Supersulfurized ardealite slag grouting material with high impermeability and preparation method of persulfurized ardealite slag grouting material

Abstract

The invention provides an over-sulfurized ardealite slag grouting material with strong impermeability and a preparation method thereof, the grouting material comprises a gel material, an additive and water, the gel material comprises the following components by mass: 40-50 parts of ardealite, 30-40 parts of slag, 10-20 parts of cement, and 1-8 parts of a superfine admixture; the additive comprises a silane coupling agent ethanol modified solution accounting for 1%-3% of the total weight of the gel material, a water reducing agent accounting for 0.5%-1.5% of the total weight of the gel material, and an alkali activator accounting for 1%-2% of the total weight of the gel material; the silane coupling agent ethanol modified solution is prepared from a silane coupling agent, ethanol and water according to the weight ratio of 1: (7.5-8): (0.5-1.5), the pH value of the modified solution is adjusted to 4.5-5.5 by using acetic acid, and the concentration of the ethanol is not less than 95%. The persulfide ardealite slag grouting material is good in homogeneity, particles are good in dispersity in slurry when diffused in a porous medium, the particles are not prone to being separated from water, and the anti-permeability grade is larger than or equal to P8.

Description

Technical Field

[0001] The invention belongs to the technical field of grouting materials, and particularly relates to a persulfate gypsum slag grouting material with strong impermeability and a preparation method thereof. Background Art

[0002] As a major byproduct of the phosphoric acid industry, phosphogypsum has seen annual production exceeding 80 million tons since 2021. Its high impurity content limits its resource utilization, and its large-scale stockpiling leads to land occupation and environmental pollution. Persulfate gypsum slag cement has become a research hotspot for replacing ordinary Portland cement due to its advantages such as simple pretreatment, high solid waste utilization rate, and strong resistance to sulfate erosion. The persulfate gypsum slag grouting material developed based on it has significant potential in foundation reinforcement and crack sealing projects, but it also faces the following challenges:

[0003] ①Poor particle dispersion: The surface energy of persulfate gypsum and slag is high and their wettability is poor, which leads to easy segregation of the slurry and insufficient homogeneity;

[0004] ② Insufficient impermeability: Traditional grading design is difficult to form a dense structure, the seepage channel is not effectively blocked, and the permeability coefficient is usually >10 -8 cm / s;

[0005] ③ Dependence on chemical admixtures: requires a large amount of water reducers, expansion agents, etc., which is costly and poses environmental risks.

[0006] In response to the above problems, CN117185759A discloses a method for preparing synchronous grouting materials for shield tunnels in coastal areas. After grinding and heat activation, phosphogypsum can react with cement and steel slag powder to form calcium aluminoferrite to form a network skeleton and partially serve as an inert filler to fill the skeleton to form a dense skeleton filling structure. However, the phosphogypsum content in this material is small, the processing procedure is complicated, the cost is relatively high, and the homogeneity problem of multiple components during grouting cannot be solved; CN119841606A adds polymer silicone emulsion to modify the slag surface, forming a hydrophobic film in the surface gaps, and at the same time adds polypropylene fiber, which greatly improves the anti-seepage ability and crack resistance of the grouting material, but the improvement in the distribution uniformity of the grouting material is not obvious.

[0007] As can be seen, existing phosphogypsum slag grouting materials are expensive, the modification process is complex, and they fail to simultaneously address the issues of impermeability and homogeneity of the grouting materials. Therefore, it is particularly important to develop a grouting material with good impermeability and homogeneity, or to improve the homogeneity and impermeability of persulfate phosphogypsum slag grouting materials. Summary of the Invention

[0008] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a persulfate gypsum slag grouting material with strong impermeability. The persulfate gypsum slag grouting material has good homogeneity, and when diffused in a porous medium, the particles are well dispersed in the slurry and are not easily separated from water. The persulfate gypsum slag grouting material has an impermeability grade of ≥P8. The present invention also provides a preparation method of the persulfate gypsum slag grouting material with strong impermeability.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A persulfate gypsum slag grouting material with strong impermeability, comprising a gel material, an admixture and water, wherein the gel material comprises the following components in parts by mass:

[0011]

[0012] The admixture includes an ethanol-modified solution of a silane coupling agent whose content accounts for 1% to 3% of the total weight of the gel material, a water-reducing agent whose content accounts for 0.5% to 1.5% of the total weight of the gel material, and an alkali activator whose content accounts for 1% to 2% of the total weight of the gel material;

[0013] The silane coupling agent ethanol modified solution is prepared by mixing silane coupling agent, ethanol and water in a weight ratio of 1:(7.5-8):(0.5-1.5), and the pH value of the modified solution is adjusted to 4.5-5.5 with acetic acid, wherein the concentration of ethanol is not less than 95%.

[0014] In the present invention, the silane coupling agent ethanol-modified solution is preferably prepared in a mass ratio of silane coupling agent: ethanol: water = 1:8:1, wherein ethanol can reduce the surface tension (22.3 mN / m) and promote the spreading of the coupling agent on the particle surface; water serves as a hydrolysis medium to fully convert ethoxy groups into silanol groups; at the same time, acetic acid is used to adjust the pH to 4.5-5.5. Under these conditions, the silanol group has the highest stability and the hydrolysis rate reaches 0.02 mol / (L·min), avoiding excessive condensation to form a gel.

[0015] The total amount of the ethanol-modified silane coupling agent solution used is 1% to 3% of the total weight of the gel material. When the ethanol-modified silane coupling agent solution is less than 1wt%, the silanol coverage is insufficient (coverage rate is less than 60%), the absolute value of the zeta potential is less than 25mV, and the particle dispersibility is poor. When the ethanol-modified silane coupling agent solution is greater than 3wt%, the excess coupling agent forms multilayer physical adsorption, resulting in a reversal of the particle surface charge (the zeta potential increases from -35mV to +10mV), which triggers secondary agglomeration.

[0016] In the present invention, the silane coupling agent is at least one of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane.

[0017] Further preferred is γ-aminopropyltriethoxysilane (silane coupling agent KH-550). The ethoxy group (-OCH2CH3) in the coupling agent molecule can be hydrolyzed to form silanol (Si-OH), which undergoes a condensation reaction with the hydroxyl (-OH) of the metal oxide (such as CaO, Al2O3) on the surface of slag / phosphogypsum to form a -Si-OM (M is a metal ion) covalent bond. The polar amino group (-NH2) at the other end directionally adsorbs water molecules, constructs a hydrophilic interface, and solves the problem of difficulty in dispersion caused by high surface energy of particles; at the same time, aminosilane can be protonated (-NH3 + ), enhances adsorption with negatively charged slag particles through electrostatic attraction, and promotes the formation of ettringite in the subsequent alkali-activated reaction.

[0018] In the present invention, the water-to-binder ratio (weight ratio of water to gel material) of the persulfate gypsum slag grouting material with strong impermeability is 0.4-0.6, which can ensure the fluidity and water retention of the grouting material.

[0019] In the present invention, the ultrafine admixture is at least one of silica fume and nano-silicon dioxide; the content of the silica fume in the gel material is 3 to 8 parts; the content of the nano-silicon dioxide in the gel material is 1 to 3 parts.

[0020] Furthermore, the particle size of the silica fume is less than 1 μm and the specific surface area is not less than 15000 m 2 / kg; the particle size of the nano-silicon dioxide is 1 to 100 nm.

[0021] Ultrafine admixtures can fill the submicron gaps of 1-10 μm between slag and phosphogypsum particles, refining the pore size to below 50 nm and blocking water seepage channels.

[0022] In the present invention, the phosphogypsum is selected from phosphogypsum particles having a main peak particle size of 10 to 30 μm after ball milling, a weight ratio of fine particles less than 10 μm ≤ 15%, a weight ratio of coarse particles greater than 30 μm ≤ 20%, and the residual phosphorus and fluorine impurities are removed by water washing.

[0023] The slag is selected from slag particles having a main peak particle size of no more than 50 μm after grinding, a weight ratio of large particles with a particle size greater than 50 μm of ≤5%, and a weight ratio of fine particles with a particle size less than 10 μm of ≤20%;

[0024] The main peak particle size of the cement is 5 to 20 μm, wherein particles with a particle size less than 10 μm account for 30% to 40%.

[0025] The present invention grinds slag, phosphogypsum and cement in a closed-circuit ball mill or pre-crushes them with a cone crusher, and then grinds them with a vertical mill. The slag is tested by a laser particle size analyzer to ensure that the d 90≤50μm, 50μm sieve residue ≤5%, fine particles (<10μm) account for ≤20%.

[0026] In the present invention, the alkali activator is NaOH or KOH; the water reducer is a polycarboxylic acid water reducer with a solid content of 20% to 50% and an effective water reduction rate greater than 25% (high performance water reducer standard in GB 8076-2008 "Concrete Admixtures"), so as to achieve a water-binder ratio while maintaining good workability.

[0027] Generally, industrial-grade NaOH / KOH (purity ≥ 96%) can meet the requirements, and there is no need to use reagent-grade NaOH / KOH (purity ≥ 99%), which can reduce costs.

[0028] Among them, the alkali activator (NaOH / KOH) is used to increase the alkalinity of the distal end of the slurry (pH ≥ 12.5) and promote the depolymerization of slag glass to form CSH gel and CASH gel; the water reducer is used to open the flocculation structure of cement particles to avoid local aggregation or uneven dispersion of cement particles, thereby improving the homogeneity of the material.

[0029] The present invention also provides a method for preparing a persulfate gypsum slag grouting material with strong impermeability, which specifically comprises the following steps:

[0030] a. Weigh each raw material according to the composition of the gel material;

[0031] b. Add the ethanol-modified silane coupling agent solution to the slag in a weight ratio of (1.5-2):10 or to the phosphogypsum in a weight ratio of (2.5-3.5):10 into a blender and stir at high speed at room temperature for 30-60 minutes to allow the ethanol-modified silane coupling agent solution to fully graft onto the surface of the phosphogypsum or slag; after the reaction, dry in an oven at 50-80°C for 3-5 hours to form a 5-10 nm hydrophilic coating on the surface of the phosphogypsum or slag particles;

[0032] c. Add cement, ultrafine admixtures, the remaining phosphogypsum, slag, and the modified phosphogypsum or slag particles in step b into a dry mixer, and stir at a low speed to mix them uniformly to form a dry mixed material with a coarse-medium-fine three-level skeleton; then add the water reducer and alkali activator, stir at a high speed to ensure that the water reducer and alkali activator are evenly dispersed in the dry mixed material, and then change to low-speed stirring; then slowly add water and stir at a medium speed to mix them uniformly.

[0033] The specific method of slowly adding water is to add all the water at a uniform speed within 3 to 5 minutes, while increasing the stirring speed to 300 to 400 r / min, and continuing stirring for 5 to 8 minutes until uniform.

[0034] The high-speed stirring rate in steps b and c is 500-800 r / min; the low-speed stirring rate in step c is 120-180 r / min, and the medium-speed stirring rate is 300-400 r / min.

[0035] In step b, the high-speed stirring rate is 500 to 800 r / min, at which point the particle surface shear force can reach 50 Pa, which can destroy the original agglomerates and expose fresh hydroxyl sites (increasing the specific surface area by 20%). Simultaneously, the stirring time is 30 to 60 minutes (in situ FTIR monitoring reveals that the condensation reaction of silanol groups with the particle surface reaches 90% completion rate at 30 minutes and reaches equilibrium after 60 minutes). At this point, the reaction temperature is room temperature (25±2°C) to avoid high temperatures that accelerate silanol self-polymerization (activation energy Ea=45kJ / mol), ensuring that the coupling agent is primarily chemically bonded. Modifying some of the particles can improve overall dispersibility through a "bridging effect" (e.g., modifying 30% to 50% of the coarse particles to make them the dispersed core).

[0036] The grouting process of the persulfate gypsum slag grouting material with strong permeability in the present invention comprises the following steps:

[0037] S1 adopts a staged grouting process. In the low-pressure infiltration stage with a pressure of 0.3-0.5 MPa and a flow rate of 8-10 L / min, the high dispersibility of the modified slurry is used to make the particles evenly penetrate the tiny pores (>100 μm) of the porous medium, avoiding the retention of coarse particles. In the high-pressure compaction stage with a pressure of 1.0-1.5 MPa and a flow rate of 3-5 L / min, the ultrafine admixture (silica fume / nano-SiO2) is promoted to fill the residual large pores (≤100 μm) to form a dense hardened body.

[0038] S2 is covered with a sealing film within 24 hours after grouting to ensure that the moisture loss rate is ≤5%. Subsequently, it is cured in an environment with a humidity ≥90% and a temperature of 20±2℃ for 7 to 10 days to ensure that the hydration product CSH gel or ettringite is fully generated at the interface of the modified particles.

[0039] The core mechanism of the present invention is as follows:

[0040] 1. Surface modification of coupling agents: ① Dispersion stabilization: Silane coupling agents bridge the "particle-coupling agent-water" hydrogen bond, reducing particle surface energy, increasing the hydrophilicity of slag / phosphogypsum, and delaying particle settling (sedimentation velocity reduced by 40%) and solid-liquid separation during the diffusion of grouting materials. ② Interface strengthening: After coupling agent modification, the hydrophilicity of the slag / phosphogypsum particle surface is improved (the contact angle is reduced from 85° to below 50°), promoting the chemical bonding between cement hydration products (CSH gel) and slag / phosphogypsum.

[0041] 2. Grading and filling effect: According to the principle of closest packing, phosphogypsum particles form a skeleton, and slag particles regulate ultrafine admixtures (silica fume / nano-SiO2) to fill 1-10μm gaps, and the pore size is refined to below 50nm, blocking the water seepage channel (permeability coefficient ≤1×10 -8 cm / s);

[0042] 3. Function of admixtures: Alkali activator is used to adjust the pH value of the system to ensure that the pH of the slurry can remain above 12.5 at the far end of grouting, thereby promoting the depolymerization of the slag glass structure; water reducer is used to open the flocculation structure of cement particles and ensure the dispersion of particles. The two work together to further improve the overall density and impermeability of the material after grouting.

[0043] Compared with the existing technology, the advantages and beneficial effects of the present invention are as follows:

[0044] 1. The present invention solves the problems of slurry component separation, water loss and insufficient remote alkalinity in porous media by regulating the particle fineness of slag, phosphogypsum and cement, coordinating the surface modification of slag or phosphogypsum, and optimizing the mixing ratio between the components.

[0045] 2. The silane coupling agent in the present invention improves the affinity between particles and the liquid phase through hydrophilic modification, inhibits sedimentation and segregation, reduces solid-liquid separation during slurry diffusion, and significantly improves homogeneity. The absolute value of the zeta potential of the modified slag / phosphogypsum particles is ≥30mV, the sedimentation rate of the grouting material particles is <5% (unmodified >30%), and the particles are well dispersed in the slurry when diffused in the porous medium and are not easily separated from the water.

[0046] 3. The preparation method of the present invention ensures the homogeneity of the slurry. At the same time, the excess phosphogypsum particles and the hydrated ettringite and CSH gel and ultrafine admixtures (silica fume / nano-SiO2) can refine the pores to below 50nm, making the permeability coefficient of the grouting material ≤1×10 -8 cm / s (60% lower than that of unmodified materials), anti-seepage grade ≥ P8 (without waterproofing agent), distal pH can reach 12.5, and stone body compressive strength can reach 40MPa. It solves the engineering problem of poor homogeneity of the grouting material when diffusing in porous media, resulting in weak consolidation and filling ability and insufficient anti-seepage, effectively improves the effective consolidation radius of the grouting material, and is suitable for sand layer foundation reinforcement, rock and soil crack sealing and other fields.

[0047] 4. It has better construction adaptability, improved slurry fluidity (220-260mm) and suspension stability, and is suitable for uniform penetration of porous media under a pressure of 0.3-0.6MPa. DETAILED DESCRIPTION

[0048] The present invention provides a persulfate gypsum slag grouting material with high permeability and a preparation method thereof. To clearly and intuitively illustrate the objectives, technical solutions, and beneficial effects of the present invention, specific embodiments are described in detail below. It should be understood that the examples cited are merely illustrative of the present invention and are not intended to limit the scope of the present invention.

[0049] In a specific embodiment of the present invention, a persulfate gypsum slag grouting material with strong impermeability is composed of a gel material, an admixture and water. The gel material contains the following components in parts by weight:

[0050]

[0051]

[0052] The admixture includes 1% to 3% of the total weight of the gel material, an ethanol-modified solution of a silane coupling agent, 0.5% to 1.5% of a water reducer, and 1% to 2% of an alkali activator;

[0053] The silane coupling agent ethanol modified solution is prepared by mixing the silane coupling agent, ethanol and water in a weight ratio of 1:(7.5-8):(0.5-1.5), and the pH value of the modified solution is adjusted to 4.5-5.5 with acetic acid, wherein the concentration of ethanol is not less than 95%.

[0054] In the embodiment of the present invention, γ-aminopropyltriethoxysilane is selected as the silane coupling agent for the test; the water-binder ratio of the persulfate gypsum slag grouting material with strong impermeability is 0.4-0.6.

[0055] In the embodiment of the present invention, the ultrafine admixture is at least one of silica fume and nano-silicon dioxide. The silica fume is selected to have a particle size of less than 1 μm and a specific surface area of ​​not less than 15000 m 2 / kg of silica fume; the particle size of nano-silicon dioxide is 1 to 100nm.

[0056] The phosphogypsum is selected from phosphogypsum particles having a main peak particle size of 10 to 30 μm after ball milling, a weight ratio of fine particles less than 10 μm ≤ 15%, a weight ratio of coarse particles greater than 30 μm ≤ 20%, and water washing to remove residual phosphorus and fluorine impurities.

[0057] The slag is selected from slag particles having a main peak particle size of no more than 50 μm after grinding, a weight ratio of large particles larger than 50 μm of ≤5%, and a weight ratio of fine particles smaller than 10 μm of ≤20%.

[0058] The main peak particle size of cement is 5 to 20 μm, of which particles with a size less than 10 μm account for 30% to 40%.

[0059] In a specific embodiment of the present invention, the method for preparing the persulfate gypsum slag grouting material with strong impermeability comprises the following steps:

[0060] a. Weigh each raw material according to the composition of the gel material;

[0061] b. Add the silane coupling agent ethanol-modified solution to the slag at a weight ratio of (1.5-2):10 or to the phosphogypsum at a weight ratio of (2.5-3.5):10 into a blender and stir at high speed (500-800 rpm) for 30-60 min at room temperature to allow the silane coupling agent ethanol-modified solution to be fully grafted onto the surface of the phosphogypsum or slag; after the reaction is completed, dry in an oven at 50-80°C for 3-5 h to form a 5-10 nm hydrophilic coating on the surface of the phosphogypsum or slag particles;

[0062] c. Add cement, ultrafine admixtures, the remaining phosphogypsum, slag, and the modified phosphogypsum or slag particles in step b into a dry mixer, first stir at a low speed (120-180 r / min) to mix them evenly to form a dry mixed material with a coarse-medium-fine three-level skeleton; then add the water reducer and alkali activator, stir at a high speed (500-800 r / min), ensure that the water reducer and alkali activator are evenly dispersed in the dry mixed material, and then stir at a low speed; then slowly add water and stir at a medium speed (300-400 r / min) until evenly mixed.

[0063] Examples and Comparative Examples

[0064] The present invention provides four groups of examples and three groups of comparative examples with different components, which demonstrate the improvement in the performance of the ultra-high performance concrete of the present invention through comparison. The weight of each component is shown in Table 1.

[0065] Table 1 Ratio of raw materials in comparative examples and examples (unit: part)

[0066]

[0067]

[0068] The silane coupling agent ethanol modified solution in Table 1 above is prepared by mixing γ-aminopropyltriethoxysilane, 95% ethanol, and water in a weight ratio of 1:8:1, and the pH of the modified solution is adjusted to 5 with acetic acid.

[0069] The grouting materials prepared in the above examples and comparative examples were subjected to construction tests according to the following grouting process. The specific process steps are as follows:

[0070] S1 adopts a staged grouting process. In the low-pressure infiltration stage with a pressure of 0.3-0.5 MPa and a flow rate of 8-10 L / min, the high dispersibility of the modified slurry is used to make the particles evenly penetrate the tiny pores (>100 μm) of the porous medium, avoiding the retention of coarse particles. In the high-pressure compaction stage with a pressure of 1.0-1.5 MPa and a flow rate of 3-5 L / min, the ultrafine admixture (silica fume / nano-SiO2) is promoted to fill the residual large pores (≤100 μm) to form a dense hardened body.

[0071] S2 should be covered with sealing film within 24 hours after grouting to ensure that the moisture loss rate is ≤5%, and then cured in an environment with humidity ≥90% and temperature of 20±2℃ for 7 to 10 days.

[0072] Performance test (compressive strength coefficient of variation test)

[0073] The grouting materials prepared in the examples and comparative examples were grouted according to the above process, and 6 150 mm cubic specimens were prepared for each group of examples and comparative examples according to GB / T 50081-2019. The compressive strength was tested after 28 days of standard curing; the average value and standard deviation were calculated, and the coefficient of variation was calculated according to the formula CV = standard deviation / average value × 100%, and the average value of the performance test results of each group was recorded in Table 2 below.

[0074] Table 2 Performance test results

[0075]

[0076]

[0077] According to the test data in Table 2, the absolute value of the Zeta potential of the persulfate gypsum slag grouting materials prepared in Examples 1-4 of the present invention is above 30 mV, and the permeability coefficient is ≤1×10 -8 cm / s, and the impermeability grade reaches P9 or above, which is more than 60% higher than that of the unmodified material (Comparative Example 1); the coefficient of variation of the 28-day compressive strength is less than 8%, ensuring performance uniformity; and the porosity of the material is reduced to 18%, and the material has good homogeneity. According to the performance test results of Comparative Example 2, when the silane coupling agent ethanol-modified solution is less than 1wt%, the silanol coverage is insufficient (coverage rate <60%), the absolute value of the Zeta potential is less than 25mV, and the particle dispersion is poor; according to the performance test results of Comparative Example 3, when the silane coupling agent ethanol-modified solution is greater than 3wt%, the excess coupling agent forms multilayer physical adsorption, resulting in a reversal of the particle surface charge (the Zeta potential increases from -35mV to +10mV), triggering secondary agglomeration and affecting the homogeneity of the grouting material.

[0078] It should be noted that, in the grouting test, comparative example 1 is prone to precipitation and segregation, and solid-liquid separation of slag / phosphogypsum is prone to occur during the grouting process, and it is difficult to diffuse and transmit to the far end. The slurry particles cannot effectively fill the small pores and have poor homogeneity. According to the test results in Table 2, its impermeability and strength properties are far inferior to those of the persulfate phosphogypsum slag grouting material prepared in the embodiment of the present invention.

[0079] Application Examples

[0080] The persulfate gypsum slag grouting material prepared in Example 1 was used in a subway tunnel sand layer grouting project. The material could be smoothly injected into narrow gaps and effectively filled and reinforced. After construction, the tunnel lining leakage rate was significantly reduced.

[0081] The persulfate gypsum slag grouting material prepared in Example 2 is used for foundation reinforcement of a large-scale water conservancy project. After long-term underwater environment testing, the foundation has good stability and reliable anti-seepage performance.

[0082] The persulfate gypsum slag grouting material prepared in Example 3 was used in the deep foundation pit support grouting operation of a high-rise building. The good homogeneity of the material ensured uniform grouting and stable support structure, meeting the strength and anti-seepage requirements of the project.

[0083] The persulfate gypsum slag grouting material prepared in Example 4 was applied to the treatment of a highway tunnel disease, effectively repairing the original problems such as water seepage and voids, and improving the tunnel structure stability and waterproof performance.

[0084] in conclusion

[0085] This patent addresses the technical challenges of poor homogeneity and insufficient impermeability of persulfated phosphogypsum slag grouting materials in porous media through particle grading control and surface modification with a silane coupling agent. The silane coupling agent chemically bonds to create a hydrophilic interface on the particle surface, increasing the absolute value of the particle zeta potential to over 30 mV and reducing the sedimentation rate to below 5%. This fundamentally improves dispersion stability and the solid-liquid separation that often occurs when the slurry diffuses in the medium. Furthermore, a four-stage gradation system (coarse skeleton-medium fill-fine cementation-ultrafine interstitial fill) designed based on the closest packing theory reduces the material's porosity from 28% to 18% and refines the peak pore size from 100 nm to 30 nm (porosity and pore size distribution are measured by mercury intrusion porosimetry (MIP) or gas adsorption, directly comparing key parameters before and after optimization). This results in a dense, impermeable structure. Furthermore, by reducing the use of traditional admixtures such as expansion agents and waterproofing agents, the phosphogypsum utilization rate is ≥40%, reducing production costs by 20%, achieving both environmental and economic advantages. This technology has been successfully applied in engineering scenarios such as subway tunnels, water conservancy hubs, and deep foundation pit support, effectively solving the problems of leakage and reinforcement in actual projects, and providing innovative solutions for the high-performance application of phosphogypsum-based grouting materials. It has significant engineering application value and promotion prospects.

Claims

1. A persulfate gypsum slag grouting material with strong impermeability, comprising a gel material, an admixture and water, characterized in that The gel material comprises the following components in parts by mass: The admixture includes an ethanol-modified solution of a silane coupling agent whose content accounts for 1% to 3% of the total weight of the gel material, a water-reducing agent whose content accounts for 0.5% to 1.5% of the total weight of the gel material, and an alkali activator whose content accounts for 1% to 2% of the total weight of the gel material; The silane coupling agent ethanol modified solution is prepared by mixing silane coupling agent, ethanol and water in a weight ratio of 1:(7.5-8):(0.5-1.5), and the pH value of the modified solution is adjusted to 4.5-5.5 with acetic acid. The concentration of the ethanol is not less than 95%.

2. The persulfate gypsum slag grouting material with strong impermeability according to claim 1, characterized in that: The silane coupling agent is at least one of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane.

3. The persulfate gypsum slag grouting material with strong impermeability according to claim 1, characterized in that: The water-cement ratio is 0.4-0.

6.

4. The persulfate gypsum slag grouting material with strong impermeability according to claim 1, characterized in that: The ultrafine admixture is at least one of silica fume and nano silicon dioxide; the content of the silica fume in the gel material is 3 to 8 parts; the content of the nano silicon dioxide in the gel material is 1 to 3 parts.

5. The persulfate gypsum slag grouting material with strong impermeability according to claim 1, characterized in that: The phosphogypsum is selected from phosphogypsum particles having a main peak particle size of 10 to 30 μm after ball milling, a weight ratio of fine particles less than 10 μm of ≤15%, a weight ratio of coarse particles greater than 30 μm of ≤20%, and the phosphogypsum particles are washed with water to remove residual phosphorus and fluorine impurities.

6. The persulfate gypsum slag grouting material with high impermeability according to claim 1, characterized in that: The slag is selected from slag particles having a main peak particle size of no more than 50 μm after grinding, a weight ratio of large particles with a particle size greater than 50 μm of ≤5%, and a weight ratio of fine particles with a particle size less than 10 μm of ≤20%.

7. The persulfate gypsum slag grouting material with high permeability according to claim 1, characterized in that: The main peak particle size of the cement is 5 to 20 μm, wherein particles with a particle size less than 10 μm account for 30% to 40%.

8. The persulfate gypsum slag grouting material with high permeability according to claim 1, characterized in that: The alkali activator is NaOH or KOH; the water reducer is a polycarboxylic acid water reducer with a solid content of 20% to 50% and an effective water reduction rate greater than 25%.

9. A method for preparing the persulfate gypsum slag grouting material with high permeability according to any one of claims 1 to 8, comprising the following steps: a. Weigh each raw material according to the composition of the gel material; b. Add the ethanol-modified silane coupling agent solution to the slag in a weight ratio of (1.5-2):10 or to the phosphogypsum in a weight ratio of (2.5-3.5):10 into a blender and stir at high speed at room temperature for 30-60 minutes to allow the ethanol-modified silane coupling agent solution to fully graft onto the surface of the phosphogypsum or slag; after the reaction, dry in an oven at 50-80°C for 3-5 hours to form a 5-10 nm hydrophilic coating on the surface of the phosphogypsum or slag particles; c. Add cement, ultrafine admixtures, the remaining phosphogypsum, slag, and the modified phosphogypsum or slag particles in step b into a dry mixer, and stir at a low speed to mix them uniformly to form a dry mixed material with a coarse-medium-fine three-level skeleton; then add the water reducer and alkali activator, stir at a high speed to ensure that the water reducer and alkali activator are evenly dispersed in the dry mixed material, stir at a low speed, and then slowly add water and stir at a medium speed to mix them uniformly.

10. The method for preparing the persulfate gypsum slag grouting material with strong impermeability according to claim 9, characterized in that The high-speed stirring rate in steps b and c is 500-800 r / min; the low-speed stirring rate in step c is 120-180 r / min, and the medium-speed stirring rate is 300-400 r / min.

Images