An ultra-high toughness polymer repair mortar and a method of making the same

Abstract

The application discloses an ultrahigh toughness polymer repair mortar and a preparation method thereof, and belongs to the technical field of building materials. The mortar comprises the following components in parts by weight: ordinary portland cement 80-88 parts, high belite sulphoaluminate cement 10-15 parts, gypsum 3-5 parts, quartz sand 55-75 parts, graft modified high-vinyl acetate content EVA latex powder 3-8 parts, surface functionalized fiber 1.0-3.0 parts, supported active nanometer diatomite 1.0-4.0 parts, polycarboxylic acid water reducing agent 0.3-0.8 parts, defoaming agent 0.05-0.3 parts, and water 20-30 parts. The application establishes a multistage energy dissipation design of 'harmony of rigidity and flexibility, step-by-step activation and dynamic energy consumption', realizes the synergistic promotion of ultrahigh toughness, ultrahigh strength, ultralow water absorption and long-term strength stability, and solves the performance bottleneck problem of a concrete structure rapid repair material.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and more specifically, to an ultra-high toughness polymer repair mortar and its preparation method. Background Technology

[0002] Ordinary silicate cement repair materials have slow setting, low early strength, and large volume shrinkage, making it difficult to meet the early traffic opening requirements of rapid repair projects. Sulfoaluminate cement has significant characteristics such as rapid early strength development, fast hardening speed, and slight volume expansion. However, its hydration product, ettringite, is prone to transforming into monosulfide-type hydrated calcium sulfoaluminate during long-term service due to carbonization and insufficient sulfate ions. This leads to volume shrinkage, microcrack initiation, and ultimately, strength reduction and increased brittleness. Under impact and fatigue loads, it is difficult to meet the deformation coordination requirements of the repair layer for long-term service.

[0003] Engineered cementitious composites (ECCs) achieve strain hardening and multi-crack characteristics through fiber-matrix interface bridging, attracting widespread attention in the repair and reinforcement field. In engineering practice, ECC materials are often synergistically incorporating ordinary silicate cement and sulfoaluminate cement to significantly improve their early mechanical properties. However, the toughness of existing ECC repair materials relies on a single source, mainly on fiber pull-out energy dissipation, which presents the following technical bottlenecks: achieving high ductility often sacrifices matrix density, resulting in poor impermeability; polymer modification can improve toughness but usually leads to a significant decrease in compressive strength; the fiber-matrix interface relies solely on physical friction and mechanical anchoring, resulting in low pull-out energy and difficulty in exceeding 2.5% ultimate tensile strain; toughness improvement is limited to the macroscopic fiber level, lacking multi-level energy dissipation design from microscopic hydration product morphology control, nano-microscopic interface chemical bonding to macroscopic fiber bridging; and no reports exist of repair materials simultaneously achieving compressive strength ≥100MPa, flexural strength ≥20MPa, and ultimate tensile strain ≥3.5%.

[0004] Extensive research has been conducted on ECC repair materials. Patent CN108911648A discloses a polymer fiber-reinforced cement-based repair material, which improves crack resistance by incorporating polymer fibers. However, this technology relies solely on the physical bond between the fiber and the matrix for toughening; the fiber surface is not chemically modified, resulting in low fiber pull-out energy. Furthermore, it does not involve nanoscale hydration product crystal morphology control or organic-inorganic chemical crosslinking, limiting the improvement in toughness and failing to meet ultra-high toughness requirements. Patent CN121225949A achieves ultra-high early strength and ductility by promoting early hydration through nano-CSH crystal nuclei. However, this material does not involve precise control of ettringite formation in the sulfoaluminate cement-gypsum system, resulting in limited matrix densification; it does not introduce polymer-modified components and lacks an organic-inorganic interpenetrating network structure; the synergistic effect of high strength and high toughness remains unclear. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an ultra-high toughness polymer repair mortar and its preparation method. This invention addresses the technical challenges of existing ECC repair mortars, which rely on a single source of toughness and struggle to simultaneously achieve high early strength, high strength, and low water absorption (3h compressive strength ≥35.0MPa, 28d compressive strength ≥100MPa, 28d water absorption ≤0.5%) with high toughness and high adhesion (3h flexural strength ≥6.0MPa, 28d flexural strength ≥20MPa, ultimate tensile strain ≥3.5%, 28d tensile bond strength ≥2.5MPa). Through a three-pronged mechanism of "crystal form regulation - chemical crosslinking - triple anchoring," a multi-level energy dissipation design of "rigidity and flexibility combined, step-by-step activation, and dynamic energy consumption" is established. This achieves a synergistic improvement in ultra-high toughness, ultra-high strength, ultra-low water absorption, and long-term strength stability, thus solving the performance bottleneck problem of rapid repair materials for concrete structures.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A high-toughness polymer repair mortar comprises the following components by weight: 80-88 parts of ordinary silicate cement, 10-15 parts of high-belite sulfoaluminate cement, 3-5 parts of gypsum, 55-75 parts of quartz sand, 3-8 parts of grafted modified high vinyl acetate content EVA latex powder, 1.0-3.0 parts of surface-functionalized fiber, 1.0-4.0 parts of supported active nano-diatomaceous earth, 0.3-0.8 parts of polycarboxylate superplasticizer, 0.05-0.3 parts of defoamer, and 20-30 parts of water.

[0008] Furthermore, the supported active nano-diatomaceous earth is a diatomaceous earth with active components loaded in the pores and selectively hydrophobically capped on the outer surface by octadecyltrimethoxysilane. The active component is a complex of nano-SiO2 sol and 4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disilane. The mass loading of the active component in the supported active nano-diatomaceous earth is 15%-35%.

[0009] Furthermore, the grafted modified high vinyl acetate content EVA latex powder is a glycidyl methacrylate grafted ethylene-vinyl acetate copolymer, and the vinyl acetate content of the high vinyl acetate content EVA latex powder is ≥85%;

[0010] The surface-functionalized fiber is a polyvinyl alcohol fiber or polyethylene fiber that has been activated by plasma and treated with biomimetic co-deposition of dopamine and nano-SiO2. The fiber surface has a polydopamine-nano-SiO2 composite biomimetic coating and is grafted with amino active groups.

[0011] Further, the nano-diatomaceous earth was calcined and then acid-activated to obtain activated nano-diatomaceous earth; nano-SiO2 sol, 4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disilane and chitosan-sodium alginate complex were mixed and ethanol was added and stirred to obtain a loading solution; the activated nano-diatomaceous earth was added to the loading solution for vacuum gradient impregnation treatment, and then the impregnated diatomaceous earth was dispersed in an organic solvent containing octadecyltrimethoxysilane for end-capping reaction to obtain supported activated nano-diatomaceous earth.

[0012] Furthermore, the mass ratio of nano-SiO2 sol, 4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disilane to chitosan-sodium alginate complex is (6-8):(1-3):1; the content of octadecyltrimethoxysilane in the organic solvent containing octadecyltrimethoxysilane is 1-3 wt%.

[0013] Furthermore, ethylene-vinyl acetate copolymer, glycidyl methacrylate and initiator are dissolved in an organic solvent and reacted under nitrogen protection to obtain graft-modified EVA latex powder with high vinyl acetate content.

[0014] Furthermore, the mass ratio of ethylene-vinyl acetate copolymer, glycidyl methacrylate, and initiator is (80-120):(2-4):(0.4-0.6), and the reaction is carried out under nitrogen protection at 70-90℃ for 5-7 hours with stirring.

[0015] Further, nano-SiO2 is dispersed in a buffer solution, dopamine hydrochloride is added, and the mixture is stirred evenly to obtain a dopamine / nano-SiO2 co-deposition solution. Plasma-activated polyvinyl alcohol fiber or polyethylene fiber is then added to react and a surface-functionalized fiber is obtained.

[0016] Furthermore, the buffer solution is a tris(hydroxymethyl)aminomethane hydrochloride buffer solution, and the concentration of nano-SiO2 in the dopamine / nano-SiO2 co-deposition solution is 0.5-2.0 g / L; the mass ratio of plasma-activated polyvinyl alcohol fiber or polyethylene fiber to dopamine / nano-SiO2 co-deposition solution is 1:(15-25).

[0017] A method for preparing ultra-high toughness polymer repair mortar involves dry mixing ordinary silicate cement, high belite sulfoaluminate cement, gypsum, quartz sand, and loaded active nano-diatomite, wet mixing with water, polycarboxylate superplasticizer, and defoamer, adding grafted modified high vinyl acetate content EVA latex powder and continuing stirring, and finally adding surface functionalized fibers and stirring to obtain ultra-high toughness polymer repair mortar.

[0018] In summary, the present invention has the following beneficial effects:

[0019] (1) Synergistic toughening of three-level energy dissipation structure: For the first time, this invention constructs a crack deflection energy dissipation microstructure (first level) composed of a nanoscale heterogeneous hydration product matrix, a molecular chain extension and slip energy dissipation structure (second level) composed of an organic-inorganic interpenetrating network, and a fiber pull-out energy dissipation structure (third level) composed of chemical bonding at the fiber-matrix interface and micro-nano rough surface in the repair mortar. The three-level structure plays a role in different stages of damage under impact load and fatigue load, covering the complete failure process of crack initiation → microcrack propagation → macroscopic penetration, and achieving a synergistic toughening effect of 1+1+1>3. The resulting repair mortar has a 28-day flexural strength ≥20MPa, an ultimate tensile strain ≥3.5%, and a bending toughness index ≥4.0, which far exceeds the existing ECC repair materials.

[0020] (2) Toughening through chemical crosslinking of flexible polyol chains and rigid networks: This invention uses high vinyl acetate content EVA latex powder (VA≥85%) grafted with glycidyl methacrylate. Its molecular chain contains a large number of vinyl acetate groups. After the introduction of epoxy groups through glycidyl methacrylate grafting, it undergoes in-situ ring-opening crosslinking with the silane coupling agent released by diatomaceous earth, and also chemically bonds with the amino groups on the fiber surface, forming a three-dimensional chemical crosslinking network with flexible EVA molecular chains as "bridges" and rigid hydration products as "nodes". When subjected to impact loads, the flexible chain segments dissipate energy through conformational changes, while the chemical crosslinking points ensure stress transmission, avoiding brittle damage caused by interfacial debonding in traditional polymer physical blending.

[0021] (3) The fiber-matrix interface “triple anchoring” significantly improves pull-out energy and ultimate strain: This invention pioneers the “plasma activation + dopamine / nano SiO2 biomimetic co-deposition” technology to construct a PDA-SiO2 composite biomimetic coating on the fiber surface, achieving triple anchoring of “chemical bonding + physical interlocking + nano reinforcement”. The pull-out energy of a single fiber is increased by 5-7 times, the fiber bridging stress reaches 10-12 MPa, and the ultimate tensile strain is increased from 2%-3% of the traditional ECC to 3.5%-5.0%. Even after 90 days of carbonization, the strain retention rate is still ≥90%, solving the problem of performance degradation of high-toughness materials during long-term service in marine and underground engineering.

[0022] (4) Intrinsic toughening of the matrix by gradient slow release and crystal form regulation of nano-diatomite: Vacuum gradient impregnation technology enables the active components to be distributed in a gradient in the multi-level pores of diatomite, achieving a step-by-step slow release. The release period is extended from the conventional 3-5 days to more than 14 days, which is highly matched with the cement hydration process. The released nano-SiO2 refines the crystal size of hydration products (the ettringite is refined from the conventional 5-10μm to 1-3μm), forming a large number of microcrystalline interfaces and increasing the crack deflection path; at the same time, the "internal curing" effect of the nano-diatomite cavity promotes the later hydration of cementitious materials, ensuring the continuous increase of 90-day strength and eliminating strength shrinkage.

[0023] (5) Ultra-low water absorption rate: The present invention achieves a water absorption rate of mortar as low as 0.26%-0.38% after 28 days through the multi-level pore filling effect of nano-diatomite, the high-density hydrophobic network constructed by in-situ crosslinking of 4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disilane bissilane, and the synergistic effect of the long-chain hydrophobic end capping of the outer surface of octadecyltrimethoxysilane. This is an excellent level of impermeability among similar repair materials.

[0024] (6) Rapid early strength development, meeting the requirements for rapid traffic opening: Through the synergistic effect of high belite sulfoaluminate cement for rapid hardening and setting and nano diatomite for early internal curing, the compressive strength at 3h is ≥35.0MPa and the flexural strength at 3h is ≥6.0MPa, which far exceeds the requirement of 3-6h traffic opening for rapid repair projects (usually ≥30MPa). It can significantly shorten the traffic closure time, and is especially suitable for emergency repair projects such as airport runways and highways with extremely high requirements for traffic efficiency.

[0025] (7) Decoupling design of OPC main cement and multi-level energy dissipation to achieve synergistic breakthrough of high strength, high toughness and high adhesion: The present invention avoids the shortcomings of traditional ECC in sacrificing strength for toughness by using the decoupling design of “OPC main cement provides long-term strength skeleton + CSA fast hardening and accelerating to compensate for early strength + matrix nano-densification to provide strength guarantee + multi-level energy dissipation to provide toughness guarantee”. It achieves synergistic breakthrough of compressive strength ≥100MPa, flexural strength ≥20MPa, ultimate tensile strain ≥3.5% and tensile bond strength ≥2.5MPa, which meets the demand of harsh environments such as underground integrated pipe gallery, cross-sea tunnel, marine engineering, airport runway, high-speed railway and highway bridge for ultra-high strength, ultra-high toughness and high adhesion repair materials. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] The ultra-high toughness polymer repair mortar of the present invention comprises the following components by weight:

[0028] 80-88 parts of ordinary silicate cement, 10-15 parts of high belite sulfoaluminate cement, 3-5 parts of gypsum, 55-75 parts of quartz sand, 3-8 parts of grafted modified high vinyl acetate content EVA latex powder, 1.0-3.0 parts of surface functionalized fiber, 1.0-4.0 parts of supported active nano diatomaceous earth, 0.3-0.8 parts of polycarboxylate superplasticizer, 0.05-0.3 parts of defoamer, and 20-30 parts of water.

[0029] Supported active nano-diatomaceous earth is a type of diatomaceous earth in which active components are loaded within the pores and the outer surface is selectively hydrophobically capped with octadecyltrimethoxysilane. The active component is a complex of nano-SiO2 sol and 4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disilane, with the active component accounting for 15%-35% of the mass loading in the supported active nano-diatomaceous earth. The supported active nano-diatomaceous earth is prepared using a vacuum gradient impregnation and selective surface capping process, resulting in a gradient distribution of the active component within the multi-level pores, achieving a stepwise slow release.

[0030] Graft-modified high vinyl acetate content EVA latex powder is a copolymer of glycidyl methacrylate grafted with ethylene-vinyl acetate, and the vinyl acetate content of the high vinyl acetate content EVA latex powder is ≥85%.

[0031] The surface-functionalized fiber is a polyvinyl alcohol fiber or polyethylene fiber that has been activated by plasma and treated with biomimetic co-deposition of dopamine and nano-SiO2. The fiber surface has a polydopamine-nano-SiO2 composite biomimetic coating and is grafted with amino active groups. The fiber length is 6-18 mm, the diameter is 20-50 μm, and the amino density on the fiber surface is ≥0.8 mmol / g.

[0032] The gypsum is selected as dihydrate gypsum or anhydrite, with a particle size ≤45μm. The quartz sand is selected as continuously graded fine quartz sand, with a particle size ≤0.85mm, of which the 0.85-0.425mm gradation accounts for 55%-65%, and the 0.425-0.15mm gradation accounts for 35%-45% respectively. The polycarboxylate superplasticizer is preferably a powdered high-performance polycarboxylate superplasticizer with a water reduction rate ≥35%. The defoamer is preferably an organosilicon or polyether powdered defoamer.

[0033] The preparation method of the ultra-high toughness polymer repair mortar of the present invention includes the following steps: dry mixing ordinary silicate cement, high belite sulfoaluminate cement, gypsum, quartz sand and supported active nano diatomaceous earth, adding water, polycarboxylate superplasticizer and defoamer for wet mixing, adding grafted modified high vinyl acetate content EVA latex powder for continued stirring, adding surface functionalized fibers for stirring, and obtaining ultra-high toughness polymer repair mortar.

[0034] The preparation method of the supported active nano-diatomite is as follows: (a) After calcining the nano-diatomite, acid activation treatment is performed to obtain activated nano-diatomite. Specifically, the nano-diatomite is calcined at 300-400℃ for 1-3h, then ultrasonically treated with 0.05-0.15mol / L dilute hydrochloric acid for 20-40min, washed until neutral, and vacuum dried at 150-250℃ for 1-3h; (b) Nano-SiO2 sol, 4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disilane and chitosan-sodium alginate complex are mixed, ethanol is added and stirred to obtain the supporting solution. - The mass ratio of sodium alginate complex is (6-8):(1-3):1. Add ethanol to dilute to a solid content of 15-25% in the loaded liquid; (c) Place the activated nano-diatomite in a sealed impregnation tank, and inject the loading liquid in three separate injections under a stepped vacuum of -0.03MPa to -0.01MPa, -0.07MPa to -0.05MPa and -0.1MPa to -0.005MPa. Stir for 10-30 min after each injection and then ultrasonically disperse for 20-40 min; then disperse the impregnated diatomite in an organic solvent containing 1-3wt% octadecyltrimethoxysilane for end-capping reaction (react at 30-50℃ for 1-3 h) to obtain the supported active nano-diatomite.

[0035] The preparation method of graft-modified EVA latex powder with high vinyl acetate content is as follows: ethylene-vinyl acetate copolymer with a VA (vinyl acetate) content of not less than 85%, glycidyl methacrylate, and an initiator are dissolved in an organic solvent and stirred for 5-7 hours under nitrogen protection at 70-90℃ to obtain graft-modified EVA latex powder with high vinyl acetate content; the mass ratio of ethylene-vinyl acetate copolymer, glycidyl methacrylate, and benzoyl peroxide initiator is (80-120):(2-4):(0.4-0.6); after the reaction is completed, the product is precipitated in a precipitant (preferably methanol), filtered, washed, vacuum dried at 50℃, pulverized and sieved to obtain graft-modified EVA latex powder with high vinyl acetate content.

[0036] The preparation method of surface-functionalized fibers is as follows: Polyvinyl alcohol fibers or polyethylene fibers are placed in a low-temperature plasma treatment instrument and treated for 3-10 minutes under an oxygen atmosphere, a pressure of 30-80 Pa, and a power of 80-150 W; nano-SiO2 is dispersed in a Tris-HCl buffer solution with a pH of 8.0-9.0, and dopamine hydrochloride is added to a concentration of 1.0-3.0 g / L, stirred evenly to obtain a dopamine / nano-SiO2 co-deposition solution with a nano-SiO2 concentration of 0.5-2.0 g / L; then, the surface-functionalized fibers are further processed... Plasma-activated polyvinyl alcohol fibers or polyethylene fibers are added to the dopamine / nano-SiO2 co-deposition solution and stirred for 12-24 hours at 25-40℃ in air atmosphere. The mass ratio of plasma-activated polyvinyl alcohol fibers or polyethylene fibers to dopamine / nano-SiO2 co-deposition solution is 1:(15-25), which allows dopamine to self-polymerize into polydopamine (PDA) and co-deposit with nano-SiO2 on the fiber surface to form a polydopamine-nano-SiO2 composite biomimetic coating. After the reaction, the resulting fibers are washed with deionized water 2-4 times and vacuum dried at 40-60℃ for 10-24 hours to obtain surface-functionalized fibers.

[0037] During the hydration and hardening process, the silane coupling agent released from the supported active nano-diatomaceous earth in this invention undergoes an in-situ ring-opening crosslinking reaction with the epoxy groups on the molecular chains of grafted modified high vinyl acetate content EVA latex powder, forming an organic-inorganic interpenetrating nanoscale dense network structure. The amino groups on the surface of the surface-functionalized fibers form chemical bonds with the epoxy groups on the EVA molecular chains, achieving chemical anchoring of the fiber-matrix interface. After releasing the active components, the multi-level porous structure of the nano-diatomaceous earth continues to exert a physical filling effect and pozzolanic activity, refining the crystal size of the hydration products.

[0038] The repair mortar of this invention has a three-level energy dissipation structure, including a nanoscale heterogeneous hydration product matrix microstructure, an organic-inorganic interpenetrating network structure, and a fiber-matrix interface chemical bonding and micro-nano roughness composite structure. The nanoscale heterogeneous hydration product matrix microstructure is composed of fine and uniform ettringite crystals and CSH gel interpenetrating each other. The organic-inorganic interpenetrating network structure includes a covalently bonded network composed of cross-linked EVA molecular chains and inorganic hydration products. The fiber-matrix interface chemical bonding and micro-nano roughness composite structure includes a polydopamine-nano SiO2 composite biomimetic coating.

[0039] Example 1

[0040] A high-toughness polymer repair mortar comprises the following components by weight: 83 parts of ordinary silicate cement (P·O52.5), 14 parts of high belite sulfoaluminate cement, 3 parts of dihydrate gypsum, 65 parts of quartz sand (two-gradation: 0.85-0.425mm accounts for 60wt%, 0.425-0.15mm accounts for 40wt%), 5 parts of grafted modified high vinyl acetate content EVA latex powder, 2.0 parts of surface-functionalized PVA fiber, 2.5 parts of supported active nano diatomaceous earth, 0.5 parts of polycarboxylate superplasticizer (powder, water reduction rate 38%), 0.15 parts of organosilicon defoamer (powder), and 26 parts of water.

[0041] The preparation method of this ultra-high toughness polymer repair mortar is as follows:

[0042] (1) Add ordinary silicate cement, high belite sulfoaluminate cement, dihydrate gypsum, quartz sand, and loaded active nano diatomaceous earth to a mixer and dry mix for 3 minutes;

[0043] (2) Add water, polycarboxylate superplasticizer, and silicone defoamer, and mix wet for 4 minutes;

[0044] (3) Add grafted modified high vinyl acetate content EVA latex powder and continue stirring for 3 minutes;

[0045] (4) Finally, add surface-functionalized PVA fibers and stir slowly for 2 minutes until the fibers are evenly dispersed to obtain repair mortar.

[0046] The preparation method of graft-modified EVA latex powder with high vinyl acetate content includes the following steps: 100 parts by weight of ethylene-vinyl acetate copolymer with a vinyl acetate content of not less than 85%, 3 parts by weight of glycidyl methacrylate, and 0.5 parts by weight of benzoyl peroxide are dissolved in 25 parts by weight of toluene, and stirred and reacted at 80°C under nitrogen protection for 6 hours; after the reaction is completed, the product is precipitated in methanol, filtered, washed, and vacuum dried at 50°C for 24 hours, and the product is pulverized and passed through a 200-mesh sieve to obtain graft-modified EVA latex powder with a grafting rate of 1.8% and high vinyl acetate content.

[0047] A method for preparing surface-functionalized PVA fibers includes the following steps: placing polyvinyl alcohol fibers in a low-temperature plasma treatment instrument and treating them for 5 minutes under an oxygen atmosphere, a pressure of 50 Pa, and a power of 100 W to obtain plasma-activated fibers; ultrasonically dispersing nano-SiO2 in a 10 mmol / L Tris-HCl buffer solution with a pH of 8.5 to achieve a nano-SiO2 concentration of 1.0 g / L; adding dopamine hydrochloride to a final concentration of 2.0 g / L; and stirring until homogeneous to obtain dopamine. Amine / nano-SiO2 co-deposition solution; plasma-activated fibers were immersed in the dopamine / nano-SiO2 co-deposition solution at a mass ratio of 1:20 and reacted at 30°C in air for 18 hours to allow dopamine to self-polymerize into polydopamine (PDA) and co-deposit it with nano-SiO2 on the fiber surface, thus obtaining polydopamine-nano-SiO2 composite biomimetic coating modified fibers; the polydopamine-nano-SiO2 composite biomimetic coating modified fibers were washed three times with deionized water and vacuum dried at 50°C for 12 hours to obtain surface-functionalized PVA fibers.

[0048] A method for preparing supported active nano-diatomaceous earth includes the following steps: calcining nano-diatomaceous earth at 350℃ for 2 hours, then ultrasonically treating it with 0.1 mol / L dilute hydrochloric acid for 30 minutes, washing it until neutral, and vacuum drying it at 200℃ for 2 hours to obtain activated nano-diatomaceous earth; mixing nano-SiO2 sol, 4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disilane, and chitosan-sodium alginate complex at a mass ratio of 7:2:1, adding ethanol to dilute to a solid content of 20%, and stirring evenly to obtain a loading solution; loading the active components using a vacuum gradient impregnation method. Activated nano-diatomaceous earth was placed in a sealed impregnation tank, and the loading liquid was injected three times in successive steps at a vacuum of -0.02MPa, -0.06MPa and -0.095MPa (the amount of loading liquid injected each time was the same, and the mixture was stirred for 20 min and then ultrasonically dispersed for 30 min after each injection). The impregnated diatomaceous earth was dispersed in a hexane solution containing 2wt% octadecyltrimethoxysilane and reacted at 40℃ for 2 h to selectively hydrophobically seal the outer surface of the diatomaceous earth. The mixture was then vacuum dried at 60℃ for 24 h and ground through a 200-mesh sieve to obtain supported activated nano-diatomaceous earth.

[0049] Example 2

[0050] A high-toughness polymer repair mortar comprises the following components by weight: 87 parts ordinary silicate cement, 10 parts high belite sulfoaluminate cement, 3 parts dihydrate gypsum, 70 parts quartz sand, 3.5 parts grafted modified high vinyl acetate content EVA latex powder, 1.5 parts surface-functionalized PVA fiber, 1.5 parts supported active nano diatomaceous earth, 0.4 parts polycarboxylate superplasticizer, 0.1 parts organosilicon defoamer, and 28 parts water.

[0051] The supported active nano-diatomaceous earth, surface-functionalized PVA fiber, grafted modified high vinyl acetate content EVA latex powder, and ultra-high toughness polymer repair mortar were all prepared according to Example 1.

[0052] Example 3

[0053] A high-toughness polymer repair mortar comprises the following components by weight: 80 parts ordinary silicate cement, 15 parts high belite sulfoaluminate cement, 5 parts dihydrate gypsum, 58 parts quartz sand, 7 parts grafted modified high vinyl acetate content EVA latex powder, 2.5 parts surface-functionalized PVA fiber, 3.5 parts supported active nano diatomaceous earth, 0.7 parts polycarboxylate superplasticizer, 0.25 parts organosilicon defoamer, and 24 parts water.

[0054] The supported active nano-diatomaceous earth, surface-functionalized PVA fiber, grafted modified high vinyl acetate content EVA latex powder, and ultra-high toughness polymer repair mortar were all prepared according to Example 1.

[0055] Comparative Example 1

[0056] Mortar was prepared according to the formulation and method of Example 1, except that the grafted modified high vinyl acetate content EVA latex powder was replaced with ordinary vinyl acetate content EVA latex powder (vinyl acetate content 70%, ungrafted glycidyl methacrylate).

[0057] Comparative Example 2

[0058] Mortar was prepared according to the formulation and method of Example 1, except that ordinary nano-diatomite was used to replace the supported active nano-diatomite.

[0059] Comparative Example 3

[0060] Mortar was prepared according to the formulation and method of Example 1, except that quartz sand was used to replace grafted modified high vinyl acetate content EVA latex powder.

[0061] Comparative Example 4

[0062] Mortar was prepared according to the formulation and method of Example 1, except that the surface-functionalized PVA fibers were replaced with quartz sand of equal quality.

[0063] Comparative Example 5

[0064] Mortar was prepared according to the formula and method of Example 1, except that ordinary silicate cement (P·O 52.5) ​​was used to replace dihydrate gypsum.

[0065] Comparative Example 6

[0066] Mortar was prepared according to the formulation and method of Example 1, except that ordinary nano zeolite (particle size ≤100nm, unloaded) was used to replace the loaded active nano diatomaceous earth.

[0067] Comparative Example 7

[0068] The mortar was prepared according to the formulation and method of Example 1, except that the grafted modified high vinyl acetate content EVA latex powder was replaced with high vinyl acetate content EVA latex powder (vinyl acetate content 85%, ungrafted glycidyl methacrylate).

[0069] Comparative Example 8

[0070] Mortar was prepared according to the formulation and method of Example 1, except that surface-functionalized fibers prepared by the ordinary dopamine impregnation method (the preparation method is as follows: polyvinyl alcohol fibers are impregnated in a Tris-HCl buffer solution containing dopamine hydrochloride (the concentration of the Tris-HCl buffer solution is 10 mmol / L (pH=8.5), the concentration of dopamine hydrochloride in the Tris-HCl buffer solution is 2.0 g / L, and the mass ratio of polyvinyl alcohol fibers to the Tris-HCl buffer solution containing dopamine hydrochloride is 1:20), and reacted at 30°C in an air atmosphere for 18 h to allow dopamine to self-polymerize into polydopamine and deposit on the fiber surface; the resulting fibers are washed three times with deionized water and vacuum dried at 50°C for 12 h to obtain surface-functionalized fibers modified by the ordinary dopamine impregnation method) are used to replace the surface-functionalized PVA fibers prepared by the biomimetic co-deposition method in Example 1.

[0071] Comparative Example 9

[0072] The mortar was prepared according to the formulation and method of Example 1, except that the surface-functionalized fiber prepared by the conventional impregnation method of silane coupling agent KH550 (the preparation method is as follows: polyvinyl alcohol fiber is impregnated in an ethanol / water solution containing γ-aminopropyltriethoxysilane (KH550) (the ethanol / water solution is prepared by mixing ethanol and water at a volume ratio of 95:5), the concentration of γ-aminopropyltriethoxysilane in the ethanol / water solution containing γ-aminopropyltriethoxysilane is 2wt%, the mass ratio of polyvinyl alcohol fiber to the ethanol / water solution containing γ-aminopropyltriethoxysilane is 1:20, and the reaction is stirred at 60°C for 4 hours to allow the silanol groups after KH550 hydrolysis to undergo a condensation reaction with the hydroxyl groups on the fiber surface to form chemical bonds; after the reaction is completed, the fiber is taken out, washed with ethanol 3 times, and vacuum dried at 80°C for 4 hours to obtain the surface-functionalized fiber modified by the conventional impregnation method of KH550) is used to replace the surface-functionalized PVA fiber prepared by the biomimetic co-deposition method in Example 1.

[0073] Comparative Example 10

[0074] The mortar was prepared according to the formulation and method of Example 1, except that in the preparation of the supported active nano diatomite, the mass of 4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disilane in the supporting liquid was replaced with γ-aminopropyltriethoxysilane, and the outer surface of the diatomite after impregnation with the supporting liquid was not subjected to octadecyltrimethoxysilane hydrophobic end-capping treatment.

[0075] In the above embodiments and comparative examples:

[0076] Ordinary Portland cement was purchased from Anhui Conch Cement Co., Ltd., and the grade was P·II 52.5R.

[0077] High-belite sulfoaluminate cement was purchased from Tangshan Arctic Bear Building Materials Co., Ltd., product number BS-WHS;

[0078] Dihydrate gypsum (CaSO4·2H2O) was purchased from Suzhou Zhongdian Desulfurization Gypsum Supply Co., Ltd., with a particle size ≤45μm;

[0079] The quartz sand was purchased from Changzhou Yaopan Building Materials Co., Ltd., with product number 1003516472; the 0.85-0.425mm gradation accounted for 60%, and the 0.425-0.15mm gradation accounted for 40% accordingly.

[0080] The polycarboxylate superplasticizer was purchased from Shanghai Hengchuang Chemical Co., Ltd., model Sika 540P.

[0081] The silicone defoamer was purchased from Jinan Ninghui Chemical Technology Co., Ltd. (industrial defoamer, also known as water-based, oil-based, high-temperature resistant, acid and alkali resistant silicone polyether alcohol defoamer), product number 12;

[0082] The ethylene-vinyl acetate copolymer with a vinyl acetate content of not less than 85% was purchased from Celanese (Shanghai) Polymer Co., Ltd., model AD0110;

[0083] The polyvinyl alcohol fiber was purchased from Guangdong Jusan Group Co., Ltd., model JS-PVA, with a fiber length of 6-18mm and a diameter of 15μm;

[0084] The nano-SiO2 was purchased from Qinghe County Kaiwei New Material Technology Co., Ltd., with a particle size of 15nm-30nm.

[0085] The nano-diatomite was purchased from Yuanda Mica Factory in Lingshou County, with a particle size ≤100nm.

[0086] The nano-SiO2 sol was purchased from Hangzhou Hengge Nanotechnology Co., Ltd., product number HN-S01A;

[0087] Chitosan-sodium alginate complex (also known as sodium alginate-chitosan polyionic complex hydrogel) was purchased from Shenzhen Meiluo Technology Co., Ltd.

[0088] EVA latex powder with ordinary vinyl acetate content (70% vinyl acetate content, ungrafted glycidyl methacrylate) was purchased from Celanese (Shanghai) Polymer Co., Ltd., model number FX2350.

[0089] The ordinary nano-zeolite was purchased from Zhengzhou Chaorong Nanomaterials Co., Ltd., model number NW01;

[0090] The high vinyl acetate content EVA latex powder (vinyl acetate content 85%, ungrafted glycidyl methacrylate) was purchased from Celanese (Shanghai) Polymer Co., Ltd., model MP2050.

[0091] Performance testing methods

[0092] (1) Compressive strength and flexural strength: 40mm×40mm×160mm prism specimens were formed according to GB / T 17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)" and cured to standard for 3h, 1d, 28d and 90d for testing. Three parallel specimens were used in each group and the average value was taken.

[0093] (2) Ultimate tensile strain: Tested according to JC / T 2461-2018 "Test Method for Mechanical Properties of High Ductility Fiber Reinforced Cement-Based Composite Materials", using dog bone-shaped specimens, uniaxial tensile test was carried out on a universal testing machine at a displacement rate of 0.1 mm / min, with 6 specimens in each group, and the average value was taken.

[0094] (3) Bending toughness index: Tested according to T / CECS 864-2021 "Standard for Test Methods of Ultra-High Performance Concrete", using 100mm×100mm×400mm prism specimens, three-point bending loading, and the bending toughness index I is calculated based on the area under the load-deflection curve. 20 Three specimens were collected in each group, and the average value was taken.

[0095] (4) Water absorption rate: Tested according to DL / T 5126-2021 "Test Procedure for Polymer Modified Cement Mortar". 28-day-old specimens were dried at 80±2℃ for 48 hours to constant weight, and the dried mass m0 was measured. After cooling, the specimens were completely immersed in water at (20±3)℃ for 48 hours. After soaking, the specimens were removed, the surface water was wiped off with a damp cloth, and the saturated mass m1 was measured. The water absorption rate was calculated using the formula W=(m1-m0) / m0×100%. Three parallel specimens were used in each group, and the average value was taken.

[0096] (5) Tensile bond strength: Tested according to GB / T 29756-2013 "Test Method for Physical Properties of Dry-Mixed Mortar". A 50mm×50mm×5mm molding frame was placed on a concrete slab and molded. After curing at (20±3)℃ and (60±5)% relative humidity for 28 days, the test was conducted. Eight parallel specimens were tested in each group, and the average value was taken.

[0097] (6) 90d compressive strength shrinkage rate: According to the formula R1=(f 90 -f 28 ) / f 28 Calculate by multiplying by 100%, where f 28 f is the 28-day compressive strength value. 90 R1 represents the 90-day compressive strength. A positive R1 indicates an increase in strength, while a negative R1 indicates a decrease in strength.

[0098] (7) 90d flexural strength shrinkage rate: according to the formula R2=(S 90 -S 28 ) / S 28 Calculated by multiplying by 100%, where S 28 The flexural strength value at 28 days, S 90 This represents the 90-day flexural strength. A positive R² value indicates an increase in strength, while a negative R² value indicates a decrease in strength.

[0099] (8) Ultimate tensile strain retention rate after carbonation: Accelerated carbonation test was conducted according to GB / T 50082-2024 "Standard for Test Methods of Long-term Performance and Durability of Concrete" (CO2 concentration 20±3%, temperature 20±2℃, humidity 70±5%). After carbonation for 90 days, the ultimate tensile strain was tested according to JC / T 2461-2018 "Test Methods for Mechanical Properties of High-ductility Fiber Reinforced Cement-based Composites". The ratio of the strain value after carbonation to the strain value of the uncarbonized specimen at the same age was calculated. The average value was taken for 6 specimens in each group.

[0100] Performance test results

[0101] Table 1 shows the test results of compressive strength and flexural strength of the mortars prepared in Examples 1-3 and Comparative Examples 1-10.

[0102] Table 1

[0103]

[0104] Table 2 shows the flexural strength test results of the mortars prepared in Examples 1-3 and Comparative Examples 1-10.

[0105] Table 2

[0106]

[0107] Table 3 shows the test results of ultimate tensile strain, flexural toughness index, 28-day water absorption, tensile bond strength, 90-day compressive strength shrinkage rate, 90-day flexural strength shrinkage rate, and 90-day carbonization strain retention rate of the mortars prepared in Examples 1-3 and Comparative Examples 1-10.

[0108] Table 3

[0109]

[0110] Note: In the 90d compressive and flexural strength reduction rates, "-" indicates strength reduction and "+" indicates strength increase.

[0111] As can be seen from Tables 1, 2, and 3:

[0112] (1) The early strength, toughness and bonding performance of the mortars prepared in Examples 1-3 all reached high standards: the 3-hour compressive strength was ≥35.0MPa (35.0-38.5MPa), and the 3-hour flexural strength was ≥6.5MPa (6.5-7.2MPa), far exceeding the requirement of 3-6 hours for rapid repair projects (usually requiring ≥30MPa), and is especially suitable for emergency repair projects such as airport runways and highways with extremely high requirements for traffic timeliness; the ultimate tensile strain was ≥3.5% (3.7%-4.9%), and the flexural toughness index I 20 All values ​​are ≥4.0 (4.3-5.2); simultaneously, the 28-day compressive strength is ≥104.8 MPa, the flexural strength is ≥21.0 MPa, the 28-day water absorption is ≤0.38% (0.26%-0.38%), and the 28-day tensile bond strength is ≥2.65 MPa; the 90-day compressive strength increases by 7.2%-7.7% compared to 28 days, with no strength reduction phenomenon; the 90-day flexural strength increases by 6.6%-7.6% compared to 28 days, indicating that the flexural strength also continues to increase, further verifying the long-term performance stability of the present invention; the strain retention rate after 90-day carbonization is ≥91.8%, indicating that the material of the present invention can still maintain excellent toughness in the carbonization environment, and is suitable for long-term service scenarios such as marine engineering and underground engineering.

[0113] (2) Long-term stability analysis of flexural strength:

[0114] The 90-day flexural strength reduction rate of the mortar prepared in Comparative Example 5 (without gypsum) was -9.3%, meaning the flexural strength decreased significantly from 18.2 MPa at 28 days to 16.5 MPa at 90 days. This demonstrates that the lack of gypsum to regulate the ettringite crystal structure not only leads to a reduction in compressive strength but also a more pronounced decrease in flexural strength, increasing matrix brittleness. In contrast, the flexural strength reduction rates of the mortars prepared in Examples 1-3 ranged from 6.6% to 7.6%, highlighting the crucial role of gypsum in stabilizing the ettringite crystal structure and maintaining long-term mechanical properties. The flexural strength of the mortar prepared in Comparative Example 1 (ordinary EVA + ordinary fiber) also showed a slight reduction (-1.8%), indicating that a physical blend system lacking a chemical cross-linking network cannot effectively suppress long-term performance degradation.

[0115] (3) Water absorption rate analysis:

[0116] The 28-day water absorption rate of the mortars prepared in Examples 1-3 was ≤0.38% (0.26%-0.38%), which is much lower than that of Comparative Example 1 (0.85%), Comparative Example 3 (1.85%), and Comparative Example 10 (0.98%). This invention achieves a breakthrough effect of ≤0.38% water absorption rate in repair mortar through the synergistic effect of the multi-level pore filling effect of nano-diatomite, the high-density hydrophobic network constructed by in-situ crosslinking of 4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disilane bissilane, and the long-chain hydrophobic end-capping of the outer surface of octadecyltrimethoxysilane. This is superior to the impermeability level of similar repair materials. The mortar prepared in Comparative Example 10 (γ-aminopropyltriethoxysilane replacing 4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disilane and without hydrophobic end caps) had a water absorption rate as high as 0.98%, further demonstrating the indispensability of dual silane anchoring and long-chain hydrophobic end caps in constructing ultra-low water absorption barriers.

[0117] Compared with existing ECC repair materials, due to the significant increase in OPC content to 80%-88% and the reduction in CSA content to 10%-15%, the 1-day compressive strength (34.2-40.8MPa) of this invention still meets the basic requirements of rapid repair engineering (≥30MPa), and the 90-day strength (112.3-122.0MPa) is significantly improved, with a 90-day strength increase of 7.2%-7.7%. This reflects the strength growth advantage brought about by the long-term continuous hydration of the OPC main cementitious component, and further verifies the long-term service stability of this invention.

[0118] (4) Experimental verification of the three-level energy dissipation structure:

[0119] The ultimate tensile strain of the mortar prepared in Comparative Example 3 (glycidyl methacrylate-g-EVA-free) was only 0.4%, the flexural toughness index was only 1.2, and the water absorption rate after 28 days was as high as 1.85%. This indicates that without the polymer crosslinking network, the material is almost purely brittle and has extremely poor impermeability. The second-level energy-consuming structure (organic-inorganic interpenetrating network molecular bridging) is completely missing, and energy is consumed only by the first level (microcrystal deflection) and the third level (fiber pull-out). However, due to the lack of lubrication and protection of the polymer interface transition layer, the fiber pull-out energy is also greatly reduced, reflecting the synergistic dependence between the energy-consuming structures at each level.

[0120] The mortar (fiber-free) prepared in Comparative Example 4 exhibited an ultimate tensile strain of only 0.6% and a flexural toughness index of only 1.9. Although it retained the first and second-level energy-dissipating structures, it lacked the third-level (fiber macroscopic bridging) energy-dissipating structure, causing the material to rapidly lose its load-bearing capacity after microcrack propagation. Compared with the mortar prepared in Example 1, the third-level energy dissipation contributed more than 85% to the ultimate tensile strain (increasing from 0.6% to 4.3%), demonstrating the dominant role of fiber bridging energy dissipation. However, without the cooperation of the first and second-level energy-dissipating structures, debonding occurred at the fiber-matrix interface in the early stages of loading, resulting in a significant decrease in fiber bridging efficiency.

[0121] The mortar prepared in Comparative Example 1 (ordinary EVA + ordinary fiber) had an ultimate tensile strain of only 2.2%, a flexural toughness index of 2.9, and a 28-day water absorption rate of 0.85%. Although it contained the prototype of a three-level energy-consuming structure, the efficiency of each level of energy consumption decreased significantly due to the lack of chemical cross-linking (no glycidyl methacrylate grafting) and fiber surface functionalization (no polydopamine-nano SiO2 composite biomimetic coating). This proves that chemical bonding is the key to the efficient coupling of each level of energy-consuming structure.

[0122] (5) Quantitative analysis of the contribution of each component to toughness and impermeability:

[0123] The ultimate tensile strain of the mortar prepared in Comparative Example 2 (without diatomaceous earth loading) was only 2.7%, lower than 4.3% in Example 1, a decrease of 37%, and the water absorption rate was 0.62%, which was also significantly higher than 0.31% in Example 1. The reason is that the diatomaceous earth without loading lacks the slow-release cross-linking function of the active components, the organic-inorganic interpenetrating network is incomplete, the efficiency of the second-stage energy-consuming structure is greatly reduced, and there is no pozzolanic effect of nano-SiO2 to refine the hydration products and fill the pores, which weakens the grain boundary deflection effect and impermeability of the first-stage energy-consuming structure.

[0124] The 90-day compressive strength of the mortar prepared in Comparative Example 5 (without gypsum) decreased by -2.4% compared to 28 days, and the flexural strength decreased by -9.3%. Furthermore, the ultimate tensile strain was only 2.5%, lower than the 4.3% in Example 1. This indicates that the lack of gypsum to regulate the ettringite structure led to a deterioration in the matrix microstructure and a decline in long-term service performance. This demonstrates the necessity of gypsum in the high-belite sulfoaluminate cement-ordinary silicate cement binary system for stabilizing the ettringite crystal structure and maintaining long-term strength.

[0125] The ultimate tensile strain of the mortar prepared in Comparative Example 6 (nanozeolite replacing nanodiatomite) was 2.9%, and the water absorption rate was 0.58%, both of which were inferior to those in Example 1. This indicates that the multi-level pore structure and active loading capacity of nanozeolite are not as good as those of nanodiatomite. Its release crosslinking efficiency and physical filling effect are both weaker, and the energy-consuming structure and impermeability of each level are affected.

[0126] The ultimate tensile strain of the mortar prepared in Comparative Example 7 (high vinyl acetate content EVA latex powder without glycidyl methacrylate grafting) was 3.1%, which was higher than 2.2% in Comparative Example 1, but significantly lower than 4.3% in Example 1. This indicates that even if the vinyl acetate content of EVA is high and its film-forming properties are good, if there are no epoxy crosslinking sites, it cannot form chemical bonds with silane coupling agents and cellulose amino groups. The organic-inorganic interpenetrating network cannot be established, and the energy-consuming structures of the second level (molecular bridging) and the third level (chemical anchoring) are severely weakened.

[0127] The ultimate tensile strain of the mortar prepared in Comparative Example 8 (ordinary dopamine impregnation, no plasma activation, no nano-SiO2 co-deposition) was 3.3%. Although the fiber surface had a certain amino density (about 0.5 mmol / g), it lacked the micro-nano rough physical interlocking and volcanic ash reinforcement provided by nano-SiO2. The fiber pull-out energy was mainly due to physical friction, lacking energy consumption from chemical bond breaking and energy consumption from the peeling of hydration product layers, resulting in limited improvement in pull-out energy.

[0128] The ultimate tensile strain of the mortar prepared in Comparative Example 9 (KH550 conventional grafting) was 2.9%, indicating that although the traditional silane coupling agent grafting method can introduce amino groups, the grafting density is low (about 0.3 mmol / g) and it cannot construct micro-nano rough structures. The fiber pull-out energy has a limited improvement range and cannot meet the requirements of ultra-high toughness.

[0129] The mortar prepared in Comparative Example 10 (using γ-aminopropyltriethoxysilane instead of 4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disilane and without long-chain hydrophobic end caps) had a 28-day water absorption rate of 0.98%, which was much higher than the 0.31% of Example 1. Its 28-day compressive strength was only 99.5 MPa (not exceeding 100 MPa), its ultimate tensile strain was only 2.8%, and its 90-day flexural strength showed a reduction (-2.1%). All properties were significantly lower than those of Example 1. This indicates that the bissilane dual-anchoring network constructed with 4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disilane and the long-chain hydrophobic end capping on the outer surface constructed with octadecyltrimethoxysilane exhibit a significant synergistic effect: the bissilane structure of 4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disilane forms a high-density cross-linked network within the pores, enhancing the bonding strength and durability of the organic-inorganic interface while reducing the surface energy of the pores; the long-chain alkyl group of octadecyltrimethoxysilane forms a dense hydrophobic molecular layer on the outer surface of diatomaceous earth, effectively blocking water intrusion. The synergistic effect of these two components—"internal cross-linking enhancement + external hydrophobic shielding"—achieves an integrated functional integration, which is a key technical means to ensure compressive strength exceeding 100%, continuous increase in flexural strength, and ultra-low water absorption. Conventional monosilanes such as γ-aminopropyltriethoxysilane cannot achieve the aforementioned synergistic effect.

[0130] (6) Comprehensive analysis of the sources of toughness:

[0131] Based on the comparative analysis above, the toughness of this invention originates from three sources: matrix microcrystal deflection (first level), interpenetrating network molecular bridging (second level), and triple fiber anchoring pull-out (third level). Each of these three aspects is indispensable, and they are interdependent and synergistically effective. The fine grains and dense matrix provided by the first level offer more anchoring nodes (chemical bonding sites on the surface of hydration products) for the molecular bridging in the second level, while also providing stronger matrix gripping force for the fiber anchoring in the third level. The organic-inorganic interpenetrating network of the second level forms a flexible buffer layer in the fiber-matrix interface transition zone, preventing fiber debonding due to stress concentration in the early stages of loading and ensuring full activation of the third-level fiber bridging structure during the macroscopic crack stage. During the fiber pull-out process in the third level, the active groups in the polydopamine-nano SiO2 composite biomimetic coating on the fiber surface can continuously react with the unreacted epoxy groups in EVA-g-methacrylic acid glycidyl ester, causing the chemical bond breakage during the pull-out process to continuously occur at new sites, achieving "dynamic chemical bond energy dissipation."

[0132] It is this multi-stage energy dissipation design, characterized by "combining rigidity and flexibility, step-by-step activation, and dynamic energy consumption," that enables this invention to achieve a compressive strength greater than 100 MPa, a flexural strength ≥20 MPa with continuous growth (without shrinkage), an ultimate tensile strain ≥3.5%, and a bending toughness index I. 20 It has a strength of ≥4.0, a 28-day water absorption rate of ≤0.38%, and a tensile bond strength of ≥2.5MPa. Its comprehensive mechanical properties and impermeability far exceed those of existing technologies.

[0133] In summary, this invention, through a multi-level energy dissipation mechanism, achieves, for the first time, energy dissipation in a ternary cement system where OPC is absolutely dominant (80%-88%) through the synergistic spatiotemporal development and nanocrystalline shape regulation of ordinary silicate cement-high belite sulfoaluminate cement-gypsum ternary cement (first-level energy consumption) + the construction of an organic-inorganic interpenetrating network by vacuum gradient impregnation and slow-release in-situ crosslinking of nano-diatomaceous earth (second-level energy consumption) + the provision of flexible molecular bridges and chemical crosslinking nodes by glycidyl methacrylate grafted with high vinyl acetate content EVA latex powder + triple anchoring by fiber plasma activation and biomimetic co-deposition (third-level energy consumption). It achieves a synergistic improvement in early strength, high strength, and low water absorption (3h compressive strength ≥35.0MPa, 28d compressive strength ≥100MPa, 28d water absorption ≤0.5%) and high toughness and high bonding (3h flexural strength ≥6.0MPa, 28d flexural strength ≥20MPa, ultimate tensile strain ≥3.5%, tensile bond strength ≥2.5MPa). It solves the technical problem that existing repair mortars in harsh environments such as underground integrated pipe corridors, cross-sea tunnels, marine engineering, airport runways, high-speed railways and highway bridges cannot simultaneously achieve ultra-high strength, ultra-high toughness, long-term stability and ultra-low water absorption.

[0134] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A high-toughness polymer repair mortar, characterized in that, The product comprises the following components by weight: 80-88 parts of ordinary silicate cement, 10-15 parts of high belite sulfoaluminate cement, 3-5 parts of gypsum, 55-75 parts of quartz sand, 3-8 parts of grafted modified high vinyl acetate content EVA latex powder, 1.0-3.0 parts of surface functionalized fiber, 1.0-4.0 parts of supported active nano diatomaceous earth, 0.3-0.8 parts of polycarboxylate superplasticizer, 0.05-0.3 parts of defoamer, and 20-30 parts of water. Supported active nano-diatomaceous earth is diatomaceous earth with active components loaded in the pores and selectively hydrophobically capped on the outer surface with octadecyltrimethoxysilane. The active component is a complex of nano-SiO2 sol and 4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disilane. The mass loading of the active component in the supported active nano-diatomaceous earth is 15%-35%. Graft-modified high vinyl acetate content EVA latex powder is a copolymer of glycidyl methacrylate grafted with ethylene-vinyl acetate, and the vinyl acetate content of the high vinyl acetate content EVA latex powder is ≥85%; The surface-functionalized fiber is a polyvinyl alcohol fiber or polyethylene fiber that has been activated by plasma and treated with biomimetic co-deposition of dopamine and nano-SiO2. The fiber surface has a polydopamine-nano-SiO2 composite biomimetic coating and is grafted with amino active groups.

2. The ultra-high toughness polymer repair mortar according to claim 1, characterized in that, Nano-diatomaceous earth was calcined and then acid-activated to obtain activated nano-diatomaceous earth. Nano-SiO2 sol, 4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disilane and chitosan-sodium alginate complex were mixed and ethanol was added and stirred to obtain a loading solution. The activated nano-diatomaceous earth was added to the loading solution and subjected to vacuum gradient impregnation. Then, the impregnated diatomaceous earth was dispersed in an organic solvent containing octadecyltrimethoxysilane for end-capping reaction to obtain supported activated nano-diatomaceous earth.

3. The ultra-high toughness polymer repair mortar according to claim 2, characterized in that, The mass ratio of nano-SiO2 sol, 4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disilane to chitosan-sodium alginate complex is (6-8):(1-3):1; the content of octadecyltrimethoxysilane in the organic solvent containing octadecyltrimethoxysilane is 1-3 wt%.

4. The ultra-high toughness polymer repair mortar according to claim 1, characterized in that, Ethylene-vinyl acetate copolymer, glycidyl methacrylate and initiator were dissolved in an organic solvent and reacted under nitrogen protection to obtain graft-modified EVA latex powder with high vinyl acetate content.

5. The ultra-high toughness polymer repair mortar according to claim 4, characterized in that, The mass ratio of ethylene-vinyl acetate copolymer, glycidyl methacrylate, and initiator is (80-120):(2-4):(0.4-0.6), and the mixture is stirred and reacted at 70-90℃ under nitrogen protection for 5-7 hours.

6. The ultra-high toughness polymer repair mortar according to claim 1, characterized in that, Nano-SiO2 is dispersed in a buffer solution, dopamine hydrochloride is added, and the mixture is stirred until homogeneous to obtain a dopamine / nano-SiO2 co-deposition solution. Plasma-activated polyvinyl alcohol fiber or polyethylene fiber is then added to the solution to react and obtain surface-functionalized fiber.

7. The ultra-high toughness polymer repair mortar according to claim 6, characterized in that, The buffer solution is a tris(hydroxymethyl)aminomethane hydrochloride buffer solution, and the concentration of nano-SiO2 in the dopamine / nano-SiO2 co-deposition solution is 0.5-2.0 g / L; the mass ratio of plasma-activated polyvinyl alcohol fiber or polyethylene fiber to dopamine / nano-SiO2 co-deposition solution is 1:(15-25).

8. A method for preparing ultra-high toughness polymer repair mortar as described in any one of claims 1-7, characterized in that, Ordinary silicate cement, high belite sulfoaluminate cement, gypsum, quartz sand and loaded active nano diatomaceous earth are mixed and dry-mixed. Water, polycarboxylate superplasticizer and defoamer are added and wet-mixed. Grafted modified high vinyl acetate content EVA latex powder is added and mixing continues. Surface functionalized fibers are added and mixed to obtain ultra-high toughness polymer repair mortar.

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