a 120-mesh sieve; S4: slurry preparation, adding graphene suspension and remaining deionized water to the mixed powder, stirring at a speed of 500-600r / min for 8-10min using a high-speed disperser to make the slurry fluidity reach 200-220mm; S5: Fiber dispersion and molding: add the pretreated composite reinforcing fiber and disperse it at a speed of 800-1000r / min for 10-15min to ensure that the fiber dispersion uniformity is ≥99%; inject the slurry into the mold preheated to 50-60℃ and vibrate it on a vibration platform with a frequency of 60-80Hz and an amplitude of 0.5-0.8mm for 30-45s; S6: Gradient curing, including low-temperature initial setting (18-22℃, 90-95% humidity, standing for 3-4h), medium-temperature strengthening (70±5℃ constant temperature curing for 6-8h), high-temperature crystallization (90±5℃ microwave-assisted heating curing for 2-3h, microwave power 300-500W), and natural curing (normal temperature and humidity environment for 96h).

6. The method for preparing the GRG gypsum composite reinforced material according to claim 5, characterized in that: The drying conditions in S1 are a temperature of 85-95° C. and a drying time of 40-50 min, so that a uniform coupling agent coating layer is formed on the fiber surface.

7. The method for preparing the GRG gypsum composite reinforced material according to claim 5, characterized in that: The high temperature crystallization stage in S6 adopts a combination of microwave assisted heating and traditional heat conduction to control the directional growth of gypsum crystals along the crystal plane, and the crystal aspect ratio is ≤3:1.

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