Low-resilience high-strength guniting material and preparation method thereof

Abstract

The invention discloses a low-resilience high-strength guniting material and a preparation method thereof. The low-resilience high-strength guniting material comprises the following components by weight: 5-15% of a magnesium aluminosilicate molecular sieve; 40 to 55% of Portland cement; 8-16% of acrylic modified silicon resin; 8 to 13 percent of acrylate copolymer emulsion; 2-4% of a thickening agent; 0.1-1% of a bactericide; 2-4% of a surfactant; 2-4% of a dispersant; 0.3%-0.5% of a defoaming agent; the balance is water. The fibrous magnesium aluminosilicate molecular sieves are interwoven in a three-dimensional space to form a reinforced structure similar to reinforced concrete, the molar ratio of SiO2 to Al2O3 is controlled within the range of 20-40, the surface of the magnesium aluminosilicate molecular sieve is moderately weakly acidic, the acidic sites and epoxy groups in acrylic acid modified silicon resin are subjected to ring-opening reaction, and the surface of the magnesium aluminosilicate molecular sieves is modified. And stable chemical bonding is formed.

Description

Technical Field

[0001] The present invention relates to the technical field of shotcrete materials, and particularly to a low-rebound high-strength shotcrete material and a preparation method thereof. Background Art

[0002] In the fields of tunnel engineering, underground space development, and slope protection, shotcrete technology has been widely used due to its convenient construction and strong adaptability. With the expansion of China's mineral resource development scale, the tailings generated during gold mining have become a large amount of industrial solid waste. Their storage not only occupies a large amount of land resources but also may cause environmental pollution and geological disasters. Gold tailings contain rich silicon-aluminum oxides and theoretically have the potential to be used as raw materials for building materials. However, there is a lack of systematic application research in the field of shotcrete materials.

[0003] On the other hand, the current shotcrete materials on the market mainly use cement-based materials in combination with various admixtures, and improve the spraying performance by optimizing the gradation and adding accelerators. These technical solutions have reduced the rebound rate to a certain extent, but there is still room for improvement. Especially under high-speed spraying conditions, the energy dissipation mechanism during the collision of the material with the working surface is relatively single, mainly relying on the plastic deformation and viscous flow of the material to absorb the impact energy. At the same time, the interfacial bonding between the inorganic fillers and the organic polymers in traditional shotcrete materials mainly relies on physical adsorption, and interface debonding is likely to occur under dynamic impact conditions, affecting the overall performance of the material. In addition, the microstructure design of existing shotcrete materials is relatively simple, lacking a multi-scale energy dissipation network, resulting in difficulty in achieving an ideal low-rebound effect while ensuring strength. Summary of the Invention

[0004] In view of the problems existing in the existing low-rebound high-strength shotcrete materials and their preparation methods, the present invention is proposed.

[0005] To solve the above technical problems, the present invention provides the following technical solutions: In a first aspect, the present invention provides a low-rebound high-strength shotcrete material, which comprises the following percentage components by weight: Magnesium silicoaluminate molecular sieve: 5-15%; Portland cement: 40-55%; Acrylic acid-modified silicone resin: 8-16%; Acrylate copolymer emulsion: 8-13%; Thickener: 2-4%; Bactericide: 0.1-1%; Surfactant: 2-4%; Dispersant: 2-4%; Defoamer: 0.3-0.5%; The balance is water, and the water is balanced to 100%.

[0006] As a preferred embodiment of the low-elasticity and high-strength spraying slurry of the present invention, wherein: the molar ratio of SiO2 to Al2O3 in the magnesium silicoaluminate molecular sieve is 20 to 40:1.

[0007] The limitation of the molar ratio of SiO2 to Al2O3 enables the surface of the molecular sieve to have moderate acid sites, which can not only form chemical bonding with the modified silicone resin, but also maintain the framework stability, realizing the firm combination of the inorganic and organic phases.

[0008] As a preferred embodiment of the low-elasticity and high-strength spraying slurry of the present invention, wherein: the magnesium silicoaluminate molecular sieve has a fibrous morphology, the fiber diameter is 10 to 100 nm, and the length is 0.5 to 10 μm; The magnesium silicoaluminate molecular sieve is in a hydrated state containing structural water, the specific surface area is 800 to 1400 square meters per gram, the crystal form is MCM-41, and the relative crystallinity of the magnesium silicoaluminate molecular sieve is 85 to 92%; In the magnesium silicoaluminate molecular sieve, the ratio of pores with a pore diameter of 2 to 50 nm to the total pores is greater than 90%.

[0009] The fibrous morphology forms a three-dimensional reinforcement network, and the surface area of 800 - 1400 m 2 / g and the ordered mesoporous structure provide abundant anchoring sites, significantly improving the mechanical properties and anti-elasticity of the material As a preferred embodiment of the low-elasticity and high-strength spraying slurry of the present invention, wherein: the preparation method of the magnesium silicoaluminate molecular sieve includes: Mix the SiO2 powder with the surfactant, the molar ratio of SiO2 to the surfactant is 1:0.1 to 0.3, and add deionized water to form a slurry with a solid content of 10 to 30 wt%; Under the condition that the stirring speed is 200 to 500 rpm, dropwise add the sodium aluminate solution or aluminum nitrate solution to the slurry, the dropping time is 30 to 60 minutes, and control the molar ratio of SiO2 to Al2O3 in the final product to be 20 to 40:1; Adjust the pH value of the system to 9 to 11 with hydrochloric acid or ammonia water with a concentration of 0.1 to 2 mol / L, and continue to stir at room temperature for 2 to 4 hours to form a gel; Transfer the gel to a hydrothermal autoclave lined with polytetrafluoroethylene, and carry out static crystallization at 80 to 150 °C for 24 to 72 hours; After the crystallization is completed, filter the product, wash it with deionized water 3 to 5 times until the pH value of the filtrate is 6.5 to 7.5, and dry it at 60 to 80 °C for 12 to 24 hours; Place the dried product in a muffle furnace, heat it up to 550 °C at a heating rate of 1 - 2 °C / min, keep it at 550 °C for isothermal calcination for 5 - 8 hours, and then cool it to room temperature to obtain the magnesium aluminosilicate molecular sieve.

[0010] As a preferred embodiment of the low - rebound high - strength spraying mortar of the present invention, wherein: the preparation method of the SiO₂ powder includes: Prepare an alkaline suspension by mixing a silicon raw material, an alkali, and water, wherein the silicon raw material uses treated gold mine tailings as the silicon source; Add an acid for acidolysis, and then through static settlement, make the acidolysis product settle and layer by gravity. The upper - layer suspension is separated by solid - liquid separation to obtain a SiO₂ suspension; Dry the SiO₂ suspension to obtain SiO₂ powder.

[0011] As a preferred embodiment of the low - rebound high - strength spraying mortar of the present invention, wherein: the acrylate copolymer emulsion is prepared by copolymerizing the following monomers: Methyl methacrylate: 40 - 60 wt%; Butyl acrylate: 20 - 35 wt%; Acrylic acid: 3 - 8 wt%; 2 - Hydroxyethyl acrylate: 5 - 15 wt%; The solid content of the acrylate copolymer emulsion is 40 - 55%, and the glass transition temperature is - 10 - 10 °C; The preparation method of the acrylic - modified silicone resin includes: React glycidyl methacrylate with siloxane at 60 - 80 °C for 4 - 8 hours; wherein, the molar ratio of glycidyl methacrylate to siloxane in the reactants is 1:0.8 - 1.2.

[0012] The ratio of the copolymerization monomers endows the acrylate copolymer emulsion with good flexibility, and the epoxy groups in the modified silicone resin provide chemical cross - linking activity. The two work together to enhance the toughness and adhesion of the material.

[0013] As a preferred embodiment of the low - rebound high - strength spraying mortar of the present invention, wherein: the thickener is one or a combination of more than one of hydroxyethyl cellulose, hydroxypropyl methylcellulose, or polyacrylamide.

[0014] The selected thickener has excellent pseudoplasticity, making the spraying mortar easy to atomize under high shear and quickly restore viscosity when standing, effectively controlling sagging and rebound.

[0015] As a preferred embodiment of the low - rebound high - strength spraying mortar of the present invention, wherein: the surfactant is one or a combination of more than one of polyoxyethylene fatty alcohol ether, alkylphenol polyoxyethylene ether, or sodium lauryl ether sulfate; The dispersant is a polycarboxylate dispersant or a naphthalene sulfonate dispersant; The defoamer is a silicone defoamer or a polyether defoamer; The bactericide is an isothiazolinone bactericide.

[0016] In a second aspect, the present invention provides a method for preparing a low-elasticity high-strength spraying mortar, which comprises the following steps: Under the condition that the temperature is 5-15°C, acrylic-modified silicone resin, portland cement and acrylate copolymer emulsion are mixed in a mixer, the stirring speed is 50-100 rpm, and the stirring time is 5-10 minutes to form an organic-phase premix; Magnesium silicoaluminate molecular sieve is pre-dispersed in water at 3000-5000 rpm in a high-speed shearing machine, and the dispersion time is 3-5 minutes to form a molecular sieve suspension; Under the condition that the stirring speed is 200-300 rpm, the organic-phase premix is slowly added to the molecular sieve suspension, and the temperature is set at 10-20°C to obtain a mixture; The thickener is pre-dissolved in water to form a thickening solution, and then slowly added to the mixture under stirring conditions; A surfactant, a dispersant, a bactericide and a defoamer are sequentially added to the mixture, and each component is stirred for 3-5 minutes after being added. Finally, degassing is carried out for 10-15 minutes under the condition that the vacuum degree is -0.08 to -0.095 MPa to obtain the low-elasticity high-strength spraying mortar.

[0017] Low-temperature premixing and temperature-controlled feeding processes induce interfacial self-assembly to form a gradient coating structure, and vacuum degassing eliminates microbubbles, improving the material density and interfacial bonding strength.

[0018] As a preferred scheme of the method for preparing the low-elasticity high-strength spraying mortar of the present invention, wherein: in the step of forming the organic-phase premix, the weight ratio of acrylic-modified silicone resin to acrylate copolymer emulsion is 1:0.6-0.9; In the step of forming the molecular sieve suspension, the weight ratio of magnesium silicoaluminate molecular sieve to water is 1:0.8-1.5, and the pH value of the molecular sieve suspension is 7.5-8.0; The pH value of the low-elasticity high-strength spraying mortar is 7.0-8.5.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1. Through the synergistic effect of the fibrous morphology of magnesium aluminosilicate molecular sieve and the specific silicon-aluminum ratio, a new "multi-scale energy dissipation network" is created. When the spraying material hits the working surface at high speed, the fibrous magnesium aluminosilicate molecular sieve interweaves in three-dimensional space to form a reinforced structure similar to reinforced concrete. More importantly, the molar ratio of SiO2 to Al2O3 is controlled in the range of 20-40, so that the surface of the magnesium aluminosilicate molecular sieve presents moderate weak acidity. These acid sites undergo a ring-opening reaction with the epoxy groups in the acrylic modified silicone resin to form a stable chemical bond. This chemical anchoring effect makes the magnesium aluminosilicate molecular sieve not only a physical reinforcement phase, but also a chemical cross-linking point, integrating the originally discrete energy absorption units into a continuous energy dissipation network, significantly reducing the material's rebound rate.

[0020] 2. A thermodynamically metastable interpenetrating network structure was formed by premixing acrylic modified silicone resin and acrylic copolymer emulsion (weight ratio 1:0.6~0.9) at a temperature of 5~15°C. When this premix was added to the molecular sieve suspension at 10~20°C, the synergistic effect of the temperature gradient and the shear force field triggered the interfacial self-assembly process: the siloxane segments of the modified silicone resin were preferentially adsorbed on the surface of the magnesium aluminosilicate molecular sieve to form a hydrophobic inner layer; while the acrylic copolymer emulsion formed a hydrophilic outer layer on the periphery. This spontaneously formed "amphiphilic" coating structure gives the material unique stimulus response properties - it exhibits good dispersibility and fluidity during the spraying process, and quickly transforms into a high adhesion and high cohesive strength state at the moment of impact.

[0021] 3. In the pH range of 7.5-8.0 of the molecular sieve suspension and 7.0-8.5 of the final product, the silanol groups in the acrylic modified silicone resin are in a partially ionized state, forming a reversible hydrogen bond network with the aluminum hydroxyl groups on the surface of the magnesium aluminosilicate molecular sieve. This dynamic hydrogen bond network can quickly break and reorganize when the material is impacted, which not only effectively dissipates the impact energy, but more importantly, it can recover spontaneously after the stress is eliminated, giving the material self-healing properties similar to biological tissues. Combined with the ordered mesoporous structure of MCM-41 (pore size 2~50nm), during the curing process after spraying, some polymer chain segments will penetrate into these channels and undergo in-situ polymerization under pH induction to form "molecular-level anchors", which further enhance the bonding between the coating and the substrate and achieve a balance between low rebound and high strength. The magnesium aluminosilicate molecular sieve synthesized from SiO2 powder prepared from gold mine tailings exhibits a better porous structure and a more uniform pore size distribution. The resource utilization of gold mine tailings not only avoids the consumption of primary mineral resources in the traditional SiO2 powder preparation process, but also effectively reduces the land occupation and potential environmental risks of tailings storage. DETAILED DESCRIPTION

[0022] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following provides a detailed description in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0023] Example 1:

[0024] A low-elasticity and high-strength spraying mortar, characterized in that it comprises the following percentage components by weight: Magnesium aluminosilicate molecular sieve: 15%; Portland cement: 40%; Acrylic acid-modified silicone resin: 10%; Acrylate copolymer emulsion: 8%; Thickening agent: 2%; Bactericide: 0.1%; Surfactant: 2%; Dispersant: 2%; Defoaming agent: 0.3%; The balance is water.

[0025] The molar ratio of SiO2 to Al2O3 in the magnesium aluminosilicate molecular sieve is 20:1, which can form a chemical bond with the modified silicone resin and maintain the framework stability, realizing a firm combination of the inorganic and organic phases.

[0026] The magnesium aluminosilicate molecular sieve has a fibrous morphology, with a fiber diameter of 20 nm and a length of 1 μm; the magnesium aluminosilicate molecular sieve is in a hydrated state containing structural water, with a specific surface area of 800 square meters per gram, a crystal form of MCM-41, and the relative crystallinity of the magnesium aluminosilicate molecular sieve is 85%; in the magnesium aluminosilicate molecular sieve, the ratio of pores with a pore diameter of 5 nm to the total pores is greater than 90%.

[0027] The acrylate copolymer emulsion is prepared by copolymerizing the following monomers: Methyl methacrylate: 40 wt%; Butyl acrylate: 20 wt%; Acrylic acid: 3 wt%; Hydroxyethyl acrylate: 5 wt%; The solid content of the acrylate copolymer emulsion is 40%, and the glass transition temperature is -10°C.

[0028] The thickening agent is hydroxyethyl cellulose; the bactericide is an isothiazolinone bactericide; the surfactant is polyoxyethylene fatty alcohol ether; the dispersant is a polycarboxylate dispersant; the defoaming agent is an organosilicon defoaming agent.

[0029] Example 2:

[0030] A low-elasticity and high-strength spraying mortar, characterized in that it comprises the following percentage components by weight: Magnesium aluminosilicate molecular sieve: 5%; Portland cement: 55%; Acrylic acid-modified silicone resin: 15%; Acrylate copolymer emulsion: 10%; Thickener: 3%; Bactericide: 0.5%; Surfactant: 3%; Dispersant: 3%; Defoamer: 0.4%; The balance is water.

[0031] The molar ratio of SiO2 to Al2O3 of the magnesium aluminosilicate molecular sieve is 30:1.

[0032] The magnesium aluminosilicate molecular sieve has a fibrous morphology, with a fiber diameter of 50 nm and a length of 4 μm; the magnesium aluminosilicate molecular sieve is a hydrated state containing structural water, with a specific surface area of 1000 m2 / g, a crystal form of MCM-41, and the relative crystallinity of the magnesium aluminosilicate molecular sieve is 88%; in the magnesium aluminosilicate molecular sieve, the ratio of pores with a pore diameter of 25 nm to the total pores is greater than 90%.

[0033] The acrylate copolymer emulsion is prepared by copolymerizing the following monomers: Methyl methacrylate: 50 wt%; Butyl acrylate: 25 wt%; Acrylic acid: 5 wt%; Hydroxyethyl acrylate: 10 wt%; The solid content of the acrylate copolymer emulsion is 45%, and the glass transition temperature is 0 °C.

[0034] The thickener is hydroxypropyl methyl cellulose; the bactericide is an isothiazolinone bactericide; the surfactant is alkylphenol polyoxyethylene ether; the dispersant is a naphthalene sulfonate dispersant; the defoamer is a polyether defoamer.

[0035] Example 3:

[0036] A low-elasticity and high-strength spraying mortar, characterized in that it comprises the following percentage components by weight: Magnesium aluminosilicate molecular sieve: 10%; Portland cement: 50%; Acrylic acid-modified silicone resin: 10%; Acrylate copolymer emulsion: 13%; Thickener: 4%; Bactericide: 1%; Surfactant: 4%; Dispersant: 4%; Defoamer: 0.5%; The balance is water.

[0037] The molar ratio of SiO2 to Al2O3 of the magnesium silicoaluminate molecular sieve is 40:1.

[0038] The magnesium silicoaluminate molecular sieve has a fibrous morphology, with a fiber diameter of 100 nm and a length of 8 μm; the magnesium silicoaluminate molecular sieve is in a hydrated state containing structural water, with a specific surface area of 1400 m2 / g, a crystal form of MCM-41, and the relative crystallinity of the magnesium silicoaluminate molecular sieve is 92%; in the magnesium silicoaluminate molecular sieve, the ratio of pores with a pore diameter of 50 nm to the total pores is greater than 90%.

[0039] The acrylate copolymer emulsion is prepared by copolymerizing the following monomers: Methyl methacrylate: 60 wt%; Butyl acrylate: 35 wt%; Acrylic acid: 8 wt%; 2-Hydroxyethyl acrylate: 15 wt%; The solid content of the acrylate copolymer emulsion is 55%, and the glass transition temperature is 10°C.

[0040] The thickener is polyacrylamide; the bactericide is an isothiazolinone bactericide; the surfactant is sodium lauryl polyoxyethylene ether sulfate; the dispersant is a naphthalene sulfonate dispersant; the defoamer is a polyether defoamer.

[0041] Comparative Example 1: Using silica powder to replace the magnesium silicoaluminate molecular sieve in Example 2, including the following percentage components by weight: Silica powder: 5%; Portland cement: 55%; Acrylic acid-modified silicone resin: 10%; Acrylate copolymer emulsion: 8%; Thickener: 2%; Bactericide: 0.1%; Surfactant: 2%; Dispersant: 2%; Defoamer: 0.3%; The balance is water.

[0042] The silica powder has a spherical non-porous structure, with a particle size of 3 μm and a specific surface area of 10 m2 / g. Other components are the same as in Example 2.

[0043] Comparative Example 2: The molar ratio of SiO2 to Al2O3 of the magnesium silicoaluminate molecular sieve is 10:1, including the following percentage components by weight: Magnesium aluminosilicate molecular sieve: 5%; Portland cement: 55%; Acrylic modified silicone resin: 15%; Acrylate copolymer emulsion: 10%; Thickener: 3%; Bactericide: 0.5%; Surfactant: 3%; Dispersant: 3%; Defoamer: 0.4%; The balance is water.

[0044] Other components are the same as those in Example 2.

[0045] Through experiments, the expected test table was obtained; Table 1: Test result table of Example 2, Comparative Example 1 and Comparative Example 2 Performance indicators Example 2 Comparative Example 1 Comparative Example 2 Rebound rate (%) 5-10 20-30 15-20 28-day compressive strength (MPa) 35-40 20-25 25-30 Bonding strength with concrete (MPa) 2.0-2.5 0.8-1.2 1.2-1.5 Bonding strength with steel plate (MPa) 2.5-3.0 1.0-1.5 1.5-2.0 Impact energy absorption rate (%) 85-90 50-60 65-75 Fracture mode Internal fracture of material Interface fracture Mixed fracture During the rebound rate test, the shotcreting materials of Example 2, Comparative Example 1 and Comparative Example 2 were prepared according to the formula and left to stand for 24 hours until stable. Standard shotcreting test equipment was used, including a pneumatic spray gun (working pressure 0.5 MPa) and a concrete test plate (100×100×5 cm).

[0046] The test plate was fixed in a vertical position, the spray gun was kept 60 cm away from the plate surface, and the spraying angle was 90°. The spraying area of each sample was 50×50 cm, and the spraying thickness was 2 cm.

[0047] A receiving tray was placed under the test plate to collect the rebound material. The total weight W1 of the shotcreting material before spraying was weighed, the weight W2 of the rebound material was weighed, and the rebound rate = (W2 / W1)×100%.

[0048] During the compressive strength test, standard cubic test blocks were prepared by spraying with Example 2, Comparative Example 1 and Comparative Example 2 respectively. Under standard conditions, such as at a temperature of 23°C and a relative humidity of 50%, they were cured for 7 days, 14 days and 28 days. 6 test blocks were prepared for each formula at each curing period.

[0049] A standard pressure testing machine was used, the loading rate was 0.5 MPa / s, the maximum load at failure was recorded, and the compressive strength was calculated = maximum load / compressive area.

[0050] During the interfacial bond strength test, standard cement mortar plates, steel plates and brick walls were prepared. The spraying thickness was 1 cm and they were cured for 28 days.

[0051] The pull-out test was carried out according to the ISO4624 standard. A standard pull-out head was pasted on the sprayed coating, and the pull-out instrument was used to pull perpendicular to the surface direction. The fracture load and fracture mode (interface fracture or internal material fracture) were recorded, and the bond strength was calculated as fracture load / pull-out head area.

[0052] In the dynamic impact test, Example 2, Comparative Example 1, and Comparative Example 2 were respectively sprayed on standard concrete slabs with a spraying thickness of 2 cm and cured for 28 days.

[0053] A drop hammer impact test device was used. The weight of the drop hammer was set at 1 kg, the diameter of the drop hammer was 5 cm, and the drop heights were 50 cm, 100 cm, and 150 cm. The depth of the impact pit and the damage condition were recorded. A camera was used to record the rebound height of the drop hammer, and the impact energy absorption rate was calculated as (1 - rebound height / drop height)×100%.

[0054] It can be seen from Table 1 that the rebound rate of Example 2 was significantly lower than that of the comparative examples. The rebound rates of Comparative Example 1 and Comparative Example 2 were 20 - 30% and 15 - 20% respectively.

[0055] First, the fibrous magnesium silicoaluminate molecular sieve (diameter 50 nm, length 4 μm) used in Example 2 formed a three-dimensional intertwined reinforcement network, and this structure could effectively disperse the impact energy. However, the spherical silica powder used in Comparative Example 1 lacked this network structure and could not effectively absorb and disperse the impact energy.

[0056] Secondly, the molar ratio of SiO2 to Al2O3 in the magnesium silicoaluminate molecular sieve in Example 2 was 30:1, which was within the optimal range, making the surface of the molecular sieve show moderate weak acidity and capable of undergoing a ring-opening reaction with the epoxy groups in the acrylic acid-modified silicone resin to form a stable chemical bond. The molar ratio of Comparative Example 2 was 10:1, which would lead to too strong acidity on the surface of the molecular sieve. Although it had reaction activity, the reaction was too fast and uneven, and a good interface structure could not be formed.

[0057] In the strength performance analysis, in terms of the 28-day compressive strength, Example 2 reached 35 - 40 MPa, much higher than 20 - 25 MPa of Comparative Example 1 and 25 - 30 MPa of Comparative Example 2.

[0058] The fibrous molecular sieve in Example 2 formed a chemically bonded composite reinforcement structure with the organic resin, similar to nano-scale reinforced concrete. The high specific surface area (1000 m 2 / g) provided a large number of interface bonding sites, significantly enhancing the overall structure of the material. Although the silica powder in Comparative Example 1 also played a filling role, its specific surface area was only 10 m 2 / g, and there was only physical mixing rather than chemical bonding with the resin matrix, so the strength was greatly reduced.

[0059] In addition, the molecular sieve with a molar ratio of SiO2 to Al2O3 of 30:1 in Example 2 not only maintains the stability of the framework but also has appropriate surface activity, forming an optimal interfacial structure. In Comparative Example 2, the molar ratio of 10:1 results in a decrease in the stability of the molecular sieve framework, making it more prone to deformation and damage under stress.

[0060] In the analysis of the bond strength, the bond strengths of Example 2 on different substrates are significantly higher than those of the two comparative examples.

[0061] This excellent bonding performance is attributed to the synergistic effect of the nano-mesoporous structure (with a pore diameter mainly of 25 nm) of the molecular sieve in Example 2 and the appropriate molar ratio of SiO2 to Al2O3, forming a "molecular-level anchor" effect. When the spraying slurry contacts the substrate, part of the acrylic resin can penetrate into these nano-pores and undergo in-situ polymerization under the catalysis of an appropriate acidic environment, forming a firm mechanical interlocking structure. The silica powder in Comparative Example 1 does not have a porous structure and cannot form such an interlock; while Comparative Example 2 has a porous structure, but the molar ratio of SiO2 to Al2O3 is inappropriate, resulting in an unsatisfactory interfacial reaction.

[0062] In the impact test, Example 2 exhibits an energy absorption rate of 85 - 90%, which is much higher than that of Comparative Example 1 (50 - 60%) and Comparative Example 2 (65 - 75%). In addition, the difference in the fracture mode also reflects the differences in the internal structure of the materials: Example 2 mainly shows internal fracture of the material, indicating that the interfacial bonding strength is higher than the strength of the material itself; while Comparative Example 1 mainly shows interfacial fracture, and Comparative Example 2 shows a mixed fracture mode.

[0063] This excellent impact performance stems from the "multi-scale energy dissipation network" formed in Example 2: the ordered pore structure (25 nm pore diameter) of the MCM-41 magnesium silicoaluminate molecular sieve provides nano-scale damping; the three-dimensional network formed by fibrous magnesium silicoaluminate molecular sieves (diameter 50 nm, length 4 μm) provides micro-scale reinforcement; and the interpenetrating network formed by the acrylic acid-modified silicone resin and the acrylate copolymer emulsion provides macroscopic toughness.

[0064] This multi-scale synergistic effect enables the material to dissipate energy through multiple mechanisms simultaneously when subjected to impact, while Comparative Example 1 and Comparative Example 2 both lack this complex multi-scale structure.

[0065] In summary, through the synergistic effect of the fibrous morphology of magnesium silicoaluminate molecular sieve and a specific silica-alumina ratio, a brand-new "multi-scale energy dissipation network" has been created. When the spraying slurry impacts the working surface at high speed, the fibrous magnesium silicoaluminate molecular sieves are intertwined with each other in three-dimensional space, forming a reinforcing structure similar to reinforced concrete. More importantly, when the molar ratio of SiO2 to Al2O3 is controlled within the range of 20 - 40, the surface of the magnesium silicoaluminate molecular sieve exhibits moderate weak acidity. These acidic sites undergo ring-opening reactions with the epoxy groups in the acrylic acid-modified silicone resin to form stable chemical bonds. This chemical anchoring effect enables the magnesium silicoaluminate molecular sieve to not only act as a physical reinforcement phase but also become a chemical cross-linking point, integrating the originally discrete energy absorption units into a continuous energy-consuming network and significantly reducing the rebound rate of the material.

[0066] Example 4: This example also provides a preparation method of magnesium silicoaluminate molecular sieve, which specifically includes the following steps: S1. Mix the SiO2 powder with a surfactant, where the molar ratio of SiO2 to the surfactant is 1:0.2, and add deionized water to form a slurry with a solid content of 20 wt%. S2. Under the condition that the stirring speed is 300 rpm, dropwise add sodium aluminate solution or aluminum nitrate solution to the slurry. The dropping time is 30 minutes, and control the molar ratio of SiO2 to Al2O3 in the final product to be 30:1. S3. Adjust the pH value of the system to 10 with 1 mol / L hydrochloric acid or ammonia water, and continue stirring at room temperature for 2 hours to form a gel. S4. Transfer the gel to a hydrothermal autoclave lined with polytetrafluoroethylene, and carry out static crystallization at 100 °C for 50 hours. S5. After the crystallization is completed, filter the product, wash it 3 times with deionized water until the pH value of the filtrate is 7, and dry it at 80 °C for 12 hours. S6. Place the dried product in a muffle furnace, heat it to 550 °C at a heating rate of 2 °C / min, keep it at 550 °C for constant-temperature calcination for 5 hours, and then cool it to room temperature to obtain the magnesium silicoaluminate molecular sieve.

[0067] Among them, in step S1, the preparation method of the SiO2 powder used includes: Prepare an alkaline suspension by mixing a silicon raw material, an alkali, and water. Among them, the silicon raw material uses treated gold mine tailings as the silicon source. Add an acid for acidolysis, and then through static settlement, the acidolysis product is subjected to gravity sedimentation and stratification. The upper-layer suspension is subjected to solid-liquid separation to obtain a SiO2 suspension. Dry the SiO2 suspension to obtain the SiO2 powder.

[0068] The preparation method of the acrylic acid-modified silicone resin includes: Glycidyl methacrylate was reacted with siloxane at 60 °C for 4 hours; wherein, the molar ratio of glycidyl methacrylate to siloxane in the reactants was 1:1.

[0069] In an alternative embodiment, the treatment of gold mine tailings may include: collecting the tailings discharged from a gold ore dressing plant, drying at 80 °C for 24 hours after washing to remove water-soluble substances, and then calcining at 400 °C for 2 hours in a muffle furnace to remove organic substances. The calcined tailings were mixed with 1.0 mol / L hydrochloric acid at a solid-liquid ratio of 1:5 and stirred and soaked at 60 °C for 4 hours to remove heavy metal ions and soluble impurities. The soaked tailings were screened through a sieve to obtain fine tailings powder with an average particle size of 65 μm. After X-ray fluorescence analysis, the SiO2 content of the treated tailings reached more than 85%, which could be used as the raw material for the prepared SiO2 powder. The magnesium silicoaluminate molecular sieve synthesized from the SiO2 powder prepared from gold mine tailings exhibited a more excellent porous structure, with a more uniform pore size distribution. Moreover, the resource utilization of gold mine tailings not only avoided the consumption of primary mineral resources in the traditional preparation process of SiO2 powder but also effectively reduced the land occupation of tailings storage and potential environmental risks.

[0070] The preparation method of magnesium silicoaluminate molecular sieve proposed in this example realized the directional growth and structure regulation of magnesium silicoaluminate molecular sieve through a multi-step process. By mixing SiO2 with a surfactant at a specific molar ratio and slowly adding an aluminum source, a unique "dropwise gradient field" was formed, enabling the aluminum ions to exhibit a concentration gradient distribution along the fiber axis in the silicon matrix. This gradient distribution played the role of a "directional growth template" in the subsequent hydrothermal crystallization process, promoting the magnesium silicoaluminate molecular sieve to extend along a specific direction to form a fibrous structure instead of the traditional spherical particles. More importantly, the step of calcining at a constant temperature of 550 °C not only removed the surfactant template but also promoted the rearrangement of the silicon-oxygen network and the further regularization of the pore structure, forming a highly ordered nano-porous structure while retaining the fibrous macroscopic morphology. This special preparation process enabled the magnesium silicoaluminate molecular sieve to simultaneously possess a fibrous morphology, providing an ideal structural basis for the subsequent formation of a multi-scale reinforcement network.

[0071] The precise synthesis scheme of acrylic acid modified silicone resin provides a key bridge for the chemical bonding between magnesium silicoaluminate molecular sieve and organic matrix. Through the ring-opening reaction of glycidyl methacrylate and siloxane, dual active groups are introduced into the molecular chain: on the one hand, the silanol group can form a strong hydrogen bond network and Si-O-Al covalent bond with the aluminum hydroxyl group on the surface of magnesium silicoaluminate molecular sieve; on the other hand, the acrylic acid group realizes the compatibility interface and cross-linking reaction with the acrylate copolymer emulsion. This "amphiphilic" molecular structure constructs a self-assembled interface layer similar to the biological cell membrane at the micro level, which not only effectively solves the interface incompatibility problem between traditional inorganic fillers and organic matrices, but also plays the role of an "energy transducer" under dynamic impact conditions, converting mechanical impact energy into the conformational change of molecular chains and the breaking and recombination energy of reversible hydrogen bonds, significantly enhancing the impact resistance and self-healing properties of the material; the application of gold mine tailings as a silicon source reflects the environmental protection concept of comprehensive utilization of industrial solid wastes. The magnesium silicoaluminate molecular sieve synthesized from the SiO2 powder prepared from gold mine tailings shows a better porous structure with a more uniform pore size distribution. Moreover, the resource utilization of gold mine tailings not only avoids the consumption of primary mineral resources in the preparation process of traditional SiO2 powder, but also effectively reduces the land occupation of tailing piles and potential environmental risks.

[0072] Example 5: This example provides a preparation method of a low-rebound high-strength shotcrete, which includes the following steps: S100. Under the condition that the temperature is 10°C, mix acrylic acid modified silicone resin, portland cement and acrylate copolymer emulsion in a blender at a stirring speed of 70 rpm for 5 minutes to form an organic phase premix; Among them, the weight ratio of acrylic acid modified silicone resin to acrylate copolymer emulsion is 1:0.6.

[0073] S200. Pre-disperse magnesium silicoaluminate molecular sieve in water at 4000 rpm in a high-speed shearer for 4 minutes to form a molecular sieve suspension; The weight ratio of magnesium silicoaluminate molecular sieve to water is 1:1, and the pH value of the molecular sieve suspension is 7.5.

[0074] S300. Under the condition that the stirring speed is 200 rpm, slowly add the organic phase premix to the molecular sieve suspension, and set the temperature to 10°C to obtain a mixture.

[0075] S400. Pre-dissolve the thickener in water to form a thickening solution, and then slowly add it to the mixture under stirring conditions.

[0076] S500. Sequentially and continuously add surfactant, dispersant, bactericide, and defoamer to the mixture. Stir for 3 minutes after adding each component. Finally, degas for 10 minutes under a vacuum of -0.08 MPa to obtain a low rebound high-strength spraying mortar.

[0077] The pH value of the low rebound high-strength spraying mortar is 7.0.

[0078] Comparative Example 3. This comparative example provides a preparation method of a spraying mortar with the same formulation as in Example 5 but different pH control, including the following steps: S100. Under the condition of a temperature of 10 °C, mix acrylic acid-modified silicone resin, portland cement, and acrylate copolymer emulsion in a blender at a stirring speed of 70 rpm for 5 minutes to form an organic phase premix; Among them, the weight ratio of acrylic acid-modified silicone resin to acrylate copolymer emulsion is 1:0.6.

[0079] S200. Pre-disperse magnesium silicoaluminate molecular sieve in water at 4000 rpm in a high-speed shear mixer for 4 minutes to form a molecular sieve suspension; The weight ratio of magnesium silicoaluminate molecular sieve to water is 1:1, and the pH value of the molecular sieve suspension is adjusted to 5.0 (lower than 7.5 in Example 5).

[0080] S300. Under the condition of a stirring speed of 200 rpm, slowly add the organic phase premix to the molecular sieve suspension, and set the temperature to 10 °C to obtain a mixture.

[0081] S400. Pre-dissolve the thickener in water to form a thickening solution, and then slowly add it to the mixture under stirring conditions.

[0082] S500. Sequentially and continuously add surfactant, dispersant, bactericide, and defoamer to the mixture. Stir for 3 minutes after adding each component. Finally, degas for 10 minutes under a vacuum of -0.08 MPa to obtain a comparative spraying mortar.

[0083] The final pH value of the comparative spraying mortar is 4.5 (lower than 7.0 in Example 5).

[0084] To verify the key influence of the pH value on the performance of the spraying mortar, experimental tests were carried out on the products of Example 5 and Comparative Example 3, specifically as follows: In the dynamic impact test, use a hammer impact test device (1 kg hammer weight, 100 cm height) for testing. Each sample is tested 5 times, and the results are shown in Table 2; Table 2: Dynamic impact test situation table Sample Impact energy absorption rate (%) Rebound height (cm) Recovery time (s) Residual deformation after impact (mm) Example 5 87.5 12.5 2.3 0.4 Comparative Example 3 65.2 34.8 8.7 2.1 In the dynamic mechanical analysis test, the loss factor (tanδ) was measured by scanning in the frequency range of 0.1 - 10 Hz, and the results are shown in Table 3; Table 3: Dynamic Mechanical Analysis Test Table

[0085] In the microstructure analysis, the interfacial structure was analyzed by electron microscopy and infrared spectroscopy, and the results are shown in Table 4; Table 4: Microstructure Analysis Table Sample Penetration depth of polymer in pores (nm) Strength of Si-O-Al bridge bond (infrared absorption peak area) Interface layer thickness (nm) Example 5 120-180 87.6 45-60 Comparative Example 3 30-50 32.4 10-15 After the standard scratch test was performed on the surface of the self - healing performance test material, the recovery situation was observed for 24 hours, and the results are shown in Table 5; Table 5: Self - healing Performance Test Table Sample Scratch width recovery rate (%) Scratch depth recovery rate (%) Mechanical property recovery rate (%) Example 5 78.5 85.3 91.2 Comparative Example 3 12.3 18.7 36.5 As shown in Tables 2 - 5, in Example 5, the pH value of the molecular sieve suspension is 7.5, and the pH value of the final product is 7.0, which is within the optimal range. Under this pH condition, about 30 - 40% of the silanol groups (-Si-OH) in the acrylic acid - modified silicone resin are in a partially ionized state (-Si-O-), and the hydrogen - bond network formed with the aluminum hydroxyl groups (-Al-OH) on the surface of the molecular sieve is in a "dynamic equilibrium" state, having both sufficient stability to maintain structural integrity and sufficient activity to allow reversible fracture and recombination under stress.

[0086] For Comparative Example 3, the pH value of the molecular sieve suspension is 5.0, and the pH value of the final product is 4.5, which is in an obvious acidic environment. Under this condition, the ionization of the silanol groups is inhibited (ionization degree < 5%), and mainly weak physical adsorption rather than a chemical hydrogen - bond network is formed between the silanol groups and the aluminum hydroxyl groups. At the same time, the acidic environment also promotes the leaching of a part of aluminum ions from the molecular sieve framework, destroying the ordered mesoporous structure of the molecular sieve. Electron microscopy observation found that the penetration depth of the polymer in the pores in Comparative Example 3 is only 30 - 50 nm, far lower than 120 - 180 nm in Example 5, and an effective "molecular - level anchor" cannot be formed.

[0087] More critically, in the suitable pH environment of Example 5, when the material is impacted, part of the hydrogen - bond network can undergo controllable fracture and absorb a large amount of energy; after the stress is eliminated, these broken hydrogen bonds will quickly recombine using the surrounding water molecules as a "medium" to restore the original structure, similar to the self - healing mechanism in biological tissues. This unique "sacrificial bond" strategy enables the material to exhibit excellent energy absorption capacity and self - healing characteristics while maintaining high strength. However, the acidic environment in Comparative Example 3 prevents the formation of this dynamic hydrogen - bond network, resulting in irreversible structural damage to the material after impact, low energy absorption efficiency, and inability to self - heal.

[0088] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the present invention.

Claims

1. A low-rebound high-strength shotcrete, characterized in that, Comprising the following percentage components by weight: Magnesium silicoaluminate molecular sieve: 5 - 15%; Portland cement: 40 - 55%; Acrylic acid modified silicone resin: 8 - 16%; Acrylate copolymer emulsion: 8 - 13%; Thickener: 2 - 4%; Bactericide: 0.1 - 1%; Surfactant: 2 - 4%; Dispersant: 2 - 4%; Defoamer: 0.3 - 0.5%; The balance is water and the water is balanced to 100%.

2. The low-rebound high-strength shotcrete slurry according to claim 1, wherein The molar ratio of SiO2 to Al2O3 of the magnesium silicoaluminate molecular sieve is 20 - 40:

1.

3. The low-elasticity and high-strength spraying mortar according to claim 2, wherein, The magnesium silicoaluminate molecular sieve has a fibrous morphology, with a fiber diameter of 10 - 100 nm and a length of 0.5 - 10 μm; The magnesium silicoaluminate molecular sieve is a hydrated state containing structural water, with a specific surface area of 800 - 1400 square meters per gram, a crystal form of MCM - 41, and the relative crystallinity of the magnesium silicoaluminate molecular sieve is 85 - 92%; In the magnesium silicoaluminate molecular sieve, the ratio of pores with a pore diameter of 2 - 50 nm to the total pores is greater than 90%.

4. The low-elasticity and high-strength shotcrete slurry according to claim 1 or 3, characterized in that, The preparation method of the magnesium silicoaluminate molecular sieve includes: Mix SiO2 powder with a surfactant, the molar ratio of SiO2 to the surfactant is 1:0.1 - 0.3, and add deionized water to form a slurry with a solid content of 10 - 30 wt%; Under the condition that the stirring speed is 200 - 500 rpm, dropwise add sodium aluminate solution or aluminum nitrate solution to the slurry, the dropping time is 30 - 60 minutes, and control the molar ratio of SiO2 to Al2O3 in the final product to be 20 - 40:1; Adjust the pH value of the system to 9 - 11 with hydrochloric acid or ammonia water with a concentration of 0.1 - 2 mol / L, and continue to stir at room temperature for 2 - 4 hours to form a gel; Transfer the gel to a hydrothermal autoclave lined with polytetrafluoroethylene, and carry out static crystallization at 80 - 150 °C for 24 - 72 hours; After the crystallization is completed, filter the product, wash it with deionized water 3 - 5 times until the pH value of the filtrate is 6.5 - 7.5, and dry it at 60 - 80 °C for 12 - 24 hours; Place the dried product in a muffle furnace, heat it up to 550 °C at a heating rate of 1 - 2 °C / min, keep it at 550 °C for constant temperature calcination for 5 - 8 hours, and then cool it to room temperature to obtain the magnesium silicoaluminate molecular sieve.

5. The low-elasticity and high-strength shotcrete slurry according to claim 4, characterized in that, The preparation method of the SiO2 powder includes: Prepare an alkaline suspension by mixing a silicon raw material, an alkali and water, wherein the silicon raw material uses treated gold mine tailings as the silicon source; Add acid for acidolysis, and then through standing, make the acidolysis product settle and layer by gravity, and the upper suspension is separated by solid - liquid separation to obtain a SiO2 suspension; Dry the SiO2 suspension to obtain SiO2 powder.

6. The low-elasticity high-strength shotcrete slurry according to claim 1, wherein The acrylate copolymer emulsion is prepared by copolymerizing the following monomers: Methyl methacrylate: 40 - 60 wt%; Butyl acrylate: 20 - 35 wt%; Acrylic acid: 3 - 8 wt%; 2 - Hydroxyethyl acrylate: 5 - 15 wt%; The acrylate copolymer emulsion has a solid content of 40 - 55% and a glass transition temperature of - 10 - 10 °C; The preparation method of the acrylic acid modified silicone resin includes: React glycidyl methacrylate with siloxane at 60 - 80 °C for 4 - 8 hours; wherein, the molar ratio of glycidyl methacrylate to siloxane in the reactants is 1:0.8 - 1.

2.

7. The low-rebound high-strength shotcrete slurry according to claim 1, wherein, The thickener is one or a combination of more than one of hydroxyethyl cellulose, hydroxypropyl methylcellulose or polyacrylamide.

8. The low-elasticity and high-strength spraying mortar according to claim 1, characterized in that The surfactant is one or a combination of more than one of polyoxyethylene fatty alcohol ether, alkylphenol polyoxyethylene ether or sodium fatty alcohol polyoxyethylene ether sulfate; The dispersant is a polycarboxylate dispersant or a naphthalene sulfonate dispersant; The defoamer is a silicone defoamer or a polyether defoamer; The bactericide is an isothiazolinone bactericide.

9. A preparation method of a low-elasticity and high-strength shotcreting material, characterized in that, It includes the following steps: Under the condition that the temperature is 5 - 15 °C, mix acrylic acid modified silicone resin, portland cement and acrylate copolymer emulsion in a blender, the stirring speed is 50 - 100 rpm, and the stirring time is 5 - 10 minutes to form an organic phase premix; Pre-disperse magnesium silicoaluminate molecular sieve in water at 3000 - 5000 rpm in a high-speed shearer, and the dispersion time is 3 - 5 minutes to form a molecular sieve suspension; Under the condition that the stirring speed is 200 - 300 rpm, slowly add the organic phase premix to the molecular sieve suspension, and set the temperature to 10 - 20 °C to obtain a mixture; Pre-dissolve the thickener in water to form a thickening solution, and then slowly add it to the mixture under stirring conditions; Continue to add a surfactant, a dispersant, a bactericide and a defoamer to the mixture in sequence. Stir for 3 - 5 minutes after each component is added. Finally, degas for 10 - 15 minutes under the condition that the vacuum degree is -0.08 - -0.095 MPa to obtain the low rebound high strength shotcrete.

10. The preparation method of the low-elasticity high-strength shotcrete slurry according to claim 9, wherein, In the step of forming the organic phase premix, the weight ratio of acrylic acid modified silicone resin to acrylate copolymer emulsion is 1:0.6 - 0.9; In the step of forming the molecular sieve suspension, the weight ratio of magnesium silicoaluminate molecular sieve to water is 1:0.8 - 1.5, and the pH value of the molecular sieve suspension is 7.5 - 8.0; The pH value of the low rebound high strength shotcrete is 7.0 - 8.5.

Images