Composite high-strength supporting material, and preparation method and construction process thereof

Abstract

The application relates to a composite high-strength supporting material and a preparation method and construction process thereof. Tailings sand powder in the application plays a certain lubricating role in the system and can reduce the slurry viscosity; the prepared special polycarboxylic acid water reducing agent has a micro-crosslinking structure and multiple adsorption groups, has extremely strong adsorption capacity on cement and tailings sand, and can reduce the slurry viscosity; the prepared organic polymer can quickly form an interpenetrating network structure with the cement-based material on the sprayed base surface, improves the slurry adhesion speed, reduces the spraying rebound rate, and effectively improves the strength, heat resistance, flame resistance and surface protection capacity of the target supporting material by introducing rigid / heat-resistant structures, flame-resistant structures and hydrophobic structures; the prepared high-strength supporting material has super-high compressive strength and bonding strength, fast hardening speed after spraying, excellent anti-cracking performance and good durability, improves the utilization rate of solid waste resources, has a simple and convenient construction process and high efficiency, and is suitable for construction in various complex environments.

Description

Technical Field

[0001] This invention relates to the field of concrete materials technology, specifically to a composite high-strength support material and its preparation method and construction process, applicable to support engineering in scenarios such as roadways, tunnels, slopes, piers, and old buildings. Background Technology

[0002] With the rapid development of my country's mining industry, the amount of tailings discharged has been increasing year by year. Statistics show that the cumulative tailings stockpile in my country has exceeded 10 billion tons, with iron tailings accounting for about half of the total. However, the comprehensive utilization rate of tailings is currently low, and a large amount of tailings is still disposed of through stockpiling and landfilling, which not only occupies a large amount of land resources but also causes serious environmental pollution and potential geological disaster risks. Therefore, promoting the resource utilization of tailings has become a critical issue that urgently needs to be addressed in the field of solid waste treatment.

[0003] Meanwhile, support projects for roadways, tunnels, slopes, and the reinforcement of old buildings place stringent demands on material performance. Traditional cement-based support materials suffer from defects such as insufficient compressive strength, high brittleness, insufficient toughness, and poor adhesion to the substrate, making them unsuitable for adapting to deformation coordination requirements under complex geological conditions. To address these issues, patent CN115947580A, published on April 11, 2023, entitled "A Cement-Based Lining Material and Method Prepared from Tailings Sand and Cement," discloses a material with high lining strength, good curing effect, and is economical and environmentally friendly. Patent CN122079578A, published on May 26, 2026, entitled "A Fast-Hardening High-Toughness Shotcrete and Its Slurry Spraying Construction Method," discloses a fast-hardening high-toughness shotcrete and a targeted set of construction techniques, achieving the technical advantages of fast-hardening load-bearing capacity, high toughness and crack resistance, and convenient construction. The accompanying process is convenient and efficient.

[0004] Polyurethane is a polymer material with excellent flexibility, bonding properties and impermeability. When introduced into cement-based materials, it can significantly improve the brittleness of cement paste, increase flexural strength and deformation capacity, and greatly enhance interfacial bonding strength. At the same time, polyurethane can form a film in cement paste to fill pores, improve impermeability and durability, and when used in conjunction with quick-setting agents, it can also accelerate the early strength development of the composite system.

[0005] Based on this, the present invention prepares a special polycarboxylate superplasticizer and a polyurethane organic polymer, providing a composite high-strength support material with cement as the inorganic cementing material and polyurethane as the organic modifying component. Through the organic-inorganic interpenetrating network structure, it synergistically leverages the high strength of cement-based materials and the high toughness and high adhesion of polyurethane, while realizing the large-scale disposal of tailings sand, providing a high-performance and low-cost solution for support engineering. Summary of the Invention

[0006] To address the problems in related technologies, this invention proposes a composite high-strength support material, its preparation method, and construction process to overcome the aforementioned technical problems in existing related technologies. The purpose of this invention is to solve the problems of excessive tailings sand stockpiles and the insufficient compressive strength, high brittleness, insufficient toughness, poor adhesion to the base surface, high rebound rate, and difficulty in construction in complex environments of traditional cement-based support materials.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a composite high-strength support material, comprising the following raw materials in parts by mass: 120-160 parts cement, 50-100 parts tailings sand powder, 80-120 parts fine sand, 60-80 parts medium sand, 4-12 parts composite fiber, 10-30 parts internal curing agent, 4-8 parts retarder, 0.5-3 parts special polycarboxylate superplasticizer, 5-8 parts quick-setting agent, 20-40 parts organic polymer, and 25-40 parts water; The special polycarboxylate superplasticizer has the following structure: In the above formula, R1, R3, and R5 are all H or CH3; R2 is H, an alkali metal ion, an alkyl group containing 1 to 6 carbon atoms, or a hydroxyalkyl group containing 1 to 6 carbon atoms; R4 is an alkyl group containing 1 to 4 carbon atoms or an alkoxy group containing 1 to 4 carbon atoms; the degrees of polymerization a, a1, b, b1, c, c1, d, and d1 are each independently 1 to 100; the degree of polymerization e is 2 to 10; and the degree of polymerization f is 10 to 100. The organic polymer is prepared by mixing a polyurethane prepolymer and an activating component in a mass ratio of 2 to 4:1, wherein the polyurethane prepolymer has the following structure: In the above formula, R6 is , , , , One or more combinations of; R7 is The degree of polymerization m is 2~20; for R8 is The degree of polymerization n is 10~40; R9 is The wavy lines represent the random repeating extensions of the polymer backbone.

[0008] Preferably, the preparation method of the special polycarboxylate superplasticizer includes the following steps: Step S01, Michael addition reaction to prepare micro-crosslinked monomers: Diol diacrylate compounds and polymerization inhibitor p-hydroxyanisole are added to the solvent acetone, and 2-methacryloyloxyethyl phosphate and base catalyst triethylamine are added dropwise to the solvent. The addition is carried out at room temperature for 0.5 h, and then kept at the temperature for 4-6 h to obtain micro-crosslinked monomers. Step S02, preparation of a special polycarboxylate superplasticizer via free radical copolymerization: The micro-crosslinked monomer obtained in step S01 is reacted with unsaturated acid and its derivative small monomers, unsaturated polyether macromonomers and [2-(methacryloyloxy)ethyl]sulfonic acid betaine in an aqueous solution with an initiator, reducing agent and chain transfer agent, and subjected to a redox free radical polymerization reaction at 10~50℃ for 2~5h to obtain the special polycarboxylate superplasticizer; wherein, the molar ratio of micro-crosslinked monomer, unsaturated acid and its derivative small monomers, unsaturated polyether macromonomers and [2-(methacryloyloxy)ethyl]sulfonic acid betaine, initiator, reducing agent and chain transfer agent is 0.01~0.1:3~6:1:0.1~0.2:0.01~0.2:0.01~0.2:0.02~0.2; In step S01, the diol diacrylate compound is one or more combinations of ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, 1,10-decanediol diacrylate, and 1,10-decanediol dimethacrylate; in step S02, the unsaturated acid and its derivative monomers are one of acrylic acid, methacrylic acid, sodium acrylate, potassium acrylate, sodium methacrylate, methyl acrylate, ethyl acrylate, and butyl acrylate. Or a combination thereof; in step S02, the unsaturated polyether macromonomer is one or more of allyl polyoxyethylene ether, methyl allyl polyoxyethylene ether, isopentenyl polyoxyethylene ether, vinyl polyoxyethylene ether, and 4-hydroxybutyl vinyl polyoxyethylene ether; in step S02, the initiator is one or more of ammonium persulfate, sodium persulfate, hydrogen peroxide, and azobisisobutyronitrile; in step S02, the reducing agent is one or more of L-ascorbic acid, sodium sulfite, sodium bisulfite, and sodium hypophosphite; in step S02, the chain transfer agent is one or more of mercaptoethanol, 2-mercaptopropionic acid, 3-mercaptopropionic acid, and dodecanethiol.

[0009] Preferably, the method for preparing the polyurethane prepolymer includes the following steps: Step S11, Preparation of DOPO modified polyether diol: DOPO and 1,4-butenediol are subjected to an addition reaction at 120°C in the presence of benzoyl peroxide catalyst. After 4-6 h of reaction, DOPO is further subjected to a ring-opening reaction with ethylene oxide in a high-pressure reactor in the presence of sodium methoxide catalyst for 1-2 h, and then kept at the temperature for 2-3 h to obtain DOPO modified polyether diol; wherein, the DOPO is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; Step S12, preparation of polyurethane prepolymer: Under nitrogen protection at 40~80℃, the diisocyanate compound is dissolved in the solvent N,N-dimethylformamide, and the catalysts stannous octoate and bisphenol fluorene are added to carry out a prepolymerization reaction for 1 h. Then, the DOPO modified polyether diol and hydroxyl-terminated polydimethylsiloxane obtained in step S11 are added, and the reaction is continued for 2~4 h. The solvent is recovered by rotary evaporation to obtain the polyurethane prepolymer. In step S11, the DOPO-modified polyether diol has the following structural formula: In the formula, R7 is The degree of polymerization m is 2~20; for In step S12, the diisocyanate compound is one or more combinations of isoflurane diisocyanate, 1,3-phenyl diisocyanate, terephthalic diisocyanate, isophthalimide diisocyanate, and naphthalene 1,5-diisocyanate; the molar ratio of the diisocyanate compound, DOPO modified polyether diol, hydroxyl-terminated polydimethylsiloxane, and bisphenol fluorene is 3~4:1:1:0.1~0.2.

[0010] Preferably, the activating component includes a chain extender, a curing agent, a foam control agent, a catalyst, and a dispersant, wherein the mass ratio of the chain extender, curing agent, foam control agent, catalyst, and dispersant is 2~3:2~4:2~4:1~2:5~10; the chain extender is one or more combinations of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane; the curing agent is one or more combinations of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, hexamethylenediamine, and octanediamine; the foam control agent is a polyether-modified siloxane; the catalyst is stannous octoate; and the dispersant is one or more combinations of acetone, butanone, cyclohexanone, and ethyl acetate.

[0011] Preferably, the tailings sand powder is prepared by grinding tailings sand and a grinding aid. The tailings sand is one or more of iron tailings sand, copper tailings sand, gold tailings sand, tungsten tailings sand, tin tailings sand, molybdenum tailings sand, lead-zinc tailings sand, and nickel tailings sand. The grinding aid is prepared by mixing an alkanolamine compound, polyethylene glycol, and water in a mass ratio of 4-5:2-3:1-2. The alkanolamine compound is one or more of triethanolamine, triisopropanolamine, and diethanolmonoisopropanolamine. The polyethylene glycol has a molecular weight of 400-1000. The grinding aid accounts for 0.05%-0.1% of the tailings sand by mass.

[0012] Preferably, the cement is ordinary Portland cement and corrosion-resistant aluminoferrite cement, with a mass ratio of 2:1; the fineness modulus of the fine sand in the ordinary Portland cement and corrosion-resistant aluminoferrite cement is 1.6~2.2, and the fineness modulus of the medium sand in the ordinary Portland cement and corrosion-resistant aluminoferrite cement is 2.3~3.0; the composite fibers in the ordinary Portland cement and corrosion-resistant aluminoferrite cement are steel fibers, polypropylene fibers, and basalt fibers with a length of 5~7mm, with a mass ratio of 2:0.5~1:0.5~1. Specifically, the strength grade of the ordinary Portland cement and corrosion-resistant aluminoferrite cement is 52.5.

[0013] Preferably, the internal curing agent is prepared by mixing superabsorbent resin, silica fume, polyethylene glycol, hydroxypropyl methylcellulose ether, and sodium gluconate in a mass ratio of 2~4:3~5:2~3:0.2:0.2, wherein the molecular weight of the polyethylene glycol is 400~1000, and the molecular weight of the hydroxypropyl methylcellulose ether is 50000~200000; the retarder is prepared by mixing sodium citrate and sodium gluconate in a mass ratio of 1:1; the accelerator is a liquid alkali-free accelerator with a solid content of 40%~50%, an initial setting time ≤2min, and a final setting time ≤4min. Specifically, the liquid alkali-free accelerator has a 28-day compressive strength ratio ≥100%.

[0014] To achieve the above objectives, the present invention also provides the following technical solution: A method for preparing a composite high-strength support material includes the following steps: Step S21, preparing special polycarboxylate superplasticizer, polyurethane prepolymer and tailings sand powder: adding grinding aid to tailings sand for grinding; specifically, controlling the residue on a 0.045mm standard sieve to be less than 5%; Step S22, preparing cement-based slurry components: cement, tailings sand powder, fine sand, medium sand, internal curing agent, retarder, special polycarboxylate superplasticizer and water are thoroughly mixed according to the required proportions, and then composite fibers are added and the mixture is stirred until uniform to obtain cement-based slurry components; Step S23, preparation of high-strength support material: add polyurethane prepolymer and quick-setting agent to the cement-based slurry component prepared in step S22, and then rapidly mix it with the activating component to obtain the target composite high-strength support material.

[0015] To achieve the above objectives, the present invention also provides the following technical solution: A construction process for a composite high-strength support material includes the following steps: Step S31, Base surface pretreatment: High-pressure water jet is used to clean and capillary activate the target support base surface, remove surface dust and loose interlayers, and artificially create a rough interface to keep the base surface clean and slightly moist. Step S32, mixing stage: In the mixing equipment, cement, tailings sand powder, fine sand, medium sand, internal curing agent, retarder, special polycarboxylate superplasticizer and water are added to the primary mixing chamber according to the required proportions, and fully mixed to form a slurry. Then, composite fibers are added and mixing is continued until the mixture is uniform. Step S33, Pre-spraying stage: The cement-based slurry components obtained in step S32 are transported from the primary mixing chamber of the mixing equipment to the secondary mixing and storage chamber of the spraying equipment via a high-pressure pump; then the slurry in the secondary mixing and storage chamber is dynamically and controlled to be transported to the tertiary pre-spraying chamber as needed via a high-pressure pump. During this transport process, the polyurethane prepolymer and the accelerator are injected into the tertiary pre-spraying chamber simultaneously according to the set ratio through an intelligent metering system to complete the instantaneous mixing before spraying. Step S34, slurry injection: After the slurry is formed in the three-stage pre-spraying chamber, the reaction components are kept within the reaction inert window period and sprayed to the target substrate within 3-5 seconds by compressed air. At the same time, the activation components are synchronously sent to the nozzle outlet through another metering channel, so that they are instantaneously mixed with the sprayed slurry in the flight path or on the sprayed substrate. Step S35, Maintenance: After spraying, the target support base surface should be moistened and maintained regularly.

[0016] Preferably, in steps S32 and S33, the volume of the primary mixing chamber and the secondary mixing and storage chamber is 200L~1000L; in steps S33 and S34, the volume of the tertiary pre-spraying chamber is 5L~20L, and it is equipped with a small mixing device; in step S34, the working width and working height of the nozzle are both 3~10m, the outlet wind speed is ≥40m / s, the outlet flow rate is 0.1~10m3 / h, and the spray thickness is 1~20cm.

[0017] Compared with the prior art, the beneficial effects of the present invention are: (1) This invention is a composite high-strength support material and its preparation method and construction process. The raw materials of this composite high-strength support material are simple and easy to obtain. The use of tailings sand improves the utilization rate of solid waste resources. After grinding and preparing tailings sand micro powder, it plays a certain filling and lubricating role in the system, which can improve the strength of the system and reduce the viscosity of the slurry. (2) This invention is a composite high-strength support material and its preparation method and construction process. By setting a special polycarboxylate superplasticizer as a micro-crosslinked structure with multiple adsorption groups such as carboxyl, phosphate and sulfonic acid groups, it has a strong adsorption capacity for cement and tailings sand and high adsorption stability. By increasing the thickness of the adsorption layer on the particle surface, the thickness of the water film layer is compressed and a certain amount of free water is released, which can further reduce the viscosity of the slurry. (3) This invention is a composite high-strength support material and its preparation method and construction process. The polyurethane prepolymer in the organic polymer of the prepared composite high-strength support material can react quickly with the activated component on the sprayed substrate and quickly form an interpenetrating network structure with the cement-based material, thereby improving the adhesion speed of the slurry and reducing the rebound rate of the spray. By introducing bisphenol fluorene with a rigid / heat-resistant structure, DOPO with a flame-retardant structure and polydimethylsiloxane with a hydrophobic structure, the strength, heat resistance, flame retardancy and surface protection of the target support material are effectively improved. (4) This invention is a composite high-strength support material and its preparation method and construction process. The prepared composite high-strength support material has not only ultra-high compressive strength after hardening, but also high bonding strength, fast hardening speed after spraying, low rebound rate, excellent crack resistance, good impermeability and good durability. The construction process of the composite high-strength support material is simple and convenient, safe and efficient, and suitable for construction in a variety of complex environments. Attached Figure Description

[0018] Figure 1 This is the GPC spectrum of the special polycarboxylate superplasticizer in the composite high-strength support material of the present invention; Figure 2 This is a flowchart illustrating the construction process of the composite high-strength support material of the present invention. Figure 3 This is a diagram illustrating the on-site spraying process of the composite high-strength support material of this invention. Figure 4 This is a diagram showing the effect of on-site spraying construction of the composite high-strength support material of this invention. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0020] Please see Figure 1 As shown, this invention proposes a technical solution for a composite high-strength support material, its preparation method, and construction process: A composite high-strength support material comprises the following raw materials in parts by mass: 120-160 parts cement, 50-100 parts tailings sand powder, 80-120 parts fine sand, 60-80 parts medium sand, 4-12 parts composite fiber, 10-30 parts internal curing agent, 4-8 parts retarder, 0.5-3 parts special polycarboxylate superplasticizer, 5-8 parts quick-setting agent, 20-40 parts organic polymer, and 25-40 parts water; The special polycarboxylate superplasticizer has the following structure (prepared for use with a solid content of 40%): In the above formula, R1, R3, and R5 are all H or CH3; R2 is H, an alkali metal ion, an alkyl group containing 1 to 6 carbon atoms, or a hydroxyalkyl group containing 1 to 6 carbon atoms; R4 is an alkyl group containing 1 to 4 carbon atoms or an alkoxy group containing 1 to 4 carbon atoms; the degrees of polymerization a, a1, b, b1, c, c1, d, and d1 are each independently 1 to 100; the degree of polymerization e is 2 to 10; and the degree of polymerization f is 10 to 100. The organic polymer is prepared by mixing polyurethane prepolymer and activating component in a mass ratio of 2~4:1, wherein the polyurethane prepolymer has the following structure: In the above formula, R6 is , , , , One or more combinations of; R7 is The degree of polymerization m is 2~20; for R8 is The degree of polymerization n is 10~40; R9 is The wavy lines represent the random repeating extensions of the polymer backbone.

[0021] The aforementioned tailings sand powder is prepared by grinding tailings sand and grinding aid. The tailings sand is one or more of the following: iron tailings sand, copper tailings sand, gold tailings sand, tungsten tailings sand, tin tailings sand, molybdenum tailings sand, lead-zinc tailings sand, and nickel tailings sand. The aforementioned grinding aid is prepared by mixing an alkanolamine compound, polyethylene glycol, and water in a mass ratio of 4~5:2~3:1~2. The aforementioned alkanolamine compound is one or more of the following: triethanolamine, triisopropanolamine, and diethanolmonoisopropanolamine. The aforementioned polyethylene glycol has a molecular weight of 400~1000. The aforementioned grinding aid accounts for 0.05%~0.1% of the mass of the tailings sand.

[0022] The aforementioned cements are ordinary Portland cement and corrosion-resistant aluminaferroaluminate cement, with a mass ratio of 2:1. The fineness modulus of the fine sand in both cements is 1.6~2.2, and the fineness modulus of the medium sand is 2.3~3.0. The composite fibers in both cements are steel fibers, polypropylene fibers, and basalt fibers with a length of 5~7mm, with a mass ratio of 2:0.5~1:0.5~1. The strength grade of both cements is 52.5.

[0023] The aforementioned internal curing agent is prepared by mixing superabsorbent resin, silica fume, polyethylene glycol, hydroxypropyl methylcellulose ether, and sodium gluconate in a mass ratio of 2~4:3~5:2~3:0.2:0.2, wherein the molecular weight of polyethylene glycol is 400~1000, and the molecular weight of hydroxypropyl methylcellulose ether is 50000~200000; the retarder is prepared by mixing sodium citrate and sodium gluconate in a mass ratio of 1:1; the accelerator is a liquid alkali-free accelerator with a solid content of 40%~50%, an initial setting time ≤2min, a final setting time ≤4min, and a 28-day compressive strength ratio ≥100%.

[0024] The preparation method of the above-mentioned composite high-strength support material includes the following steps: Step S21, preparing special polycarboxylate superplasticizer, polyurethane prepolymer and tailings sand powder: adding grinding aid to tailings sand and grinding, controlling the residue on a 0.045mm standard sieve to be less than 5%; Step S22, preparing cement-based slurry components: cement, tailings sand powder, fine sand, medium sand, internal curing agent, retarder, special polycarboxylate superplasticizer and water are thoroughly mixed according to the required proportions, and then composite fibers are added and the mixture is stirred until uniform to obtain cement-based slurry components; Step S23, preparation of high-strength support material: add polyurethane prepolymer and quick-setting agent to the cement-based slurry component prepared in step S22, and then rapidly mix it with the activating component to obtain the target composite high-strength support material.

[0025] Example 1 (1) A composite high-strength support material, comprising the following raw materials in parts by weight: 130 parts cement, 60 parts tailings sand powder, 90 parts fine sand, 80 parts medium sand, 8 parts composite fiber, 12 parts internal curing agent, 4 parts retarder, 1.5 parts special polycarboxylate superplasticizer, 6 parts quick-setting agent, 30 parts organic polymer, and 28 parts water.

[0026] (2) The preparation method of the special polycarboxylate superplasticizer includes the following steps: Step S01, Michael addition reaction to prepare micro-crosslinked monomer: Ethylene glycol diacrylate (1.05 mol) and polymerization inhibitor p-hydroxyanisole (0.005 mol) were added to the solvent acetone (200 mL), and 2-methacryloyloxyethyl phosphate (1 mol) and base catalyst triethylamine (0.1 mol) were added dropwise to the solvent. The addition was carried out at room temperature for 0.5 h, and then kept at the temperature for 4 h. The solvent was recovered by rotary evaporation to obtain the micro-crosslinked monomer. Step S02, preparation of special polycarboxylate superplasticizer by free radical copolymerization: The micro-crosslinked monomer (0.1 mol) obtained in step S01 is reacted with acrylic acid (4 mol), methyl allyl polyoxyethylene ether (1 mol, Mw=2400 g / mol) and [2-(methacryloyloxy)ethyl]sulfonic acid betaine (0.1 mol) in an aqueous solution with ammonium persulfate (0.11 mol), L-ascorbic acid (0.07 mol) and 3-mercaptopropionic acid (0.09 mol) and subjected to redox free radical polymerization at 30 °C for 4 h to obtain special polycarboxylate superplasticizer (Mw=62000 g / mol).

[0027] In the structure of the special polycarboxylate superplasticizer it generates, R1 is H; R2 is H; R3 is CH3; R4 is CH2; R5 is H; degree of polymerization (a+a1):b:(c+c1):(d+d1)=4:0.1:1:0.1, and a+a1+b+c+c1+d+d1≈23; degree of polymerization e is 2; degree of polymerization f is 53.

[0028] (3) The organic polymer is prepared by mixing polyurethane prepolymer and activating component in a mass ratio of 3:1, wherein the preparation method of polyurethane prepolymer includes the following steps: Step S11, Preparation of DOPO modified polyether diol: DOPO (1 mol) and 1,4-butenediol (1.05 mol) are added at 120 °C in the presence of benzoyl peroxide catalyst (0.01 mol). After 4 h of reaction, DOPO is then reacted with ethylene oxide (8 mol) in a high-pressure reactor in the presence of sodium methoxide catalyst (0.01 mol) for 1.5 h of ring-opening reaction, and then kept at the temperature for 2.5 h to obtain DOPO modified polyether diol; Step S12, preparation of polyurethane prepolymer: Under nitrogen protection, 1,3-phenyl diisocyanate (3.1 mol) was dissolved in solvent N,N-dimethylformamide (120 mL) at 50 °C. Stannous octoate (0.02 mol) and bisphenol fluorene (0.1 mol) were added to carry out a prepolymerization reaction for 1 h. Then, DOPO modified polyether diol (1 mol) and dihydroxyl-terminated polydimethylsiloxane (1 mol, Mw=2000) obtained in step S11 were added and the reaction was continued for 3 h. The solvent was recovered by rotary evaporation to obtain polyurethane prepolymer.

[0029] In the polyurethane prepolymer structure it generates, R6 is... R7 is The degree of polymerization m is 4; R8 is The degree of polymerization, n, is 27.

[0030] The aforementioned activating components include a chain extender (N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane), a curing agent (triethylenetetramine), a foam control agent (polyether-modified siloxane), a catalyst (stannous octoate), and a dispersant (cyclohexanone), with a mass ratio of 3:3:4:1.5:8.

[0031] (4) Preparation of high-strength support materials According to the above preparation method, the tailings sand is prepared by mixing iron tailings sand and copper tailings sand at a mass ratio of 3:1. The grinding aid is prepared by mixing triethanolamine, polyethylene glycol, and water at a mass ratio of 4:2:2, wherein the molecular weight of polyethylene glycol is 400; the grinding aid accounts for 0.05% of the mass of the tailings sand; the composite fiber is steel fiber, polypropylene fiber, and basalt fiber with a length of 5-7 mm, wherein the mass ratio is 2:1:0.5; the internal curing agent is prepared by mixing superabsorbent resin, silica fume, polyethylene glycol, hydroxypropyl methylcellulose ether, and sodium gluconate at a mass ratio of 3:3:2:0.2:0.2, wherein the molecular weight of polyethylene glycol is 600, and the molecular weight of hydroxypropyl methylcellulose ether is 100,000.

[0032] Example 2 (1) A composite high-strength support material, comprising the following raw materials in parts by weight: 140 parts cement, 70 parts tailings sand powder, 110 parts fine sand, 70 parts medium sand, 7 parts composite fiber, 18 parts internal curing agent, 6 parts retarder, 2.2 parts special polycarboxylate superplasticizer, 6 parts quick-setting agent, 25 parts organic polymer, and 33 parts water.

[0033] (2) The preparation method of the special polycarboxylate superplasticizer includes the following steps: Step S01, Michael addition reaction to prepare micro-crosslinked monomer: 1,4-Butanediol dimethacrylate (1.05 mol) and polymerization inhibitor p-hydroxyanisole (0.005 mol) were added to the solvent acetone (260 mL), and 2-methacryloyloxyethyl phosphate (1 mol) and base catalyst triethylamine (0.1 mol) were added dropwise to the solvent. The addition was carried out at room temperature for 0.5 h, and then kept at the temperature for 4.5 h. The solvent was recovered by rotary evaporation to obtain the micro-crosslinked monomer. Step S02, preparation of special polycarboxylate superplasticizer by free radical copolymerization: The micro-crosslinked monomer (0.05 mol) obtained in step S01 is reacted with methacrylic acid (5 mol), isopentenyl alcohol polyoxyethylene ether (1 mol, Mw=3000 g / mol) and [2-(methacryloyloxy)ethyl]sulfonic acid betaine (0.15 mol) in an aqueous solution with sodium persulfate (0.13 mol), sodium hypophosphite (0.18 mol) and mercaptoethanol (0.06 mol) and subjected to redox free radical polymerization at 35 °C for 5 h to obtain special polycarboxylate superplasticizer (Mw=56000 g / mol).

[0034] In the structure of the special polycarboxylate superplasticizer it generates, R1 is CH3; R2 is H; R3 is CH3; R4 is CH2CH2; R5 is CH3; the degree of polymerization (a+a1):b:(c+c1):(d+d1)=5:0.05:1:0.15, and a+a1+b+c+c1+d+d1≈16; the degree of polymerization e is 4; the degree of polymerization f is 66.

[0035] (3) The organic polymer is prepared by mixing polyurethane prepolymer and activating component at a mass ratio of 3.2:1, wherein the preparation method of polyurethane prepolymer includes the following steps: Step S11, Preparation of DOPO modified polyether diol: DOPO (1 mol) and 1,4-butenediol (1.05 mol) are subjected to an addition reaction at 120 °C in the presence of benzoyl peroxide catalyst (0.01 mol). After the reaction is carried out for 4.5 h, DOPO is then subjected to a ring-opening reaction with ethylene oxide (10 mol) in a high-pressure reactor in the presence of sodium methoxide catalyst (0.01 mol) for 1.6 h, and then kept at the temperature for 2.2 h to obtain DOPO modified polyether diol; Step S12, preparation of polyurethane prepolymer: Under nitrogen protection, isoflurane diisocyanate (3.5 mol) was dissolved in N,N-dimethylformamide (140 mL) at 60 °C. Stannous octoate (0.02 mol) and bisphenol fluorene (0.18 mol) were added as catalysts and the prepolymerization reaction was carried out for 1 h. Then, DOPO modified polyether diol (1 mol) and dihydroxyl-terminated polydimethylsiloxane (1 mol, Mw=3000) obtained in step S11 were added and the reaction was continued for 4 h. The solvent was recovered by rotary evaporation to obtain polyurethane prepolymer.

[0036] In the polyurethane prepolymer structure it generates, R6 is... R7 is The degree of polymerization m is 5; R8 is The degree of polymerization, n, is 40.

[0037] The aforementioned activating components include a chain extender (3-aminopropyltriethoxysilane), a curing agent (diethylenetriamine), a foam control agent (polyether-modified siloxane), a catalyst (stannous octoate), and a dispersant (butanone), with a mass ratio of 2.5:4:3:1:10.

[0038] (4) Preparation of high-strength support materials According to the above preparation method, the tailings sand is iron tailings sand, the grinding aid is prepared by mixing triisopropanol with polyethylene glycol and water in a mass ratio of 4.5:3:2, wherein the molecular weight of polyethylene glycol is 600; the grinding aid accounts for 0.08% of the tailings sand by mass; the composite fiber is steel fiber, polypropylene fiber and basalt fiber with a length of 5-7 mm, wherein the mass ratio is 2:1:1; the internal curing agent is prepared by mixing superabsorbent resin, silica fume, polyethylene glycol, hydroxypropyl methylcellulose ether and sodium gluconate in a mass ratio of 4:3:3:0.2:0.2, wherein the molecular weight of polyethylene glycol is 800 and the molecular weight of hydroxypropyl methylcellulose ether is 200,000.

[0039] Example 3 (1) A composite high-strength support material, comprising the following raw materials in parts by weight: 120 parts cement, 90 parts tailings sand powder, 110 parts fine sand, 75 parts medium sand, 10 parts composite fiber, 25 parts internal curing agent, 8 parts retarder, 2.8 parts special polycarboxylate superplasticizer, 7 parts quick-setting agent, 35 parts organic polymer, and 30 parts water.

[0040] (2) The preparation method of the special polycarboxylate superplasticizer includes the following steps: Step S01, Michael addition reaction to prepare micro-crosslinked monomers: 1,10-decanediol diacrylate (1.05 mol) and polymerization inhibitor p-hydroxyanisole (0.005 mol) were added to the solvent acetone (280 mL), and 2-methacryloyloxyethyl phosphate (1 mol) and base catalyst triethylamine (0.1 mol) were added dropwise to the solvent. The addition was carried out at room temperature for 0.5 h, and then kept at the temperature for 6 h. The solvent was recovered by rotary evaporation to obtain the micro-crosslinked monomers. Step S02, preparation of special polycarboxylate superplasticizer by free radical copolymerization: The micro-crosslinked monomer (0.03 mol) obtained in step S01 is reacted with sodium acrylate (6 mol), vinyl polyoxyethylene ether (1 mol, Mw=1200 g / mol) and [2-(methacryloyloxy)ethyl]sulfonic acid betaine (0.14 mol) in an aqueous solution with hydrogen peroxide (0.14 mol), sodium sulfite (0.09 mol) and 2-mercaptopropionic acid (0.09 mol) for redox free radical polymerization at 15 °C for 2 h to obtain special polycarboxylate superplasticizer (Mw=40000 g / mol).

[0041] In the structure of the special polycarboxylate superplasticizer it generates, R1 is H; R2 is Na; R3 is H; R4 is OCH2CH2; R5 is H; the degree of polymerization (a+a1):b:(c+c1):(d+d1)=6:0.03:1:0.14, and a+a1+b+c+c1+d+d1≈22; the degree of polymerization e is 10; and the degree of polymerization f is 25.

[0042] (3) The organic polymer is prepared by mixing polyurethane prepolymer and activating component in a mass ratio of 4:1, wherein the preparation method of polyurethane prepolymer includes the following steps: Step S11, Preparation of DOPO modified polyether diol: DOPO (1 mol) and 1,4-butenediol (1.05 mol) are added at 120 °C in the presence of benzoyl peroxide catalyst (0.01 mol). After 4 h of reaction, DOPO is then reacted with ethylene oxide (32 mol) in a high-pressure reactor in the presence of sodium methoxide catalyst (0.01 mol) for 2 h of ring-opening reaction, and then kept at the temperature for 2.5 h to obtain DOPO modified polyether diol; Step S12, preparation of polyurethane prepolymer: Under nitrogen protection, terephthalic diisocyanate (3.5 mol) was dissolved in solvent N,N-dimethylformamide (130 mL) at 70 °C. Stannous octoate catalyst (0.02 mol) and bisphenol fluorene (0.15 mol) were added to carry out a prepolymerization reaction for 1 h. Then, DOPO modified polyether diol (1 mol) and dihydroxyl-terminated polydimethylsiloxane (1 mol, Mw=1500) obtained in step S11 were added, and the reaction was continued for 3.5 h. The solvent was recovered by rotary evaporation to obtain polyurethane prepolymer.

[0043] In the polyurethane prepolymer structure it generates, R6 is... R7 is The degree of polymerization m is 16; R8 is The degree of polymerization, n, is 20.

[0044] The aforementioned activating components include a chain extender (N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane), a curing agent (hexamethylenediamine), a foam control agent (polyether-modified siloxane), a catalyst (stannous octoate), and a dispersant (ethyl acetate), with a mass ratio of 2.8:2.5:3:1:10.

[0045] (4) Preparation of high-strength support materials According to the above preparation method, the tailings sand is prepared by mixing iron tailings sand, copper tailings sand and gold tailings sand in a mass ratio of 2:1:1. The grinding aid is prepared by mixing diethanol monoisopropanolamine, polyethylene glycol and water in a mass ratio of 5:2:1.5, wherein the molecular weight of polyethylene glycol is 1000; the grinding aid accounts for 0.1% of the tailings sand by mass. The composite fiber is steel fiber, polypropylene fiber and basalt fiber with a length of 5-7 mm, wherein the mass ratio is 2:1:0.5. The internal curing agent is prepared by mixing superabsorbent resin, silica fume, polyethylene glycol, hydroxypropyl methylcellulose ether and sodium gluconate in a mass ratio of 4:5:2.5:0.2:0.2, wherein the molecular weight of polyethylene glycol is 1000 and the molecular weight of hydroxypropyl methylcellulose ether is 200000.

[0046] Example 4 (1) A composite high-strength support material, comprising the following raw materials in parts by weight: 160 parts cement, 55 parts tailings sand powder, 80 parts fine sand, 65 parts medium sand, 12 parts composite fiber, 10 parts internal curing agent, 7 parts retarder, 1.0 part special polycarboxylate superplasticizer, 6 parts quick-setting agent, 38 parts organic polymer, and 40 parts water.

[0047] (2) The preparation method of the special polycarboxylate superplasticizer includes the following steps: Step S01, Michael addition reaction to prepare micro-crosslinked monomers: 1,5-pentanediol diacrylate (1.05 mol) and polymerization inhibitor p-hydroxyanisole (0.005 mol) were added to the solvent acetone (350 mL), and 2-methacryloyloxyethyl phosphate (1 mol) and base catalyst triethylamine (0.1 mol) were added dropwise to the solution. The addition was carried out at room temperature for 0.5 h, and then kept at the temperature for 5 h to obtain micro-crosslinked monomers; Step S02, preparation of a special polycarboxylate superplasticizer by free radical copolymerization: The micro-crosslinked monomer (0.08 mol) obtained in step S01 is reacted with sodium methacrylate (4.5 mol), isopentenyl alcohol polyoxyethylene ether (1 mol, Mw=2400 g / mol) and [2-(methacryloyloxy)ethyl]sulfonyl betaine (0.2 mol) in an aqueous solution with azobisisobutyronitrile (0.18 mol), sodium bisulfite (0.08 mol) and 3-mercaptopropionic acid (0.06 mol) in a redox free radical polymerization reaction at 42 °C for 4.5 h to obtain a special polycarboxylate superplasticizer (Mw=70000 g / mol).

[0048] In the structure of the special polycarboxylate superplasticizer generated therein, R1 is CH3; R2 is Na; R3 is CH3; R4 is CH2CH2; R5 is H; the degree of polymerization (a+a1):b:(c+c1):(d+d1) = 4.5:0.08:1:0.2, and a+a1+b+c+c1+d+d1≈24; the degree of polymerization e is 5; and the degree of polymerization f is 53.

[0049] (3) The organic polymer is prepared by mixing polyurethane prepolymer and activating component at a mass ratio of 3.5:1, wherein the preparation method of polyurethane prepolymer includes the following steps: Step S11, Preparation of DOPO modified polyether diol: DOPO (1 mol) and 1,4-butenediol (1.05 mol) are added at 120 °C in the presence of benzoyl peroxide catalyst (0.01 mol). After 4 h of reaction, DOPO is then reacted with ethylene oxide (16 mol) in a high-pressure reactor in the presence of sodium methoxide catalyst (0.01 mol) for 2 h of ring-opening reaction, and then kept at the temperature for 2 h to obtain DOPO modified polyether diol; Step S12, preparation of polyurethane prepolymer: Under nitrogen protection, 3 mol of 1,5-diisocyanate was dissolved in 160 mL of N,N-dimethylformamide at 45 °C. Stannous octoate (0.02 mol) and 0.12 mol of bisphenol fluorene were added to carry out a prepolymerization reaction for 1 h. Then, 1 mol of DOPO modified polyether diol and 1 mol of dihydroxyl-terminated polydimethylsiloxane (Mw=2000) obtained in step S11 were added and the reaction was continued for 3.5 h. The solvent was recovered by rotary evaporation to obtain the polyurethane prepolymer.

[0050] In the polyurethane prepolymer structure it generates, R6 is... R7 is The degree of polymerization m is 8; R8 is The degree of polymerization, n, is 27.

[0051] The aforementioned activating components include a chain extender (3-aminopropyltriethoxysilane), a curing agent (diethylenetriamine), a foam control agent (polyether-modified siloxane), a catalyst (stannous octoate), and a dispersant (acetone), with a mass ratio of 2:3:2:1:7.

[0052] (4) Preparation of high-strength support materials According to the above preparation method, the tailings sand is prepared by mixing copper tailings sand and tin tailings sand at a mass ratio of 5:2. The grinding aid is prepared by mixing triethanolamine, polyethylene glycol, and water at a mass ratio of 4.5:2.5:2, wherein the molecular weight of polyethylene glycol is 1000; the grinding aid accounts for 0.08% of the mass of the tailings sand; the composite fiber is steel fiber, polypropylene fiber, and basalt fiber with a length of 5-7 mm, wherein the mass ratio is 2:0.5:0.5; the internal curing agent is prepared by mixing superabsorbent resin, silica fume, polyethylene glycol, hydroxypropyl methylcellulose ether, and sodium gluconate at a mass ratio of 4:4:2.5:0.2:0.2, wherein the molecular weight of polyethylene glycol is 1000, and the molecular weight of hydroxypropyl methylcellulose ether is 50000.

[0053] Example 5 (1) A composite high-strength support material, comprising the following raw materials in parts by weight: 130 parts cement, 90 parts tailings sand powder, 115 parts fine sand, 60 parts medium sand, 4 parts composite fiber, 20 parts internal curing agent, 6 parts retarder, 2.5 parts special polycarboxylate superplasticizer, 8 parts quick-setting agent, 23 parts organic polymer, and 34 parts water.

[0054] (2) The preparation method of the special polycarboxylate superplasticizer includes the following steps: Step S01, Michael addition reaction to prepare micro-crosslinked monomers: 1,10-decanediol dimethacrylate (1.05 mol) and polymerization inhibitor p-hydroxyanisole (0.005 mol) were added to the solvent acetone (230 mL), and 2-methacryloyloxyethyl phosphate (1 mol) and base catalyst triethylamine (0.1 mol) were added dropwise to the solvent. The addition was carried out at room temperature for 0.5 h, and then kept at the temperature for 6 h. The solvent was recovered by rotary evaporation to obtain the micro-crosslinked monomers. Step S02, preparation of special polycarboxylate superplasticizer by free radical copolymerization: The micro-crosslinked monomer (0.07 mol) obtained in step S01 is reacted with potassium acrylate (5.5 mol), allyl polyoxyethylene ether (1 mol, Mw=2000 g / mol) and [2-(methacryloyloxy)ethyl]sulfonic acid betaine (0.17 mol) in an aqueous solution with ammonium persulfate (0.13 mol), sodium sulfite (0.1 mol) and dodecyl mercaptan (0.17 mol) and subjected to redox free radical polymerization reaction at 28 °C for 4 hours to obtain special polycarboxylate superplasticizer (Mw=35000 g / mol).

[0055] In the structure of the special polycarboxylate superplasticizer it generates, R1 is H; R2 is K; R3 is H; R4 is CH2; R5 is CH3; the degree of polymerization (a+a1):b:(c+c1):(d+d1)=5.5:0.07:1:0.17, and a+a1+b+c+c1+d+d1≈13; the degree of polymerization e is 10; and the degree of polymerization f is 44.

[0056] (3) The organic polymer is prepared by mixing polyurethane prepolymer and activating component at a mass ratio of 2.8:1, wherein the preparation method of polyurethane prepolymer includes the following steps: Step S11, Preparation of DOPO modified polyether diol: DOPO (1 mol) and 1,4-butenediol (1.05 mol) are added at 120 °C in the presence of benzoyl peroxide catalyst (0.01 mol). After 4 h of reaction, DOPO is then reacted with ethylene oxide (12 mol) in a high-pressure reactor in the presence of sodium methoxide catalyst (0.01 mol) for 2 h of ring-opening reaction, and then kept at the temperature for 2.5 h to obtain DOPO modified polyether diol; Step S12, preparation of polyurethane prepolymer: Under nitrogen protection, isophthalamide diisocyanate (3.8 mol) was dissolved in N,N-dimethylformamide (130 mL) at 60 °C. Stannous octoate (0.02 mol) and bisphenol fluorene (0.12 mol) were added as catalysts to carry out a prepolymerization reaction for 1 h. Then, DOPO modified polyether diol (1 mol) and dihydroxyl-terminated polydimethylsiloxane (1 mol, Mw=3000) obtained in step S11 were added, and the reaction was continued for 3.5 h. The solvent was recovered by rotary evaporation to obtain the polyurethane prepolymer.

[0057] In the polyurethane prepolymer structure it generates, R6 is... R7 is The degree of polymerization m is 6; R8 is The degree of polymerization, n, is 40.

[0058] The aforementioned activating components include a chain extender (N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane), a curing agent (triethylenetetramine), a foam control agent (polyether-modified siloxane), a catalyst (stannous octoate), and a dispersant (cyclohexanone), with a mass ratio of 2.5:3:4:1.5:7.

[0059] (4) Preparation of high-strength support materials According to the above preparation method, the tailings sand is prepared by mixing iron tailings sand and molybdenum tailings sand at a mass ratio of 6:1. The grinding aid is prepared by mixing diethanol monoisopropanolamine, polyethylene glycol, and water at a mass ratio of 5:2:1, wherein the molecular weight of polyethylene glycol is 800; the grinding aid accounts for 0.06% of the tailings sand by mass. The composite fiber is steel fiber, polypropylene fiber, and basalt fiber with a length of 5-7 mm, wherein the mass ratio is 2:0.8:0.5. The internal curing agent is prepared by mixing superabsorbent resin, silica fume, polyethylene glycol, hydroxypropyl methylcellulose ether, and sodium gluconate at a mass ratio of 4:3.5:1.8:0.2:0.2, wherein the molecular weight of polyethylene glycol is 600, and the molecular weight of hydroxypropyl methylcellulose ether is 50,000.

[0060] Example 6 (1) A composite high-strength support material, comprising the following raw materials in parts by weight: 145 parts cement, 85 parts tailings sand powder, 100 parts fine sand, 70 parts medium sand, 9 parts composite fiber, 15 parts internal curing agent, 5 parts retarder, 2 parts special polycarboxylate superplasticizer, 4 parts quick-setting agent, 26 parts organic polymer, and 37 parts water.

[0061] (2) The preparation method of the special polycarboxylate superplasticizer includes the following steps: Step S01, Michael addition reaction to prepare micro-crosslinked monomer: 1,6-hexanediol diacrylate (1.05 mol) and polymerization inhibitor p-hydroxyanisole (0.005 mol) were added to the solvent acetone (250 mL), and 2-methacryloyloxyethyl phosphate (1 mol) and base catalyst triethylamine (0.1 mol) were added dropwise to the solvent. The addition was carried out at room temperature for 0.5 h, and then kept at the temperature for 4.5 h. The solvent was recovered by rotary evaporation to obtain the micro-crosslinked monomer. Step S02, preparation of special polycarboxylate superplasticizer by free radical copolymerization: The micro-crosslinked monomer (0.03 mol) obtained in step S01 is reacted with methacrylic acid (6 mol), methallyl polyoxyethylene ether (1 mol, Mw=3000 g / mol) and [2-(methacryloyloxy)ethyl]sulfonic acid betaine (0.12 mol) in an aqueous solution with hydrogen peroxide (0.14 mol), sodium hypophosphite (0.1 mol) and mercaptoethanol (0.06 mol) for redox free radical polymerization at 25 °C for 5 h to obtain special polycarboxylate superplasticizer (Mw=60000 g / mol).

[0062] In the structure of the special polycarboxylate superplasticizer it generates, R1 is H; R2 is H; R3 is CH3; R4 is CH2; R5 is H; degree of polymerization (a+a1):b:(c+c1):(d+d1)=6:0.03:1:0.12, and a+a1+b+c+c1+d+d1≈17; degree of polymerization e is 6; degree of polymerization f is 67.

[0063] (3) The organic polymer is prepared by mixing polyurethane prepolymer and activating component in a mass ratio of 3:1, wherein the preparation method of polyurethane prepolymer includes the following steps: Step S11, Preparation of DOPO modified polyether diol: DOPO (1 mol) and 1,4-butenediol (1.05 mol) are subjected to an addition reaction at 120 °C in the presence of benzoyl peroxide catalyst (0.01 mol). After the reaction is carried out for 4 h, DOPO is then subjected to a ring-opening reaction with ethylene oxide (30 mol) in a high-pressure reactor in the presence of sodium methoxide catalyst (0.01 mol) for 2 h, and then kept at the temperature for 2.5 h to obtain DOPO modified polyether diol; Step S12, preparation of polyurethane prepolymer: Under nitrogen protection, isoflurane diisocyanate (3.2 mol) was dissolved in N,N-dimethylformamide (140 mL) at 70 °C. Stannous octoate (0.02 mol) and bisphenol fluorene (0.1 mol) were added as catalysts to carry out a prepolymerization reaction for 1 h. Then, DOPO modified polyether diol (1 mol) and dihydroxyl-terminated polydimethylsiloxane (1 mol, Mw=2000) obtained in step S11 were added and the reaction was continued for 3.5 h. The solvent was recovered by rotary evaporation to obtain the polyurethane prepolymer.

[0064] In the polyurethane prepolymer structure it generates, R6 is... R7 is The degree of polymerization m is 15; R8 is The degree of polymerization, n, is 27.

[0065] The aforementioned activating components include a chain extender (3-aminopropyltriethoxysilane), a curing agent (tetraethylenepentamine), a foam control agent (polyether-modified siloxane), a catalyst (stannous octoate), and a dispersant (butanone), with a mass ratio of 3:2.6:3.5:2:10.

[0066] (4) Preparation of high-strength support materials According to the above preparation method, the tailings sand is prepared by mixing iron tailings sand, copper tailings sand and lead-zinc tailings sand in a mass ratio of 3:2:1. The grinding aid is prepared by mixing triisopropanolamine, polyethylene glycol and water in a mass ratio of 4:3:1.5, wherein the molecular weight of polyethylene glycol is 600; the grinding aid accounts for 0.07% of the mass of the tailings sand. The composite fiber is steel fiber, polypropylene fiber and basalt fiber with a length of 5-7 mm, wherein the mass ratio is 2:0.5:0.8. The internal curing agent is prepared by mixing superabsorbent resin, silica fume, polyethylene glycol, hydroxypropyl methylcellulose ether and sodium gluconate in a mass ratio of 3.5:3.5:2.2:0.2:0.2, wherein the molecular weight of polyethylene glycol is 800 and the molecular weight of hydroxypropyl methylcellulose ether is 150,000.

[0067] Comparative Example 1 Materials for preparing ordinary shotcrete: 130 parts cement, 100 parts fine sand, 100 parts medium sand, 150 parts small stones, 1.6 parts commercially available ordinary polycarboxylate superplasticizer, 10 parts quick-setting agent, and 45 parts water.

[0068] Comparative Example 2 Commercially available high-strength shotcrete support materials.

[0069] Comparative Example 3 The difference from Example 2 is that the special polycarboxylate superplasticizer is replaced with a commercially available ordinary polycarboxylate superplasticizer, with a water reduction rate of 40%.

[0070] Comparative Example 4 The difference from Example 2 is that the components do not contain organic polymers.

[0071] Example 7 The preparation method of the composite high-strength support material in Example 2 was adopted, and the following construction process was used, including the following steps: Step S31, Base surface pretreatment: High-pressure water jet is used to clean and capillary activate the target support base surface, remove surface dust and loose interlayers, and artificially create a rough interface to keep the base surface clean and slightly moist. Step S32, mixing stage: In the mixing equipment, cement and tailings sand powder, fine sand and medium sand aggregate, internal curing agent, retarder, special polycarboxylate superplasticizer and water are added to the primary mixing chamber according to the required proportions, and the mixture is fully mixed to form a slurry. Then, composite fibers are added and the mixing continues until the mixture is uniform. Step S33, Pre-spraying stage: The cement-based slurry components obtained in step S32 are transported from the primary mixing chamber of the mixing equipment to the secondary mixing and storage chamber of the spraying equipment via a high-pressure pump; then the slurry in the secondary mixing and storage chamber is dynamically and controlled to be transported to the tertiary pre-spraying chamber as needed via a high-pressure pump. During this transport process, the polyurethane prepolymer and the accelerator are injected into the tertiary pre-spraying chamber simultaneously according to the set ratio through an intelligent metering system to complete the instantaneous mixing before spraying. Step S34, slurry injection: After the slurry is formed in the three-stage pre-spraying chamber, the reaction components are kept within the reaction inert window period and sprayed to the target substrate within 3 to 5 seconds by compressed air. At the same time, the activation components are synchronously sent to the nozzle outlet through another metering channel, so that they are instantaneously mixed with the sprayed slurry in the flight path or on the sprayed substrate. Step S35, Maintenance: After spraying, the target support base surface should be moistened and maintained regularly.

[0072] The volume of the primary mixing chamber and the secondary mixing and storage chamber is 800L; the volume of the tertiary pre-spray chamber is 15L; the working width and working height of the nozzle are 5m and 8m respectively, the outlet wind speed is ≥40m / s, the outlet flow rate is 5m3 / h, and the spray thickness is 4cm.

[0073] Example 8 The difference from Example 7 is that the base surface preprocessing step S31 is not performed.

[0074] Example 9 The difference from Example 7 is that the spray thickness is 6 cm.

[0075] Example 10 The preparation method of the composite high-strength support material of Example 7 is adopted, and the difference from Example 7 is that the components do not contain organic polymers.

[0076] Comparative Example 5 Comparative Example 2 uses commercially available high-strength shotcrete support material and is applied using a standard wet spraying machine of the same size.

[0077] Comparative Example 6 The preparation method of the composite high-strength support material of Example 7 was adopted, and the difference from Example 7 is that the components do not contain organic polymers, and the ordinary wet spraying machine of the same size is used for spraying.

[0078] Test case 1. Product performance testing The setting time of the samples was tested according to standard GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", using the penetration resistance method. The compressive strength at 1 day, 3 days, and 28 days, and the splitting tensile strength at 28 days were tested according to standard GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". The concrete specimen dimensions were 100mm × 100mm × 100mm. The shrinkage, impermeability, frost resistance, and chloride ion resistance of the samples were tested according to standard GB / T 50082-2024 "Standard for Test Methods of Long-Term Performance and Durability of Concrete". The shrinkage test method was a non-contact method; the impermeability test used frustum specimens, and the impermeability grade was determined after standard curing for 28 days; the frost resistance test used a rapid freeze-thaw cycle test after standard curing for 28 days. The test was terminated when the relative dynamic modulus of elasticity decreased to 60% or the mass loss exceeded 5%, and the number of freeze-thaw cycles was recorded; the chloride ion penetration resistance test used the RCM method.

[0079] The performance test results of the product of this invention are shown in Table 1 below.

[0080] Table 1 Product Performance Test Results The results showed that Examples 1-6 had shorter setting times compared to Comparative Examples 1-2. Furthermore, the concrete from these examples exhibited higher compressive strength at all ages, with 1-day compressive strength reaching 58.3-62.8 MPa, 3-day compressive strength reaching 91.1-98.6 MPa, and 28-day compressive strength reaching 110.4-120.5 MPa, significantly higher than ordinary shotcrete (Comparative Example 1) and commercially available high-strength shotcrete support materials (Comparative Example 2). In addition, the 28-day splitting tensile strength of the concrete from these examples reached 6.54-7.74 MPa, representing increases of approximately 132%-174% and 65%-95% compared to Comparative Examples 1 and 2, respectively, indicating that the material of this invention possesses superior crack resistance and load-bearing capacity.

[0081] The concrete in this example exhibits lower drying shrinkage and superior durability, with a 28-day drying shrinkage rate controlled between 0.0198% and 0.0231%, a permeability grade of P40, and over 1000 freeze-thaw cycles. The chloride ion migration coefficient is (0.03~0.08)×10⁻⁶. -12 m 2 / s, significantly superior to ordinary shotcrete and commercially available high-strength shotcrete materials. This indicates that the high-strength support material of the present invention effectively improves the internal structural density of concrete and enhances its resistance to impermeability, frost damage, and chloride ion erosion.

[0082] The 28-day compressive strength of Comparative Example 3 was basically equivalent to that of Example 2, but its 28-day splitting tensile strength decreased from 7.15 MPa to 6.80 MPa, and its drying shrinkage increased from 0.0204% to 0.0234%. This indicates that ordinary polycarboxylate superplasticizer can meet basic dispersion requirements, but due to insufficient compatibility with tailings sand powder and aluminoferrite cement systems, its effect on improving the microstructure and crack resistance of concrete is limited. Compared with Example 2, Comparative Example 4 did not add an appropriate amount of organic polymer. Its 28-day splitting tensile strength and durability both decreased to some extent, specifically, the 28-day splitting tensile strength decreased from 7.15 MPa to 6.71 MPa, and the drying shrinkage increased from 0.0204% to 0.0226%. This indicates that organic polymer can improve the interfacial transition zone of cement-based materials, increase matrix toughness, and reduce shrinkage deformation.

[0083] 2. Performance testing of products using different spraying processes The bond strength and rebound rate of the samples to the substrate were tested according to standard JGJ / T 372-2016 "Technical Specification for Application of Shotcrete". The bond strength test was conducted after 28 days using the pull-out method; the rebound rate was the ratio of rebound mass to total shotcrete mass. Specific results are shown in Table 2 below.

[0084] Table 2. Product performance test results under different spraying processes It can be observed that, compared with ordinary shotcrete, the high-strength shotcrete support material of this invention exhibits superior shotcrete construction performance. Specifically, the bond strength between Example 7 and the substrate reaches 3.8 MPa, while the bond strength of Example 8 is 0.4 MPa lower than that of Example 7, but the rebound rate is increased by 1.6%, indicating that proper substrate treatment is beneficial to improving the bond performance between the material and the substrate. In Example 9, after increasing the shotcrete thickness to 6 cm, the bond strength with the substrate is 4.1 MPa, demonstrating that even under thicker shotcrete layers, the material of this invention maintains good interfacial bonding performance.

[0085] The bonding strength with the substrate in Examples 7-9 is significantly higher than that in Comparative Example 6 (which uses a conventional wet spraying machine of the same size and specifications, and commercially available high-strength shotcrete support material). The rebound rate in Examples 7-9 is also significantly lower than the 17.6% of Comparative Example 6. This indicates that the high-strength support material of the present invention has excellent adhesion to the substrate, better spraying stability, and higher material utilization.

[0086] Examples 10 and Comparative Example 6, which do not contain organic polymers, show a slight decrease in bond strength to the substrate compared to Example 7, but a slight increase in rebound rate. This indicates that organic polymers can effectively improve the bonding performance between the slurry and the substrate. Comparing Examples 7-10 of the construction process of this invention with Comparative Examples 5 and 6, which utilize conventional wet spraying machines, it can be seen that the construction process of this invention has certain advantages in terms of bonding performance to the substrate and construction efficiency. This demonstrates that by optimizing the construction process and improving the rheological properties and spraying adaptability of concrete, this invention improves on-site construction efficiency while ensuring high strength performance.

[0087] In summary, the high-strength shotcrete prepared by this invention has high strength, high crack resistance, high durability, and excellent construction performance, which can meet the application needs of support engineering in special scenarios such as roadways, tunnels, slopes, piers, and old buildings.

[0088] 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 composite high-strength support material, characterized in that, Including the following raw materials by weight: 120-160 parts cement, 50-100 parts tailings sand powder, 80-120 parts fine sand, 60-80 parts medium sand, 4-12 parts composite fiber, 10-30 parts internal curing agent, 4-8 parts retarder, 0.5-3 parts special polycarboxylate superplasticizer, 5-8 parts quick-setting agent, 20-40 parts organic polymer, and 25-40 parts water; The special polycarboxylate superplasticizer has the following structure: In the above formula, R1, R3, and R5 are all H or CH3; R2 is H, an alkali metal ion, an alkyl group containing 1 to 6 carbon atoms, or a hydroxyalkyl group containing 1 to 6 carbon atoms; R4 is an alkyl group containing 1 to 4 carbon atoms or an alkoxy group containing 1 to 4 carbon atoms; the degrees of polymerization a, a1, b, b1, c, c1, d, and d1 are each independently 1 to 100; the degree of polymerization e is 2 to 10; and the degree of polymerization f is 10 to 100. The organic polymer is prepared by mixing a polyurethane prepolymer and an activating component in a mass ratio of 2 to 4:1, wherein the polyurethane prepolymer has the following structure: In the above formula, R6 is , , , , One or more combinations of; R7 is The degree of polymerization m is 2~20; for R8 is The degree of polymerization n is 10~40; R9 is The wavy lines represent the random repeating extensions of the polymer backbone.

2. The composite high-strength support material according to claim 1, characterized in that, The preparation method of the special polycarboxylate superplasticizer includes the following steps: Step S01, Michael addition reaction to prepare micro-crosslinked monomers: Diol diacrylate compounds and polymerization inhibitor p-hydroxyanisole are added to the solvent acetone, and 2-methacryloyloxyethyl phosphate and base catalyst triethylamine are added dropwise to the solvent. The addition is carried out at room temperature for 0.5 h, and then kept at the temperature for 4-6 h to obtain micro-crosslinked monomers. Step S02, preparation of a special polycarboxylate superplasticizer via free radical copolymerization: The micro-crosslinked monomer obtained in step S01 is reacted with unsaturated acid and its derivative small monomers, unsaturated polyether macromonomers and [2-(methacryloyloxy)ethyl]sulfonic acid betaine in an aqueous solution with an initiator, reducing agent and chain transfer agent, and subjected to a redox free radical polymerization reaction at 10~50℃ for 2~5h to obtain the special polycarboxylate superplasticizer; wherein, the molar ratio of micro-crosslinked monomer, unsaturated acid and its derivative small monomers, unsaturated polyether macromonomers and [2-(methacryloyloxy)ethyl]sulfonic acid betaine, initiator, reducing agent and chain transfer agent is 0.01~0.1:3~6:1:0.1~0.2:0.01~0.2:0.01~0.2:0.02~0.2; In step S01, the diol diacrylate compound is one or more combinations of ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, 1,10-decanediol diacrylate, and 1,10-decanediol dimethacrylate; in step S02, the unsaturated acid and its derivative monomers are one of acrylic acid, methacrylic acid, sodium acrylate, potassium acrylate, sodium methacrylate, methyl acrylate, ethyl acrylate, and butyl acrylate. Or a combination thereof; in step S02, the unsaturated polyether macromonomer is one or more of allyl polyoxyethylene ether, methyl allyl polyoxyethylene ether, isopentenyl polyoxyethylene ether, vinyl polyoxyethylene ether, and 4-hydroxybutyl vinyl polyoxyethylene ether; in step S02, the initiator is one or more of ammonium persulfate, sodium persulfate, hydrogen peroxide, and azobisisobutyronitrile; in step S02, the reducing agent is one or more of L-ascorbic acid, sodium sulfite, sodium bisulfite, and sodium hypophosphite; in step S02, the chain transfer agent is one or more of mercaptoethanol, 2-mercaptopropionic acid, 3-mercaptopropionic acid, and dodecanethiol.

3. The composite high-strength support material according to claim 1, characterized in that: The method for preparing the polyurethane prepolymer includes the following steps: Step S11, Preparation of DOPO modified polyether diol: DOPO and 1,4-butenediol are subjected to an addition reaction at 120°C in the presence of benzoyl peroxide catalyst. After the reaction is carried out for 4-6 h, DOPO is then subjected to a ring-opening reaction with ethylene oxide in a high-pressure reactor in the presence of sodium methoxide catalyst for 1-2 h, and then kept at the temperature for 2-3 h to obtain DOPO modified polyether diol; wherein, the DOPO is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; Step S12, preparation of polyurethane prepolymer: Under nitrogen protection at 40~80℃, the diisocyanate compound is dissolved in the solvent N,N-dimethylformamide, and the catalysts stannous octoate and bisphenol fluorene are added to carry out a prepolymerization reaction for 1 h. Then, the DOPO modified polyether diol and hydroxyl-terminated polydimethylsiloxane obtained in step S11 are added, and the reaction is continued for 2~4 h. The solvent is recovered by rotary evaporation to obtain the polyurethane prepolymer. In step S11, the DOPO-modified polyether diol has the following structural formula: In the formula, R7 is The degree of polymerization m is 2~20; for In step S12, the diisocyanate compound is one or more combinations of isoflurane diisocyanate, 1,3-phenyl diisocyanate, terephthalic diisocyanate, isophthalimide diisocyanate, and naphthalene 1,5-diisocyanate; the molar ratio of the diisocyanate compound, DOPO modified polyether diol, hydroxyl-terminated polydimethylsiloxane, and bisphenol fluorene is 3~4:1:1:0.1~0.

2.

4. The composite high-strength support material according to claim 1, characterized in that: The activating component includes a chain extender, a curing agent, a foam control agent, a catalyst, and a dispersant, wherein the mass ratio of the chain extender, curing agent, foam control agent, catalyst, and dispersant is 2~3:2~4:2~4:1~2:5~10; the chain extender is one or more combinations of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane; the curing agent is one or more combinations of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, hexamethylenediamine, and octanediamine; the foam control agent is a polyether-modified siloxane; the catalyst is stannous octoate; and the dispersant is one or more combinations of acetone, butanone, cyclohexanone, and ethyl acetate.

5. The composite high-strength support material according to claim 1, characterized in that: The tailings sand powder is prepared by grinding tailings sand and a grinding aid. The tailings sand is one or more of iron tailings sand, copper tailings sand, gold tailings sand, tungsten tailings sand, tin tailings sand, molybdenum tailings sand, lead-zinc tailings sand, and nickel tailings sand. The grinding aid is prepared by mixing an alkanolamine compound, polyethylene glycol, and water in a mass ratio of 4~5:2~3:1~2. The alkanolamine compound is one or more of triethanolamine, triisopropanolamine, and diethanolmonoisopropanolamine. The polyethylene glycol has a molecular weight of 400~1000. The grinding aid accounts for 0.05%~0.1% of the tailings sand by mass.

6. The composite high-strength support material according to claim 1, characterized in that: The cement is ordinary Portland cement and corrosion-resistant aluminoferrite cement, with a mass ratio of 2:1; the fineness modulus of the fine sand in the ordinary Portland cement and corrosion-resistant aluminoferrite cement is 1.6~2.2, and the fineness modulus of the medium sand in the ordinary Portland cement and corrosion-resistant aluminoferrite cement is 2.3~3.0; the composite fiber in the ordinary Portland cement and corrosion-resistant aluminoferrite cement is steel fiber, polypropylene fiber and basalt fiber with a length of 5~7mm, with a mass ratio of 2:0.5~1:0.5~1.

7. The composite high-strength support material according to claim 1, characterized in that: The internal curing agent is prepared by mixing superabsorbent resin, silica fume, polyethylene glycol, hydroxypropyl methylcellulose ether, and sodium gluconate in a mass ratio of 2~4:3~5:2~3:0.2:0.2, wherein the molecular weight of polyethylene glycol is 400~1000, and the molecular weight of hydroxypropyl methylcellulose ether is 50000~200000; the retarder is prepared by mixing sodium citrate and sodium gluconate in a mass ratio of 1:1; the accelerator is a liquid alkali-free accelerator with a solid content of 40%~50%, an initial setting time ≤2min, and a final setting time ≤4min.

8. A method for preparing a composite high-strength support material as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Step S21, prepare special polycarboxylate superplasticizer, polyurethane prepolymer and tailings sand powder: add grinding aid to tailings sand and grind it. Step S22, preparing cement-based slurry components: cement, tailings sand powder, fine sand, medium sand, internal curing agent, retarder, special polycarboxylate superplasticizer and water are thoroughly mixed according to the required proportions, and then composite fibers are added and the mixture is stirred until uniform to obtain cement-based slurry components; Step S23, preparation of high-strength support material: add polyurethane prepolymer and quick-setting agent to the cement-based slurry component prepared in step S22, and then rapidly mix it with the activating component to obtain the target composite high-strength support material.

9. A construction process for a composite high-strength support material as described in any one of claims 1 to 8, characterized in that, Includes the following steps: Step S31, Base surface pretreatment: High-pressure water jet is used to clean and capillary activate the target support base surface, remove surface dust and loose interlayers, and artificially create a rough interface to keep the base surface clean and slightly moist. Step S32, mixing stage: In the mixing equipment, cement, tailings sand powder, fine sand, medium sand, internal curing agent, retarder, special polycarboxylate superplasticizer and water are added to the primary mixing chamber according to the required proportions, and fully mixed to form a slurry. Then, composite fibers are added and mixing is continued until the mixture is uniform. Step S33, Pre-spraying stage: The cement-based slurry components obtained in step S32 are transported from the primary mixing chamber of the mixing equipment to the secondary mixing and storage chamber of the spraying equipment via a high-pressure pump; then the slurry in the secondary mixing and storage chamber is dynamically and controlled to be transported to the tertiary pre-spraying chamber as needed via a high-pressure pump. During this transport process, the polyurethane prepolymer and the accelerator are injected into the tertiary pre-spraying chamber simultaneously according to the set ratio through an intelligent metering system to complete the instantaneous mixing before spraying. Step S34, slurry injection: After the slurry is formed in the three-stage pre-spraying chamber, the reaction components are kept within the reaction inert window period and sprayed to the target substrate within 3-5 seconds by compressed air. At the same time, the activation components are synchronously sent to the nozzle outlet through another metering channel, so that they are instantaneously mixed with the sprayed slurry in the flight path or on the sprayed substrate. Step S35, Maintenance: After spraying, the target support base surface should be moistened and maintained regularly.

10. The construction process of a composite high-strength support material according to claim 9, characterized in that: In steps S32 and S33, the volume of the primary mixing chamber and the secondary mixing and storage chamber is 200L~1000L; in steps S33 and S34, the volume of the tertiary pre-spraying chamber is 5L~20L, and it is equipped with a small mixing device; in step S34, the working width and working height of the nozzle are both 3~10m, the outlet wind speed is ≥40m / s, the outlet flow rate is 0.1~10m3 / h, and the spray thickness is 1~20cm.

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