A water-resistant dispersible grouting slurry, preparation method and application

Abstract

The present invention provides a water-resistant dispersible grouting slurry, a preparation method and an application, which belong to the field of shield construction materials. A stable cementitious system is formed by the synergistic ratio of cement, slaked lime and fly ash, combined with the introduction of a composite anti-dispersant. When the composite anti-dispersant polyacrylamide grafted silane anti-dispersant comes into contact with water, the silane group hydrolyzes to form silanol, forming a nano-scale siloxane film layer on the surface of the slurry to prevent water molecules from invading. When the film layer is washed by water, the unreacted silane groups can continue to cross-link, automatically filling the damaged areas and maintaining the anti-dispersibility. In addition, the carboxyl groups on the anti-dispersant molecular chain react with the cement hydration product Ca(OH)2 to form calcium carboxylate, which enhances the bonding force between particles; the silane groups form covalent bonds with the hydroxyl groups on the surface of fly ash / bentonite, firmly connecting the cementitious material and the aggregate, thereby improving the overall slurry's ability to resist water scouring.

Description

Technical Field

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

[0002] With the continuous development of railway construction in my country, shield tunneling has been widely used in large-scale underground projects such as railways and highways. Among various tunnel construction methods, shield tunneling has become the preferred method for the construction of numerous urban subways and underwater tunnels crossing rivers or seas due to its minimal impact on the surrounding environment, strong adaptability to complex geological conditions, and safe and rapid construction.

[0003] During shield construction, synchronous grouting is a crucial process for filling the gap at the shield tail and stabilizing the ground. The slurry required for synchronous grouting requires excellent fluidity and stability, minimal fluidity loss over time, and a reasonable setting time. Synchronous grouting significantly impacts preventing surface deformation, controlling tunnel settlement, enhancing the waterproofing of lining joints, improving the stress conditions of the lining, and assisting in shield deviation correction. However, in highly water-rich formations, conventional synchronous grouting slurries are prone to filling the gap at the shield tail with groundwater, leading to segregation of conventional grouting materials and loss of cementitious materials during synchronous grouting operations.

[0004] Therefore, there is an urgent need to develop a synchronous grouting slurry that is resistant to water dispersion. 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 dispersible grouting slurry, a preparation method and application.

[0006] One of the objects of the present invention is to provide a water-resistant dispersible grouting slurry, which comprises the following raw materials in parts by weight:

[0007] 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-dispersant and 260-340 parts of water;

[0008] The composite anti-dispersant is polyacrylamide grafted silane, and the molecular weight of the polyacrylamide is 10 million to 15 million.

[0009] Preferably, 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.

[0010] Preferably, the mass ratio of the cement to the composite anti-dispersant is 8-11:1.

[0011] Preferably, the mass ratio of the cement, slaked lime and fly ash is 1.2~3.33:1:2.5~5.83.

[0012] Preferably, the mass ratio of the cement, slaked lime and fly ash is 1.67~2.57:1:3.5~5.0.

[0013] Preferably, the calcium oxide content in the fly ash is 15% to 30%.

[0014] Preferably, the water-to-binder ratio of the water-resistant dispersion grouting slurry is 0.47~0.55.

[0015] A second object of the present invention is to provide a method for preparing the water-resistant dispersion grouting slurry as described above, comprising the following steps:

[0016] S1. Sieve the fly ash and then grind it into powder to obtain a specific surface area of ​​600~1000m 2 / kg of activated fly ash;

[0017] S2. Place cement, slaked lime, activated fly ash, and bentonite into a mixer and dry-mix at 25-35 rpm for 1-2 minutes, then at 35-45 rpm for 2-5 minutes to obtain a gel material mixture.

[0018] S3, dissolving the composite anti-dispersant in water to obtain a composite anti-dispersant aqueous solution;

[0019] S4, uniformly mixing the gel material mixture, the composite anti-dispersant aqueous solution and water to obtain a mixed slurry;

[0020] S5. Add sand to the mixed slurry and stir evenly to obtain a water-resistant dispersible grouting slurry.

[0021] Preferably, the step of adding sand to the mixed slurry in S5 includes:

[0022] Mix fine sand and medium sand evenly to obtain mixed sand;

[0023] The mixed sand is added to the mixed slurry twice and stirred evenly to obtain a water-resistant dispersed grouting slurry.

[0024] The third object of the present invention is to provide an application of the water-resistant dispersing grouting slurry as described above in shield construction in high water-rich strata.

[0025] Beneficial effects of the present invention:

[0026] The present invention provides a water-resistant, dispersible grouting slurry. This slurry forms a stable cementitious system through the synergistic mix of cement, slaked lime, and fly ash, combined with the introduction of a composite anti-dispersant. The composite anti-dispersant is a polyacrylamide-grafted silane with a molecular weight of 10 to 15 million, grafted with 3-aminopropyltriethoxysilane. Upon contact with water, the silane groups of the polyacrylamide-grafted silane anti-dispersant hydrolyze to form silanols, forming a nanoscale siloxane film on the slurry surface that prevents water molecules from invading. When the film is eroded by water, unreacted silane groups continue to crosslink, automatically filling damaged areas and maintaining anti-dispersibility. Furthermore, the carboxyl groups on the anti-dispersant molecular chain react with the cement hydration product, Ca(OH)2, to form calcium carboxylate, enhancing interparticle adhesion. The silane groups form covalent bonds with the hydroxyl groups on the fly ash / bentonite surface, firmly connecting the cementitious material to the aggregate and improving overall water erosion resistance. DETAILED DESCRIPTION

[0027] According to a first aspect of the present invention, a water-resistant dispersible grouting slurry is provided, wherein the grouting slurry comprises the following raw materials in parts by weight:

[0028] 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-dispersant and 260-340 parts of water;

[0029] The composite anti-dispersant is polyacrylamide grafted silane, and the molecular weight of the polyacrylamide is 10 million to 15 million.

[0030] In the present invention, the polyacrylamide has a molecular weight of 10 to 15 million and is grafted with 3-aminopropyltriethoxysilane. When the polyacrylamide-grafted silane anti-dispersant comes into contact with water, the silane groups hydrolyze to form silanols, forming a nanoscale siloxane film on the slurry surface to prevent water molecules from invading. When the film is washed by water, the unreacted silane groups can continue to cross-link, automatically filling the damaged areas and maintaining the anti-dispersibility. In addition, the carboxyl groups on the anti-dispersant molecular chain react with the cement hydration product Ca(OH)2 to form calcium carboxylate, which enhances the adhesion between particles. The silane groups form covalent bonds with the hydroxyl groups on the fly ash / bentonite surface, firmly connecting the cementitious material to the aggregate and improving the overall resistance to water scouring.

[0031] 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; and the mass ratio of the fine sand to the medium sand is 3-5:5-7.

[0032] In the present invention, the fine sand has a small particle size and can fill the pores between the medium sand particles, forming a tightly packed structure, reducing the voids inside the slurry, and improving the density and compressive strength of the stone body after hardening. 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 the excessive fine particles, affecting the fluidity. This mass ratio range can minimize the porosity of the mixed sand, thereby obtaining higher density and mechanical properties at the same water-cement ratio. Medium sand acts as a skeleton particle, providing support against water erosion; fine sand fills the gaps and absorbs moisture, reducing the loss of fine particles such as cement and fly ash when the slurry is dispersed in water. If the proportion of medium sand is less than 5 parts, the skeleton structure is weak and the slurry is easily dispersed by water; if the proportion of medium sand is greater than 7 parts, the excessive coarse particles may cause the slurry to settle and separate during transportation, especially during underwater grouting. Sand-water separation is prone to occur. When the proportion of fine sand is moderate, the moisture adsorbed on its surface can form a lubricating layer, improve the fluidity of the slurry and reduce pumping resistance; if there is too much fine sand, the friction between particles increases, the viscosity increases, and pumping may become difficult.

[0033] In construction scenarios with abundant groundwater or underwater, proper sand grading can reduce the risk of slurry dilution by water flow. For example, fine sand absorbs cement slurry to form a cementitious coating, strengthening interparticle bonding. Medium sand acts as a framework to resist water flow, preventing slurry collapse and potentially grouting failure. Different grouting pressures correspond to different fissures. When fine sand accounts for a high proportion, the slurry is more suitable for filling fine fissures less than 1 mm wide. When medium sand accounts for a high proportion, it is more suitable for larger fissures 1-3 mm wide or for rapid plugging, utilizing the rapid accumulation of coarse particles to form a water barrier. Furthermore, optimizing sand grading can reduce the need for pore-filling in cementitious materials such as cement and fly ash, thereby reducing costs while ensuring performance. A combination of coarse and fine sand can inhibit shrinkage in the hardened body through micro-aggregate filling. Fine sand fills microscopic pores, while medium sand limits macroscopic shrinkage and deformation, thereby reducing the risk of cracking after the slurry hardens.

[0034] In a preferred embodiment of the present invention, the mass ratio of cement to composite anti-dispersant is 8-11:1.

[0035] 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 to 11:1, the anti-dispersant molecular chains form a moderate bridging network between the cement particles, which can not only enhance the adhesion between the particles, but also avoid the sudden increase in slurry viscosity due to excessive entanglement of the molecular chains. If the composite anti-dispersant accounts for more than 1 / 8, the dense adsorption of the molecular chains may cause excessive wrapping of the cement particles, hinder the cement hydration reaction, and reduce the early strength; if the composite anti-dispersant accounts for less than 1 / 11, the adsorption layer is weak and cannot effectively resist water erosion, and the slurry is easily dispersed.

[0036] Silane groups react with hydroxyl groups in cement hydration products to form chemical covalent bonds, strengthening interfacial bonding. At this ratio, the degree of reaction between silane groups and cement hydration products reaches 60% to 80%, creating a stable chemical anchor while preventing slurry stratification caused by unreacted silane residue.

[0037] Polyacrylamide dissolves to form a high-viscosity solution. At a mass ratio of 8 to 11:1, the apparent viscosity of the slurry is controlled between 500 and 800 mPa·s. This solution resists water erosion, while the high-viscosity liquid phase hinders particle diffusion, maintaining overall stability in water. The anti-dispersant, through adsorption and bridging, helps cement particles form flocs. At this ratio, the flocs are of moderate size and strong enough to withstand the shear forces of water flow. Even after being disrupted by pumping shear forces, they quickly reform upon standing, maintaining uniformity and exhibiting both impact resistance and resilience.

[0038] The polyacrylamide adsorption layer can delay the early hydration of cement, providing ample time for slurry spreading and filling in underwater environments. When the mass ratio is 8-11:1, the initial setting time is controlled within 4-6 hours and the final setting time is 8-10 hours. This prevents the slurry from setting too quickly, which may cause construction difficulties, and prevents slow setting, which may affect the project progress.

[0039] 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.

[0040] In this invention, cement is the primary source of the slurry's early strength. Its hydration reaction generates CSH gel and Ca(OH)₂, providing initial bonding strength. When the cement ratio relative to slaked lime is greater than 4.5, the hydration exotherm is concentrated, leading to rapid early strength growth. However, excessive Ca(OH)₂ production leads to insufficient activation of the fly ash. When the cement ratio relative to slaked lime is less than 1.2, insufficient early cementitious products are produced, prolonging the slurry's initial setting time and making it difficult to withstand initial erosion in underwater environments. Slaked lime provides an alkaline environment, stimulating the pozzolanic reaction of the vitreous SiO₂ and Al₂O₃ in the fly ash, generating ettringite (AFt) and CSH gel, which enhances later strength. When the slaked lime ratio is fixed at 1, the cement-to-fly ash ratio must match the alkaline activation efficiency. If the proportion of fly ash relative to slaked lime is greater than 5.83, insufficient alkalinity will lead to incomplete pozzolanic reaction and the 28-day strength increase will be less than 15%; if the proportion of fly ash relative to slaked lime is less than 1, there will be insufficient active material and it will be difficult to exert the secondary hydration enhancement effect. Moreover, since fly ash is usually industrial waste residue and its cost is lower than cement, the slurry cost will increase.

[0041] 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.

[0042] In the present invention, cement particles are relatively fine, with an average particle size of approximately 10-30 μm. Fly ash particles are even finer, with a particle size of approximately 1-20 μm. Slaked lime particles are intermediate, with a particle size of approximately 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 size distribution is formed, which allows for tighter packing, reduces free water and porosity in the slurry, and reduces the risk of component loss due to water infiltration.

[0043] In a preferred embodiment of the present invention, the calcium oxide content in the fly ash is 15% to 30%.

[0044] 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, reducing the amount of slaked lime used and alleviating the high slurry viscosity and construction difficulties that may be caused by excessive slaked lime. It also reduces cement usage, lowers the heat of hydration, and avoids slurry cracking due to excessive temperatures, while also saving costs.

[0045] The self-hydration characteristics of high-calcium fly ash allow it to quickly participate in the reaction after slurry mixing, interweaving with cement hydration products to form an early gelling network, shortening the initial setting time of the slurry and enabling 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, reducing free water channels, hindering the intrusion 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 interact with CaO. 2+ Form ionic bonds or coordination bonds to anchor 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 increase the adsorption efficiency and network strength of the anti-dispersant, significantly enhancing the scouring resistance and slurry retention capabilities of the slurry in water.

[0046] The calcium aluminate minerals in high-calcium fly ash have a certain water-reducing effect, reducing the slurry's water demand and free water content. A low water-binder ratio makes the slurry more viscous, increasing its plastic viscosity and enhancing its ability to resist water shear forces, thereby preventing component loss due to water erosion. This reduces bleeding and prevents stratification and segregation during slurry rest or pumping, indirectly improving dispersion stability.

[0047] In a preferred embodiment of the present invention, the water-binder ratio of the water-resistant dispersion grouting slurry is 0.47~0.55.

[0048] In the present invention, the water-cement ratio is the mass ratio of water and 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, has poor fluidity, is difficult to mix, and easily leads to uneven dispersion of particles. It is difficult to pump or penetrate into the target area during construction, which indirectly increases the risk of segregation. When there is insufficient free water, the cementitious material cannot be fully hydrated, the early gel network forms slowly, and the slurry is easily dispersed in water due to the shedding of unbonded particles. When the water-cement ratio is greater than 0.55, there is too much free water, the slurry is diluted, the plastic viscosity is reduced, and the ability to resist the shear force of the water flow is significantly reduced. It is easily washed away by water, resulting in the loss of cementitious materials and the separation of aggregates. After the excess water evaporates, pore channels are left behind, which not only reduces the anti-dispersion property, but also causes the density of the hardened body to decrease and the long-term impermeability to deteriorate.

[0049] According to a second aspect of the present invention, there is provided a method for preparing the water-resistant dispersible grouting slurry as described above, comprising the following steps:

[0050] S1. Sieve the fly ash and then grind it into powder to obtain a specific surface area of ​​600~1000m 2 / kg of activated fly ash;

[0051] S2. Place cement, slaked lime, activated fly ash, and bentonite into a mixer and dry-mix at 25-35 rpm for 1-2 minutes, then at 35-45 rpm for 2-5 minutes to obtain a gel material mixture.

[0052] S3, dissolving the composite anti-dispersant in water to obtain a composite anti-dispersant aqueous solution;

[0053] S4, uniformly mixing the gel material mixture, the composite anti-dispersant aqueous solution and water to obtain a mixed slurry;

[0054] S5. Add sand to the mixed slurry and stir evenly to obtain a water-resistant dispersible grouting slurry.

[0055] In the present invention, fly ash screening can remove coarse particle impurities and avoid the internal porosity or poor dispersion of slurry caused by uneven particles. Grinding to a high specific surface area of ​​600~1000m 2 / kg significantly increases the surface energy of fly ash particles, enabling more complete contact with the hydration products of cement, slaked lime, and other cementitious materials. Through physical adsorption and chemical reactions, a tighter network is formed, enhancing the overall stability of the slurry and inhibiting particle segregation during water dispersion. Highly reactive fly ash fills the gaps between cement particles, reducing the free water content and the slurry's tendency to disperse in water. Fine fly ash particles have a large specific surface area and form a gradient with cement particles, filling pores, reducing the slurry's porosity, and increasing density, thereby enhancing its resistance to water dispersion.

[0056] Low-speed dry mixing can avoid particle agglomeration caused by high speed. For example, bentonite tends to clump before contacting water. It can initially disperse cement, slaked lime, activated fly ash, and bentonite, ensuring uniform contact between the surfaces of each component particle, laying the foundation for subsequent hydration reaction 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 absorption of bentonite particles into the tiny pores on the surfaces of cement and fly ash, while the Ca released by slaked lime 2+ It can undergo ion exchange with the montmorillonite in bentonite, enhancing the colloidal viscosity of the bentonite and forming a more stable clay colloidal network. This hinders particle diffusion when the slurry encounters water, improving its anti-dispersion properties. The pre-dispersed system formed by dry mixing can shorten the subsequent wet mixing time and reduce the risk of slurry segregation caused by delayed water-gel reaction.

[0057] The composite anti-dispersant must be pre-dissolved in water to form a uniform solution to avoid direct addition to the dry material, which can cause agglomeration or localized over-concentration, affecting the overall viscosity and anti-dispersibility of the slurry. Dissolved anti-dispersant molecules form a polymer network in water, encapsulating the gel particles and sand grains. This prevents the particles from dispersing in water through steric hindrance and viscous adsorption, while also increasing the plastic viscosity and yield stress of the slurry.

[0058] 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 the particles from being easily dispersed due to excessive water. After the gel materials such as cement, slaked lime, fly ash and bentonite are mixed with the anti-dispersant aqueous solution, hydration reaction and colloid adsorption will occur immediately. Cement hydration generates CSH gel and Ca(OH)2, and slaked lime supplements Ca 2+ The colloidization of bentonite is accelerated, 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 surface of the gel particles, forming a polymer-colloid composite network, which significantly improves the anti-scour ability of the slurry.

[0059] Sand, as an inert aggregate, can be added too early in the dry mixing process because mechanical friction can damage the colloidal particles formed by the bentonite and anti-dispersant, reducing its anti-dispersibility. Adding sand later and stirring it evenly coats the sand particles within the already formed gel-polymer matrix. The mechanical interlocking forces and colloidal adhesion between the sand particles create a stable solid-liquid-solid three-phase structure, enhancing the slurry's overall resistance to water impact. The addition of sand can adjust the slurry's density and impermeability while preventing the development of excessively large local pores caused by uneven sand dispersion, which can weaken its anti-water dispersion properties.

[0060] Through the synergistic effect of the above steps, the slurry can form a high-viscosity, low-permeability, densely structured whole in water, effectively resisting particle dispersion and component loss caused by water erosion, and meeting the engineering requirements of water-resistant dispersion grouting.

[0061] In a preferred embodiment of the present invention, the step of adding sand to the mixed slurry in S5 includes:

[0062] Mix fine sand and medium sand evenly to obtain mixed sand;

[0063] The mixed sand is added to the mixed slurry twice and stirred evenly to obtain a water-resistant dispersed grouting slurry.

[0064] In the present invention, a portion of the mixed sand is first added, for example, 50% to 70% of the total amount of sand, and stirred evenly with the formed gel-polymer mixed slurry. At this time, the slurry already has a certain viscosity. The first addition of sand can make the sand particles quickly wrapped by the viscous matrix to form an initial sand-colloid complex, avoiding direct contact of the sand particles with the stirring blades to produce violent friction and destroy the colloid structure. The gaps between some sand particles are filled with gelling material, and an anti-dispersion skeleton is preliminarily constructed to provide a stable base for subsequent sand addition. After the first addition of sand and stirring are evenly completed, the remaining mixed sand is added and stirred until the whole is uniform, avoiding adding all the sand at once to cause the slurry to be too thick, and the stirring resistance increases suddenly, which may cause insufficient stirring to cause the sand particles to agglomerate and form dry sand cores. The surrounding gelling material cannot be effectively wrapped, and the agglomerated sand particles are easy to fall off and disperse when encountering water; high-resistance stirring may interrupt the bentonite colloid chain or the anti-dispersant polymer network, reducing the viscosity of the slurry and other problems. Adding sand in batches allows each part of the sand particles to fully contact the cementitious matrix, ensuring that the sand-colloid interface is firmly bonded, and ultimately forming a structure with evenly distributed sand particles, complete colloid wrapping, and a continuous and dense skeleton, thereby maximizing the ability to resist water erosion.

[0065] According to the third aspect of the present invention, there is provided an application of the water-resistant dispersible grouting slurry as described above in shield construction in highly water-rich strata.

[0066] Example 1

[0067] A method for preparing a water-resistant dispersible grouting slurry comprises the following steps:

[0068] S1. Sieve the fly ash and then grind it into powder to obtain a specific surface area of ​​600~1000m 2 / kg of activated fly ash;

[0069] 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, then dry-mix at 40 rpm for 3 minutes to obtain a gel material mixture;

[0070] S3, dissolving 12 parts of the composite anti-dispersant in water to obtain a composite anti-dispersant aqueous solution;

[0071] S4, uniformly mixing the gel material mixture, the composite anti-dispersant aqueous solution and 260 parts of water to obtain a mixed slurry;

[0072] S5. Mix the fine sand and the medium sand evenly to obtain 1100 parts of mixed sand;

[0073] The mixed sand is added to the mixed slurry twice and stirred evenly to obtain a water-resistant dispersed grouting slurry.

[0074] Example 2

[0075] In this embodiment, 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 composite anti-dispersant, and 290 parts of water are used; the remaining steps and parameters are the same as those in Example 1.

[0076] Example 3

[0077] In this embodiment, 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 composite anti-dispersant, and 340 parts of water are used; the remaining steps and parameters are the same as those in Example 1.

[0078] Example 4

[0079] In this embodiment, 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 composite anti-dispersant, and 300 parts of water are used; the remaining steps and parameters are the same as those in Example 1.

[0080] Example 5

[0081] In this embodiment, 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 composite anti-dispersant, and 280 parts of water are used; the remaining steps and parameters are the same as those in Example 1.

[0082] Example 6

[0083] In this embodiment, 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 composite anti-dispersant, and 320 parts of water are used; the remaining steps and parameters are the same as those in Example 1.

[0084] Example 7

[0085] In this embodiment, 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 composite anti-dispersant, and 270 parts of water are used; the remaining steps and parameters are the same as those in Example 1.

[0086] Example 8

[0087] In this embodiment, 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 composite anti-dispersant, and 340 parts of water are used; the remaining steps and parameters are the same as those in Example 1.

[0088] Example 9

[0089] In this embodiment, 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 composite anti-dispersant, and 310 parts of water are used; the remaining steps and parameters are the same as those in Example 1.

[0090] Example 10

[0091] In this embodiment, 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 composite anti-dispersant, and 295 parts of water are used; the remaining steps and parameters are the same as those in Example 1.

[0092] Comparative Example 1

[0093] In this embodiment, 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 composite anti-dispersant, and 300 parts of water are used; the remaining steps and parameters are the same as those in Example 1.

[0094] Comparative Example 2

[0095] In this embodiment, 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 composite anti-dispersant, and 300 parts of water are used; the remaining steps and parameters are the same as those in Example 1.

[0096] Comparative Example 3

[0097] In this embodiment, 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 composite anti-dispersant, and 300 parts of water are used; the remaining steps and parameters are the same as those in Example 1.

[0098] Comparative Example 4

[0099] In this embodiment, 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 composite anti-dispersant, and 300 parts of water are used; the remaining steps and parameters are the same as those in Example 1.

[0100] Comparative Example 5

[0101] In this embodiment, 220 parts of cement, 50 parts of slaked lime, and 360 parts of fly ash are used; the remaining steps and parameters are the same as those in Example 1.

[0102] Comparative Example 6

[0103] In this embodiment, 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 composite anti-dispersant, and 280 parts of water are used; the remaining steps and parameters are the same as those in Example 1.

[0104] Performance Testing

[0105] The grouting slurries prepared in the above examples and comparative examples were tested for fluidity, slump, setting time, compressive strength, water dispersibility and consistency. The test results are shown in Table 1:

[0106] The fluidity test is based on the GB / T50080-2016 standard and adopts the slump expansion method. The slurry is placed in the slump cone and lifted vertically. The maximum diameter of the slurry after expansion is measured, and the average value of two mutually perpendicular measurements is taken as the fluidity index.

[0107] The slump is determined according to GB / T50080-2016 standard. A slump cone (bottom inner diameter 200mm, top inner diameter 100mm, height 300mm) is used. The slurry is loaded into and compacted in three layers. After the slump cone is lifted vertically, the height to which the slurry falls is the slump value.

[0108] The setting time is based on GB / T1346-2011 standard. The Vicat apparatus method is used to test the time from the addition of water to the initial setting (the test needle sinks 4±1mm from the bottom plate) and the final setting (the test needle sinks less than 0.5mm).

[0109] The 28d compressive strength is tested in accordance with GB / T50081-2019 standard. The mold is formed in water. An open water tank is prepared and water is added to 100mm above the upper limit of the 70.7mm×70.7mm×70.7mm test mold with a bottom. The test mold with a bottom is completely immersed in water and kept horizontally. The slurry to be tested is carefully poured into the water-filled mold from the water surface until the slurry fills the test mold and overflows. The test mold is carefully taken out and vibrated to form. The excess slurry on the top of the test mold is wiped off with a scraper. The mold is placed in a standard curing box until it is 28 days old, then the mold is removed and the compressive strength is tested.

[0110] Anti-water dispersion (static water turbidity NTU) static water test: Pour the slurry into a water container (water depth ≥ 100mm), observe whether it separates within 30 minutes, and measure the water turbidity (NTU).

[0111] The consistency test refers to the JGJ / T70-2023 standard and uses a mortar consistency meter (cone mass 300g, cone tip diameter 10mm). After the slurry is placed in a container, the depth (cm) of the cone that freely sinks into the slurry for 10 seconds is measured, which is the consistency value.

[0112] Table 1 Performance test results

[0113]

[0114] The present invention forms a stable cementitious system through the synergistic proportioning of cement, slaked lime, and fly ash, combined with the introduction of a composite anti-dispersant. The combination of 140-180 parts medium cement and 280-320 parts fly ash, as in Examples 2 and 10, performs best, with a fluidity of 19-21 cm and a slump of 180-190 mm, meeting construction pumping requirements; a setting time of 5.0-5.5 hours, meeting the synchronous grouting time window; a 28-day compressive strength of 1.5-1.7 MPa, a water-dispersibility static turbidity of ≤60 NTU, and uniform sand encapsulation without segregation. When fly ash or the composite anti-dispersant was removed, the slurry severely segregated within 10 minutes, with a still water turbidity exceeding 500 NTU and a cementitious material loss rate exceeding 30%, confirming the irreplaceable role of fly ash micro-aggregate filling and anti-dispersant. When the cement content was less than 120 parts or the slaked lime content was greater than 100 parts, the slurry showed insufficient strength or abnormal setting times (>8 hours or <4 hours), exceeding the feasible construction range. An imbalance in the ternary mix ratio led to a sudden change in consistency and a breakdown in anti-dispersibility (turbidity >400 NTU). This comparison confirmed the rationality of the specific weight ranges of the various raw materials and the combination of the components. By limiting the cement-slaked lime-fly ash ratio and the composite anti-dispersant dosage, a systematic balance of slurry fluidity, strength, and water dispersibility was achieved, resolving the segregation problem of traditional slurries in water-rich formations.

Claims

1. A water-resistant dispersible grouting slurry, characterized in that: 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-dispersant and 260-340 parts of water; The composite anti-dispersant is polyacrylamide grafted with 3-aminopropyltriethoxysilane, and the molecular weight of the polyacrylamide is 10 million to 15 million; 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; The calcium oxide content in the fly ash is 15% to 30%; The water-binder ratio of the water-resistant dispersion grouting slurry is 0.47~0.

55.

2. The water-resistant 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.

3. The water-resistant dispersion grouting slurry according to claim 1, characterized in that: The mass ratio of the cement, slaked lime and fly ash is 1.2-3.33:1:2.5-5.

83.

4. The water-resistant dispersion grouting slurry according to claim 3, characterized in that: The mass ratio of the cement, slaked lime and fly ash is 1.67-2.57:1:3.5-5.

0.

5. A method for preparing the water-resistant dispersion grouting slurry according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Sieve and grind the fly ash to obtain activated fly ash with a specific surface area of ​​600-1000 m² / kg; S2. Place cement, slaked lime, activated fly ash, and bentonite into a mixer and dry-mix at 25-35 rpm for 1-2 minutes, then at 35-45 rpm for 2-5 minutes to obtain a gel material mixture. S3, dissolving the composite anti-dispersant in water to obtain a composite anti-dispersant aqueous solution; S4, uniformly mixing the gel material mixture, the composite anti-dispersant aqueous solution and water to obtain a mixed slurry; S5. Add sand to the mixed slurry and stir evenly to obtain a water-resistant dispersible grouting slurry.

6. The preparation method according to claim 5, wherein Adding sand to the mixed slurry in S5 includes: Mix fine sand and medium sand evenly to obtain mixed sand; The mixed sand is added to the mixed slurry twice and stirred evenly to obtain a water-resistant dispersed grouting slurry.

7. Use of the water-resistant dispersible grouting slurry according to any one of claims 1 to 4 in shield construction in high water-rich strata.

Images