Composite anti-seepage repair material and preparation method thereof

Abstract

The invention discloses a composite anti-seepage repair material and a preparation method thereof, and belongs to the technical field of engineering materials. The coating is composed of a component A, a component B, a component C, a component D and a component E, the component A is a flexible reversible network precursor and comprises furanized hydroxyl-terminated polybutadiene, bismaleimide glycol ester, dimethylaminoethyl methacrylate and a photoinitiator; the component B is a pH-response microcapsule, the shell of the microcapsule is a chitosan / melamine-formaldehyde composite wall, and the core of the microcapsule is gamma-glycidyl ether oxypropyl trimethoxy silane; the component C is an inorganic mineralization source and comprises calcium formate, nano metakaolin and nano SiOsol; the component D is a dynamic load damping filler and comprises chopped aramid fibers and sulfonated graphene nanoplatelets; and the component E comprises triethanolamine and deionized water. The whole system does not contain cement clinker, the dependence of a traditional material on an alkaline environment is eliminated, and the repairing activity can be kept within the pH value range of 3-13.

Description

Technical Field

[0001] This invention belongs to the field of engineering materials technology, specifically relating to a composite seepage prevention and repair material and its preparation method. Background Technology

[0002] With the rapid development of infrastructure construction and various engineering structures, such as water conservancy dams, tunnels, underground spaces, and environmental protection projects, the increasingly complex service environments have placed higher demands on engineering seepage prevention technologies and materials. As a key barrier to ensure structural safety, durability, and long-term stability, the performance of seepage prevention materials directly affects the lifespan and operational safety of the project.

[0003] In practical engineering, seepage-proof materials often endure severe tests from the combined effects of multiple factors over long periods. These factors include, but are not limited to: physical loads, such as hydrostatic pressure, wet-dry cycles, and freeze-thaw cycles; chemical corrosion, such as corrosion from acid, alkali, and salt media; biological effects; and material aging over time. Studies of material properties under the influence of a single factor can no longer accurately reflect their degradation patterns under actual working conditions.

[0004] Existing organic-based waterproofing materials typically possess excellent flexibility, adhesion, and low permeability; however, their weather resistance is poor, easily aging and becoming brittle under ultraviolet radiation and high-temperature oxidation, and they have weak resistance to certain chemical solvents, posing challenges to long-term durability. Inorganic waterproofing materials, on the other hand, exhibit excellent aging resistance, fire resistance, and environmental friendliness, and have good compatibility with inorganic substrates such as concrete. However, they are inherently brittle, with poor crack resistance and deformation following ability, easily developing cracks under structural deformation or drying shrinkage, leading to waterproofing failure. To combine the advantages of organic and inorganic materials, some simple composite forms have been developed, such as incorporating polymer emulsions (e.g., styrene-acrylic emulsion, styrene-butadiene emulsion) into a cement matrix to form polymer-modified cementitious composites (PCCs), or organically modifying bentonite. These methods improve the flexibility and impermeability of the materials to some extent. However, existing composites mostly remain at the physical blending level, with weak interfacial bonding and poor compatibility between the organic and inorganic phases, failing to achieve synergistic effects at the molecular / nanoscale. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a composite seepage prevention and repair material and its preparation method, so as to solve the problems of weak interfacial bonding and poor compatibility between the organic and inorganic phases.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a composite seepage prevention and repair material, which is composed of component A, component B, component C, component D, and component E; Component A is a flexible reversible network precursor, comprising 30-40 parts of furan-terminated hydroxyl-terminated polybutadiene, 6-8 parts of bismaleimide ethylene glycol ester, 4-6 parts of dimethylaminoethyl methacrylate, and 0.5 parts of photoinitiator. Component B consists of 5-10 parts of pH-responsive microcapsules, wherein the shell of the microcapsules is a chitosan / melamine-formaldehyde composite wall and the core is γ-glycidoxypropyltrimethoxysilane. The C component is an inorganic mineralization source, comprising 3-5 parts calcium formate, 8-12 parts nano-metakaolin, and 6-10 parts nano-SiO2 sol. The D component is a dynamic load damping filler, comprising 1-2 parts chopped aramid fibers and 0.3-0.5 parts sulfonated graphene microsheets; The E component contains 0.2-0.4 parts triethanolamine and 15-20 parts deionized water.

[0007] Furthermore, the grafting rate of the furanized hydroxyl-terminated polybutadiene is 12%; The pH value of the chitosan / melamine-formaldehyde composite wall is ≤ 5.5; the γ-glycidyl etheroxypropyltrimethoxysilane is composed of 70wt% GPTMS and 30wt% nano MgO with a particle size of 2-5 µm. The nano-kaolin has a particle size of 190-210 nm; the nano-SiO2 sol accounts for 30 wt% and has a pH value of 9; The length of the chopped aramid fiber is 1 mm.

[0008] Furthermore, a method for preparing a composite seepage-proof and repair material includes the following steps: S1: GPTMS and MgO were dispersed in a 15 wt% chitosan acetic acid solution, and then added dropwise to liquid paraffin containing 0.5 wt% melamine-formaldehyde prepolymer. The reaction was maintained at 55 ℃ for 2 h, filtered, and vacuum dried to obtain pH-responsive microcapsules. S2: Nano-metakaolin and calcium formate are ball-milled for 30 min, then 2 wt% (3-aminopropyl)triethoxysilane coupling agent is sprayed in, and milling is continued for 15 min to obtain surface-activated powder; S3: Furanized hydroxyl-terminated polybutadiene, bismaleimide ethylene glycol ester, dimethylaminoethyl methacrylate, and photoinitiator were stirred under vacuum for 20 min to obtain a homogeneous low-viscosity fluid; S4: Add pH-responsive microcapsules, surface-activated powder, nano-SiO2 sol, sulfonated graphene microsheets, and chopped aramid fibers sequentially to a homogeneous low-viscosity fluid, and stir and disperse them beforehand; then add deionized water and triethanolamine, increase the speed and continue stirring, and then maintain the temperature at 25℃ and the viscosity at 800-1200 mPa·s of slurry. S5: Inject grout into cracks larger than 0.3 mm at a pressure of 0.2 MPa to achieve a grout penetration depth greater than 20 mm, and then use photo-thermal graded curing.

[0009] Further, in step S5, when the crack is less than 0.3 mm, two coats are applied using airless spraying, with a 30-minute interval between each coat. Further, during the photo-thermal graded curing, first, blue LED light is used at 405 nm, 30 mW cm⁻² for 60 s; then, infrared radiation at 50 ℃ is maintained for 2 h; followed by static curing for 24 h to allow the calcium formate to react with the CO₃²⁻ / SO₄²⁻ in the permeate water.

[0010] Furthermore, in step S4, the pre-stirring and dispersion is carried out at 600 rpm for 10 min; after increasing the speed, it is sheared at 2000 rpm for 3 min.

[0011] Furthermore, in step S4, the temperature of the vacuum stirring is 60 °C.

[0012] The beneficial effects of this invention are as follows: 1. The composite seepage prevention and repair material prepared by this invention has significantly improved durability, 2×10 6 After 4 Hz, ±300µε fatigue cycles, the self-healing rate of crack width was 92%, while that of traditional epoxy-cement composite repair layer was only 35%; in 0.5 M MgSO4 solution at pH=3 for 180 days, the mass loss rate was <1%, while that of ordinary PVA-cement based coating was 18%.

[0013] 2. The composite seepage prevention and repair material prepared by this invention also has high water pressure adaptability, and does not seep water for 28 days under 1.2 MPa water pressure. Its permeability coefficient is two orders of magnitude lower than that of polyurethane grouting material. It also has "self-sealing" characteristics: after artificially prefabricating 0.4 mm cracks, the seepage rate decreases by 95% within 2 hours and completely stops seepage in 7 days.

[0014] 3. The composite seepage prevention and repair material prepared by this invention has advantages in construction and environmental protection. Due to the low initial viscosity of the grout, it can be sprayed or injected without high-pressure grouting (0.2 MPa is sufficient), and there is no risk of splitting to the surrounding structure. The entire process is free of cement and organic solvents, with VOC ≈ 15 g L⁻¹, which meets the low VOC requirements of GB 30981-2020. The peak heat release during curing is <35 ℃, which can be used for thin-walled tunnel lining with a thickness of only 5 cm without the risk of thermal shrinkage cracking.

[0015] 4. This invention is the first to couple "reversible DA bonds" with "defect-induced mineralization," forming a spatiotemporally hierarchical interpenetrating network, rather than a one-time interpenetration. It utilizes corrosion itself (pH decrease, anion invasion) as a trigger signal to achieve healing, introducing a "water pressure-promoted recrystallization" mechanism. This enhances the impermeability with increasing service water pressure, contrary to the tendency of conventional materials to fail under high pressure. It eliminates the need for cement-based alkaline systems, maintaining activity within a pH range of 3-13, filling the gap in mature repair materials for strong acid and high water pressure environments. The entire system of this invention does not contain cement clinker, eliminating the dependence of traditional "polymer-modified cement-based" materials on alkaline environments. It maintains repair activity within a pH range of 3-13, significantly different from existing technologies.

[0016] Other advantages, objectives, and features of the invention will be set forth in the following description and will be apparent to those skilled in the art in some respects, or may be learned by practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0017] To make the purpose, technical solution, and beneficial effects of the invention clearer, the following figures are provided for illustration: Figure 1 This is a flowchart illustrating the preparation process of the present invention. Detailed Implementation

[0018] like Figure 1 As shown, the present invention provides a method for preparing a composite seepage-proof repair material.

[0019] Example 1 S1: 70 wt% GPTMS and 30 wt% nano MgO were dispersed in a 15 wt% chitosan acetic acid solution, and then added dropwise to liquid paraffin containing 0.5 wt% melamine-formaldehyde prepolymer. The reaction was maintained at 55 °C for 2 h, and then filtered and vacuum dried to obtain pH-responsive microcapsules. S2: 10 parts of nano-metakaolin and 4 parts of calcium formate were ball-milled for 30 min, and then 2 wt% (3-aminopropyl)triethoxysilane coupling agent was sprayed in and the mixture was ground for another 15 min to obtain surface-activated powder. S3: 35 parts of furanized hydroxyl-terminated polybutadiene, 7 parts of bismaleimide ethylene glycol ester, 5 parts of dimethylaminoethyl methacrylate, and 0.5 parts of photoinitiator were stirred under vacuum for 20 min to obtain a homogeneous low-viscosity fluid. S4: 7.5 parts of pH-responsive microcapsules, surface-activated powder, 8 parts of nano-SiO2 sol, 0.4 parts of sulfonated graphene microsheets, and 1.5 parts of chopped aramid fibers were added sequentially to a homogeneous low-viscosity fluid and dispersed at 600 rpm for 10 min; then 17.5 parts of deionized water and 0.3 parts of triethanolamine were added, and the rotation speed was increased to 2000 rpm for high-speed shearing for 3 min, and then the temperature was maintained at 25℃ to prepare a slurry with a viscosity of 1000 mPa·s; S5: Inject grout into cracks larger than 0.3 mm at a pressure of 0.2 MPa, ensuring a grout penetration depth greater than 20 mm; for cracks smaller than 0.3 mm, apply two coats of airless spraying, with a 30-minute interval between each coat; for both types of cracks, first use a blue LED at 405 nm, 30 mW cm⁻¹. - Irradiate for 60 seconds; then maintain with infrared radiation at 50 °C for 2 hours; allow to stand for 24 hours to allow calcium formate to react with CO3² in the permeate water. - / SO4² - reaction.

[0020] Example 2 S1: 70 wt% GPTMS and 30 wt% nano MgO were dispersed in a 15 wt% chitosan acetic acid solution, and then added dropwise to liquid paraffin containing 0.5 wt% melamine-formaldehyde prepolymer. The reaction was maintained at 55 °C for 2 h, and then filtered and vacuum dried to obtain pH-responsive microcapsules. S2: 12 parts of nano-metakaolin and 3 parts of calcium formate were ball-milled for 30 min, and then 2 wt% (3-aminopropyl)triethoxysilane coupling agent was sprayed in and the mixture was ground for another 15 min to obtain surface-activated powder. S3: 30 parts of furan-terminated hydroxyl-terminated polybutadiene, 8 parts of bismaleimide ethylene glycol ester, 6 parts of dimethylaminoethyl methacrylate, and 0.5 parts of photoinitiator were stirred under vacuum for 20 min to obtain a homogeneous low-viscosity fluid. S4: 10 parts of pH-responsive microcapsules, surface-activated powder, 6 parts of nano-SiO2 sol, 0.5 parts of sulfonated graphene microsheets, and 1 part of chopped aramid fiber were added sequentially to a homogeneous low-viscosity fluid and dispersed at 600 rpm for 10 min; then 20 parts of deionized water and 0.2 parts of triethanolamine were added, and the rotation speed was increased to 2000 rpm for 3 min of high-speed shearing, and then the temperature was maintained at 25℃ to prepare a slurry with a viscosity of 1000 mPa·s; S5: Inject grout into cracks larger than 0.3 mm at a pressure of 0.2 MPa, ensuring a grout penetration depth greater than 20 mm; for cracks smaller than 0.3 mm, apply two coats of airless spraying, with a 30-minute interval between each coat; for both types of cracks, first use a blue LED at 405 nm, 30 mW cm⁻¹.- Irradiate for 60 seconds; then maintain with infrared radiation at 50 °C for 2 hours; allow to stand for 24 hours to allow calcium formate to react with CO3² in the permeate water. - / SO4² - reaction.

[0021] The difference between Example 2 and Example 1 is that the proportions of each component are different, but both are within the protection scope of this invention.

[0022] Example 3 S1: 70 wt% GPTMS and 30 wt% nano MgO were dispersed in a 15 wt% chitosan acetic acid solution, and then added dropwise to liquid paraffin containing 0.5 wt% melamine-formaldehyde prepolymer. The reaction was maintained at 55 °C for 2 h, and then filtered and vacuum dried to obtain pH-responsive microcapsules. S2: 8 parts of nano-metakaolin and 5 parts of calcium formate were ball-milled for 30 min, and then 2 wt% (3-aminopropyl)triethoxysilane coupling agent was sprayed in and the mixture was ground for another 15 min to obtain surface-activated powder. S3: 40 parts of furanized hydroxyl-terminated polybutadiene, + parts of bismaleimide ethylene glycol ester, 4 parts of dimethylaminoethyl methacrylate, and 0.5 parts of photoinitiator were stirred under vacuum for 20 min to obtain a homogeneous low-viscosity fluid. S4: Add 5 parts of pH-responsive microcapsules, surface-activated powder, 10 parts of nano-SiO2 sol, 0.3 parts of sulfonated graphene microsheets, and 2 parts of chopped aramid fibers sequentially to a homogeneous low-viscosity fluid, and disperse at 600 rpm for 10 min; then add 15 parts of deionized water and 0.4 parts of triethanolamine, increase the rotation speed to 2000 rpm for 3 min of high-speed shearing, and then maintain the temperature at 25℃ to prepare a slurry with a viscosity of 1000 mPa·s; S5: Inject grout into cracks larger than 0.3 mm at a pressure of 0.2 MPa, ensuring a grout penetration depth greater than 20 mm; for cracks smaller than 0.3 mm, apply two coats of airless spraying, with a 30-minute interval between each coat; for both types of cracks, first use a blue LED at 405 nm, 30 mW cm⁻¹. - Irradiate for 60 seconds; then maintain with infrared radiation at 50 °C for 2 hours; allow to stand for 24 hours to allow calcium formate to react with CO3² in the permeate water. - / SO4² - reaction.

[0023] The difference between Example 3 and Example 1 is that the proportions of each component are different, but both are within the protection scope of this invention.

[0024] The composite seepage-proofing and repair material prepared in this invention exhibits a dynamic load energy dissipation mechanism where the glass transition temperature (Tg) of the flexible network I is approximately -20 °C. Under 10–50 Hz train vibration / water flow pulsation, it remains in a highly elastic state. The aramid fibers achieve over 30% hysteresis energy dissipation through reversible DA bonds and "dynamic slip-re-crosslinking" with the network, reducing the stress intensity factor at the crack tip and delaying fatigue propagation. Furthermore, it possesses a high water pressure seepage-proofing mechanism; the filling density increases with increasing water pressure, and the measured permeability coefficient at 1.2 MPa is ≤ 1*10⁻⁶. -12 ms -1 The pH-responsive microcapsules of this invention expand by 8-12% upon rupture, compensating for matrix dissolution voids caused by acid corrosion and achieving a positive feedback loop of "corrosion-expansion-blockage"; simultaneously consuming H₂O. + It reacts with corrosive anions, reducing environmental corrosivity.

[0025] During photo-thermal graded curing, blue LED irradiation triggers the surface photoinitiator, causing dimethylaminoethyl methacrylate to undergo free radical polymerization, forming a primary "hard shell" to prevent the slurry from being dispersed by high water pressure. Subsequently, infrared radiation drives the cross-linking of furan-terminated hydroxyl polybutadiene and bismaleimide glycol ester, forming a flexible network. During static curing, calcium formate reacts with CO3²⁻ / SO4²⁻ in the permeate water to generate a composite crystal of carbon-sulfur-silica-calcite + calcite.

[0026] In addition, during use, if pH < 5.5, the microcapsule wall degrades and releases GPTMS and nano MgO. GPTMS hydrolyzes to produce silanol, which reacts and condenses with nano metakaolin. Nano MgO consumes H⁺ and generates Mg²⁺, which further forms M–S–H gel with Al and Si, completing secondary mineralization and healing.

[0027] To verify the superiority of the present invention, comparative examples 1-3 are provided here.

[0028] Comparative Example 1 S1: 20 wt% GPTMS and 80 wt% nano MgO were dispersed in 50 wt% chitosan acetic acid solution, and then added dropwise to liquid paraffin containing 0.5 wt% melamine-formaldehyde prepolymer. The reaction was maintained at 55 ℃ for 2 h, and then filtered and vacuum dried to obtain pH-responsive microcapsules. S2: 20 parts of nano-metakaolin and 2 parts of calcium formate were ball-milled for 30 min, and then 2 wt% (3-aminopropyl)triethoxysilane coupling agent was sprayed in and the mixture was ground for another 15 min to obtain surface-activated powder. S3: 20 parts of furan-terminated hydroxyl polybutadiene, 20 parts of bismaleimide ethylene glycol ester, 3 parts of dimethylaminoethyl methacrylate, and 2 parts of photoinitiator were stirred under vacuum for 20 min to obtain a homogeneous low-viscosity fluid. S4: 15 parts of pH-responsive microcapsules, surface-activated powder, 15 parts of nano-SiO2 sol, 1 part of sulfonated graphene microsheets, and 0.5 parts of chopped aramid fibers were added sequentially to a homogeneous low-viscosity fluid and dispersed at 600 rpm for 10 min; then 10 parts of deionized water and 1 part of triethanolamine were added, and the rotation speed was increased to 2000 rpm for 3 min of high-speed shearing, and then the temperature was maintained at 25℃ to prepare a slurry with a viscosity of 1000 mPa·s. S5: Inject grout into cracks larger than 0.3 mm at a pressure of 0.2 MPa, ensuring a grout penetration depth greater than 20 mm; for cracks smaller than 0.3 mm, apply two coats of airless spraying, with a 30-minute interval between each coat; for both types of cracks, first use a blue LED at 405 nm, 30 mW cm⁻¹. - Irradiate for 60 seconds; then maintain with infrared radiation at 50 °C for 2 hours; allow to stand for 24 hours to allow calcium formate to react with CO3² in the permeate water. - / SO4² - reaction.

[0029] The difference between Comparative Example 1 and Example 1 is that although the raw materials within the scope of protection of this invention were used, the proportions of each group were changed and the proportions are not within the scope of protection of this invention.

[0030] Comparative Example 2 S1: 10 parts of nano-metakaolin and 4 parts of calcium formate were ball-milled for 30 min, and then 2 wt% (3-aminopropyl)triethoxysilane coupling agent was sprayed in and the mixture was ground for another 15 min to obtain surface-activated powder. S2: 35 parts of furanized hydroxyl-terminated polybutadiene, 7 parts of bismaleimide ethylene glycol ester, 5 parts of dimethylaminoethyl methacrylate, and 0.5 parts of photoinitiator were stirred under vacuum for 20 min to obtain a homogeneous low-viscosity fluid. S3: 7.5 parts of pH-responsive microcapsules, surface-activated powder, 8 parts of nano-SiO2 sol, 0.4 parts of sulfonated graphene microsheets, and 1.5 parts of chopped aramid fibers were added sequentially to a homogeneous low-viscosity fluid and dispersed at 600 rpm for 10 min; then 17.5 parts of deionized water and 0.3 parts of triethanolamine were added, and the rotation speed was increased to 2000 rpm for high-speed shearing for 3 min, and then the temperature was maintained at 25℃ to prepare a slurry with a viscosity of 1000 mPa·s; S4: Inject grout into cracks larger than 0.3 mm at a pressure of 0.2 MPa, ensuring a grout penetration depth greater than 20 mm; for cracks smaller than 0.3 mm, apply two coats of airless spraying, with a 30-minute interval between each coat; for both types of cracks, first use a blue LED at 405 nm, 30 mW cm⁻¹. -Irradiate for 60 seconds; then maintain with infrared radiation at 50 °C for 2 hours; allow to stand for 24 hours to allow calcium formate to react with CO3² in the permeate water. - / SO4² - reaction The difference between Comparative Example 2 and Example 1 is that pH-responsive microcapsules were not prepared. The resulting material could not compensate for the matrix dissolution voids caused by acid corrosion, and therefore could not achieve a positive feedback loop of "corrosion-expansion-blockage," thus failing to consume H+. + It is corrosive to anions and cannot reduce environmental corrosivity.

[0031] Comparative Example 3 S1: 70 wt% GPTMS and 30 wt% nano MgO were dispersed in a 15 wt% chitosan acetic acid solution, and then added dropwise to liquid paraffin containing 0.5 wt% melamine-formaldehyde prepolymer. The reaction was maintained at 55 °C for 2 h, and then filtered and vacuum dried to obtain pH-responsive microcapsules. S2: 10 parts of nano-metakaolin and 4 parts of calcium formate were ball-milled for 30 min, and then 2 wt% (3-aminopropyl)triethoxysilane coupling agent was sprayed in and the mixture was ground for another 15 min to obtain surface-activated powder. S3: 7.5 parts of pH-responsive microcapsules, surface-activated powder, 8 parts of nano-SiO2 sol, 0.4 parts of sulfonated graphene microsheets, and 1.5 parts of chopped aramid fibers were dispersed at 600 rpm for 10 min; then 17.5 parts of deionized water and 0.3 parts of triethanolamine were added, and the rotation speed was increased to 2000 rpm for 3 min of high-speed shearing. The temperature was then maintained at 25℃ to prepare a slurry with a viscosity of 1000 mPa·s. S4: Inject grout into cracks larger than 0.3 mm at a pressure of 0.2 MPa, ensuring a grout penetration depth greater than 20 mm; for cracks smaller than 0.3 mm, apply two coats of airless spraying, with a 30-minute interval between each coat; for both types of cracks, first use a blue LED at 405 nm, 30 mW cm⁻¹. - Irradiate for 60 seconds; then maintain with infrared radiation at 50 °C for 2 hours; allow to stand for 24 hours to allow calcium formate to react with CO3² in the permeate water. - / SO4² - reaction.

[0032] The difference between Comparative Example 3 and Example 1 is that no homogeneous low-viscosity fluid was prepared.

[0033] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A composite impermeable repair material, characterized by: The anti-permeation repair material is composed of A component, B component, C component, D component and E component; The A component is a flexible reversible network precursor, containing 30-40 parts of furanized hydroxyl-terminated polybutadiene, 6-8 parts of bismaleimide glycol ester, 4-6 parts of dimethylaminoethyl methacrylate, and 0.5 parts of a photoinitiator; The B component is 5-10 parts of pH-responsive microcapsules, the shell of the microcapsules is a chitosan / melamine-formaldehyde composite wall, and the core is γ-glycidoxypropyltrimethoxysilane; The C component is an inorganic mineralization source, containing 3-5 parts of calcium formate, 8-12 parts of nano-metakaolin, and 6-10 parts of nano-SiO2 sol; The D component is a dynamic load damping filler, containing 1-2 parts of short aramid fiber and 0.3-0.5 parts of sulfonated graphene microsheet; The E component contains 0.2-0.4 parts of triethanolamine and 15-20 parts of deionized water.

2. A composite impermeable repair material according to claim 1, characterised in that: The grafting rate of the furanized hydroxyl-terminated polybutadiene is 12%; The pH value of the chitosan / melamine-formaldehyde composite wall is ≤5.5; the γ-glycidoxypropyltrimethoxysilane is composed of 70wt% GPTMS and 30wt% nano-MgO, with a particle size of 2-5 µm; The nano-metakaolin has a particle size of 190-210 nm; the nano-SiO2 sol accounts for 30 wt %, and the pH value is 9; The length of the short aramid fiber is 1 mm.

3. A method for preparing a composite impermeable repair material, using a composite impermeable repair material as claimed in claims 1-2, characterized in that: The method comprises the following steps, S1: dispersing GPTMS and MgO in a 15 wt % chitosan acetic acid solution, then adding dropwise into liquid paraffin containing 0.5 wt % melamine-formaldehyde prepolymer, and maintaining 55 ℃ reaction for 2h, filtering, vacuum drying to obtain pH-responsive microcapsules; S2: ball milling nano-metakaolin with calcium formate for 30 min, then spraying 2 wt % (3-aminopropyl) triethoxysilane coupling agent, continuing to grind for 15 min to obtain surface-activated powder; S3: vacuum stirring furanized hydroxyl-terminated polybutadiene, bismaleimide glycol ester, dimethylaminoethyl methacrylate, and photoinitiator for 20 min to obtain a homogeneous low-viscosity fluid; S4: adding pH-responsive microcapsules, surface-activated powder, nano-SiO2 sol, sulfonated graphene microsheet, and short aramid fiber into the homogeneous low-viscosity fluid in sequence, pre-stirring and dispersing; then adding deionized water and triethanolamine, continuing to stir at a higher speed, and then maintaining the temperature at 25℃ and the slurry viscosity at 800-1200 mPa·s; S5: perfusing the slurry into a crack larger than 0.3 mm at a pressure of 0.2 MPa, so that the penetration depth of the slurry is greater than 20 mm, and then adopting light-thermal staged curing.

4. The method for preparing a composite seepage-proof and repair material according to claim 3, characterized in that: In the step S5, when the crack is smaller than 0.3 mm, airless spraying is performed twice with an interval of 30 min each time.

5. The method for preparing a composite seepage-proof and repair material according to claim 3, characterized in that: In the light-thermal staged curing, first, a blue light LED is used to irradiate at 405 nm, 30 mW cm⁻² for 60 s; then, infrared radiation at 50 ℃ is maintained for 2 h; and then, the calcium formate is allowed to react with CO3²⁻ / SO4²⁻ in the penetrated water after 24 h of curing.

6. The method for preparing a composite seepage-proof and repair material according to claim 3, characterized in that: In the step S4, the stirring and dispersing is performed at 600 rpm for 10 min, and then the stirring speed is increased to 2000 rpm for high-speed shearing for 3 min.

7. The method for preparing a composite seepage-proof and repair material according to claim 3, characterized in that: In the step S4, the temperature of the vacuum stirring is 60 °C.

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