Water dispersion resistant grouting slurry, preparation method and application

Abstract

The invention provides water dispersion resistant grouting slurry, a preparation method and application, and belongs to the field of shield construction materials. The cement, the slaked lime and the fly ash are synergistically proportioned, and the composite anti-dispersing agent is introduced, so that a stable gelling system is formed. After the composite anti-dispersing agent polyacrylamide grafted silane anti-dispersing agent encounters water, silane groups are hydrolyzed to generate silanol, a nanoscale siloxane film layer is formed on the surface of slurry, and invasion of water molecules is prevented. When the film layer is washed by water flow, unreacted silane groups can continue to be crosslinked, the damaged part is automatically filled, and the dispersion resistance is maintained. In addition, carboxyl on a molecular chain of the anti-dispersing agent reacts with a cement hydration product Ca (OH) 2 to generate calcium carboxylate, so that the cohesive force among particles is enhanced; silane groups and hydroxyl groups on the surface of the fly ash / bentonite form covalent bonds, so that the cementing material is firmly connected with the aggregate, and the water washing resistance of the whole slurry is improved.

Description

Technical Field

[0001] The present invention belongs to the field of shield construction materials, and particularly relates to a water-resistant dispersion grouting slurry, a preparation method and an application thereof. Background Art

[0002] With the continuous development of railway construction in China, the shield method has been widely used in large-scale underground projects such as railways and highways. Among many tunnel construction methods, the shield method has become the preferred construction method for the construction of a large number of urban subways, cross-river or cross-sea underwater tunnels due to its small impact on the surrounding environment, strong adaptability to complex geological conditions, and fast and safe construction.

[0003] During the shield construction process, synchronous grouting is an important process for filling the shield tail gap and stabilizing the formation. The slurry required during the synchronous grouting process needs to have good fluidity, stability, small fluidity loss over time, and reasonable setting time and other properties. Synchronous grouting has a great impact on preventing ground surface deformation, controlling tunnel settlement, increasing the waterproof function of the lining joint, improving the stress state of the lining, and shield deviation correction. In high water-rich strata, the shield tail gap is easily filled with groundwater during the traditional synchronous grouting process, resulting in the segregation of ordinary grouting materials and the loss of gelling materials during the synchronous grouting operation.

[0004] Therefore, there is an urgent need to develop a water-resistant dispersion synchronous grouting slurry. Summary of the Invention

[0005] In view of the technical problems existing in the prior art, the present invention aims to provide a water-resistant dispersion grouting slurry, a preparation method and an application thereof.

[0006] One of the purposes of the present invention is to provide a water-resistant dispersion grouting slurry, and the grouting slurry comprises the following raw materials in parts by weight: 120-200 parts of cement, 60-100 parts of slaked lime, 250-350 parts of fly ash, 40-60 parts of bentonite, 1100-1250 parts of sand, 12-18 parts of a composite anti-dispersant and 260-340 parts of water; The composite anti-dispersant is polyacrylamide grafted silane, and the molecular weight of polyacrylamide is 10 million - 15 million.

[0007] Preferably, the sand comprises fine sand and medium sand; the particle size of the fine sand is ≤ 0.3 mm, and the particle size of the medium sand is 0.3 - 0.8 mm; the mass ratio of the fine sand to the medium sand is 3 - 5:5 - 7.

[0008] Preferably, the mass ratio of the cement to the composite anti-dispersant is 8 - 11:1.

[0009] Preferably, the mass ratio of the cement, slaked lime and fly ash is 1.2 - 3.33:1:2.5 - 5.83.

[0010] Preferably, the mass ratio of the cement, hydrated lime and fly ash is 1.67 - 2.57:1:3.5 - 5.0.

[0011] Preferably, the calcium oxide content in the fly ash is 15% - 30%.

[0012] Preferably, the water - binder ratio of the water - resistant and anti - dispersion grouting slurry is 0.47 - 0.55.

[0013] The second object of the present invention is to provide a preparation method of the water - resistant and anti - dispersion grouting slurry as described above, comprising the following steps: S1. Screen and then grind the fly ash to obtain activated fly ash with a specific surface area of 600 - 1000 m 2 / kg; S2. Put the cement, hydrated lime, activated fly ash and bentonite into a mixer, dry - mix at 25 - 35 rpm for 1 - 2 minutes first, and then dry - mix at 35 - 45 rpm for 2 - 5 minutes to obtain a gel material mixture; S3. Dissolve the composite anti - dispersion agent in water to obtain an aqueous solution of the composite anti - dispersion agent; S4. Mix the gel material mixture, the aqueous solution of the composite anti - dispersion agent and water evenly to obtain a mixed slurry; S5. Add sand to the mixed slurry and stir evenly to obtain the water - resistant and anti - dispersion grouting slurry.

[0014] Preferably, the step of adding sand to the mixed slurry in S5 includes: Mix the fine sand and medium sand evenly to obtain a mixed sand; Add the mixed sand to the mixed slurry in two portions and stir evenly to obtain the water - resistant and anti - dispersion grouting slurry.

[0015] The third object of the present invention is to provide an application of the water - resistant and anti - dispersion grouting slurry as described above in shield construction in high - water - rich strata.

[0016] The beneficial effects of the present invention: The present invention provides a water-resistant dispersion grouting slurry. Through the synergistic proportioning of cement, slaked lime, and fly ash, combined with the introduction of a composite anti-dispersion agent, a stable gelling system is formed. Polyacrylamide grafted with silane is used as the composite anti-dispersion agent, and the molecular weight of polyacrylamide is 10 million to 15 million, grafted with 3-aminopropyltriethoxysilane. When the polyacrylamide grafted silane anti-dispersion agent encounters water, the silyl groups hydrolyze to form silanols, forming a nanoscale siloxane film layer on the surface of the slurry to prevent water molecules from invading. When the film layer is washed by water flow, the unreacted silyl groups can continue to crosslink and automatically fill the damaged areas to maintain the anti-dispersion performance. In addition, the carboxyl groups on the molecular chain of the anti-dispersion agent react with the calcium hydroxide (Ca(OH)2) in the cement hydration products to form calcium carboxylate, enhancing the adhesion between particles; the silyl groups form covalent bonds with the hydroxyl groups on the surface of fly ash / bentonite, firmly connecting the gelling material and the aggregate, and improving the overall water erosion resistance ability. Detailed Embodiments

[0017] According to the first aspect of the present invention, a water-resistant dispersion grouting slurry is provided, and the grouting slurry comprises the following raw materials in parts by weight: 120 - 200 parts of cement, 60 - 100 parts of slaked lime, 250 - 350 parts of fly ash, 40 - 60 parts of bentonite, 1100 - 1250 parts of sand, 12 - 18 parts of composite anti-dispersion agent, and 260 - 340 parts of water; The composite anti-dispersion agent is polyacrylamide grafted with silane, and the molecular weight of polyacrylamide is 10 million to 15 million.

[0018] In the present invention, the molecular weight of polyacrylamide is 10 million to 15 million, grafted with 3-aminopropyltriethoxysilane. When the polyacrylamide grafted silane anti-dispersion agent encounters water, the silyl groups hydrolyze to form silanols, forming a nanoscale siloxane film layer on the surface of the slurry to prevent water molecules from invading. When the film layer is washed by water flow, the unreacted silyl groups can continue to crosslink and automatically fill the damaged areas to maintain the anti-dispersion performance. In addition, the carboxyl groups on the molecular chain of the anti-dispersion agent react with the calcium hydroxide (Ca(OH)2) in the cement hydration products to form calcium carboxylate, enhancing the adhesion between particles; the silyl groups form covalent bonds with the hydroxyl groups on the surface of fly ash / bentonite, firmly connecting the gelling material and the aggregate, and improving the overall water erosion resistance ability.

[0019] In a preferred embodiment of the present invention, the sand includes fine sand and medium sand; the particle size of the fine sand is ≤ 0.3 mm, and the particle size of the medium sand is 0.3 - 0.8 mm; the mass ratio of the fine sand to the medium sand is 3 - 5:5 - 7.

[0020] In the present invention, the fine sand has a small particle size, which can fill the pores between the medium sand particles, form a tightly packed structure, reduce the internal voids of the slurry, and improve the density and compressive strength of the hardened stone body. If the proportion of fine sand is less than 3 parts, the pores between the medium sand are insufficiently filled, which may lead to a loose structure and low strength after the slurry hardens; if the proportion of fine sand is greater than 5 parts, the viscosity of the slurry may increase significantly due to excessive fine particles, affecting the fluidity. This mass ratio range can minimize the void ratio of the mixed sand, thereby obtaining higher density and mechanical properties at the same water-cement ratio. The medium sand serves as the skeleton particles, providing a supporting effect against water flow erosion; the fine sand fills the gaps and adsorbs water, reducing the loss of fine particles such as cement and fly ash when the slurry disperses in water. If the proportion of medium sand is less than 5 parts, the skeleton structure is weak and the slurry is easily washed away by the water flow; if the proportion of medium sand is greater than 7 parts, excessive coarse particles may cause the slurry to settle and segregate during transportation, especially prone to sand-water separation during underwater grouting. When the proportion of fine sand is appropriate, the water adsorbed on its surface can form a lubricating layer, improving the fluidity of the slurry and reducing the pumping resistance; if there is too much fine sand, the friction between particles increases, the viscosity rises, and it may lead to difficult pumping.

[0021] In scenarios with abundant groundwater or underwater construction, a reasonable sand gradation can reduce the risk of the slurry being diluted by water flow. For example, the fine sand adsorbs the cement slurry to form a gel coating layer, enhancing the bonding force between particles; the medium sand acts as a skeleton to resist water flow impact, preventing the slurry from collapsing and causing grouting failure. Different grouting pressures correspond to different fissures. When the proportion of fine sand is high, the slurry is more suitable for filling fine fissures with a width less than 1 mm; when the proportion of medium sand is high, it is more suitable for larger fissures with a width of 1 - 3 mm or rapid plugging scenarios, using the rapid accumulation of coarse particles to form a water-blocking barrier. Additionally, optimizing the sand gradation can reduce the pore filling requirements of cementitious materials such as cement and fly ash, reducing costs while ensuring performance. The compounding of coarse and fine sands can inhibit the shrinkage of the hardened body through micro-aggregate filling. The fine sand fills the micro-pores, and the medium sand restricts the macroscopic shrinkage deformation, thereby reducing the risk of cracking after the slurry hardens.

[0022] In a preferred embodiment of the present invention, the mass ratio of cement to the composite anti-dispersant is 8 - 11:1.

[0023] In the present invention, the long-chain structure of polyacrylamide contains a large number of amide groups, which can be adsorbed on the surface of cement particles through hydrogen bonding to form an adsorption layer. When the mass ratio is 8 - 11:1, the molecular chains of the anti-dispersant form a moderate bridging network between the cement particles, which can not only enhance the bonding force between particles but also avoid a sudden increase in the viscosity of the slurry due to excessive entanglement of the molecular chains. If the proportion of the composite anti-dispersant is greater than 1 / 8, the dense adsorption of molecular chains may lead to excessive coating of cement particles, hindering the cement hydration reaction and reducing the early strength; if the proportion of the composite anti-dispersant is lower than 1 / 11, the adsorption layer is weak and cannot effectively resist water flow erosion, and the slurry is easily dispersed.

[0024] The silyl groups can undergo a condensation reaction with the hydroxyl groups in the cement hydration products to form chemical covalent bonds, strengthening the interfacial bonding force. At this ratio, the reaction degree of the silyl groups with the cement hydration products reaches 60% - 80%, which can not only form a stable chemical anchoring but also avoid the slurry stratification caused by the residue of unreacted silane.

[0025] After polyacrylamide is dissolved, it forms a high-viscosity solution. When the mass ratio is 8 - 11:1, the apparent viscosity of the slurry is controlled at 500 - 800 mPa·s. It can not only resist the erosion of water flow, but also the high-viscosity liquid phase hinders the diffusion of particles, making the slurry maintain overall stability in water. The anti-dispersant forms a floc structure of cement particles through adsorption bridging. At this ratio, the floc size is moderate, and the floc strength is sufficient to resist the shear force of water flow. After the floc is destroyed by the pumping shear force, it can quickly reform the structure when standing still, maintaining uniformity, and having both impact resistance and recoverability.

[0026] The adsorption layer of polyacrylamide can delay the early hydration of cement, providing sufficient time for the paving and filling of the slurry in the underwater environment. When the mass ratio is 8 - 11:1, the initial setting time is controlled at 4 - 6 hours, and the final setting time is 8 - 10 hours, which can not only avoid the construction difficulties caused by the too-fast setting of the slurry but also prevent the slow setting from affecting the project progress.

[0027] In a preferred embodiment of the present invention, the mass ratio of cement, slaked lime, and fly ash is 1.2 - 3.33:1:2.5 - 5.83.

[0028] In the present invention, cement is the main source of the early strength of the slurry. Its hydration reaction generates C-S-H gel and Ca(OH)2, providing the initial bonding force. When the proportion of cement relative to slaked lime is greater than 4.5, the heat of hydration is concentrated, and the early strength increases rapidly, but the generation amount of Ca(OH)2 is too high, resulting in insufficient activation of the activity of fly ash. When the proportion of cement relative to slaked lime is less than 1.2, the early cementitious products are insufficient, the initial setting time of the slurry is prolonged, and it is difficult to resist the initial erosion in the underwater environment. Slaked lime provides an alkaline environment to stimulate the pozzolanic reaction of vitreous SiO2 and Al2O3 in fly ash, generating ettringite (AFt) and C-S-H gel, improving the later strength. When the proportion of slaked lime is fixed at 1, the ratio of cement to fly ash needs to match its alkaline activation efficiency. If the proportion of fly ash relative to slaked lime is greater than 5.83, the alkalinity is insufficient, resulting in incomplete pozzolanic reaction, and the strength growth in 28 days < 15%. If the proportion of fly ash relative to slaked lime is less than 1, the active materials are insufficient, it is difficult to exert the secondary hydration strengthening effect, and since fly ash is usually industrial waste residue with a lower cost than cement, the cost of the slurry increases.

[0029] In a preferred embodiment of the present invention, the mass ratio of cement, slaked lime, and fly ash is 1.67 - 2.57:1:3.5 - 5.0.

[0030] In the present invention, cement particles are relatively fine, with an average particle size of about 10-30 μm, fly ash particles are finer, with a particle size of about 1-20 μm, and slaked lime particles are between the two, with a particle size of about 10-50 μm. When the three are mixed in a ratio of 1.67-2.57:1:3.5-5.0, a multi-level particle gradation is formed, which is more densely packed, reduces free water and pores in the slurry, and reduces the risk of component loss caused by water penetration.

[0031] In a preferred embodiment of the present invention, the calcium oxide content in the fly ash is 15% to 30%.

[0032] In the present invention, the CaO content is 15% to 30%, and it contains a large amount of free CaO, calcium aluminate and other active phases. It can undergo hydration reaction even in a neutral or weakly alkaline environment, and its gelling activity is significantly higher than that of low-calcium fly ash. Free CaO generates Ca(OH)2 when it meets water, providing an alkaline environment, accelerating the volcanic ash reaction of its own active components such as glassy SiO2 and Al2O3 with cement hydration products, and generating more CSH gel and calcium aluminum feldspar. When the CaO content in fly ash is 15% to 30%, the CaO released by itself 2+ and OH - It can partially replace the alkalinity contribution of slaked lime or cement, reduce the amount of slaked lime, and reduce the problems of excessive slurry viscosity and construction difficulties caused by excessive slaked lime. It can also reduce the amount of cement, reduce the hydration heat, avoid slurry cracking due to excessive temperature, and save costs.

[0033] The self-hydration characteristics of high-calcium fly ash enable it to quickly participate in the reaction after the slurry is mixed, interweaving with cement hydration products to form an early gelling network, shortening the initial setting time of the slurry, and allowing the slurry to form an initial structure with anti-scouring ability in water more quickly. The generated CSH gel and calcium aluminum feldspar and other products fill the gaps between particles, reduce free water channels, and hinder the invasion of water molecules and particle dispersion. The high content of CaO in fly ash can produce a stronger ion bridging effect with the composite anti-dispersant; the carboxylic acid groups and silane groups on the anti-dispersant molecular chain and Ca 2+ The formation of ionic bonds or coordination bonds anchors cement particles and fly ash particles in the polymer network, forming a more stable spatial network structure. Compared with low-calcium fly ash, high-calcium fly ash provides Ca 2+ Higher concentrations improve the adsorption efficiency and network strength of the anti-dispersant, significantly enhancing the scouring resistance and slurry retention capabilities of the slurry in water.

[0034] The calcium aluminate minerals in high-calcium fly ash have a certain water-reducing effect, which can reduce the water demand of the slurry and reduce the free water content. The low water-binder ratio makes the slurry more viscous, increases the plastic viscosity, and enhances the ability to resist the shear force of water flow, avoiding the loss of components caused by water scouring. It reduces the phenomenon of water seepage and prevents the slurry from stratification and segregation during standing or pumping, which indirectly improves the anti-dispersion stability.

[0035] In a preferred embodiment of the present invention, the water-cement ratio of the water-resistant dispersion grouting slurry is 0.47 to 0.55.

[0036] In the present invention, the water-cement ratio is the mass ratio of water to the gel material; the gel material includes cement, slaked lime, fly ash, and bentonite. When the water-cement ratio is lower than 0.47, the slurry is too thick, with poor fluidity and difficult mixing, which easily leads to uneven particle dispersion. During construction, it is difficult to pump or penetrate into the target area, indirectly increasing the risk of segregation; there is insufficient free water, and the cementitious material cannot be fully hydrated, resulting in a slow formation of the early gel network. The slurry is prone to dispersion due to the shedding of unbonded particles in water. When the water-cement ratio is greater than 0.55, there is too much free water, the slurry is thinned, the plastic viscosity is reduced, and the ability to resist the shear force of water flow decreases significantly. It is easily washed away by water, resulting in the loss of cementitious material and aggregate separation. After the excessive water evaporates, pore channels are left behind, which not only reduces the anti-dispersion property but also leads to a decrease in the compactness of the hardened body and deterioration of the long-term impermeability.

[0037] According to the second aspect of the present invention, there is provided a method for preparing the water-resistant dispersion grouting slurry as described above, comprising the following steps: S1. First, sieve the fly ash and then grind it to obtain activated fly ash with a specific surface area of 600 - 1000 m 2 / kg; S2. Put the cement, slaked lime, activated fly ash, and bentonite into a mixer, dry mix at 25 - 35 rpm for 1 - 2 minutes, and then dry mix at 35 - 45 rpm for 2 - 5 minutes to obtain a gel material mixture; S3. Dissolve the composite anti-dispersant in water to obtain an aqueous solution of the composite anti-dispersant; S4. Mix the gel material mixture, the aqueous solution of the composite anti-dispersant, and water evenly to obtain a mixed slurry; S5. Add sand to the mixed slurry and stir evenly to obtain the water-resistant dispersion grouting slurry.

[0038] In the present invention, sieving the fly ash can remove coarse particle impurities, avoiding internal pores or poor dispersion in the slurry due to uneven particles. Grinding to a high specific surface area of 600 - 1000 m 2 / kg can significantly increase the surface energy of fly ash particles, making them contact more fully with the hydration products of cementitious materials such as cement and slaked lime, forming a denser network structure through physical adsorption and chemical action, enhancing the overall stability of the slurry, and inhibiting particle segregation during water dispersion. High-activity fly ash can fill the gaps between cement particles, reduce the free water content, and lower the dispersion tendency of the slurry in water. Fine-particle fly ash has a large specific surface area and forms a gradient grading with cement particles, filling pores, reducing the porosity of the slurry, and increasing the compactness, thereby enhancing the water-resistant dispersion ability.

[0039] Low-speed dry mixing can avoid particle agglomeration caused by high rotational speeds. For example, bentonite is prone to caking before encountering water. It initially disperses cement, slaked lime, activated fly ash, and bentonite to ensure uniform contact on the surfaces of each component's particles, laying the foundation for subsequent hydration reactions and colloid formation. Uniform dry material mixing can reduce local concentration differences during slurry preparation and avoid weak points during water dispersion caused by uneven distribution of cementitious materials. Medium-speed dry mixing further promotes the adsorption of bentonite particles onto the tiny pores on the surfaces of cement and fly ash. At the same time, Ca 2+ released by slaked lime can undergo ion exchange with montmorillonite in bentonite, enhancing the colloidal viscosity of bentonite and forming a more stable clay colloid network, thereby hindering particle diffusion when the slurry encounters water and improving the anti-dispersion property. The pre-dispersed system formed by dry mixing can shorten the subsequent wet mixing time and reduce the risk of slurry segregation caused by the lag of the water-cement reaction.

[0040] The composite anti-dispersant needs to be pre-dissolved in water to form a uniform solution to avoid caking or excessive local concentration when directly added to the dry materials, which may affect the overall viscosity and anti-dispersion performance of the slurry. The dissolved anti-dispersant molecules can form a polymer network in water, wrapping the cementitious particles and sand grains, and preventing particle dispersion in water through steric hindrance effects and viscous adsorption. At the same time, it can increase the plastic viscosity and yield stress of the slurry.

[0041] The water-cement ratio is between 0.47 and 0.55 to ensure that the slurry has a certain consistency, reduce the free water content, and avoid easy particle dispersion due to excessive water. After cement, slaked lime, fly ash, and bentonite, these gel materials are mixed with the anti-dispersant aqueous solution, hydration reactions and colloid adsorption occur immediately. Cement hydration generates C-S-H gel and Ca(OH)2, and slaked lime supplements Ca 2+ to accelerate the colloidization of bentonite, and the active components of fly ash participate in secondary hydration to fill the structural pores. The anti-dispersant polymer chains are adsorbed on the surfaces of the cementitious particles to form a polymer-colloid composite network, significantly improving the anti-scouring ability of the slurry.

[0042] As an inert aggregate, if sand is added too early to the dry mixing step, it may damage the colloidal particles formed by bentonite and the anti-dispersant due to mechanical friction, reducing the anti-dispersion property. Adding sand later and stirring can evenly wrap the sand grains in the already formed cementitious-polymer viscous matrix, using the mechanical biting force and colloidal bonding force between the sand grains to form a stable solid-liquid-solid three-phase structure, enhancing the overall anti-water flow impact ability of the slurry. The addition of sand can adjust the slurry density and anti-seepage property, and at the same time avoid excessive local pores caused by uneven dispersion of sand grains, weakening the anti-water dispersion performance.

[0043] Through the synergistic effect of the above steps, the slurry can form a high-viscosity, low-permeability, and structurally dense whole in water, effectively resisting particle dispersion and component loss caused by water flow scouring, and meeting the engineering requirements of anti-water dispersion grouting.

[0044] In a preferred embodiment of the present invention, the step of adding sand to the mixed slurry in S5 includes: Mix fine sand and medium sand evenly to obtain mixed sand; Add the mixed sand to the mixed slurry in two portions and stir evenly to obtain the water-resistant and anti-dispersion grouting slurry.

[0045] In the present invention, first add a part of the mixed sand, for example, 50% - 70% of the total amount of sand, and stir evenly with the formed cementitious-polymer mixed slurry. At this time, the slurry already has a certain viscosity. The first addition of sand can quickly wrap the sand particles with the viscous matrix, forming an initial sand-colloid complex, avoiding direct contact between the sand particles and the stirring blades, which may cause intense friction and damage the colloid structure. The gaps between some sand particles are filled with the cementitious material, initially constructing an anti-dispersion framework and providing a stable base for subsequent sand addition. After the first addition of sand and stirring evenly, then add the remaining mixed sand and continue to stir until the whole is uniform, avoiding adding all the sand at once, which may cause the slurry to be too thick, a sudden increase in stirring resistance, possible insufficient stirring resulting in sand particle agglomeration, forming dry sand cores, and the surrounding cementitious material cannot effectively wrap them. When encountering water, the agglomerated sand particles are likely to fall off and disperse; high-resistance stirring may break the bentonite colloid chain or the high-molecular network of the anti-dispersant, reducing the viscosity of the slurry and other problems. Adding sand in portions enables each part of the sand particles to fully contact the cementitious matrix, ensuring a firm bond at the sand-colloid interface, and finally forming a structure with uniformly distributed sand particles, completely wrapped by the colloid, and a continuous and dense framework, maximizing the ability to resist water flow scouring.

[0046] According to the third aspect of the present invention, there is provided an application of the water-resistant and anti-dispersion grouting slurry as described above in shield construction in a high water-rich stratum.

[0047] Example 1 A preparation method of a water-resistant and anti-dispersion grouting slurry includes the following steps: S1. First, sieve and then grind fly ash to obtain activated fly ash with a specific surface area of 600 - 1000 m 2 / kg; S2. Put 120 parts of cement, 60 parts of slaked lime, 250 parts of activated fly ash, and 40 parts of bentonite into a mixer, first dry-mix at 30 rpm for 2 minutes, and then dry-mix at 40 rpm for 3 minutes to obtain a gel material mixture; S3. Dissolve 12 parts of the composite anti-dispersant in water to obtain an aqueous solution of the composite anti-dispersant; S4. Mix the gel material mixture, the aqueous solution of the composite anti-dispersant, and 260 parts of water evenly to obtain a mixed slurry; S5. Mix fine sand and medium sand evenly to obtain 1100 parts of mixed sand; Add the mixed sand to the mixed slurry in two portions and stir evenly to obtain the water-resistant and anti-dispersion grouting slurry.

[0048] Example 2 In this example, there are 150 parts of cement, 60 parts of slaked lime, 300 parts of fly ash, 50 parts of bentonite, 1150 parts of sand, 15 parts of compound anti-dispersant, and 290 parts of water; the remaining steps and parameters are the same as those in Example 1.

[0049] Example 3 In this example, there are 200 parts of cement, 60 parts of slaked lime, 350 parts of fly ash, 60 parts of bentonite, 1250 parts of sand, 18 parts of compound anti-dispersant, and 340 parts of water; the remaining steps and parameters are the same as those in Example 1.

[0050] Example 4 In this example, there are 120 parts of cement, 80 parts of slaked lime, 300 parts of fly ash, 50 parts of bentonite, 1150 parts of sand, 15 parts of compound anti-dispersant, and 300 parts of water; the remaining steps and parameters are the same as those in Example 1.

[0051] Example 5 In this example, there are 160 parts of cement, 80 parts of slaked lime, 250 parts of fly ash, 45 parts of bentonite, 1120 parts of sand, 14 parts of compound anti-dispersant, and 280 parts of water; the remaining steps and parameters are the same as those in Example 1.

[0052] Example 6 In this example, there are 160 parts of cement, 100 parts of slaked lime, 300 parts of fly ash, 55 parts of bentonite, 1200 parts of sand, 17 parts of compound anti-dispersant, and 320 parts of water; the remaining steps and parameters are the same as those in Example 1.

[0053] Example 7 In this example, there are 180 parts of cement, 80 parts of slaked lime, 250 parts of fly ash, 45 parts of bentonite, 1130 parts of sand, 14 parts of compound anti-dispersant, and 270 parts of water; the remaining steps and parameters are the same as those in Example 1.

[0054] Example 8 In this example, there are 120 parts of cement, 100 parts of slaked lime, 350 parts of fly ash, 60 parts of bentonite, 1250 parts of sand, 18 parts of compound anti-dispersant, and 340 parts of water; the remaining steps and parameters are the same as those in Example 1.

[0055] Example 9 In this example, there are 160 parts of cement, 96 parts of slaked lime, 350 parts of fly ash, 50 parts of bentonite, 1200 parts of sand, 16 parts of compound anti-dispersant, and 310 parts of water; the remaining steps and parameters are the same as those in Example 1.

[0056] Example 10 In this embodiment, there are 140 parts of cement, 70 parts of slaked lime, 280 parts of fly ash, 48 parts of bentonite, 1180 parts of sand, 15 parts of compound anti-dispersant, and 295 parts of water; the remaining steps and parameters are the same as those in Embodiment 1.

[0057] Comparative Example 1 In this embodiment, there are 160 parts of cement, 80 parts of slaked lime, 0 parts of fly ash, 50 parts of bentonite, 1200 parts of sand, 16 parts of compound anti-dispersant, and 300 parts of water; the remaining steps and parameters are the same as those in Embodiment 1.

[0058] Comparative Example 2 In this embodiment, there are 100 parts of cement, 80 parts of slaked lime, 300 parts of fly ash, 50 parts of bentonite, 1200 parts of sand, 16 parts of compound anti-dispersant, and 300 parts of water; the remaining steps and parameters are the same as those in Embodiment 1.

[0059] Comparative Example 3 In this embodiment, there are 160 parts of cement, 120 parts of slaked lime, 300 parts of fly ash, 50 parts of bentonite, 1200 parts of sand, 16 parts of compound anti-dispersant, and 300 parts of water; the remaining steps and parameters are the same as those in Embodiment 1.

[0060] Comparative Example 4 In this embodiment, there are 160 parts of cement, 80 parts of slaked lime, 200 parts of fly ash, 50 parts of bentonite, 1200 parts of sand, 16 parts of compound anti-dispersant, and 300 parts of water; the remaining steps and parameters are the same as those in Embodiment 1.

[0061] Comparative Example 5 In this embodiment, there are 220 parts of cement, 50 parts of slaked lime, and 360 parts of fly ash; the remaining steps and parameters are the same as those in Embodiment 1.

[0062] Comparative Example 6 In this embodiment, there are 160 parts of cement, 80 parts of slaked lime, 250 parts of fly ash, 45 parts of bentonite, 1120 parts of sand, 0 parts of compound anti-dispersant, and 280 parts of water; the remaining steps and parameters are the same as those in Embodiment 1.

[0063] Performance Test The grouting slurries prepared in the above embodiments and comparative examples were tested for fluidity, slump, setting time, compressive strength, water anti-dispersibility, and consistency. The test results are shown in Table 1: The fluidity test was carried out according to the GB / T50080-2016 standard using the slump flow method. The slurry was poured into the slump cone and then lifted vertically, and the maximum diameter of the slurry after spreading was measured. The average value of two mutually perpendicular measurements was taken as the fluidity index.

[0064] The slump is measured according to the standard of GB / T50080 - 2016. Using a slump cone (inner diameter of the bottom surface is 200mm, inner diameter of the top surface is 100mm, and height is 300mm), the slurry is filled in three layers and tamped. After the slump cone is vertically lifted, the height of the slurry drop is measured, which is the slump value.

[0065] The setting time is measured according to the standard of GB / T1346 - 2011. Using the Vicat apparatus method, the time from adding water and mixing to the initial setting (the test needle sinks 4 ± 1mm from the bottom plate) and the final setting (the test needle sinks below 0.5mm) of the slurry is tested.

[0066] The 28 - day compressive strength is measured according to the standard of GB / T50081 - 2019. Using underwater molding, prepare an open - top water storage tank and add water to 100mm above the upper limit of the bottom - attached test mold with dimensions of 70.7mm×70.7mm×70.7mm. Completely immerse the bottom - attached test mold in water and keep it horizontally placed. Carefully pour the slurry to be tested from the water surface height into the mold filled with water until the mold is full and overflows. Carefully take out the test mold and vibrate it into shape. Use a spatula to scrape off the excess slurry on the top of the test mold, place it in a standard curing box, and demold it after 28 - day age. Then test the compressive strength.

[0067] Hydrostatic test for water resistance dispersion (hydrostatic turbidity NTU): Pour the slurry into a water - containing container (water depth ≥ 100mm), observe whether segregation occurs within 30 minutes, and measure the water turbidity (NTU).

[0068] The consistency test refers to the standard of JGJ / T70 - 2023. Using a mortar consistency meter (the mass of the cone is 300g, and the diameter of the cone tip is 10mm), after filling the slurry into the container, measure the depth (cm) of the free sinking of the cone into the slurry for 10s, which is the consistency value.

[0069] Table 1 Performance test results

[0070] Through the coordinated proportioning of cement, slaked lime, and fly ash, combined with the introduction of a composite anti-dispersant, a stable cementitious system is formed. Among them, the combination of 140 - 180 parts of medium cement and 280 - 320 parts of fly ash performs best in Examples 2 and 10, with a fluidity of 19 - 21 cm, a slump of 180 - 190 mm, meeting the requirements of construction pumping; the setting time is 5.0 - 5.5 h, conforming to the synchronous grouting time window; the 28-day compressive strength is 1.5 - 1.7 MPa, and the anti-water dispersion static turbidity is ≤ 60 NTU, with uniform sand particle wrapping and no segregation. When fly ash or the composite anti-dispersant is removed, the slurry segregates severely within 10 minutes, the static turbidity > 500 NTU, and the loss rate of the cementitious material exceeds 30%, verifying the irreplaceability of fly ash micro-aggregate filling and the anti-dispersant; when the cement is less than 120 parts or the slaked lime is more than 100 parts, the strength is insufficient or the setting time is abnormal (> 8 h or < 4 h), breaking through the feasible range of construction; the imbalance of the ternary proportion leads to a sudden change in consistency and the collapse of anti-dispersibility (turbidity > 400 NTU). The above comparisons prove by contradiction the scientific nature of the weight part ranges and component combinations of each raw material. By limiting the ratio of cement - slaked lime - fly ash and the dosage of the composite anti-dispersant, a systematic balance of the fluidity, strength, and anti-water dispersion of the slurry is achieved, solving the segregation problem of traditional slurries in water-rich strata.

Claims

1. A water-resistant dispersion grouting slurry, characterized in that, The grouting slurry described above comprises raw materials in the following parts by weight: 120 - 200 parts of cement, 60 - 100 parts of slaked lime, 250 - 350 parts of fly ash, 40 - 60 parts of bentonite, 1100 - 1250 parts of sand, 12 - 18 parts of a composite anti-dispersant, and 260 - 340 parts of water; The composite anti-dispersant is polyacrylamide grafted silane, and the molecular weight of polyacrylamide is 10 million - 15 million.

2. The water-resistant dispersion grouting slurry according to claim 1, characterized in that, The sand includes fine sand and medium sand; the particle size of the fine sand is ≤ 0.3 mm, and the particle size of the medium sand is 0.3 - 0.8 mm; the mass ratio of the fine sand to the medium sand is 3 - 5:5 - 7.

3. The anti-water dispersion grouting slurry according to claim 1, characterized in that, The mass ratio of the cement to the composite anti-dispersant is 8 - 11:

1.

4. The anti-water dispersion grouting slurry according to claim 1, wherein The mass ratio of the cement, slaked lime, and fly ash is 1.2 - 3.33:1:2.5 - 5.

83.

5. The anti-water dispersion grouting slurry according to claim 4, wherein The mass ratio of the cement, slaked lime, and fly ash is 1.67 - 2.57:1:3.5 - 5.

0.

6. The anti-water dispersion grouting slurry according to claim 1, characterized in that, The calcium oxide content in the fly ash is 15% - 30%.

7. The water-resistant dispersion grouting slurry according to claim 1, characterized in that The water-binder ratio of the anti-water-dispersing grouting slurry is 0.47 - 0.

55.

8. A method for preparing the water-resistant dispersion grouting slurry according to any one of claims 1 to 7, characterized in that, It includes the following steps: S1. First, sieve the fly ash and then grind it to obtain activated fly ash with a specific surface area of 600 - 1000 m² / kg; S2. Put the cement, slaked lime, activated fly ash, and bentonite into a mixer, dry mix at 25 - 35 rpm for 1 - 2 minutes first, and then dry mix at 35 - 45 rpm for 2 - 5 minutes to obtain a gel material mixture; S3. Dissolve the composite anti-dispersant in water to obtain an aqueous solution of the composite anti-dispersant; S4. Mix the gel material mixture, the aqueous solution of the composite anti-dispersant, and water evenly to obtain a mixed slurry; S5. Add the sand to the mixed slurry and stir evenly to obtain the anti-water-dispersing grouting slurry.

9. The preparation method according to claim 8, wherein, The adding of the sand to the mixed slurry in S5 includes: Mix the fine sand and the medium sand evenly to obtain a mixed sand; Add the mixed sand to the mixed slurry in two portions and stir evenly to obtain the anti-water-dispersing grouting slurry.

10. Application of an anti-water-dispersing grouting slurry as described in any one of claims 1 - 7 in shield construction in a high water-rich stratum.

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