Glass fiber reinforced phosphogypsum panel and preparation method thereof

Abstract

The invention relates to the technical field of building materials, and discloses a glass fiber reinforced ardealite panel and a preparation method thereof.The glass fiber reinforced ardealite panel comprises an ardealite base body and a reinforcing structure, the reinforcing structure is formed by laying gridding cloth at the positions 0.5-1 cm away from the bottom face and the top face of the panel, and the ardealite base body comprises, by mass, 70-85% of ardealite, 5-10% of glass fiber and 5-10% of glass fiber. 3-10% of small materials, 2-3% of polypropylene fibers and the balance of water. A zinc-citric acid-calcium ternary complex is decomposed under an energy barrier of 28-30 kJ / mol, a hydration exothermic peak is regulated and controlled so as to avoid temperature stress cracks, and the yield stress of slurry is reduced by cooperating with a water reducing agent, so that the compressive strength of the panel reaches 12.5-15.0 MPa specified by the ISO679 standard, the crack width is smaller than or equal to 0.08 mm under the hanging load of 100 kg, and the compressive strength of the panel is higher than that of the panel under the hanging load of 100 kg. Therefore, the ardealite panel can be ensured to have high strength performance and crack resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, in particular to a glass fiber reinforced phosphogypsum panel and a preparation method thereof. Background Art

[0002] Building materials refer to the general term for material materials used to construct building structures, enclosure systems and functional systems in construction projects. They must meet core indicators such as mechanical properties, functional characteristics, durability and environmental protection, and achieve performance transformation from raw materials to components through mechanisms such as gelation reaction, interface composite or microstructure regulation. Among them, phosphogypsum panel is an important building material.

[0003] Existing phosphogypsum panels are made of phosphogypsum. The soluble phosphorus pentoxide impurities and fluoride ion impurities in phosphogypsum interfere with the hydration and crystallization process, forming needle-shaped dihydrate gypsum crystals. The result is a 28-day compressive strength of only 6 to 10 MPa, which is lower than the minimum requirement of 12 MPa specified in the ISO679 standard. Under a hanging load of 100 kg, the crack width reaches 0.15 to 0.30 mm, resulting in low strength of the phosphogypsum panels and prone to cracking. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a glass fiber reinforced phosphogypsum panel and a preparation method thereof, which solves the problem that the phosphogypsum panel has low strength and is prone to cracking due to the interference of soluble phosphorus pentoxide impurities and fluoride ion impurities in the phosphogypsum with the hydration crystallization process.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: a glass fiber reinforced phosphogypsum panel and a preparation method thereof, comprising a phosphogypsum matrix and a reinforcement structure, wherein the reinforcement structure comprises mesh cloth laid on the bottom surface and 0.5-1 cm above the top surface of the panel, and the phosphogypsum matrix comprises the following components by mass percentage:

[0006] Phosphogypsum 70-85%, small materials 3-10%, polypropylene fiber 2-3%, and the balance is water.

[0007] According to the above technical solution, 70-85% phosphogypsum powder, 3-10% small materials, and 2-3% polypropylene fibers are weighed by mass percentage and water is added to make up the balance. A 10-20 μm polydimethylsiloxane release agent is applied to the inside of the mold, and a glass fiber mesh with a monofilament diameter of 9-13 μm is pretreated with a 1% silane ethanol solution. The small materials are stirred in water at a speed of 600 r / min for 30 seconds to raise the pH of the system to 10-11, activate the water reducer and chelate calcium ions. After adding the phosphogypsum powder, the stirring speed is 1650 r / min, and the polypropylene fiber is added at a rate of 0.5 g / s. The polycarboxylic acid water reducer reduces the yield stress of the slurry, and the zinc ions and citric acid The roots form a ternary complex and are stirred for 90 seconds to ensure that the fiber dispersion uniformity is ≥95% and the slurry expansion is 180-200mm; when layered injection molding, first pour 0.5-1cm slurry to lay the first layer of mesh cloth, and then pour it to 0.5-1cm from the top surface to lay the second layer to form an interface layer ≥1.2MPa; let it stand for 110 minutes for final setting to regulate crystal growth and hydration heat release; after demoulding, cure it in a dark environment at 15-30℃, 40-70% humidity and 0.5-2m / s wind speed for 28 days to reduce porosity, improve compressive strength, and give the material hanging and humidity regulation properties, so as to ensure that the phosphogypsum panel has high strength and crack resistance.

[0008] Preferably, the mesh cloth is a double-sided glass fiber mesh cloth.

[0009] Preferably, based on 1000 parts of phosphogypsum, the small material is composed of the following components in a mass ratio:

[0010] 30 parts of calcium hydroxide, 1.5 parts of retarder, 2.5 parts of water reducer, 0.5 parts of regulator, and 400 parts of water.

[0011] Preferably, the water reducer is a polycarboxylate water reducer with a bulk density of 400-700 kg / m 3 , moisture content ≤3%, chloride ion content ≤0.05% and pH value 7-9.

[0012] Preferably, the retarder is a citric acid compound and the regulator is a water-soluble zinc salt, and the two act synergistically on the β-CaSO4·0.5H2O phase in the phosphogypsum.

[0013] Preferably, a method for preparing a glass fiber reinforced phosphogypsum panel comprises the following steps:

[0014] S1. Prepare materials: prepare small materials, water, phosphogypsum and mold;

[0015] S2. Mix small ingredients with water: put the small ingredients into water and stir for 30 seconds;

[0016] S3. Add phosphogypsum and stir: Add phosphogypsum to the stirred water and stir at 1650 r / min for 1 minute and 30 seconds using a handheld blender;

[0017] S4, injection molding, pouring the stirred slurry into the mold;

[0018] S5, solidification and curing;

[0019] S6. After standing for 1 hour and 50 minutes until final setting, remove the gypsum board and place it under natural ventilation conditions for curing for 28 days.

[0020] Preferably, polypropylene fibers are added simultaneously during the stirring process in S3 at a rate of 5 g / 10 seconds, and the fiber dispersion uniformity is ≥85%.

[0021] Preferably, in S4, first pour 0.5-1 cm thick slurry to the bottom of the mold and lay the first layer of mesh cloth; continue pouring until it is 0.5-1 cm from the top surface and then lay the second layer of mesh cloth, and finally fill with the remaining slurry.

[0022] Preferably, during S4 injection molding, a 0.1-0.3 mm thick interface agent is pre-coated on the surface of the mesh cloth. The interface agent is prepared by mixing the S2 solution and calcium hydroxide in a volume ratio of 10:1. After coating, the mixture is allowed to stand for 20 seconds before pouring the slurry.

[0023] Preferably, the S6 curing conditions are: ambient temperature 15-30°C, relative humidity 40-70%, wind speed 0.5-2m / s, and avoid direct sunlight.

[0024] The present invention provides a glass fiber reinforced phosphogypsum panel and a preparation method thereof. It has the following beneficial effects:

[0025] 1. The present invention decomposes the zinc-citrate-calcium ternary complex at an energy barrier of 28-30 kJ / mol, regulates the appearance of the hydration exothermic peak to avoid temperature stress cracks, and cooperates with the water reducer to reduce the slurry yield stress. As a result, the compressive strength of the panel reaches 12.5-15.0 MPa as specified in the ISO679 standard, and the crack width is ≤0.08 mm under a hanging load of 100 kg, thereby ensuring that the phosphogypsum panel has high strength and crack resistance.

[0026] 2. The present invention achieves stress dispersion by controlling the porosity of the phosphogypsum matrix, combining plate-like dihydrate gypsum crystals with directional stacking along the mesh cloth to form a micro-arch structure, and installing double layers of mesh cloth at a depth of 0.5-1 cm at the bottom and top of the gypsum panel. This results in a finished product density of ≤1.2 g / cm3, thereby reducing the weight of existing cement concrete walls and meeting the demand for lightweight building materials in prefabricated buildings.

[0027] 3. The present invention uses industrial by-product phosphogypsum as the main matrix, and reacts calcium hydroxide in the small material with phosphorus impurities to form inert calcium phosphate precipitate, and zinc ions solidify fluoride ions to form zinc fluoride, thereby reducing raw material costs and absorbing ≥800 kg of industrial solid waste per ton of product, thereby avoiding water pollution caused by the storage of phosphogypsum.

[0028] 4. The present invention forms through-going capillary channels by stacking plate-like dihydrate gypsum crystals in the direction of the mesh cloth, and cooperates with Zn2 in zinc-doped calcium silicate to form a through-going capillary channel. + The specific adsorption effect of vacancies on water molecules can ensure that the phosphogypsum panels automatically adjust their humidity in a humid environment, thereby preventing condensation and mildew on the panels in a hot and humid environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a preparation flow chart of a glass fiber reinforced phosphogypsum panel and a preparation method thereof proposed in the present invention. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] An embodiment of the present invention provides a glass fiber reinforced phosphogypsum panel and a method for preparing the same. The panel comprises a phosphogypsum matrix and a reinforcement structure. The reinforcement structure comprises mesh cloths laid 0.5-1 cm above the bottom and top surfaces of the panel. The phosphogypsum matrix comprises the following components by mass percentage:

[0032] Phosphogypsum 70-85%, small materials 3-10%, polypropylene fiber 2-3%, and the balance is water.

[0033] Specifically, the glass fiber reinforced phosphogypsum panel is composed of a phosphogypsum matrix and a reinforcement structure, wherein the reinforcement structure adopts a double-layer reinforcement design in which a layer of mesh cloth is laid at a depth of 0.5-1 cm below the bottom surface and the top surface of the panel. The phosphogypsum matrix contains the following components in percentage by mass: phosphogypsum accounts for 70%-85%, which is the core cementitious material. The dihydrate calcium sulfate contained in it is converted into a semi-hydrated gypsum phase with cementing properties under the action of calcium hydroxide. At the same time, calcium hydroxide neutralizes the residual phosphoric acid and hydrogen fluoride impurities in the phosphogypsum to generate inert calcium phosphate and calcium fluoride precipitates; small materials account for 3%-10%, which are composed of 1000 parts of phosphogypsum, 30 parts of calcium hydroxide, 1.5 parts of retarder, 2.5 parts of water reducer, 0.5 parts of regulator and 400 parts of water, wherein the retarder is a citric acid compound, which delays the crystallization rate of dihydrate gypsum by chelating calcium ions with carboxyl groups. The regulator is zinc sulfate, and its zinc ions induce the formation of plate-like dihydrate gypsum crystals to improve the density and reduce The water-reducing agent is a polycarboxylic acid compound that reduces the water-cement ratio and increases the fluidity of the slurry through the steric hindrance effect. Polypropylene fibers account for 2%-3% and are 6-12mm in length, forming a three-dimensional crack-resistant network in the matrix. The water addition is controlled within the range of 35%-40% of the mass of the phosphogypsum, and the water amount is inversely proportional to the water reducer dosage. When the water addition is 35%, the water reducer dosage needs to reach 40 parts, and when the water addition is 40%, the water reducer dosage is 2.5 parts, thereby balancing fluidity and ultimate strength. Through the synergistic effect of the retarder and zinc salt regulator, this ratio system controls the hydration exothermic peak to appear 25-35 minutes after stirring is completed, and the final setting time is stably maintained within 110±5 minutes, ensuring that the slurry remains in a plastic state during the injection molding stage. At the same time, the plate-like calcium sulfate dihydrate crystals generated form a multi-scale reinforcement system with the polypropylene fibers and mesh cloth, ultimately achieving crack-free performance under a 100kg hanging load and the ability to regulate indoor relative humidity to 5%.

[0034] The mesh cloth is a double-sided glass fiber mesh cloth.

[0035] Specifically, the double-sided glass fiber mesh cloth is woven from glass fibers with a single fiber diameter of 9-13μm. After surface treatment with a silane coupling agent, active silanol groups are formed. The silanol groups on the surface of the glass fibers undergo a condensation reaction with the calcium hydroxide in the phosphogypsum matrix to form a cross-linked layer of calcium silicate hydrate and calcium aluminate hydrate, which increases the interfacial bonding strength to above 1.2MPa. At the same time, the mesh cloth has a mesh size of 4mm×4mm, which can constrain the distribution of polypropylene fibers and block the propagation path of hydration shrinkage cracks. The surface-treated glass fibers have a mass loss rate of less than 0.5% in an alkaline environment, ensuring that the tensile strength retention rate exceeds 85% after a 28d curing period. The double-layer reinforced structure, through the dual effects of chemical bonding and mechanical interlocking, ensures that when the gypsum panel is subjected to a hanging load of 100kg, the maximum crack width at 10cm from the edge does not exceed 0.1mm, and the interface peeling length after the wet-heat cycle test is less than 3mm.

[0036] Based on 1000 parts of phosphogypsum, the small material is composed of the following components in mass ratio:

[0037] 30 parts of calcium hydroxide, 1.5 parts of retarder, 2.5 parts of water reducer, 0.5 parts of regulator, and 400 parts of water.

[0038] Specifically, the small material is composed of 30 parts of calcium hydroxide, 1.5 parts of retarder, 2.5 parts of water reducer, 0.5 parts of regulator and 400 parts of water according to the mass ratio; wherein the phosphogypsum provides calcium sulfate dihydrate as a hydration reaction matrix, and the calcium hydroxide converts the residual phosphorus pentoxide in the phosphogypsum into tricalcium phosphate precipitation through acid-base neutralization reaction, while increasing the alkalinity of the system to pH 10-11 to activate the effectiveness of the water reducer; the retarder uses a citric acid compound, the carboxyl functional group of which forms a stable chelate with calcium ions, extending the crystallization induction period of dihydrate gypsum to 25-35 minutes; the water reducer It is a polycarboxylic acid-based polymer compound that reduces the slurry yield stress by 45%-50% through the steric hindrance effect, achieving high fluidity at a water-cement ratio of 0.35-0.40. The regulator is a zinc sulfate compound, and zinc ions are preferentially adsorbed on the axial growth surface of the gypsum crystals, inducing the formation of plate-like dihydrate gypsum crystals with an aspect ratio of 1.5-2.0, reducing the porosity of the hardened body to 18%-22%. The amount of water added is strictly controlled at 400 parts, of which 30% participates in the hydration reaction to form ettringite and calcium silicate hydrate, and 70% serves as a reaction medium and evaporates during the curing period to form a humidity regulation channel.

[0039] The water reducer is polycarboxylate water reducer with a bulk density of 400-700kg / m 3 , moisture content ≤3%, chloride ion content ≤0.05% and pH value 7-9.

[0040] Specifically, polycarboxylate water reducer is a polymer compound with a comb-like molecular structure, the main chain of which contains carboxyl groups and the side chains are polyoxyethylene ether units; the relevant performance parameters of the water reducer are as follows: bulk density 400-700kg / m3, ensuring the formation of a uniform mixture with phosphogypsum during the dry powder mixing stage; moisture content does not exceed 3% to prevent molecular chain hydrolysis and the attenuation of water reduction efficiency; chloride ion content is less than 0.05% to avoid reaction with calcium fluoride in phosphogypsum to form corrosive chlorofluoro compounds; 10wt% aqueous solution has a pH value of 7-9 at 20°C, which is compatible with the phosphogypsum system and does not produce precipitation; during the reaction process, the carboxyl groups of the main chain of the water reducer molecule are adsorbed on the surface of the gypsum particles through ionic bonds, and the polyethylene oxide side chains extend to the liquid phase to form a steric hindrance layer with a thickness of 1.2-1.5nm, which reduces the slurry yield stress by 45-50%, from the initial 85Pa to 45Pa; each gram of water reducer can cover 2 .5-3.0m2 gypsum particle surface area, through the synergistic effect of electrostatic repulsion and steric hindrance, the water-solid ratio is reduced from 0.45 to the range of 0.35-0.40, and the slurry expansion is increased to 180-200mm; the water reducer maintains the molecular chain extension state in a pH10-11 environment, and its polyether side chain forms a hydrogen bond network with water molecules, reducing the free water content by 23-25%, while inhibiting the ineffective consumption of the retarder citric acid, so that the nucleation induction period of dihydrate gypsum is stabilized at 25-35min. The water reducer has a synergistic effect with the zinc sulfate regulator: zinc ions preferentially occupy the active sites of gypsum crystal growth, and the water reducer adsorption film hinders the ion deposition in the c-axis direction of the crystal. Under the action of the dual mechanism, the aspect ratio of the dihydrate gypsum crystal is controlled to 1.5-2.0, and the porosity of the hardened body is reduced to 18-22%, ultimately achieving a 28d compressive strength of 12.5-15.0MPa, meeting the 100kg hanging load requirement.

[0041] The retarder is a citric acid compound and the regulator is a water-soluble zinc salt, and the two act synergistically on the β-CaSO4·0.5H2O phase in the phosphogypsum.

[0042] Specifically, the retarder citric acid compound releases hydrogen ions and citrate anions in aqueous solution through the ionization characteristics of three carboxyl groups and one hydroxyl group in its molecular structure; at the same time, the water-soluble zinc sulfate compound as a regulator dissociates to form zinc ions and sulfate ions, which synergistically act on the β-type hemihydrate calcium sulfate phase in phosphogypsum to form a triple reaction control mechanism: the citrate anion combines with the calcium ion to form a six-membered ring chelate with a stability constant of logK=10.9, covering 60-65% of the active sites on the surface of the hemihydrate gypsum particles, extending the nucleation induction period of dihydrate gypsum to 25-35 minutes; the zinc ion is selectively adsorbed on the c-axis 001 crystal plane of the dihydrate gypsum crystal, inhibiting the binding rate of hydroxyl ions, reducing the axial growth rate of the crystal by 35-40%, and promoting the development of long crystals along the ab plane. Plate-shaped crystals with a diameter ratio of 1.5-2.0; during this process, citric acid chelate preferentially consumes free calcium ions to promote the enrichment of zinc ions at the solid-liquid interface, forming a zinc-citrate-calcium ternary complex. The decomposition energy barrier of this complex at a pH value of 10-11 is 28-30 kJ / mol, and the hydration exothermic peak appears 25-35 minutes after stirring; this synergistic system controls the conversion rate of hemihydrate gypsum to 0.8-1.2% per minute, and the final setting time is stabilized at 110±5 minutes. The generated parallel stacked plate-shaped dihydrate gypsum crystals form capillary channels with an pore size of 50-200 nm in the gaps, resulting in the porosity of the hardened body reduced to 18-22%, the 28-day compressive strength reaching 12.5-15.0 MPa, and the humidity regulation capability achieving a relative humidity fluctuation range of ±5%.

[0043] Please see the attached Figure 1 A method for preparing a glass fiber reinforced phosphogypsum panel comprises the following steps:

[0044] S1. Prepare materials: prepare small materials, water, phosphogypsum and mold;

[0045] S2. Mix small ingredients with water: put the small ingredients into water and stir for 30 seconds;

[0046] S3. Add phosphogypsum and stir: Add phosphogypsum to the stirred water and stir at 1650 r / min for 1 minute and 30 seconds using a handheld blender;

[0047] S4, injection molding, pouring the stirred slurry into the mold;

[0048] S5, solidification and curing;

[0049] S6. After standing for 1 hour and 50 minutes until final setting, remove the gypsum board and place it under natural ventilation conditions for curing for 28 days.

[0050] Specifically, in the S1 material preparation stage, 70-85% of phosphogypsum powder, 3-10% of small materials and 2-3% of polypropylene fiber are weighed by mass percentage, and the rest is supplemented with water; the inner surface of the mold is coated with polydimethylsiloxane release agent with a coating thickness of 10-20 μm; the mesh cloth is woven with glass fiber, with a single fiber diameter of 9-13 μm, and is pretreated with a 1% mass fraction silane ethanol solution to form an active silanol group; in the S2 small material premixing stage, the small material is put into water and stirred at a speed of 600 r / min for 30 seconds, and the calcium hydroxide is dissolved to raise the pH of the system to 10-11, activating the reduction The molecular chain of the water agent stretches, and at the same time, the citric acid ionizes to produce hydrogen ions and citrate ions, which initially chelate the calcium ions in the solution. After adding the phosphogypsum powder in the S3 main material mixing stage, the mixture is immediately stirred at a speed of 1650r / min, and polypropylene fiber is added at a rate of 0.5g / s. The polycarboxylate water reducer reduces the slurry yield stress from 85Pa to 45Pa through the steric hindrance effect. The zinc ions dissociated from the zinc sulfate compete with the citrate to bind to the calcium ions to form a zinc-citrate-calcium ternary complex. Stirring is continued for 90s to ensure that the fiber dispersion uniformity reaches ≥95% and the slurry expansion reaches 180- 200mm; S4 layered injection molding stage, first pour 0.5-1cm slurry to the bottom of the mold and lay the first layer of mesh cloth, continue pouring to a height of 0.5-1cm from the top surface and lay the second layer of mesh cloth, the silanol group on the surface of the glass fiber condenses with calcium hydroxide to form a calcium silicate hydrate interface layer with a bonding strength of ≥1.2MPa; S5 solidification control stage, let it stand for 110min until final setting, zinc ions inhibit the growth of the c-axis of the dihydrate gypsum crystal to form plate-like crystals with an aspect ratio of 1.5-2.0, and the ternary complex decomposes at an energy barrier of 28-30kJ / mol, causing the hydration exothermic peak to After demoulding in the S6 curing and strengthening stage, the material is placed in a dark environment with a temperature of 15-30°C, a relative humidity of 40-70% and a wind speed of 0.5-2m / s for curing for 28 days. The plate-like dihydrate gypsum crystals are stacked in a directional manner along the mesh cloth to form capillary channels with an average pore size of 50-200nm, reducing the porosity to 18-22%. The 28d compressive strength reaches 12.5-15.0MPa, and finally achieves the ability to withstand a 100kg hanging load without cracking and the ability to adjust the relative humidity by ±5%.

[0051] See attached Figure 1 During the stirring process of S3, polypropylene fiber is added simultaneously at a rate of 5 g / 10 seconds, and the fiber dispersion uniformity is ≥85%.

[0052] Specifically, polypropylene fiber was added simultaneously during the stirring process of S3, and the addition rate was controlled to be 5.0±0.2g / 10s. The shear rate formed by the speed of 1650r / min was The fibers are evenly dispersed under a shear force of F = 1.8-2.2 mN. The polypropylene fibers are 6-12 mm in length and 18-22 μm in diameter. Their surfaces are treated with 0.5-0.8 wt% silane coupling agent to form active groups, which bind to the gypsum hydration products through hydrogen bonds in the alkaline slurry. When the fiber addition reaches 85% of the total, the slurry viscosity must be maintained in the range of 1.2-1.5 Pa·s to ensure that the fiber spacing is ≤ 0.8 mm. Finally, the dispersion uniformity is measured according to ISO3443 standard to be ≥ 85%.

[0053] See attached Figure 1 In S4, first pour 0.5-1 cm thick slurry to the bottom of the mold and lay the first layer of mesh cloth; continue pouring until it is 0.5-1 cm away from the top surface, lay the second layer of mesh cloth, and finally pour the remaining slurry.

[0054] Specifically, in S4, a 0.5-1 cm thick slurry layer is first poured into the bottom of the mold, and then the first layer of glass fiber mesh cloth pretreated with silane is laid. Within 30 seconds after contacting the slurry, a condensation reaction occurs with calcium hydroxide to form a calcium silicate hydrate interface layer with a thickness of 200-300 nm and a bond energy of 215 kJ / mol, so that the bonding strength is stable ≥ 1.2 MPa. The slurry is continued to be poured to a height of 0.5-1 cm from the top surface of the mold, and the second layer of mesh cloth is laid. Its position is precisely controlled at a depth of 45-55% of the panel thickness. At this time, the pH value of the slurry is 1 The 0-11 environment promotes the dissociation of zinc ions from the zinc sulfate regulator, which is enriched in the interface area of ​​the mesh cloth and forms a Zn[SiO4] doped structure with calcium silicate hydrate, thereby improving the moisture and heat resistance of the interface. Finally, the remaining slurry is poured into the full mold, and the total injection molding time is controlled to be ≤3 minutes to ensure that the slurry remains in a fluid state under the action of the citric acid retarder and the hydration exothermic peak has not yet appeared. At this time, it is less than 25 minutes since the completion of S3 stirring. The mesh size of 4×4mm can constrain the distribution of polypropylene fibers, so that the crack propagation within 8mm from the fiber can be absorbed by more than 90%.

[0055] See attached Figure 1 When S4 is injected into the mold, a 0.1-0.3mm thick interface agent is pre-coated on the surface of the mesh cloth. The interface agent is prepared by S2 mixed liquid and calcium hydroxide in a volume ratio of 10:1. After coating, let it stand for 20 seconds before pouring the slurry.

[0056] Specifically, the mesh cloth interface strengthening treatment is carried out in the S4 injection molding stage: the small material mixture prepared in S2 is taken and the interface agent is prepared with calcium hydroxide in a volume ratio of 10:1. This ratio ensures that the calcium ion concentration in the solution is stable at 120-150mmol / L; the interface agent is coated on the surface of the mesh cloth to form a 0.1-0.3mm continuous film layer. After coating, it is allowed to stand for 20 seconds. During this time window, the calcium ions dissociated from the calcium hydroxide diffuse to the surface of the glass fiber and react with the silanol group to form a calcium silicate hydrate transition layer with a bond energy of 215kJ / mol, which increases the interface bonding strength to 1.5M Pa, the citrate anions in the interface agent synchronously chelate excess calcium ions, control the reaction rate and avoid local gelation; the zinc ions dissociated from zinc sulfate are doped into the calcium silicate lattice to form a tetrahedral structure, which enhances the moisture and heat resistance of the interface layer; when pouring the slurry on the coated mesh cloth, the newly formed three-dimensional cross-linked network can increase the interface peeling energy to 450-500J / m2. This treatment makes the interface peeling length under 100kg hanging load ≤2.0mm, while the untreated sample is ≥5.0mm, and the strength loss rate after moisture and heat cycling under 40℃ / 90%RH conditions is ≤3%.

[0057] See attached Figure 1 , S6 curing conditions are: ambient temperature 15-30℃, relative humidity 40-70% and wind speed 0.5-2m / s, and avoid direct sunlight.

[0058] Specifically, during the curing stage, the demoulding gypsum board needs to be placed in a dark environment with an ambient temperature of 15-30°C, a relative humidity of 40-70%, and a wind speed of 0.5-2m / s for 28 days; during this process, the temperature fluctuation is controlled within ±2°C / h to avoid the plate-shaped calcium sulfate dihydrate crystals with an aspect ratio of 1.5-2.0 from generating phase change or microcracks due to thermal stress; the gradient environment with a relative humidity of 40-70% promotes the water content in the capillary channels with an average pore size of 50-200nm to be 0.1-0.3g / (m 2 h) rate of evaporation, simultaneously promoting a secondary hydration reaction between calcium silicate hydrate and zinc-doped calcium silicate to form a more cross-linked hexacalcium hexasilicate hydrate phase; an airflow of 0.5-2 m / s creates a laminar flow field with a Reynolds number of 8000-10000, evenly discharging surface moisture and ensuring that the porosity difference at different depths of the hardened body is ≤2%, with a baseline porosity range of 18-22%; and light protection conditions require a light intensity of ≤100 lux. This measure can prevent ultraviolet rays from decomposing the silane coupling agent on the surface of the polypropylene fiber, maintain a fiber-matrix interface bonding energy of ≥450 J / m2, and prevent local temperature rise exceeding 35°C, which would trigger the reverse transformation of calcium sulfate hemihydrate.

[0059] The following is the complete replacement of the embodiment content, only the preparation process part is modified to the specified format, and the rest of the description (ingredients, properties, applications, control experimental group) remains strictly unchanged:

[0060] Example 1:

[0061] 1. Ingredients:

[0062] Phosphogypsum 70%;

[0063] Small material 3% (components: 30 parts of calcium hydroxide / 1.5 parts of retarder / 40 parts of water reducer / 0.5 parts of regulator / 400 parts of water, based on 1000 parts of phosphogypsum);

[0064] Polypropylene fiber 2%;

[0065] Water 25%.

[0066] 2. Preparation process:

[0067] S1. Prepare materials: prepare small materials, water, phosphogypsum and mold;

[0068] S2. Mix small ingredients with water: put the small ingredients into water and stir for 30 seconds;

[0069] S3. Add phosphogypsum and stir: Add phosphogypsum to the stirred water and stir at 1650 r / min for 1 minute and 30 seconds using a handheld blender;

[0070] S4, injection molding, pouring the stirred slurry into the mold;

[0071] S5, solidification and curing;

[0072] S6. After standing for 1 hour and 50 minutes until final setting, remove the gypsum board and place it under natural ventilation conditions for curing for 28 days.

[0073] Control experimental group 1:

[0074] 1. Ingredients:

[0075] Phosphogypsum 70%, small material 3% (without zinc sulfate), polypropylene fiber 2% and water 25%.

[0076] 2. Preparation process:

[0077] S1. Prepare materials: prepare small materials, water, phosphogypsum and mold;

[0078] S2. Mix small ingredients with water: put the small ingredients into water and stir for 30 seconds;

[0079] S3. Add phosphogypsum and stir: Add phosphogypsum to the stirred water and stir at 1650 r / min for 1 minute and 30 seconds using a handheld blender;

[0080] S4, injection molding, pouring the stirred slurry into the mold;

[0081] S5, solidification and curing;

[0082] S6. After standing for 1 hour and 50 minutes until final setting, remove the gypsum board and place it under natural ventilation conditions for curing for 28 days.

[0083] Performance comparison table 1:

[0084]

[0085] Example 2

[0086] 1. Ingredients:

[0087] phosphogypsum 77.5%;

[0088] Small material 6.5% (same components as standard, 21.25 parts of water reducer);

[0089] Polypropylene fiber 2.5%;

[0090] Water 13.5%.

[0091] 2. Preparation process:

[0092] S1. Prepare materials: prepare small materials, water, phosphogypsum and mold;

[0093] S2. Mix small ingredients with water: put the small ingredients into water and stir for 30 seconds;

[0094] S3. Add phosphogypsum and stir: Add phosphogypsum to the stirred water and stir at 1650 r / min for 1 minute and 30 seconds using a handheld blender;

[0095] S4, injection molding, pouring the stirred slurry into the mold;

[0096] S5, solidification and curing;

[0097] S6. After standing for 1 hour and 50 minutes until final setting, remove the gypsum board and place it under natural ventilation conditions for curing for 28 days.

[0098] Control experimental group 2

[0099] 1. Ingredients:

[0100] Phosphogypsum 77.5%, small materials 6.5%, fiber 2.5%, water 20%.

[0101] 2. Preparation process:

[0102] S1. Prepare materials: prepare small materials, water, phosphogypsum and mold;

[0103] S2. Mix small ingredients with water: put the small ingredients into water and stir for 30 seconds;

[0104] S3. Add phosphogypsum and stir: Add phosphogypsum to the stirred water and stir at 1650 r / min for 1 minute and 30 seconds using a handheld blender;

[0105] S4, injection molding, pouring the stirred slurry into the mold;

[0106] S5, solidification and curing;

[0107] S6. After standing for 1 hour and 50 minutes until final setting, remove the gypsum board and place it under natural ventilation conditions for curing for 28 days.

[0108] Performance comparison table 2:

[0109]

[0110] Example 3

[0111] 1. Ingredients:

[0112] Phosphogypsum 85%;

[0113] Small material 10% (2.5 parts of water reducer);

[0114] Polypropylene fiber 3%;

[0115] Water 2%.

[0116] 2. Preparation process:

[0117] S1. Prepare materials: prepare small materials, water, phosphogypsum and mold;

[0118] S2. Mix small ingredients with water: put the small ingredients into water and stir for 30 seconds;

[0119] S3. Add phosphogypsum and stir: Add phosphogypsum to the stirred water and stir at 1650 r / min for 1 minute and 30 seconds using a handheld blender;

[0120] S4, injection molding, pouring the stirred slurry into the mold;

[0121] S5, solidification and curing;

[0122] S6. After standing for 1 hour and 50 minutes until final setting, remove the gypsum board and place it under natural ventilation conditions for curing for 28 days.

[0123] Control experimental group 3

[0124] 1. Ingredients: Same as Example 3.

[0125] 2. Preparation process:

[0126] S1. Prepare materials: prepare small materials, water, phosphogypsum and mold;

[0127] S2. Mix small ingredients with water: put the small ingredients into water and stir for 30 seconds;

[0128] S3. Add phosphogypsum and stir: Add phosphogypsum to the stirred water and stir at 1650 r / min for 1 minute and 30 seconds using a handheld blender;

[0129] S4, injection molding, pouring the stirred slurry into the mold;

[0130] S5, solidification and curing;

[0131] S6. After standing for 1 hour and 50 minutes until final setting, remove the gypsum board and place it under natural ventilation conditions for curing for 28 days.

[0132] Performance comparison table 3:

[0133]

[0134]

[0135] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A glass fiber reinforced phosphogypsum panel, characterized in that: It includes a phosphogypsum matrix and a reinforcement structure. The reinforcement structure is a mesh cloth laid on the bottom surface and 0.5-1 cm of the top surface of the panel. The phosphogypsum matrix includes the following components by mass percentage: Phosphogypsum 70-85%, small materials 3-10%, polypropylene fiber 2-3%, and the balance is water.

2. The glass fiber reinforced phosphogypsum panel according to claim 1, characterized in that: The mesh cloth is a glass fiber mesh cloth laid on both sides.

3. The glass fiber reinforced phosphogypsum panel according to claim 1, characterized in that: Based on 1000 parts of phosphogypsum, the small material is composed of the following components in proportion by mass: 30 parts of calcium hydroxide, 1.5 parts of retarder, 2.5 parts of water reducer, 0.5 parts of regulator, and 400 parts of water.

4. The glass fiber reinforced phosphogypsum panel according to claim 1, characterized in that: The water reducer is polycarboxylate water reducer with a bulk density of 400-700kg / m 3 , moisture content ≤3%, chloride ion content ≤0.05% and pH value 7-9.

5. The glass fiber reinforced phosphogypsum panel according to claim 1, characterized in that: The retarder is a citric acid compound and the regulator is a water-soluble zinc salt, and the two act synergistically on the β-CaSO4·0.5H2O phase in the phosphogypsum.

6. A method for preparing a glass fiber reinforced phosphogypsum panel, characterized in that: A glass fiber reinforced phosphogypsum panel as claimed in any one of claims 1 to 5 comprises the following steps: S1. Prepare materials: prepare small materials, water, phosphogypsum and mold; S2. Mix small ingredients with water: put the small ingredients into water and stir for 30 seconds; S3. Add phosphogypsum and stir: Add phosphogypsum to the stirred water and stir at 1650 r / min for 1 minute and 30 seconds using a handheld blender; S4, injection molding, pouring the stirred slurry into the mold; S5, solidification and curing; S6. After standing for 1 hour and 50 minutes until final setting, remove the gypsum board and place it under natural ventilation conditions for curing for 28 days.

7. The method for preparing a glass fiber reinforced phosphogypsum panel according to claim 6, characterized in that: During the stirring process of S3, polypropylene fibers are added simultaneously at a rate of 5 g / 10 seconds, and the fiber dispersion uniformity is ≥85%.

8. The method for preparing a glass fiber reinforced phosphogypsum panel according to claim 6, characterized in that: In S4, first pour 0.5-1 cm thick slurry to the bottom of the mold and lay the first layer of mesh cloth; continue pouring until it is 0.5-1 cm away from the top surface, then lay the second layer of mesh cloth, and finally pour the remaining slurry.

9. The method for preparing a glass fiber reinforced phosphogypsum panel according to claim 6, characterized in that: When S4 is injected into the mold, a 0.1-0.3 mm thick interface agent is pre-coated on the surface of the mesh cloth. The interface agent is prepared by mixing S2 and calcium hydroxide in a volume ratio of 10:

1. After coating, let it stand for 20 seconds before pouring the slurry.

10. The method for preparing a glass fiber reinforced phosphogypsum panel according to claim 6, characterized in that: S6 curing conditions are: ambient temperature 15-30℃, relative humidity 40-70% and wind speed 0.5-2m / s, and avoid direct sunlight.

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