High-anti-crack slope anti-seepage waterproof composite material and preparation method thereof

Abstract

The application relates to the technical field of building materials and geotechnical engineering protection, in particular to a high-anti-crack slope anti-seepage and waterproof composite material and a preparation method thereof. The application discloses a high-anti-crack slope anti-seepage and waterproof composite material and a preparation method thereof, wherein the preparation method divides fly ash into two routes, one route is activated by grinding to obtain double-activated fly ash, and the other route is maintained in the original state; water glass and sodium metaaluminate are prepared into a silicate-aluminate precursor solution for in-situ generation of C-A-S-H nano reinforced phase; and short fibers and a dispersing agent are premixed. Subsequently, the above components are mixed with cement, an expanding agent, a shrinkage reducing agent, a thixotropic agent and the like to prepare a thixotropic slurry, the wet spraying process is adopted for construction, and the finished product is obtained after standing and initial setting. Through double-mode filling of fly ash, in-situ nano reinforcement and multi-scale cooperation of fibers, the anti-crack and anti-seepage performances are remarkably improved, and the unification of high-value solid waste and construction adaptability is realized.

Description

Technical Field

[0001] This invention relates to the field of building materials and geotechnical engineering protection technology, specifically to a high crack-resistant slope seepage prevention and waterproofing composite material and its preparation method. Background Technology

[0002] In water conservancy and hydropower, transportation hubs, and mining ecological engineering, slope seepage prevention and reinforcement are crucial for maintaining the long-term safety and stability of the project. Slopes are constantly exposed to complex natural environments, and rainfall infiltration and groundwater erosion can easily weaken the slope's structural integrity, inducing disasters such as landslides and debris flows. Constructing surface impermeable layers using shotcrete or mortar is currently the most common engineering intervention method. However, slope protection layers are often large-area, thin-layer structures, which, under the combined effects of gravity flow, alternating wet and dry conditions, and external loads, are highly susceptible to developing self-shrinking microcracks and drying shrinkage cracks, leading to the complete failure of the seepage prevention system.

[0003] To address the cracking problem in waterproofing materials, existing technologies utilize modified cellulose to limit crack propagation under external forces. For example, CN121022086A discloses a polymeric waterproofing material with both oil resistance and impermeability, along with its preparation method and applications. This material comprises the following components by weight: 120 parts polyurethane prepolymer, 20-45 parts diluent, 10-30 parts additives, 15-20 parts micro-powder filler, 10-15 parts carboxymethyl cellulose, and 3-8 parts dihydrogen phosphate. The polyurethane prepolymer is prepared by reacting a diisocyanate compound with a polyether polyol. The micro-powder filler consists of sodium acrylate hydrogel micro-powder and seaweed. A mixture of sodium hydrogel micropowder; wherein, dihydrogen phosphate is a monovalent ionic salt; the polymeric impermeable material prepared therefrom has excellent impermeability and high adhesion in oil storage environments, and is suitable for grouting in humid environments; it can better achieve water and oil resistance in underground water-sealed rock cavern oil depot environments; however, the existing technology still has the problems of poor compatibility between inorganic reinforcing components and organic matrix interfaces, insufficient resistance to ultraviolet aging, and has not solved the problem of microcrack initiation and propagation caused by hydration shrinkage of cement-based materials.

[0004] In summary, how to innovate a new preparation method that can further improve the crack resistance and construction adaptability of slope seepage prevention materials based on existing technologies has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high crack-resistant slope seepage prevention and waterproofing composite material and its preparation method, so as to solve the technical problems such as the lack of gradient reinforcement system and insufficient crack resistance of the existing seepage prevention material.

[0006] The specific technical solution is as follows: This invention provides a high-crack-resistant, seepage-proof, and waterproof composite material for slope protection. Based on 100 parts of silicate cement, the composite material comprises the following components by weight: 35-45 parts fly ash or granulated blast furnace slag, 0.01-0.02 parts alkali activator, 0.1-0.5 parts sodium silicate, 2-5 parts water glass, 0.5-1.5 parts sodium aluminate, 0.5-1 parts chopped fiber, 0.005-0.02 parts sodium dodecyl sulfate, 0.2-0.6 parts modified attapulgite, 3-8 parts silica fume, 3-8 parts ettringite-based expanding agent, 0.5-2 parts polypropylene glycol monobutyl ether shrinkage reducer, 0.6-1.0 parts naphthalene-based high-efficiency water-reducing agent, and 28-32 parts deionized water.

[0007] Furthermore, the composite material includes a nano-reinforcing phase, an active filler, an inert filler, and chopped fibers; the nano-reinforcing phase is generated in situ from an aluminosilicate precursor solution in a high-alkali environment during cement hydration, with a particle size <100 nm; the active filler is fine-grained fly ash or granulated blast furnace slag that has undergone grinding and chemical activation treatment, with a particle size D 50 =5μm; the inert filler is untreated undisturbed coarse-grained fly ash or granulated blast furnace slag, with a particle size D 50 =20μm; the length of the chopped fiber is 6mm; the scale of the nano-reinforcing phase, active filler, inert filler and chopped fiber are distributed in an increasing order, forming a four-level continuous scale reinforcement network from nanoscale, fine meter scale, coarse micrometer scale to millimeter scale.

[0008] Furthermore, the alkali activator is either lithium carbonate or sodium hydroxide; the chopped fiber is either chopped basalt fiber or polypropylene fiber.

[0009] This invention also provides a method for preparing a high-crack-resistant slope seepage-proof and waterproof composite material, comprising the following steps: S1: The silicate cement raw material is ground in a ball mill to a specific surface area of ​​350m². 2 / kg for later use; fly ash raw materials are divided into two streams: one stream is fine-particle fly ash ground by an air jet mill, and the other stream is coarse-particle fly ash that remains in its original state; the fine-particle fly ash is added to lithium carbonate and sodium silicate, and then placed in a planetary mixer for chemical activation to obtain fine-particle dual-activated fly ash, while the coarse-particle fly ash is used directly for later use; water glass and sodium aluminate are added to deionized water and stirred until completely dissolved to prepare an aluminosilicate precursor solution for later use; short-cut basalt fibers are dry-premixed with sodium dodecyl sulfate and used directly as a fiber-dispersant composite material for later use; S2: Add silicate cement, fine-grained double-activated fly ash, coarse-grained fly ash, modified attapulgite, silica fume, ettringite-based expansion agent, polypropylene glycol monobutyl ether shrinkage reducer, naphthalene-based high-efficiency water-reducing agent, and aluminosilicate precursor solution into a mixer, add deionized water, first stir at low speed to uniformly wet the dry materials, then increase the speed and stir until uniform to obtain a thixotropic matrix slurry with thixotropic anti-flow properties; S3: The fiber-dispersant composite material is added to the mixer and mixed with the thixotropic matrix slurry to obtain a uniformly dispersed composite material slurry. The slurry is then transferred to the hopper of the wet spraying machine, the hydraulic pumping system is started, the pumping pressure is adjusted, and an 8mm diameter spray gun is used. The spray gun is kept 300mm vertically from the rock slope surface and at an upward throw angle of 70° with the horizontal plane. A single layer of continuous spraying is carried out at a spraying speed of 0.6m / s, and the thickness of each spray is controlled. After spraying, the mixture is allowed to stand until initial setting, and the high crack-resistant slope waterproofing composite material is obtained.

[0010] Furthermore, the stirring described in S1 is for chemical activation, with a rotation speed of 40-80 rpm and a time of 5-15 minutes; the stirring until completely dissolved is performed with a rotation speed of 40-80 rpm and a stirring time of 5-10 minutes.

[0011] Furthermore, in step S2, the dry material is first uniformly moistened by stirring at a low speed, and then the speed is increased to stir until uniform. The stirring speed for moistening is 40~80 rpm and the time is 2~5 minutes. Then the speed is increased to 100~150 rpm and the stirring time is 3~8 minutes.

[0012] Furthermore, the composite stirring described in S3 has a rotation speed of 30~60 rpm and a stirring time of 2~5 minutes; the pump pressure adjustment is set to 0.8~1.5 MPa; and the single spray thickness control is set to 5~15 mm.

[0013] Compared with the prior art, the present invention has the following beneficial effects: (1) Significantly improved crack resistance: By constructing an active-inert dual-mode gradient filling system through graded activation of fly ash, combined with the CASH nanophase generated in situ from aluminosilicate precursor and short-cut fibers, a four-level continuous scale reinforcement network is formed, which effectively inhibits the initiation and propagation of cracks from nanopores to macroscopic cracks. (2) Waterproof and seepage-proof dual protection: The in-situ generated CASH nano phase fills the nano-sized pores of cement stone, and the fine and coarse fly ash forms a bimodal gradation to optimize the micron-sized pore structure, which greatly improves the density of the body and significantly enhances the seepage resistance. (3) Excellent construction adaptability: Modified attapulgite soil gives the slurry shear thinning thixotropic properties, so it does not drip or blister after spraying, and the thickness of a single layer can reach 10mm; when it is washed by rainwater, the thixotropic network hinders the migration of cement particles, and the surface loss rate is significantly reduced, making it especially suitable for wet spraying operations on outdoor slopes. (4) Green, low-carbon, economical and environmentally friendly: Fly ash accounts for a high proportion of cementitious materials. Through graded activation, it can be used for high-value utilization, which can significantly reduce cement consumption and carbon emissions. At the same time, it provides a feasible path for the resource utilization of industrial solid waste, which has both environmental and economic benefits. Attached Figure Description

[0014] Figure 1 This is a flowchart of a high crack-resistant slope seepage prevention and waterproofing composite material and its preparation method according to the present invention.

[0015] Figure 2 This is a SEM cross-sectional view of the composite material in Example 1 of the present invention. Detailed Implementation

[0016] This invention proposes a high-crack-resistant slope seepage prevention and waterproofing composite material and its preparation method, such as... Figure 1 The diagram shows a flowchart of a high-crack-resistant slope seepage-proof and waterproof composite material and its preparation method according to the present invention. The detailed preparation steps are as follows: 1. Pre-preparation of functional components Cement is ground to increase hydration active sites; fly ash is divided into two streams: one stream is ground to a fine particle size and then chemically activated with lithium carbonate and sodium silicate to depolymerize the glassy structure and release active silica-alumina, forming active fly ash with both filling effect and pozzolanic activity; the other stream remains in its original state as a coarse-particle inert filler; water glass and sodium aluminate are dissolved in water to prepare an aluminosilicate precursor solution, which utilizes the alkaline environment generated by cement hydration to generate CASH nanogel phase in situ; fibers and dispersants are dry-premixed to avoid entanglement and clumping during stirring; 2. Preparation of matrix slurry Cement, activated fly ash, inert fly ash, attapulgite, silica fume, expanding agent, shrinkage reducing agent, water reducing agent, and aluminosilicate precursor solution are mixed with water. The activated fly ash and inert fly ash form a fine-coarse bimodal gradation, increasing the bulk density. The precursor solution generates a CASH nanogel phase in situ in the alkaline environment of cement, filling nanoscale pores and providing a nucleation effect to accelerate hydration. The expanding agent generates ettringite to compensate for early shrinkage, and the shrinkage reducing agent reduces the surface tension of the pore solution and decreases capillary stress. The attapulgite forms a three-dimensional network skeleton, giving the slurry thixotropic properties, resulting in a yield value of 10~20 Pa, which flows during spraying and does not sag after standing. 3. Fiber composite - wet spray The fiber-dispersant composite is added to the slurry and stirred evenly to form a three-dimensional randomly distributed network of fibers. A single layer is sprayed onto the slope using a wet spraying process. The high shear during spraying reduces the viscosity of the slurry, which is beneficial for spraying. After spraying, the thixotropic network is rapidly rebuilt to resist sagging. After standing until initial setting, the hydration products bind the components into a dense whole, thus obtaining the finished product.

[0017] The technical solution designed by this invention to solve the existing problems includes the following key points: 1. A four-level continuous-scale enhancement system based on particle size matching Addressing the shortcomings of existing technologies, such as the direct addition of fly ash with a single particle size, the difficulty in effectively dispersing nanomaterials due to agglomeration, and the lack of a multi-scale reinforcement system due to weak interfacial bonding between fibers and the matrix, this invention proposes for the first time a four-level continuous-scale reinforcement design based on particle size matching. Specifically, fly ash is actively differentiated into fine-particle and coarse-particle components. The fine-particle component, after chemical activation with lithium carbonate and sodium silicate, exhibits pozzolanic activity and can participate in the hydration reaction to form CSH gel, thus forming an "active layer." The coarse-particle component remains unchanged, serving only as micro-aggregate to fill the gaps between particles and does not participate in the hydration reaction, thus forming an "inert layer." The two components form a micron-level bimodal gradation, with the fine particles... Filling the gaps between coarse particles and cement particles significantly reduces micron-level porosity. Simultaneously, the active layer contributes to later-stage strength, and the inert layer reduces heat of hydration, achieving a balance between functional differentiation and particle size matching. Furthermore, CASH nanogel phases are generated in situ in the alkaline environment of cement via aluminosilicate precursor solution. These nanophases are uniformly distributed between hydrated calcium silicate gel layers, filling nanoscale pores and providing a nucleation effect, accelerating early cement hydration. In addition, short-cut basalt fibers randomly distribute within the matrix to form a three-dimensional bridging network. When the matrix is ​​tensile and cracks, the fibers cross both sides of the crack, consuming fracture energy through pull-out and debonding processes, thus inhibiting the propagation and penetration of macroscopic cracks. The above four scales, namely nanoscale CASH, fine-particle activated fly ash, coarse-particle undisturbed fly ash, and millimeter-scale short-cut fibers, are sequentially connected in terms of particle size from small to large, with no functional gaps between adjacent scales. Functionally, they form a synergistic reinforcement chain of "nano-filler-submicron-micron skeleton-fiber bridging", which fundamentally solves the problems of poor impermeability and easy crack propagation caused by the lack of gradient reinforcement system in existing technologies. To verify the advantages of the microstructure of this invention, scanning electron microscopy was used to observe the microstructure of the cross-section of the composite material obtained in Example 1, such as... Figure 2As shown in the SEM images, the short-cut basalt fibers are uniformly dispersed in the cement matrix, with no visible fiber agglomeration. The fiber surface is tightly wrapped by hydrated calcium silicate gel, and the interfacial transition zone is dense without microcracks. The in-situ generated CASH (calcium-aluminum-silicon-hydration) nanogel phase is uniformly distributed in the hydration products, with no obvious agglomerates, forming a continuous and dense microstructure with the cement hydration products. Fine-grained activated fly ash particles fill the gaps between coarse-grained fly ash and cement particles, forming a continuous particle size distribution. The interfacial transition zone is dense and intact, without microcracks or voids. 2. In-situ nano-reinforcement technology based on aluminosilicate precursors Addressing the technical challenges of existing technologies, such as the tendency of exfoliated nanomaterials to agglomerate, difficulty in dispersion, weak interfacial bonding with the cement matrix, and the difficulty in scaling up pretreatment processes like ultrasonic dispersion, this invention utilizes an aluminosilicate precursor solution to generate a CASH nanogel phase in situ during cement hydration. This nanophase precipitates uniformly within the pores of the cement paste, growing synchronously and interpenetrating with the CASH gel, forming a continuous, transitional chemically bonded interface without any weak interfacial layer. When the matrix is ​​subjected to tensile cracking, the CASH nanophase plays the following anti-crack role: First, the nanophase is uniformly distributed between the CSH gel layers, filling the nanoscale pores that would otherwise easily become microcrack initiation sites, thus reducing the chance of crack initiation at the source; Second, the CASH nanophase and CSH gel form a network-like interwoven structure, which acts as a "pinning" effect on microcrack propagation. During the propagation process, the crack needs to bypass or cut off the nanophase in order to continue to advance, thereby consuming more fracture energy; Third, since the nanophase and the matrix are continuously chemically bonded, the stress is continuously transmitted at the interface, avoiding the stress concentration and interface debonding caused by the weak interface in traditional externally doped nanomaterials, so that the material exhibits a higher critical cracking stress when under tension.

[0018] Example 1: Table 1 Raw Material Information Table A high crack-resistant slope seepage prevention and waterproofing composite material and its preparation method include the following steps: S1: Grind 100 parts of silicate cement raw material using a ball mill to achieve a specific surface area of ​​350 m². 2 / kg for later use; take 30 parts of fly ash raw material and divide them into two groups, one group of 20 parts is ground into powder using an air jet mill to D. 50 =5μm to obtain fine-grained fly ash, another route is 10 parts to maintain the original state D 50=20μm coarse-grained fly ash; 0.015 parts lithium carbonate and 0.3 parts sodium silicate were added to 20 parts fine-grained fly ash, and the mixture was placed in a planetary mixer and stirred at 60 rpm for 10 minutes for chemical activation to obtain fine-grained double-activated fly ash; 10 parts coarse-grained fly ash were used directly; 3 parts water glass and 0.8 parts sodium aluminate were added to 16 parts deionized water and stirred at 60 rpm for 8 minutes until completely dissolved to prepare a homogeneous aluminosilicate precursor solution for later use; 0.7 parts chopped basalt fiber and 0.01 parts sodium dodecyl sulfate were dry-premixed and used directly as fiber-dispersant composite material for later use; S2: Add silicate cement, fine-grained double-activated fly ash, coarse-grained fly ash, 0.4 parts modified attapulgite, 5 parts silica fume, 5.5 parts ettringite-based expansion agent, 1 part polypropylene glycol monobutyl ether shrinkage reducer, 0.8 parts naphthalene-based high-efficiency water-reducing agent, and 19.8 parts aluminosilicate precursor solution into a mixer, add 30 parts deionized water, stir at 60 rpm for 3 minutes to uniformly wet the dry materials, and then stir at 120 rpm for 5 minutes until uniform to obtain a thixotropic matrix slurry with thixotropic anti-flow properties; S3: Add the fiber-dispersant composite material to the mixer and mix it with the thixotropic matrix slurry at 45 rpm for 3 minutes to obtain a uniformly dispersed composite material slurry. Then, transfer the slurry to the hopper of the wet spraying machine, start the hydraulic pumping system, adjust the pumping pressure to 1.2 MPa, use an 8 mm diameter spray gun, maintain the vertical distance of the spray gun from the rock slope surface at 300 mm, the upward throw angle at 70° with the horizontal plane, and spray a single layer continuously at a spraying speed of 0.6 m / s, controlling the thickness of each spray layer to 10 mm. After spraying, let it stand until initial setting to obtain the finished product of high crack-resistant slope seepage prevention and waterproofing composite material.

[0019] Example 2: The preparation method is the same as in Example 1, except that: S1: 15 parts fine-grained fly ash; 0.01 parts lithium carbonate and 0.1 parts sodium silicate; 5 parts coarse-grained fly ash; 2 parts water glass and 0.5 parts sodium aluminate dissolved in 12 parts water; 0.5 parts short-cut basalt fiber and 0.005 parts sodium dodecyl sulfate; S2: 0.2 parts modified attapulgite, 3 parts silica fume, 3 parts ettringite-based expanding agent, 0.5 parts polypropylene glycol monobutyl ether shrinkage reducer, 0.6 parts naphthalene-based high-efficiency water-reducing agent, and 14.5 parts aluminosilicate precursor solution; 32 parts deionized water; All other steps are the same.

[0020] Example 3: The preparation method is the same as in Example 1, except that: S1: 25 parts fine-grained fly ash; 0.02 parts lithium carbonate and 0.5 parts sodium silicate; 15 parts coarse-grained fly ash; 5 parts water glass and 1.5 parts sodium aluminate dissolved in 20 parts water; 1 part short-cut basalt fiber and 0.02 parts sodium dodecyl sulfate; S2: 0.6 parts modified attapulgite, 8 parts silica fume, 8 parts ettringite-based expanding agent, 2 parts polypropylene glycol monobutyl ether shrinkage reducer, 1.0 part naphthalene-based high-efficiency water-reducing agent, and 26.5 parts aluminosilicate precursor solution; 28 parts deionized water; All other steps are the same.

[0021] Example 4: The preparation method is the same as in Example 1, except that: S1: Chemical activation is initiated by stirring at 40 rpm for 5 minutes; then, stirring at 40 rpm for 5 minutes until completely dissolved. S2: First, stir at 40 rpm for 2 minutes to evenly moisten the dry material, then stir at 100 rpm for 3 minutes until uniform; S3: Mix at 30 rpm for 2 minutes; adjust pump pressure to 0.8 MPa; control single spray thickness to 5 mm; All other steps are the same.

[0022] Example 5: The preparation method is the same as in Example 1, except that: S1: Chemical activation is initiated by stirring at 80 rpm for 15 minutes; then, stirring at 80 rpm for 10 minutes until completely dissolved. S2: First, stir at 80 rpm for 5 minutes to evenly moisten the dry material, then stir at 150 rpm for 8 minutes until uniform; S3: Mix at 60 rpm for 5 minutes; adjust pump pressure to 1.5 MPa; control single spray thickness to 15 mm; All other steps are the same.

[0023] Example 6: The preparation method is the same as in Example 1, except that: S1: Replace fly ash raw material with granulated blast furnace slag. Both can be classified into submicron grades by air jet mill. All other steps are the same.

[0024] Example 7: The preparation method is the same as in Example 1, except that: S1: Replace lithium carbonate with sodium hydroxide. Both can be combined with sodium silicate to form an alkaline activation system for fly ash. All other steps are the same.

[0025] Example 8: The preparation method is the same as in Example 1, except that: S1: Replacing basalt fibers with polypropylene fibers, both of which can form a three-dimensional bridging network in the cement matrix to inhibit crack propagation; All other steps are the same.

[0026] Comparative Example 1: A waterproof and seepage-proof composite material was prepared using a traditional process. The preparation method was as follows: 100 parts of ordinary silicate cement, 25 parts of undisturbed fly ash with a particle size of 15~20μm, and 10 parts of silica fume were put into a mixer and dry-mixed for 2 minutes; then 0.5 parts of 12mm long polypropylene fiber, 5 parts of calcite-based expansion agent, and 1.5 parts of polycarboxylate superplasticizer were added, and dry-mixed for another minute; then 40 parts of water were added, and the mixture was stirred at 120rpm for 5 minutes to obtain a composite material slurry; finally, the obtained slurry was sprayed onto the slope using a wet spraying process with a spray thickness of 10mm. After initial setting, the waterproof and seepage-proof composite material was obtained.

[0027] Comparative Example 2: The preparation method is the same as in Example 1, except that: S1: Omit the step of grading and activating fly ash, and directly mix 30 parts of fly ash with other dry materials; All other steps are the same.

[0028] Comparative Example 3: The preparation method is the same as in Example 1, except that: S1: Omit the step of preparing the aluminosilicate precursor solution and instead prepare the nano-SiO2 pre-dispersion: Mix 3 parts of nano-SiO2 with 0.15 parts of polyethylene glycol monomethyl ether dispersion stabilizer and 20 parts of water, and shear and disperse at 3000 rpm for 15 min to prepare a nano-SiO2 pre-dispersion with a solid content of about 13% for later use. All other steps are the same.

[0029] Comparative Example 4: The preparation method is the same as in Example 1, except that: S1: The preparation steps of the fiber-dispersant composite material are omitted; All other steps are the same.

[0030] Comparative Example 5: The preparation method is the same as in Example 1, except that: S2: The steps of adding attapulgite and ettringite-based expansion agents are omitted; All other steps are the same.

[0031] The following is a more detailed description of a high crack-resistant slope seepage-proof and waterproof composite material and its preparation method. This description does not limit the scope of protection of this application, which is defined by the claims. Certain specific details disclosed provide a full understanding of the various disclosed embodiments. However, those skilled in the art will know that the embodiments can also be implemented without using one or more of these specific details, but with other materials, etc.

[0032] Unless the context otherwise requires, the terms “comprising” and “including” in the specification and claims shall be understood as open-ended and inclusive, meaning “including, but not limited to”.

[0033] The terms "implementation," "an implementation," "another implementation," or "certain implementations" used in this specification refer to specific features, structures, or characteristics described in relation to the implementation, which are included in at least one implementation. Therefore, "implementation," "an implementation," "another implementation," or "certain implementations" need not all refer to the same implementation. Furthermore, specific features, structures, or characteristics can be combined in any way in one or more implementations. Each feature disclosed in this specification can be replaced by any alternative feature that provides the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the disclosed features are merely general examples of equivalent or similar features.

[0034] Experimental Example 1: The impermeable and waterproof composite materials prepared in Examples 1-8 and Comparative Examples 1-5 were tested: (1) 28-day compressive strength: Referring to GB / T 17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)", the composite material slurry was cast into prism specimens of 40mm×40mm×160mm. After curing in a curing chamber at a temperature of 20±2℃ and a relative humidity of not less than 90% for 24 hours, the specimens were demolded and then transferred to saturated lime water at 20±2℃ for curing until 28 days. The compressive strength of the specimens was tested by a pressure testing machine at a loading rate of 2.4kN / s. The arithmetic mean of the test results of three specimens was taken as the 28-day compressive strength value. Each group of valid specimens should have no less than 5 specimens, and the final result is the average. (2) Permeability grade: Referring to GB / T 50082-2024 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete", the composite material slurry was cast into a frustum-shaped specimen with a height of 150 mm, an upper diameter of 175 mm, and a lower diameter of 185 mm. After standard curing for 28 days, the specimen was removed and the surface was wiped dry. The specimen was placed in a permeability tester, and the pressure was increased from 0.1 MPa. The pressure was increased by 0.1 MPa every 8 hours until water seepage appeared on the end face of 3 out of 6 specimens. The permeability grade value was taken as 0.1 times the water pressure when the pressure was stopped. At least 5 parallel specimens were tested in each group, and the average value was taken. (3) Crack reduction coefficient: Referring to GB / T 50082-2024 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete", the composite material slurry was poured into a flat mold with a stress inducer at the bottom. The mold size was 600mm×600mm×63mm. It was placed in a dry environment with a temperature of 20±2℃ and a wind speed of 5m / s. The width and length of the cracks on the surface of the specimen were observed within 24 hours. The crack reduction coefficient was calculated by the following formula: Crack reduction coefficient = (total cracked area of ​​the reference specimen - total cracked area of ​​the specimen of this invention) / total cracked area of ​​the reference specimen × 100%, where the total cracked area is the sum of the products of the length and average width of each crack. In order to obtain reliable data, at least 3 parallel samples were tested in each group, and the average value of the results was taken.

[0035] Experimental Example 2: The microstructure of the waterproof composite material prepared in Example 1 was characterized by scanning electron microscopy (SEM): (1) Sampling: After curing the composite material specimen for 28 days, samples were taken from the central area inside the specimen. Small samples of the fresh fracture surface were obtained by tapping with a small hammer; (2) Termination of hydration: Immediately immerse the small sample in anhydrous ethanol for at least 24 hours to displace the free water in the pores, completely terminate the internal hydration reaction, and fix its microstructure. (3) Vacuum drying: Take out the soaked sample and put it into a vacuum drying oven and dry it at 50~60℃ until constant weight; (4) Attaching the sample: Use conductive adhesive to fix the dried sample onto the aluminum sample stage, ensuring that the fresh cross-section to be observed is facing upwards; (5) Surface conductive treatment: The fixed sample is placed in an ion sputtering instrument for surface gold sputtering treatment; (6) Setting parameters: the acceleration voltage is set to 10~15kV and the working distance is set to 8~12mm.

[0036] Table 2 Comparison of experimental results of Examples 1-8 and Comparative Examples 1-5 The experimental results of Examples 1-8 and Comparative Examples 1-5 are shown in Table 2. The waterproof and seepage-proof composite material prepared by the present invention achieves the tightest gradient filling effect through the dual activation of submicron-level fly ash, provides the most uniform nano-reinforcing network through nano-SiO2 pre-dispersion liquid, and achieves the optimal synergistic matching between basalt fiber and thixotropic-expansion-shrinkage system. As a result, the 28-day compressive strength, seepage pressure and crack reduction coefficient of the composite material all reach the highest values, thus making it the best implementation method.

[0037] Example 2 reduced the dosage of key components such as activated fly ash, nano-SiO2, fibers, expanding agents, and thixotropic agents, resulting in discontinuities in the submicron-level filling network, weakened nanocrystal nucleation effects, insufficient fiber bridging density, and decreased shrinkage compensation capacity. This significantly reduced compressive strength, impermeability, and crack reduction coefficient, demonstrating a dosage-dependent synergistic effect among the functional components. Example 3 increased the dosage of each component, but excessive dosage led to deterioration of slurry rheological properties, increased fiber agglomeration tendency, and micro-expansion stress concentration caused by excessive expanding agents. This weakened the density of the interfacial transition zone, preventing further improvement in compressive strength and crack reduction coefficient, demonstrating the existence of an optimal synergistic dosage range for functional components. Example 4 reduced the chemically activated stirring intensity and nano-shear dispersion speed, resulting in incomplete deagglomeration of fly ash glass and insufficient dispersal of nano-SiO2 agglomerates. This reduced the amount of hydration products generated and the loss of the nano-filling effect, thereby reducing impermeability and crack resistance, demonstrating the decisive role of process parameters in the evolution of microstructure. Effects: Example 5 improved the process strength parameters, resulting in more uniform nano-dispersion and more complete activation of fly ash. However, excessively high shear speeds may break the molecular chains of the dispersion stabilizers grafted onto the surface of nano-SiO2, and excessively long chemically activated stirring may damage the morphology of fly ash particles, leading to limited improvement in the reinforcing effect. This demonstrates that there is a diminishing marginal benefit between process parameters and material properties. Example 6 replaced fly ash with granulated blast furnace slag. The Ca-O bond energy in the glassy network structure of slag is higher than that of the Si-O-Al network in fly ash. Under the same lithium carbonate-sodium silicate activation conditions, the depolymerization rate is slower and the release of active SiO2 is lower, resulting in a decrease in the pozzolanic reaction degree of submicron particles and a reduction in the amount of CSH gel formation, thus reducing strength and impermeability. This demonstrates that the glassy structure of fly ash is more easily activated by the activation system of this invention. Example 7 replaced lithium carbonate with sodium hydroxide. Although sodium hydroxide can provide a stronger alkaline environment, Li⁺ can simultaneously accelerate C3S hydration and participate in CSH lattice formation, while Na⁺... + Lithium carbonate can only increase the pH value without participating in the structural construction of hydration products, resulting in a delay in the early hydration exothermic peak and a decrease in the polymerization degree of hydrated calcium silicate gel, which reduces the degree of microstructure densification. This proves that the lattice doping effect of lithium carbonate is irreplaceable. In Example 8, basalt fibers were replaced with polypropylene fibers. The surface of polypropylene fibers is chemically inert and does not contain polar functional groups. There are only van der Waals forces and mechanical anchoring between the fibers and the cement matrix. However, the Si-OH and Al-OH groups on the surface of basalt fibers can form covalent bonds with hydration products, resulting in a significant reduction in interfacial bonding strength and fiber pull-out energy. This proves that the chemical affinity of basalt fibers is a key contribution to crack bridging efficiency.

[0038] Due to the lack of key technologies, the overall performance of Comparative Examples 1-5 was reduced to varying degrees compared to the Examples. Comparative Example 1 used a traditional cement mortar formula, lacking all the core technologies such as fly ash graded activation, nano-pre-dispersion reinforcement, fiber bridging, and expansion-shrinkage compensation. This resulted in the complete absence of the nano-submicron-micron level filling network in the hydration products, the absence of crack bridging mechanisms, and the inability to control shrinkage throughout the entire lifespan. Consequently, its performance was the lowest among all samples. Comparative Example 2 directly added fly ash in its original state without graded activation treatment, resulting in the absence of the submicron level active filling layer and the failure to deagglomerate the fly ash glass structure. The pozzolanic reaction only occurred slowly in the later stages, leading to increased early porosity, reduced hydration product formation, and disruption of particle size distribution continuity. Therefore, its compressive strength and impermeability were significantly lower than those of the Examples. Comparative Example 3 replaced the aluminosilicate precursor solution with nano-SiO2 pre-dispersion liquid. Although the added nano-SiO2 underwent pre-dispersion treatment, its interface with the cement matrix was still poor. The surface is mainly filled with physical fillers, lacking in-situ chemical bonding, and some nanoparticles still agglomerate, resulting in low density and increased micro-defects in the interface transition zone. Therefore, the impermeability pressure and crack reduction coefficient are significantly lower than those of Example 1. Comparative Example 4 completely omits short-cut fibers and their dispersants, resulting in the absence of millimeter-level crack bridging networks in the matrix. When the material is tensile and cracked, if there are no fibers bridging both sides of the crack, the fracture energy cannot be absorbed through the fiber pull-out and debonding process, and the crack will rapidly expand and penetrate. Therefore, the crack reduction coefficient is significantly lower than that of the examples containing fibers. Comparative Example 5 omits both thixotropic agents and expanding agents, resulting in insufficient thixotropy of the slurry during wet spraying, leading to sagging and hollowing. Furthermore, there are no expanding components to compensate for plastic shrinkage and drying shrinkage during the hardening process. The shrinkage stress caused by capillary tension generates a large number of micro-cracks inside the matrix and weakens the density of the interface transition zone. Therefore, the impermeability pressure and crack reduction coefficient are reduced to a level comparable to that of Comparative Example 1.

[0039] In summary, this invention successfully solves the technical problems of low early strength of high-volume fly ash, difficulty in the engineering dispersion of nanomaterials, and difficulty in the coordinated control of scouring and shrinkage cracking during wet spraying of slopes by constructing an active-inert dual-mode gradient filling system through graded activation of fly ash, forming a four-level continuous scale reinforcement network through nano pre-dispersion liquid and short-cut fibers, and achieving integrated protection of slopes during construction and service through thixotropic regulation and expansion-shrinkage synergy. It achieves a unity of high crack resistance, high impermeability and construction adaptability.

Claims

1. A high-crack-resistant, seepage-proof, and waterproof composite material for slope protection, characterized in that, Based on 100 parts of silicate cement, the following components are included by weight: 35-45 parts fly ash or granulated blast furnace slag, 0.01-0.02 parts alkali activator, 0.1-0.5 parts sodium silicate, 2-5 parts water glass, 0.5-1.5 parts sodium aluminate, 0.5-1 parts chopped fiber, 0.005-0.02 parts sodium dodecyl sulfate, 0.2-0.6 parts modified attapulgite, 3-8 parts silica fume, 3-8 parts ettringite-based expanding agent, 0.5-2 parts polypropylene glycol monobutyl ether shrinkage reducer, 0.6-1.0 parts naphthalene-based high-efficiency water-reducing agent, and 28-32 parts deionized water.

2. The high crack-resistant slope waterproofing composite material as described in claim 1, characterized in that, The composite material comprises a nano-reinforcing phase, an active filler, an inert filler, and chopped fibers; the nano-reinforcing phase is generated in situ from an aluminosilicate precursor solution in a high-alkali environment during cement hydration, with a particle size <100 nm; the active filler is fine-grained fly ash or granulated blast furnace slag that has undergone grinding and chemical activation treatment, with a particle size D 50 =5μm; the inert filler is untreated undisturbed coarse-diameter fly ash or granulated blast furnace slag, with a particle size D 50 =20μm; the length of the chopped fiber is 6mm; the scale of the nano-reinforcing phase, active filler, inert filler and chopped fiber are distributed in an increasing order, forming a four-level continuous scale reinforcement network from nanoscale, fine meter scale, coarse micrometer scale to millimeter scale.

3. The high crack-resistant slope waterproofing composite material as described in claim 1, characterized in that, The alkali activator is either lithium carbonate or sodium hydroxide; the chopped fiber is either chopped basalt fiber or polypropylene fiber.

4. A method for preparing a high crack-resistant slope seepage-proof and waterproof composite material as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S1: Grind silicate cement raw materials to a specific surface area of ​​350m². 2 / kg for later use; Fly ash or granulated blast furnace slag is divided into two streams: one stream is fine-grained fly ash or granulated blast furnace slag obtained through grinding, and the other stream is coarse-grained fly ash or granulated blast furnace slag that remains in its original state; The fine-grained fly ash or granulated blast furnace slag is added to an alkali activator and sodium silicate, and stirred for chemical activation to obtain fine-grained double-activated fly ash or granulated blast furnace slag, while the coarse-grained fly ash or granulated blast furnace slag is used directly for later use; Water glass and sodium aluminate are added to deionized water and stirred until completely dissolved to prepare an aluminosilicate precursor solution for later use; Short-cut fibers are also premixed with sodium dodecyl sulfate by dry method and used directly as a fiber-dispersant composite material for later use; S2: Mix silicate cement, coarse-grained double-activated fly ash or granulated blast furnace slag, fine-grained fly ash or granulated blast furnace slag, modified attapulgite, silica fume, ettringite-based expansion agent, polypropylene glycol monobutyl ether shrinkage reducer, naphthalene-based high-efficiency water-reducing agent and aluminosilicate precursor solution, add deionized water, stir first to uniformly wet the dry materials, then increase the speed and stir until uniform to obtain a thixotropic matrix slurry with thixotropic anti-flow properties; S3: The fiber-dispersant composite material and the thixotropic matrix slurry are mixed together to obtain a uniformly dispersed composite material slurry; then the slurry is wet-sprayed onto the rock slope for single-layer continuous spraying, and the thickness of each spray is controlled; after spraying, it is left to stand until initial setting to obtain the finished product of high crack-resistant slope seepage prevention and waterproofing composite material.

5. The preparation method of the high crack-resistant slope seepage prevention and waterproofing composite material as described in claim 4, characterized in that, The stirring described in S1 is used for chemical activation, with a rotation speed of 40~80 rpm and a time of 5~15 minutes.

6. The preparation method of the high crack-resistant slope seepage prevention and waterproofing composite material as described in claim 4, characterized in that, Stirring until completely dissolved as described in S1, with a speed of 40-80 rpm and a stirring time of 5-10 minutes.

7. The preparation method of the high crack-resistant slope seepage prevention and waterproofing composite material as described in claim 4, characterized in that, The stirring described in S2 wets the dry material evenly, and then the speed is increased to stir until uniform. The stirring speed for wetting is 40~80 rpm and the time is 2~5 minutes. Then the speed is increased to 100~150 rpm and the stirring time is 3~8 minutes.

8. The preparation method of the high crack-resistant slope seepage prevention and waterproofing composite material as described in claim 4, characterized in that, The composite stirring described in S3 has a speed of 30-60 rpm and a stirring time of 2-5 minutes.

9. The preparation method of a high crack-resistant slope seepage-proof and waterproof composite material as described in claim 4, characterized in that, S3 describes the wet spraying of slurry onto a rocky slope at a pressure of 0.8~1.5 MPa.

10. The preparation method of a high crack-resistant slope seepage-proof and waterproof composite material as described in claim 4, characterized in that, S3 describes controlling the thickness of a single spray coat, with the thickness controlled to be 5~15mm.

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