High-toughness cement-based repairing material based on bionic adhesion and self-repairing functions and preparation method of high-toughness cement-based repairing material

Abstract

The invention belongs to the technical field of building materials, and discloses a high-toughness cement-based repairing material based on bionic adhesion and self-repairing functions and a preparation method thereof.The high-toughness cement-based repairing material is prepared from, by mass, 400-500 parts of ordinary Portland cement, 250-300 parts of high belite sulphoaluminate cement, 100-150 parts of mineral powder, 20-50 parts of silica fume and 10-30 parts of redispersible latex powder; the invention relates to a high-temperature-resistant and wear-resistant concrete which is prepared from the following components in parts by weight: 5-20 parts of gas-phase nano silicon dioxide, 800-1000 parts of machine-made sand, 0.05-0.5 part of polydopamine modified graphene oxide, 1-5 parts of an epoxy curing agent, 2-5 parts of a water reducing agent, 2.5-3 parts of a defoaming agent, 0.4-0.5 part of a retarder and 250-300 parts of water. Wherein the epoxy curing agent is wrapped in the resin microcapsule. The interface bonding strength and toughness of the cement-based repairing material can be improved, and the repairing material has the damage self-recovery capability.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing functions and its preparation method. Background Technology

[0002] Cement concrete is the most widely used material in modern engineering construction. However, existing structures commonly suffer from cracking, spalling, and other damage under environmental and load conditions. Repairing damaged structures instead of demolishing and rebuilding them is crucial for saving resources and ensuring safety, and has also created a huge market demand for repair materials.

[0003] Currently, cement-based inorganic repair materials are commonly used in repair projects. While these materials are relatively inexpensive, they have inherent drawbacks: firstly, they are brittle and lack toughness; secondly, and most critically, the interfacial bonding between the old and new materials is weak, often becoming the most vulnerable link in the repair system. Existing technologies mainly improve some properties by adding polymers, but they still fail to fundamentally solve the core technical bottlenecks of weak interfacial chemical bonding and the lack of self-repairing capabilities for microcracks.

[0004] Therefore, developing a new type of high-performance repair material that can actively strengthen interfacial adhesion, improve bulk toughness, and possess self-healing capabilities is of great significance for improving the reliability and durability of repair projects. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention aims to provide a high-strength and tough cement-based repair material with biomimetic adhesion and self-healing functions, and its preparation method. The present invention can improve the interfacial bonding strength and toughness of cement-based repair materials and enable the repair material to have damage self-healing ability.

[0006] The objective of this invention can be achieved through the following technical solutions: A high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing functions, comprising, by weight, the following raw materials: 400-500 parts of ordinary silicate cement, 250-300 parts of high belite sulfoaluminate cement, 100-150 parts of mineral powder, 20-50 parts of silica fume, 10-30 parts of redispersible latex powder, 5-20 parts of fumed nano silica, 800-1000 parts of manufactured sand, 0.05-0.5 parts of polydopamine-modified graphene oxide, 1-5 parts of epoxy curing agent, 2-5 parts of water-reducing agent, 2.5-3 parts of defoamer, 0.4-0.5 parts of retarder, and 250-300 parts of water; The epoxy curing agent is encapsulated in resin microcapsules.

[0007] Preferably, the microcapsule wall material of the resin microcapsules is urea-formaldehyde resin, melamine resin, or polyurethane.

[0008] Preferably, the process of encapsulating the epoxy curing agent in resin microcapsules includes: An epoxy resin curing agent is mixed with an isocyanate monomer to form an oil phase, wherein the mass ratio of the epoxy resin curing agent to the isocyanate monomer is 5:1; an emulsifier is dissolved in water to form an aqueous phase, wherein the emulsifier accounts for 1%-5% of the water mass. The oil phase is added to the aqueous phase and sheared and emulsified at a speed of 1000-3000 rpm for 10-30 minutes to form an oil-in-water emulsion; wherein the mass-volume ratio of the oil phase to the aqueous phase is 24:(195-205). An aqueous solution of a diamine compound is added dropwise to the oil-in-water emulsion, and then the mixture is stirred at 40-60°C and 340-360 rpm for 2-6 hours. After the reaction is complete, the mixture is filtered, washed, and dried, and then ground into powder to obtain a powdered epoxy curing agent encapsulated in resin microcapsules, thus achieving the encapsulation of the epoxy curing agent in resin microcapsules. The molar ratio of the diamine compound to the isocyanate monomer is (0.9-1.1):1, and the diamine compound accounts for 3%-8% of the water mass in the aqueous solution.

[0009] Preferably, the epoxy resin curing agent is isophorone diamine or hexamethylene diamine; the isocyanate monomer is toluene diisocyanate or hexamethylene diisocyanate; The emulsifier used is polyvinyl alcohol and / or sodium dodecyl sulfate; Diamine compounds are made of ethylenediamine or hexamethylenediamine; During washing and drying, the filtered solid product is washed 2-4 times with deionized water, then vacuum dried at 40-60℃ for 12-24 hours to remove moisture, and then ground into powder to obtain a powdered epoxy curing agent encapsulated in resin microcapsules.

[0010] Preferably, the average particle size of the epoxy curing agent encapsulated in the resin microcapsules is 10-100 micrometers.

[0011] Preferably, the preparation method of polydopamine-modified graphene oxide includes: Graphene oxide was dispersed in a buffer solution with a pH of 8.0-9.0 to form a uniform graphene oxide dispersion. Dopamine hydrochloride was added to the graphene oxide dispersion, and the mixture was stirred at 20-30°C for 12-48 hours. After that, solid-liquid separation was performed, and the separated solid product was washed and dried to obtain the polydopamine-modified graphene oxide. The mass ratio of dopamine hydrochloride to graphene oxide was (0.5-2):1, and the stirring rate during the reaction was 390-410 rpm.

[0012] Preferably, the buffer solution is a tris(hydroxymethyl)aminomethane hydrochloride buffer solution, with each gram of graphene oxide dispersed in 495-505 mL of tris(hydroxymethyl)aminomethane hydrochloride buffer solution; After adding graphene oxide to a tris(hydroxymethyl)aminomethane hydrochloride buffer solution, the solution is treated in an ice-water bath under ultrasonic conditions of 300-500W for 30-60 minutes to form a uniform graphene oxide dispersion.

[0013] Preferably, when washing and drying the separated solid product, the solid product is washed with deionized water and ethanol alternately 2-4 times, then dried at -45°C to -55°C for 24-48 hours, and then ground into powder to obtain powdered polydopamine modified graphene oxide.

[0014] Preferably, the water-reducing agent is a polycarboxylate high-efficiency water-reducing agent, the defoamer is an organosilicon defoamer, the retarder is sodium gluconate, the ordinary silicate cement is P·O 42.5 ordinary silicate cement, and the mineral powder is S95 grade mineral powder.

[0015] This invention also provides a method for preparing a high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing functions as described above, characterized by comprising the following steps: Ordinary silicate cement, high belite sulfoaluminate cement, mineral powder, silica fume, fumed nano silica, redispersible latex powder and manufactured sand are dry-mixed to obtain a uniform premix; wherein the mixing speed is 15-30 rpm and the mixing time is 10-20 minutes. Add polydopamine-modified graphene oxide to the premix and continue mixing for 5-10 minutes to obtain the first mixture; Under stirring conditions of 100-300 rpm, epoxy curing agent encapsulated in resin microcapsules is added to the first mixture. The mixing time is 3-8 minutes. After mixing, the material is discharged to obtain dry powder of repair material. The dry powder of the repair material is mixed with water, water-reducing agent, defoamer and retarder to obtain the high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing function.

[0016] The present invention has the following beneficial effects: This invention relates to a high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing functions. Through the rational combination of various raw material components and the design of specific functional structures, it specifically solves the core technical bottlenecks of existing cement-based repair materials, achieving a breakthrough improvement in comprehensive performance. Specifically, this material incorporates 0.05-0.5 parts of polydopamine-modified graphene oxide. The catechol groups on its surface can irreversibly chemically crosslink with the active groups at the interface of old concrete. The two-dimensional sheets simultaneously penetrate deep into the micropores and cracks of the old concrete to form physical anchorage, constructing a dual mechanism of chemical bonding and physical anchoring. This upgrades the interface bonding between new and old materials from traditional physical interlocking to stable chemical bonding. Combined with 10-30 parts of redispersible latex powder to further optimize interface compatibility, the tensile bond strength reaches 5.3-5.8 MPa, significantly improved compared to materials without this modified component, fundamentally addressing the problem of weak and easily failed interfacial bonding. 5-20 parts of fumed silica and polydopamine-modified graphene oxide work synergistically to form a nanoscale reinforcing and filling system. The former fills the micropores of cement hydration products with small particle size and refines the crystal structure, while the latter constructs a three-dimensional support network, bridging cracks and dispersing stress during external force-induced cracking. Combined with 400-500 parts of ordinary silicate cement and 250-300 parts of high-belite... The optimization of sulfoaluminate cement compound and active admixtures such as mineral powder and silica fume resulted in a 28-day flexural strength of 11.9-13.1 MPa, effectively overcoming the inherent brittleness of cement-based materials and significantly improving their toughness and crack resistance. Encapsulating 1-5 parts of epoxy curing agent in resin microcapsules creates a damage-triggered intelligent self-healing mechanism. Stress generated by microcrack propagation can rupture the capsules to release the curing agent, which then cross-links at the crack interface to form a dense adhesive layer, filling voids and blocking the penetration of corrosive media, thus achieving self-healing. With a setting rate of 78%-83%, it significantly extends the long-term durability of the repair system. At the same time, 0.4-0.5 parts of retarder can control the setting time to adapt to different construction scenarios, and 2-5 parts of water-reducing agent and 2.5-3 parts of defoamer can reduce water consumption and eliminate internal air bubbles to improve density. The synergistic effect of the components makes the material's 28-day compressive strength reach 75.8-82.0 MPa, taking into account excellent mechanical properties, bonding performance, self-healing ability and construction adaptability, providing reliable support for the long-term repair of damaged concrete structures. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with embodiments and comparative examples. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0018] By weight, the high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing functions of this invention comprises the following raw materials: 400-500 parts of ordinary silicate cement, 250-300 parts of high-belite sulfoaluminate cement, 100-150 parts of mineral powder, 20-50 parts of silica fume, 10-30 parts of redispersible latex powder, 5-20 parts of fumed nano-silica, 800-1000 parts of manufactured sand, 0.05-0.5 parts of polydopamine-modified graphene oxide, 1-5 parts of epoxy curing agent, 2-5 parts of water-reducing agent, 2.5-3 parts of defoamer, 0.4-0.5 parts of retarder, and 250-300 parts of water. In the above formulation, the water-reducing agent can be a polycarboxylate high-efficiency water-reducing agent, the defoamer can be an organosilicon defoamer, and the retarder can be sodium gluconate.

[0019] Polydopamine-modified graphene oxide is prepared by in-situ polymerization and coating of graphene oxide with dopamine on its surface; epoxy curing agent is encapsulated in resin microcapsules, and the epoxy curing agent encapsulated in the resin microcapsules is made of urea-formaldehyde resin, melamine resin or polyurethane, and the core encapsulant of the microcapsule wall is epoxy resin curing agent.

[0020] The polydopamine-modified graphene oxide of the present invention is prepared by the following steps: Step A1: Disperse graphene oxide in a buffer solution with a pH of 8.0-9.0, and sonicate it for 30-60 minutes in an ice-water bath at a power of 300-500W to form a uniform graphene oxide dispersion. The buffer solution can be tris(hydroxymethyl)aminomethane hydrochloride buffer solution, with each gram of graphene oxide dispersed in 500±5 mL of tris(hydroxymethyl)aminomethane hydrochloride buffer solution. In the experiment, 1 g of graphene oxide was dispersed in 500 mL of buffer solution, and the buffer solution was measured using a 500 mL graduated cylinder with an error range of ±5 mL. It is understood that in this invention, when 1 g of graphene oxide is dispersed in 500 mL of buffer solution, the actual volume of the buffer solution is 495-505 mL, and the technical solution of this invention is feasible within this range. Step A2: Add dopamine hydrochloride to the graphene oxide dispersion at a mass ratio of (0.5-2):1, and continuously stir at 400±10 rpm for 12-48 hours at 20-30°C; where "±10" represents the speed deviation of the stirring equipment. For those skilled in the art, the technical solution of the present invention is feasible within the stirring rate range of 390-410 rpm determined by the set value of 400 rpm and the equipment deviation value of ±10 rpm. Step A3: After the reaction in step A2 is completed, centrifugation is performed to obtain a solid product. The solid product is washed with deionized water and ethanol alternately 2-4 times, and finally freeze-dried at -45℃ to -55℃ for 24-48 hours. After that, it is ground into powder to obtain powdered polydopamine modified graphene oxide. The epoxy curing agent encapsulated in the resin microcapsules of the present invention is prepared by the following steps: Step B1: Mix the epoxy resin curing agent with the isocyanate monomer to form the oil phase, wherein the mass ratio of the epoxy resin curing agent to the isocyanate monomer is 5:1. The epoxy resin curing agent can be isophorone diamine or hexamethylene diamine, and the isocyanate monomer can be toluene diisocyanate or hexamethylene diisocyanate. Dissolve the emulsifier in water to form the aqueous phase; wherein the emulsifier can be polyvinyl alcohol and / or sodium dodecyl sulfate, and the emulsifier accounts for 1%-5% of the water mass. Step B2: Add the oil phase prepared in step B1 to the aqueous phase prepared in step B1, wherein the mass-to-volume ratio of the oil phase to the aqueous phase is 24:(195-205); then perform high-speed shear emulsification at 1000-3000 rpm for 10-30 minutes to form a stable oil-in-water emulsion. In the experiment, the aqueous phase was prepared by measuring water using a 200 mL graduated cylinder, and then adding the emulsifier to the 200 mL of water. The error range of the graduated cylinder is ±5 mL, and the present invention ignores the volume change after adding the emulsifier to 200 mL of water. It is understood that in the present invention, when the oil phase is added to the aqueous phase, the actual volume of the aqueous phase is 195-205 mL, and the technical solution of the present invention is feasible within this range.

[0021] Step B3: Add an aqueous solution of the diamine compound to the oil-in-water emulsion prepared in step B2 at a molar ratio of (0.9-1.1):1. Stir the mixture at 40-60°C and 350±10 rpm for 2-6 hours to allow polymerization at the oil-water interface to form a polyurea wall material. The molar ratio of the diamine compound to the isocyanate monomer is (0.9-1.1):1, and the diamine compound accounts for 3%-8% of the water mass in the aqueous solution. "±10" represents the rotational speed deviation of the stirring equipment. For those skilled in the art, the technical solution of this invention is feasible within the stirring rate range of 340-360 rpm, determined by the set value of 350 rpm and the equipment deviation value of ±10 rpm. Step B4: After the reaction in step B3 is completed, filter the reaction solution obtained in step B3, wash the filtered solid product 2-4 times with deionized water, then vacuum dry it at 40-60℃ for 12-24 hours to remove moisture, and then grind it into powder to obtain a powdered epoxy curing agent encapsulated in resin microcapsules. The average particle size of the microcapsules (i.e., the epoxy curing agent encapsulated in resin microcapsules) is 10-100 micrometers.

[0022] The method for preparing the high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing function according to the present invention using the above raw materials includes the following steps: Step S1: Weigh the ordinary silicate cement, high belite sulfoaluminate cement, mineral powder, silica fume, redispersible latex powder, fumed nano silica and manufactured sand into a mixer and dry mix at a speed of 15-30 rpm for 10-20 minutes to obtain a uniform premix. Step S2: Add polydopamine-modified graphene oxide to the premix obtained in step S1, and continue mixing for 5-10 minutes to obtain the first mixture; Step S3: Under low-speed stirring (100-300 rpm), add the epoxy curing agent encapsulated in resin microcapsules to the first mixture obtained in step S2, mix for 3-8 minutes and then discharge to obtain dry powder of repair material. Step S4: During construction, mix the dry powder of the repair material obtained in step S3 with water, water-reducing agent and defoamer, and stir for 3-5 minutes to obtain a workable repair mortar.

[0023] Example 1 By weight, the high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing functions of this invention comprises the following raw materials: 450 parts of P·O 42.5 ordinary silicate cement, 280 parts of high belite sulfoaluminate cement, 120 parts of S95 grade mineral powder, 30 parts of silica fume, 20 parts of redispersible latex powder, 12 parts of fumed nano silica, 900 parts of manufactured sand, and 0.3 parts of polydopamine-modified graphene oxide. The resin microcapsules contain 3 parts epoxy curing agent, 4 parts polycarboxylate superplasticizer, 0.5 parts silicone defoamer, 0.4 parts sodium gluconate retarder, and 270 parts water.

[0024] The method for preparing the high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing function according to the present invention using the above raw materials includes the following steps: Step S1: Weigh the ordinary silicate cement, high belite sulfoaluminate cement, mineral powder, silica fume, redispersible latex powder, fumed nano silica and manufactured sand into a mixer and dry mix at 25 rpm for 15 minutes to obtain a uniform premix. Step S2: Add polydopamine-modified graphene oxide to the premix obtained in step S1, and continue mixing for 8 minutes to obtain the first mixture; Step S3: Under low-speed stirring at 200 rpm, add epoxy curing agent encapsulated in resin microcapsules to the first mixture obtained in step S2, mix for 5 minutes and then discharge to obtain dry powder of repair material. Step S4: During construction, mix the dry powder of the repair material obtained in step S3 with water, water-reducing agent and defoamer, and stir for 4 minutes to obtain a workable repair mortar.

[0025] The polydopamine-modified graphene oxide used in this embodiment is prepared through the following steps: Step A1: Add 1.0g of graphene oxide to 500mL of Tris-HCl buffer solution (i.e., tris(hydroxymethyl)aminomethane hydrochloride buffer solution, pH=8.5), and ultrasonically disperse it for 45 minutes at 400W power under ice-water bath conditions to obtain a uniform graphene oxide dispersion. Step A2: Add 1.2g of dopamine hydrochloride to the graphene oxide dispersion obtained in step A1, and stir at 400rpm at 25°C for 36 hours. Step A3: After the reaction in step A2 is completed, centrifuge to obtain a solid product. Wash the solid product three times with deionized water and ethanol alternately. Finally, freeze-dry at -50±5℃ for 48 hours and then grind to obtain polydopamine-modified graphene oxide powder.

[0026] The epoxy curing agent encapsulated in resin microcapsules used in this embodiment is prepared through the following steps: Step B1: Mix 20g of isophorone diamine with 4g of toluene diisocyanate to form the oil phase; dissolve 5g of polyvinyl alcohol and 1g of sodium dodecyl sulfate in 200mL of deionized water to form the aqueous phase. Step B2: Add the oil phase prepared in step B1 to the aqueous phase prepared in step B1 at 50°C, and then emulsify at a high speed of 2500 rpm for 20 minutes to form a stable oil-in-water emulsion. Step B3: Add an aqueous solution containing 2.2 g of ethylenediamine dropwise to the oil-in-water emulsion prepared in step B2, and react at 50°C and 350 rpm for 4 hours. The diamine compound in the aqueous solution accounts for 5% of the water mass. Step B4: After the reaction in step B3 is completed, filter the reaction solution obtained in step B3, wash the filtered solid product three times with deionized water, then dry it under vacuum at 55°C for 24 hours, then grind it into powder, and sieve it to obtain microcapsule powder with a particle size of 30-80μm.

[0027] Example 2 By weight, the high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing functions of this invention comprises the following raw materials: 420 parts of P·O 42.5 ordinary silicate cement, 260 parts of high belite sulfoaluminate cement, 110 parts of mineral powder, 25 parts of silica fume, 25 parts of redispersible latex powder, 8 parts of fumed nano silica, 850 parts of manufactured sand, 0.1 parts of polydopamine-modified graphene oxide, 4.5 parts of resin microcapsule curing agent, 5 parts of polycarboxylate superplasticizer, 0.8 parts of defoamer, 0.3 parts of sodium gluconate, and 250 parts of water.

[0028] The method for preparing the high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing function according to the present invention using the above raw materials includes the following steps: Step S1: Weigh the ordinary silicate cement, high belite sulfoaluminate cement, mineral powder, silica fume, redispersible latex powder, fumed nano silica and manufactured sand into a mixer and dry mix at 30 rpm for 10 minutes to obtain a uniform premix. Step S2: Add polydopamine-modified graphene oxide to the premix obtained in step S1, and continue mixing for 5 minutes to obtain the first mixture; Step S3: Add the epoxy curing agent encapsulated in resin microcapsules under low-speed stirring at 150 rpm, mix for 8 minutes and then discharge to obtain dry powder of repair material; Step S4: During construction, mix the dry powder of the repair material obtained in step S3 with water, water-reducing agent and defoamer, and stir for 5 minutes to obtain a workable repair mortar.

[0029] The polydopamine-modified graphene oxide used in this embodiment is prepared through the following steps: Step A1: Add 1.0g of graphene oxide to 500mL of Tris-HCl buffer solution (pH=8.5), and ultrasonically disperse it for 45 minutes at 400W power under ice-water bath conditions to obtain a uniform graphene oxide dispersion. Step A2: Add 1.2g of dopamine hydrochloride to the graphene oxide dispersion obtained in step A1, and stir at 400rpm at 25°C for 36 hours. Step A3: After the reaction in step A2 is completed, centrifuge to obtain a solid product. Wash the solid product four times with deionized water and ethanol alternately. Finally, freeze-dry at -50±5℃ for 36 hours and then grind to obtain polydopamine-modified graphene oxide powder.

[0030] The epoxy curing agent encapsulated in resin microcapsules used in this embodiment is prepared through the following steps: Step B1: Mix 20g of isophorone diamine with 4g of toluene diisocyanate to form the oil phase; dissolve 5g of polyvinyl alcohol and 1g of sodium dodecyl sulfate in 200mL of deionized water to form the aqueous phase. Step B2: Add the oil phase prepared in step B1 to the aqueous phase prepared in step B1 at 50°C, and then emulsify at a high speed of 1000 rpm for 30 minutes to form a stable oil-in-water emulsion. Step B3: Add an aqueous solution containing 2.2 g of ethylenediamine dropwise to the oil-in-water emulsion prepared in step B2, and react at 50°C and 350 rpm for 4 hours. The diamine compound in the aqueous solution accounts for 5% of the water mass. Step B4: After the reaction in step B3 is completed, filter the reaction solution obtained in step B3, wash the filtered solid product twice with deionized water, then dry it under vacuum at 40°C for 20 hours, then grind it into powder, and sieve it to obtain microcapsule powder with a particle size of 30-80μm.

[0031] Example 3 By weight, the high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing functions of this invention comprises the following raw materials: 480 parts of P·O 42.5 ordinary silicate cement, 300 parts of high belite sulfoaluminate cement, 140 parts of mineral powder, 40 parts of silica fume, 15 parts of redispersible latex powder, 18 parts of fumed nano silica, 950 parts of manufactured sand, 0.5 parts of polydopamine-modified graphene oxide, 1.5 parts of resin microcapsule curing agent, 3 parts of polycarboxylate superplasticizer, 0.3 parts of defoamer, 0.5 parts of sodium gluconate, and 300 parts of water.

[0032] The method for preparing the high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing function according to the present invention using the above raw materials includes the following steps: Step S1: Weigh the ordinary silicate cement, high belite sulfoaluminate cement, mineral powder, silica fume, redispersible latex powder, fumed nano silica and manufactured sand into a mixer and dry mix at 15 rpm for 20 minutes to obtain a uniform premix. Step S2: Add polydopamine-modified graphene oxide to the premix obtained in step S1, and continue mixing for 10 minutes to obtain the first mixture; Step S3: Add the epoxy curing agent encapsulated in resin microcapsules under low-speed stirring at 280 rpm, mix for 3 minutes and then discharge to obtain dry powder of repair material; Step S4: During construction, mix the dry powder of the repair material obtained in step S3 with water, water-reducing agent and defoamer, and stir for 3 minutes to obtain a workable repair mortar.

[0033] The polydopamine-modified graphene oxide used in this embodiment is prepared through the following steps: Step A1: Add 1.0g of graphene oxide to 500mL of Tris-HCl buffer solution (pH=8.5), and ultrasonically disperse it for 45 minutes at 400W power under ice-water bath conditions to obtain a uniform graphene oxide dispersion. Step A2: Add 1.2g of dopamine hydrochloride to the graphene oxide dispersion obtained in step A1, and stir at 400rpm at 25°C for 36 hours. Step A3: After the reaction in step A2 is completed, centrifuge to obtain a solid product. Wash the product twice with deionized water and ethanol alternately. Finally, freeze-dry at -50±5℃ for 24 hours and then grind to obtain polydopamine-modified graphene oxide powder.

[0034] The epoxy curing agent encapsulated in resin microcapsules used in this embodiment is prepared through the following steps: Step B1: Mix 20g of isophorone diamine with 4g of toluene diisocyanate to form the oil phase; dissolve 5g of polyvinyl alcohol and 1g of sodium dodecyl sulfate in 200mL of deionized water to form the aqueous phase. Step B2: Add the oil phase prepared in step B1 to the aqueous phase prepared in step B1 at 50°C, and then emulsify at a high speed of 3000 rpm for 10 minutes to form a stable oil-in-water emulsion. Step B3: Add an aqueous solution containing 2.2 g of ethylenediamine dropwise to the oil-in-water emulsion prepared in step B2, and react at 50°C and 350 rpm for 4 hours. The diamine compound in the aqueous solution accounts for 5% of the water mass. Step B4: After the reaction in step B3 is completed, filter the reaction solution obtained in step B3, wash the filtered solid product four times with deionized water, then vacuum dry it at 60°C for 12 hours, then grind it into powder, and sieve it to obtain microcapsule powder with a particle size of 30-80μm.

[0035] Comparative Example 1: Basic formulation, without the addition of polydopamine-modified graphene oxide and resin microcapsule curing agent, otherwise the same as Example 1.

[0036] Comparative Example 2: Only 0.3 parts of polydopamine-modified graphene oxide were added, without adding resin microcapsule curing agent, and the rest was the same as in Example 1.

[0037] Comparative Example 3: Only 3 parts of resin microcapsule curing agent were added, without adding polydopamine-modified graphene oxide, and the rest was the same as in Example 1.

[0038] Comparative Example 4: An equal amount of ordinary graphene oxide (unmodified) was used to replace polydopamine-modified graphene oxide, and the rest was the same as in Example 1.

[0039] According to GB / T 17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)", JGJ / T 70-2009 "Test Method for Basic Properties of Building Mortar" and related professional testing methods, the performance of the high-strength and tough cement-based repair materials prepared in Examples 1-3 and Comparative Examples 1-4 was tested, and the results are shown in Table 1 below: Table 1

[0040] Note: Self-healing efficiency was determined by ultrasonic rapid recovery rate. The test method was to cure the pre-cracked specimen in an environment of 20℃ and 95%RH for 14 days.

[0041] This invention achieves a comprehensive breakthrough in performance through the synergistic effect of polydopamine-modified graphene oxide (PDA-GO) and resin microcapsule curing agents. Data shows that Example 1 exhibits a tensile bond strength of 5.6 MPa, an improvement of over 50% compared to the basic formulation, demonstrating the superior biomimetic adhesion and interface strengthening capabilities of PDA-GO. Its self-healing rate is as high as 81%, while the control groups containing only PDA-GO or only microcapsules have rates of 0% and 65%, respectively, highlighting the indispensability and synergistic effect of both in triggering intelligent repair. Crucially, the self-healing rate of Comparative Example 4, using ordinary graphene oxide, plummeted to 15%, indicating that polydopamine surface modification is a core prerequisite for solving the dispersion of nanomaterials and enabling their effective synergy with the microcapsule system. As shown in Table 1, the experimental results of this application are significantly superior to the comparative examples in terms of mechanical properties, bond strength, and self-healing ability.

[0042] The experimental results above show that the technical solution of the present invention has the following characteristics: (i) By introducing polydopamine-modified graphene oxide, the strong chemical interaction between its surface catechol groups and the interface between new and old concrete is utilized to achieve a leap from physical bonding to chemical bonding, which significantly improves the bonding strength.

[0043] (ii) Through the synergy of fumed nano-silica and modified graphene oxide, nanoscale filling and reinforcement were achieved. At the same time, the graphene oxide sheets could bridge microcracks, greatly improving the toughness and crack resistance of the material.

[0044] (iii) By introducing epoxy curing agents encapsulated in resin microcapsules, the material is endowed with intelligent self-healing capabilities. Microcracks can trigger the release and curing of the repair agent, automatically repairing the damage and thus blocking the erosion path, greatly improving long-term durability.

[0045] (iv) Polydopamine-modified graphene oxide can significantly improve the bonding strength and bulk toughness of the material at the interface with old concrete; the curing agent is encapsulated in microcapsules, which can rupture when microcracks occur in the material and trigger a repair reaction to achieve self-healing. The two work synergistically to give the material both excellent immediate bonding performance and long-term durability.

[0046] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing functions, characterized in that, The raw materials, by mass parts, include: 400-500 parts of ordinary silicate cement, 250-300 parts of high belite sulfoaluminate cement, 100-150 parts of mineral powder, 20-50 parts of silica fume, 10-30 parts of redispersible latex powder, 5-20 parts of fumed nano silica, 800-1000 parts of manufactured sand, 0.05-0.5 parts of polydopamine-modified graphene oxide, 1-5 parts of epoxy curing agent, 2-5 parts of water-reducing agent, 2.5-3 parts of defoamer, 0.4-0.5 parts of retarder, and 250-300 parts of water; The epoxy curing agent is encapsulated in resin microcapsules.

2. The high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing function according to claim 1, characterized in that, The microcapsule wall material of the resin microcapsules is made of urea-formaldehyde resin, melamine resin, or polyurethane.

3. A high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing functions according to claim 1 or 2, characterized in that, The process of encapsulating epoxy curing agents in resin microcapsules includes: An epoxy resin curing agent is mixed with an isocyanate monomer to form an oil phase, wherein the mass ratio of the epoxy resin curing agent to the isocyanate monomer is 5:1; an emulsifier is dissolved in water to form an aqueous phase, wherein the emulsifier accounts for 1%-5% of the water mass. The oil phase is added to the aqueous phase and sheared and emulsified at a speed of 1000-3000 rpm for 10-30 minutes to form an oil-in-water emulsion; wherein the mass-volume ratio of the oil phase to the aqueous phase is 24:(195-205). An aqueous solution of a diamine compound is added dropwise to the oil-in-water emulsion, and then the mixture is stirred at 40-60°C and 340-360 rpm for 2-6 hours. After the reaction is complete, the mixture is filtered, washed, and dried, and then ground into powder to obtain epoxy curing agent encapsulated in resin microcapsules. The epoxy curing agent is encapsulated in resin microcapsules. The molar ratio of the diamine compound to the isocyanate monomer is (0.9-1.1):1, and the diamine compound accounts for 3%-8% of the water mass in the aqueous solution.

4. The high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing function according to claim 3, characterized in that, The epoxy resin curing agent is isophorone diamine or hexamethylene diamine; the isocyanate monomer is toluene diisocyanate or hexamethylene diisocyanate. The emulsifier used is polyvinyl alcohol and / or sodium dodecyl sulfate; Diamine compounds are made of ethylenediamine or hexamethylenediamine; During washing and drying, the filtered solid product is washed 2-4 times with deionized water, then vacuum dried at 40-60℃ for 12-24 hours to remove moisture, and then ground into powder to obtain epoxy curing agent encapsulated in resin microcapsules.

5. A high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing function according to claim 3, characterized in that, The average particle size of the epoxy curing agent encapsulated in resin microcapsules is 10-100 micrometers.

6. The high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing function according to claim 1, characterized in that, The preparation methods of polydopamine-modified graphene oxide include: Graphene oxide was dispersed in a buffer solution with a pH of 8.0-9.0 to form a uniform graphene oxide dispersion. Dopamine hydrochloride was added to the graphene oxide dispersion, and the mixture was stirred at 20-30°C for 12-48 hours. After that, solid-liquid separation was performed, and the separated solid product was washed and dried to obtain the polydopamine-modified graphene oxide. The mass ratio of dopamine to graphene oxide was (0.5-2):1, and the stirring rate during the reaction was 390-410 rpm.

7. A high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing function according to claim 6, characterized in that, The buffer solution used is tris(hydroxymethyl)aminomethane hydrochloride buffer solution, with each gram of graphene oxide dispersed in 495-505 mL of tris(hydroxymethyl)aminomethane hydrochloride buffer solution. After adding graphene oxide to a tris(hydroxymethyl)aminomethane hydrochloride buffer solution, the solution is treated in an ice-water bath under ultrasonic conditions of 300-500W for 30-60 minutes to form a uniform graphene oxide dispersion.

8. A high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing function according to claim 6, characterized in that, When washing and drying the separated solid product, the solid product is washed with deionized water and ethanol alternately 2-4 times, and then dried at -45℃ to -55℃ for 24-48 hours. Then it is ground into powder to obtain the polydopamine modified graphene oxide.

9. A high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing functions according to claim 1, characterized in that, The water-reducing agent is polycarboxylate high-efficiency water-reducing agent, the defoamer is organosilicon defoamer, the retarder is sodium gluconate, the ordinary silicate cement is P·O 42.5 ordinary silicate cement, and the mineral powder is S95 grade mineral powder.

10. A method for preparing a high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing function as described in any one of claims 1-9, characterized in that, The process includes the following: Ordinary silicate cement, high belite sulfoaluminate cement, mineral powder, silica fume, fumed nano silica, redispersible latex powder and manufactured sand are dry-mixed to obtain a uniform premix; wherein the mixing speed is 15-30 rpm and the mixing time is 10-20 minutes. Add polydopamine-modified graphene oxide to the premix and continue mixing for 5-10 minutes to obtain the first mixture; Under stirring conditions of 100-300 rpm, epoxy curing agent encapsulated in resin microcapsules is added to the first mixture. The mixing time is 3-8 minutes. After mixing, the material is discharged to obtain dry powder of repair material. The dry powder of the repair material is mixed with water, water-reducing agent, defoamer and retarder to obtain the high-strength and tough cement-based repair material based on biomimetic adhesion and self-healing function.

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