A cement-based tough water-stopping mortar suitable for underwater repair of concrete joints and its rapid construction process.

Abstract

This invention discloses a cement-based tough water-stopping mortar suitable for underwater repair of concrete joints and its rapid construction process. The cement-based tough water-stopping mortar is formulated from three components: powder, polymer emulsion, and water. The powder is composed of cement, vitrified microspheres, modified fibers, modified rubber particles, quartz sand, water-reducing agent, defoamer, and anti-dispersing agent. Based on cement-based materials, this invention achieves a paste-like consistency after mixing through multi-component optimization and synergistic effects. It does not flow at joints, has low viscosity, and exhibits excellent underwater anti-dispersibility, making it suitable for long-distance pressurized pipeline transportation and underwater extrusion molding. It also boasts high underwater interfacial bonding strength and, after hardening, exhibits low elastic modulus, high elasticity, and high toughness. The invention proposes an underwater construction process of "caulking repair," using a trowel to apply the mortar to the joint while simultaneously applying the mortar, suitable for rapid and long-lasting underwater repair of defects in hydraulic concrete joints.

Description

Technical Field

[0001] This invention belongs to the field of underwater repair technology for hydraulic concrete structures, and relates to a cement-based tough water-stopping mortar suitable for underwater repair of concrete joints and its rapid construction process. Background Technology

[0002] Large water conveyance structures are mainly made of concrete. Considering factors such as concrete shrinkage, temperature changes, and segmented construction, joints are often required in concrete structures. Affected by structural loads, temperature stress, and water erosion, the joints of water conveyance structures are prone to deformation, cracking, leakage, and other defects during long-term operation, leading to water loss and even major safety hazards.

[0003] The commonly used repair method is to create a dry environment during water outage maintenance by using methods such as dike isolation and venting, clean the original materials at the joint, set a waterstop on the water-facing side of the structure, and inject organic repair materials such as polyurethane or epoxy resin into the joint to achieve repair. However, the joint is often in a damp, seeping, or even underwater environment, making it impossible to achieve a dry foundation construction environment, and it needs to be quickly irrigated after construction. Unlike dry construction conditions, underwater joint repair materials need to have the following characteristics: (1) good anti-dispersion performance to prevent the repair material from dispersing and segregating underwater; (2) high underwater bonding strength, requiring a certain degree of hydrophilicity to ensure bonding with the concrete water-bearing base surface; (3) fast setting and hardening to avoid the repair material being washed away by water flow; (4) strong deformation capacity, possessing a certain degree of deformation adaptability.

[0004] Cement is a common hydraulic cementitious material widely used in civil engineering, water conservancy, and national defense projects. It sets and hardens normally in the presence of water, bonding other materials. However, when formed underwater, it easily disperses and fluidizes, affecting bond strength. Currently, underwater repair cement-based materials mainly include underwater non-dispersible cement-based materials and polymer-modified cement-based materials. Underwater non-dispersible cement-based materials are made by adding anti-dispersing agents to ordinary cement-based materials. The long-chain molecules in the anti-dispersing agent attract and overlap each other, forming a network structure that ensures the components of the cement-based material are bonded together when exposed to water. Polymer-modified cement-based materials are organic-inorganic composite materials obtained by incorporating polymers into cement mortar or concrete. The polymer can form a film with high bonding strength between aggregates and cement paste, filling the pores in the mortar and improving the density of the hardened mortar. Due to the inherent properties of the materials and the influence of construction techniques, joint repair still faces problems such as cement-based repair materials being easily washed away, slow hardening speed, low bonding strength to damp or underwater substrates, large shrinkage deformation and easy cracking after hardening, poor water-stopping effect, and poor elastic deformation capacity of materials, making it difficult to guarantee the repair effect.

[0005] Chinese patent CN112341140A discloses a concrete interface agent for wet joints in prefabricated buildings and its preparation method. The interface agent consists of two components: a powder and a liquid. The powder is composed of ultrafine cement and fly ash microspheres, and the polymer emulsion used is one or both of styrene-acrylic emulsion and pure acrylic emulsion. The concrete interface agent for wet joints in prefabricated buildings provided by this invention has high fluidity, good workability, and is easy to apply. After using the interface agent provided by this invention, the bond strength of the interface between the old concrete-interface agent-new concrete composite structure is significantly improved, and the impermeability of the wet joint interface is significantly improved. However, this invention can only be used as an interface agent and is not suitable for filling and repairing concrete joints. It needs to be applied to a dry interface, and the interface usually needs to be roughened.

[0006] Chinese patent CN110423073A discloses an ultra-early strength compensating shrinkage wet joint concrete dry mix and its preparation method. This invention utilizes the expansion effect of expansive components (calcium oxide, calcium sulfoaluminate, magnesium oxide, or calcium oxide-calcium sulfoaluminate) to compensate for the shrinkage deformation of concrete, and uses hybrid fibers (steel fibers and synthetic organic fibers) to achieve high ductility. However, it relies solely on the bond strength between cement and the old interface, without improving the bonding effect at the interface, especially at the wet interface.

[0007] Chinese patent CN114057439A discloses an elastic mortar for building exterior walls and its preparation process. Through the reaction of 2,4-toluene diisocyanate with polyether glycol, the carbon-carbon double bonds at both ends of the monomer can polymerize with the double bonds of the acrylate monomer, producing micro-crosslinks. This results in a waterproof elastic emulsion that combines the advantages of both polyurethane and acrylate emulsions. However, this invention ① only applies to building exterior wall insulation and waterproofing, and roof decoration; it does not address the bonding effect on wet or underwater interfaces in hydraulic structures. ② The mortar performance only mentions tensile bond strength under dry conditions; the mortar deformation performance remains unknown.

[0008] Chinese patent CN114163185A discloses an elastic concrete suitable for bridge expansion joints and its preparation method. Through the synergistic effect of surface hydrophilic silicone rubber and carboxylic acid-modified terminal amino water-soluble hyperbranched polyamide, the introduction of the hyperbranched structure and silicone rubber structure gives the concrete good toughness and elasticity, overcoming the defects of ordinary concrete such as low adhesion between rubber particles and cement paste, resulting in poor concrete strength, impermeability, and density. While the disclosed elastic concrete exhibits high compressive strength and modulus of elasticity, it does not describe the material's deformation properties or interfacial bond strength, making it unsuitable for underwater repair of hydraulic concrete joints.

[0009] Chinese patent CN107867814A discloses an elastic mortar composed of organic and inorganic materials. It exhibits high elasticity and flexibility. This invention utilizes the elasticity of polysulfide rubber powder and introduces flexible segments into the epoxy resin molecules through a reaction between water-based epoxy resin and the thiol groups at the ends of the polysulfide rubber, increasing the plastic deformation capacity of the matrix. It is primarily intended for use on floors in recreational venues. However, the raw materials contain emulsified asphalt and water-based epoxy resin emulsion, which can affect interfacial adhesion in humid environments, making it unsuitable for repairing damp joints.

[0010] Chinese patent CN110204836A discloses a waterproof joint material for tunnel concrete structure joints. It consists of a substrate made of closed-cell rubber foam board and a self-adhesive layer coated on the side of the substrate for bonding with the concrete surface. The joint uses a double-sided self-adhesive rubber waterproof material, with the self-adhesive strip bonded to the concrete. The material requires heating and insulation during construction, making the process complex, and the raw materials may cause environmental pollution.

[0011] Chinese patent CN101684643A discloses the application of a fly ash-based channel joint waterproofing material in damp interfaces or underwater construction. The material is synthesized from fly ash, polyether-type polyurethane prepolymer, curing agent, catalyst, antioxidant, and UV absorber. However, this invention has several drawbacks: ① the material composition contains a large amount of organic matter such as polyether-type polyurethane prepolymer, petroleum asphalt, thin oil, and toluene, and the preparation process is complex; ② although the bonding strength of the joint waterproofing material in damp interfaces or underwater construction reaches more than 80% of the bonding strength in dry interfaces, the bonding strength at both dry and damp interfaces is low, not exceeding 1.1 MPa; ③ the underwater construction performance and deformation performance of the material are not mentioned.

[0012] Chinese patent CN109305789A discloses a cement-based elastic grouting material suitable for repairing deep-water concrete cracks and its preparation method. Using cement, slag powder, and rubber powder as base materials, silica fume, gypsum powder, polyester fiber, water-reducing agent, water-based latex, and water-based curing agent are added in a certain proportion. After mixing with water, an underwater non-dispersible plastic body suitable for grouting is formed. After solidification, it forms an elastic solid that firmly bonds to the interface of the concrete crack. The addition of water-based acrylic emulsion and water-based epoxy curing agent improves the underwater bonding strength of the elastic solidified body; the water-based epoxy curing agent effectively promotes the curing and film formation of the acrylic latex; and the polyester fiber and rubber powder give the solidified body elastic deformation capability. However, this invention has the following drawbacks: ① using mortar flexural strength to characterize bonding strength is inaccurate; ② the material is mainly applied to repairing cracks of about 2mm in hydraulic concrete structures, and its effectiveness in repairing larger-width concrete joints is unknown; ③ it does not propose the material's underwater anti-dispersion effect or corresponding underwater construction technology.

[0013] Chinese patent CN102674779A discloses a modified expandable waterproof mortar and its preparation method. It uses a mixed lightweight aggregate composed of waste rubber powder and waste polyurethane as the crack-resistant component of the mortar, significantly improving its flexibility and elasticity. However, this invention ① while incorporating waste polyurethane particles and rubber particles reduces the material's compressive strength and elastic modulus, does not address its elastic deformation capacity or adhesion performance at wet interfaces. ② its application in waterproofing door and window openings and cantilever structures in building engineering, and its effectiveness in underwater repair of concrete joints, remains unknown.

[0014] Chinese patent CN111362646A discloses a low-modulus, flexible, ultra-high-toughness mortar concrete system and its preparation method. It addresses the problems of low early strength, high modulus of elasticity, insufficient flexibility, and large shrinkage deformation in existing ultra-high-toughness mortar concretes by employing sulfoaluminate cement, rubber powder, blends of different fibers, and calcium oxide-based expansive agents. The fiber content is as high as 10-40 kg / m³. 3 The rubber powder has a relatively large particle size of 200-300 mesh, and the fiber is a new type of polyoxymethylene fiber. Although this mortar concrete has low elastic modulus and high uniaxial tensile deformation performance, its shrinkage deformation and interfacial bonding performance are not mentioned. It can be used for earthquake-resistant, impact-resistant, or collision-resistant concrete structures, but is not suitable for repairing defects in concrete in humid or underwater environments.

[0015] Chinese patent CN108585700A discloses a joint mortar and its preparation method. It addresses the shortcomings of traditional building mortars, such as easy cracking and weak adhesion, by incorporating vermiculite to improve compressive and bond strength, styrene-butadiene emulsion to enhance density, and tributyl acetylacetonate to improve water retention. However, this invention has several drawbacks: ① the mortar's 28-day compressive strength does not exceed 30 MPa, and its 28-day bond strength at the dry interface is less than 1.5 MPa. There is no data to support its crack resistance and shrinkage deformation performance. ② When applied to wall joints in building construction, its effectiveness for underwater repair of concrete joints remains unknown.

[0016] Chinese patent CN110357521A discloses a lightweight, high-strength, and high-ductility mortar and its preparation method. It uses slag powder, silica fume, and recycled powder as active mineral admixtures, cement as a cementing material, and fly ash cenospheres, glass microspheres, and recycled rubber powder as lightweight fillers. It also incorporates water-reducing agents and reinforcing fibers. Through appropriate composition, the mortar material possesses lightweight, high compressive strength, high tensile strength, and high tensile ductility. Fly ash cenospheres, glass microspheres, and recycled rubber powder are used to reduce the mortar density. By reducing the sand ratio and selecting ultra-high molecular weight polyethylene fibers and polyester fibers, fiber bridging is achieved, resulting in a toughening effect. However, this invention has high requirements for mortar raw materials, composition ratios, preparation, and curing conditions, primarily emphasizing lightweight and high ductility, but does not address the interfacial bonding performance of the materials.

[0017] Chinese patent CN110357521A discloses a rubber powder ultra-high ductility mortar for architectural 3D printing, solving the problems of poor tensile strength and inability to completely detach from reinforcing steel in ordinary 3D printing mortar materials. Silica fume is used as an active admixture to improve the long-term strength of the material, while the addition of rubber powder regulates the matrix strength, improving tensile strength and elongation. However, the order of raw material addition and the quality of mixing have a significant impact on the subsequent printing performance and mechanical properties of the mortar, requiring preparation according to a specific mixing method.

[0018] In summary, there is currently limited research on cement-based tough water-stopping mortars for underwater repair of hydraulic concrete joints. This invention, based on cement-based materials, proposes a new approach to underwater repair materials for concrete joints and corresponding rapid construction techniques by improving underwater bonding and deformation properties, providing a reference for underwater reinforcement and strengthening of concrete structures. Summary of the Invention

[0019] To improve the treatment of underwater defects in hydraulic structures and solve problems such as the difficulty of underwater repair of concrete joints, easy dispersion of repair materials underwater, low bonding strength with the substrate, and poor deformation adaptability after hardening, this invention develops a cement-based tough water-stopping mortar with properties such as non-dispersion underwater, high bonding strength underwater, low elastic modulus and high toughness, and proposes its rapid underwater construction process.

[0020] The present invention discloses a cement-based tough water-stopping mortar suitable for underwater repair of concrete joints and its rapid construction process, comprising the following contents:

[0021] The cement-based tough water-stopping mortar for underwater repair of concrete joints described in this invention is composed of three parts: powder, polymer emulsion and water, wherein the mass ratio of powder, polymer emulsion and water is (83~90):(1~6):(9~11).

[0022] The polymer emulsion is one or two of the following: acrylic copolymer emulsion, styrene-butadiene emulsion, ethylene-vinyl acetate copolymer emulsion, styrene-acrylic emulsion, chloroprene rubber emulsion, and polyvinyl acetate emulsion.

[0023] The type and amount of polymer emulsion directly affect the underwater interfacial bonding strength of mortar materials. By reducing the width of the transition zone between the mortar and the substrate, improving compactness, reducing interfacial microcracks, and increasing the mechanical interlocking force and chemical bonding with the old interface.

[0024] Preferably, the polymer emulsion is a combination of ethylene-vinyl acetate copolymer emulsion and polyvinyl acetate emulsion in a mass ratio of (4~6):(0~2);

[0025] More preferably, the polymer emulsion is a combination of ethylene-vinyl acetate copolymer emulsion and polyvinyl acetate emulsion, with the ratio of the two emulsions being (3~5):1.

[0026] More preferably, the polymer emulsion is a combination of ethylene-vinyl acetate copolymer emulsion and polyvinyl acetate emulsion in a mass ratio of 5:1;

[0027] The powder is composed of 850-950 parts of cement, 50-150 parts of vitrified microspheres, 2-4 parts of modified fiber, 300-650 parts of modified rubber particles, 1500-1850 parts of quartz sand, 2-4 parts of water-reducing agent, 0.5-1 part of defoamer, and 1-2 parts of anti-dispersing agent.

[0028] The cement is general-purpose Portland cement with a strength grade ≥42.5;

[0029] The vitrified microspheres are made from mineral sand with a silica content of over 90%, finely ground to 100-300 mesh, granulated, calcined, and cooled before being placed in a high-speed mixer. During stirring at 500-1000 rpm, 1%-2% of γ-aminopropylsilane coupling agent is added uniformly. After all the silane coupling agent is added, hot air at 60-80℃ is introduced into the mixer, and the reaction time is 30-60 minutes. Finally, the mixture is naturally cooled to room temperature and sieved to obtain a sphere formation rate ≥90%, a closed-cell rate ≥85%, and a specific surface area ≥1200 m². 2 Vitrified microspheres with an activity index ≥100% for 28 days / kg;

[0030] The antidispersant is one of polyacrylamide, hydroxypropyl methylcellulose ether, and polyacrylamide;

[0031] The water-reducing agent is one of melamine-based high-efficiency water-reducing agent and polycarboxylate-based high-performance water-reducing agent, in powder form, with a water reduction rate of not less than 25%.

[0032] The defoamer is one of amine polyether defoamer and polyether-modified silicone defoamer;

[0033] The quartz sand has a particle size range of 0.315~1.25mm and an apparent density of not less than 2500kg / m³. 3 .

[0034] The modified fiber is obtained by impregnating the fiber in a mixture of γ-aminopropylsilane coupling agent and then drying it.

[0035] More preferably, the modified fiber is obtained by immersing the selected fiber in a γ-aminopropylsilane coupling agent mixture at 40~60℃ for 60~90 minutes and then drying it; the fiber is selected from one or two of polyvinyl alcohol fiber (PVA), polypropylene fiber (PP), polyoxymethylene fiber (POM), and polyacrylonitrile fiber (PAN), with an equivalent diameter of 5~200µm and a length of 6~12mm.

[0036] The γ-aminopropylsilane coupling agent mixture is obtained by hydrolyzing the γ-aminopropylsilane coupling agent in a solution of water: anhydrous ethanol = (1~3):(7~9) and adjusting the pH to 3~5.

[0037] Modifying fibers with γ-aminopropylsilane coupling agent is more effective than other modification methods, significantly improving the bond strength between fibers and hardened cement paste and enhancing synergistic performance.

[0038] The type and amount of modified fibers directly affect the tensile deformation performance of mortar materials. Increasing the amount of modified fibers can increase the ultimate tensile value of mortar, and the performance of the combination of two fibers is better than that of a single fiber under the same dosage.

[0039] The modified fiber is preferably a mixture of two types, polypropylene fiber (PP) and polyoxymethylene fiber (POM), in a mass ratio of (2~4):(0~2).

[0040] More preferably, the modified fiber is a mixture of polypropylene fiber (PP) and polyoxymethylene fiber (POM) in a mass ratio of 3:1.

[0041] The modified rubber particles have a fineness range of 16~60 mesh;

[0042] The modified rubber granules are composed of two particle sizes, 16-30 mesh and 30-60 mesh, in a mass ratio of 3:1, with a density of 0.85-1.20 kg / m³. 3 .

[0043] The mass ratio of two types of rubber particles directly affects the state of the mortar mixture, as well as the probability of interface defects in the hardened mortar and the tensile deformation properties of the mortar. In this invention, it is preferred that the two particle sizes, 16~30 mesh and 30~60 mesh, be composed in a mass ratio of 3:1.

[0044] The rubber granules are first washed with water and air-dried; then soaked in a 5% NaOH aqueous solution for 20-30 minutes, washed until neutral, and dried at a low temperature of 30-40℃; then placed in a solution containing 1% NaOH... c The modified rubber particles were obtained by immersing the 1-(methacryloyloxy)propyltrimethoxysilane coupling agent in an ethanol solution for 30-40 minutes and then drying it at a low temperature of 30-40℃.

[0045] The powder, through the "ball effect" of vitrified microspheres combined with a high-performance water-reducing agent, can improve the workability of the repair mortar and enhance its fluidity for pressurized transportation over long distances. A preferred anti-dispersing agent further improves the underwater anti-dispersibility of the repair mortar. The cement-based toughening waterproofing mortar, after mixing, is a paste with high underwater anti-dispersibility, a viscosity ≤5 Pa·s, and an adjustable setting and hardening time within the range of 1~5 hours. It is suitable for pressurized transportation over long distances and underwater extrusion molding.

[0046] The "ball effect" of vitrified microspheres can reduce the viscosity of mortar mixtures, and the viscosity of mortar gradually decreases as the amount of vitrified microspheres increases.

[0047] Choosing the right type of antidispersant and increasing the amount of antidispersant can improve the underwater antidispersibility of the mixture. Polyacrylamide has the best effect at the same dosage. Although increasing the amount of antidispersant will significantly reduce the underwater antidispersibility turbidity of the mixture, it will also increase the plastic viscosity of the mixture and affect the underwater interfacial adhesion of the material.

[0048] The experiment of this invention found that when the viscosity of the cement-based mortar mixture is ≤5 Pa·s and the underwater anti-dispersion turbidity is ≤50 NTU by adjusting the amount of vitrified microspheres and anti-dispersion agent, the repair mortar has the fluidity required for long-distance pipeline pressurized transportation and the anti-dispersion properties required for underwater extrusion molding.

[0049] As the amount of modified rubber particles increases, the tensile elastic modulus of cement-based mortar gradually decreases. However, the increased amount of rubber particles will increase the probability of weak interfaces in the material, which will reduce the tensile deformation performance and flexural toughness of the mortar. The optimal range for the amount of modified rubber particles is 300 to 750 parts (14% to 32% of the total mass of sand), with the optimal value being 550 parts.

[0050] The synergistic effect of modified rubber particles and hybrid fibers enables hardened cement-based mortar to possess properties such as low elastic modulus, high elasticity, high toughness, and adaptability to large deformations, with a 28-day tensile modulus of elasticity <4.0 GPa and an ultimate tensile strength ≥400 × 10⁻⁶. -6 Flexural toughness index I 5 > 4.0.

[0051] The preferred mass ratio of powder, polymer emulsion and water in the cement-based tough water-stopping mortar used for underwater repair of concrete joints is 85:(4~6):(9~11).

[0052] The polymer emulsion is preferably an ethylene-vinyl acetate copolymer emulsion and a polyvinyl acetate emulsion, with the two emulsions blended in a ratio of 5:1.

[0053] More preferably, the powder of this invention is composed of 850-900 parts of cement, 100-150 parts of vitrified microspheres, 2-4 parts of modified fiber, 550-650 parts of modified rubber particles, 1600-1850 parts of quartz sand, 2-4 parts of water-reducing agent, 1 part of defoamer, and 1-2 parts of anti-dispersing agent.

[0054] More preferably, the powder is composed of 850 parts cement, 150 parts vitrified microspheres, 4 parts modified fiber, 550 parts modified rubber particles, 1600 parts quartz sand, 3-4 parts water-reducing agent, 1 part defoamer, and 1.5-2 parts anti-dispersant agent.

[0055] The preparation method of the cement-based tough water-stopping mortar for underwater repair of concrete joints according to the present invention is as follows: First, add the weighed polymer emulsion and water to the mixing tank and stir at a speed of 300~500 r / min for 10~15 min; then add the pre-mixed powder and stir at a speed of 1000~1200 r / min for 3~5 min to obtain the final product.

[0056] The prepared cement-based tough water-stopping mortar, after mixing, is in the form of a paste with a plastic viscosity ≤5 Pa·s, an underwater anti-dispersion turbidity ≤50 NTU, an underwater forming strength of ≥1.0 MPa after 1 day and ≥2.5 MPa after 28 days, and a tensile modulus of elasticity <4.0 GPa and an ultimate tensile strength ≥400 × 10⁻⁶ after 28 days of hardening. -6 Flexural toughness index I 5 > 4.0, meeting the needs for rapid and long-term underwater repair of materials.

[0057] This invention discloses a rapid construction process for cement-based tough water-stopping mortar suitable for underwater repair of concrete joints. It adopts a "caulking and repair" approach. The cement-based tough water-stopping mortar is prepared on land and then extruded through pipelines to an underwater operating platform. Divers or underwater robots operate a trowel with a pre-reserved discharge port, pressing the mortar onto the joint while moving it to discharge the mortar for repair. The specific steps are as follows:

[0058] ① Use specialized equipment to mix and store cement-based tough water-stopping mortar on the shore;

[0059] ② Connect the material container outlet and the trowel through the high-pressure pipe, move it to the underwater joint repair work surface, and press the trowel onto the joint;

[0060] ③ The material is extruded through a grouting machine and squeezed into the joint through the pre-drilled holes in the trowel.

[0061] ④ A diver or underwater robot carrying a trowel moves forward along the joint defect location, maintaining a certain pressure on the trowel while moving and discharging material to complete the filling and repair of the joint defect.

[0062] This invention is based on cement-based materials. Through multi-component optimization and synergistic effects, it improves the viscosity, underwater adhesion, and elastic deformation properties of the mixture. The resulting cement-based tough water-stopping mortar is paste-like, does not flow at joints, has low viscosity, and excellent underwater anti-dispersion properties. It is suitable for long-distance pipeline pressurization and underwater extrusion molding. It has high underwater interfacial bonding strength and, after hardening, exhibits low modulus of elasticity, high elasticity, and high toughness. The invention also proposes an underwater construction process for "joint caulking repair," which involves pressing a trowel onto the joint while simultaneously applying the material and smoothing the surface. This process is suitable for rapid and long-lasting underwater repair of joint defects in hydraulic concrete structures.

[0063] The cement-based toughening waterproof mortar for underwater repair of concrete joints and its rapid construction process described in this invention can be applied to underwater repair projects for defects in concrete structures. Compared with the prior art, the beneficial effects of this invention are:

[0064] ① By combining the "ball effect" of vitrified microspheres with high-performance water-reducing agents, the workability of the repair mortar is improved, and the fluidity of pressurized transportation in long-distance pipelines is enhanced; an anti-dispersing agent is selected to improve the underwater anti-dispersibility of the repair mortar. The cement-based tough water-stopping mortar is paste-like after mixing, has high underwater anti-dispersibility, a viscosity ≤5Pa·s, and an adjustable setting and hardening time within the range of 1~5h, making it suitable for pressurized transportation in long-distance pipelines and underwater extrusion molding.

[0065] ② The addition of polymer emulsion significantly reduces the width of the transition zone between the mortar and the substrate, improves compactness, reduces microcracks at the interface, increases the mechanical interlocking force and chemical bonding with the old interface, and greatly improves the underwater bonding strength of the repair mortar. The bonding strength with concrete after 1 day of underwater curing is ≥1.0MPa, the bonding strength after 28 days is ≥2.5MPa, and the ratio of water-land compressive strength is ≥90%. It is suitable for rapid and long-term repair of underwater defects.

[0066] ③ Through modification, the interfacial adhesion between rubber particles, fibers, and cement-based materials is enhanced. Specifically, rubber particles reduce the elastic modulus of the repair material and impart elasticity; the synergistic effect of rubber particles and hybrid fibers improves the tensile deformation performance of the cement-based repair material, reduces energy dissipation during deformation, and significantly enhances the toughness of the repair material. After hardening, the cement-based toughening waterproof mortar exhibits characteristics such as low elastic modulus, high elasticity, high toughness, and adaptability to large deformations, with a 28-day tensile modulus <4.0 GPa and an ultimate tensile value ≥400 × 10⁻⁶. -6 Flexural toughness index I 5 > 4.0.

[0067] ④ Based on the characteristics of repair mortar materials, a "caulking repair" construction process was proposed, which involves simultaneous onshore slurry preparation, pipeline transportation, and troweling. This process can solve the problems of carrying repair materials and rapidly forming a troweled surface under the influence of flowing water. Combined with underwater defect detection technology and equipment, it can be extended to the operation and maintenance and emergency rescue of underwater structures in major engineering projects, such as reservoirs, dams, water diversion projects, water-related bridges, and municipal pipelines, with significant economic and social benefits.

[0068] ⑤ The raw materials of cement-based tough water-stopping mortar are mostly cement-based materials such as cement and fly ash. It not only has the characteristics of hydraulicity, but also has the advantages of wide material source and low cost. In addition, it uses a large amount of waste recycled raw material rubber particles. Compared with commonly used organic repair products such as epoxy resin and polyurethane, the cost of the repair mortar material of this invention is significantly reduced. Detailed Implementation

[0069] To more clearly describe the technical solution of the present invention, the present invention will be further described below with reference to specific embodiments. These embodiments are only used to better explain the content of the present invention, but do not limit the present invention. All similar embodiments listed based on the present invention should fall within the protection scope of the present invention.

[0070] All raw materials described in this invention can be obtained through publicly available means.

[0071] Example 1

[0072] 1) Cement-based tough water-stopping mortar for underwater repair of concrete joints is composed of three parts: powder, polymer emulsion, and water, with a mass ratio of 85:4:11. The polymer emulsion is an acrylic copolymer emulsion; the powder is composed of 950 parts cement, 50 parts vitrified microspheres, 2 parts modified fiber, 300 parts rubber granules, 1850 parts quartz sand, 2 parts water-reducing agent, 0.5 parts defoamer, and 1 part anti-dispersant. The cement is P∙O 42.5 ordinary Portland cement; the vitrified microspheres have a sphericity rate ≥90%, a closed-cell rate ≥95%, and a specific surface area ≥1200 m². 2 / kg, 28d activity index ≥100%; the rubber granules are unmodified, composed of two particle sizes, 16~30 mesh and 30~60 mesh, in a mass ratio of 3:1, with a density of 0.85~1.20 kg / m³. 3 The anti-dispersant is hydroxypropyl methylcellulose ether; the water-reducing agent is a polycarboxylate-based high-performance water-reducing agent in powder form; the defoamer is a polyether-modified silicone defoamer; the quartz sand has a particle size range of 0.315~1.25mm and an apparent density of not less than 2500kg / m³. 3 .

[0073] 2) The modified fiber is polyvinyl alcohol (PVA) fiber with an equivalent diameter of 200µm and a length of 6mm. The γ-aminopropylsilane coupling agent is pre-hydrolyzed in a solution of water:anhydrous ethanol = 3:7, and the pH is adjusted to 3-5. The selected fiber is then immersed in the mixture at 60℃ for 60 minutes and dried.

[0074] 3) First, add the weighed polymer emulsion and water to the mixing tank and stir at 500 r / min for 10 min; then add the pre-mixed powder and stir at 1000 r / min for 5 min to obtain the final product.

[0075] Example 2

[0076] 1) Cement-based tough water-stopping mortar for underwater repair of concrete joints is composed of three parts: powder, polymer emulsion, and water, with a mass ratio of 85:4:11. The polymer emulsion is an acrylic copolymer emulsion; the powder is composed of 950 parts cement, 50 parts vitrified microspheres, 2 parts fiber, 300 parts modified rubber particles, 1850 parts quartz sand, 2 parts water-reducing agent, 0.5 parts defoamer, and 1 part anti-dispersant agent. The cement is P∙O 42.5 ordinary Portland cement; the vitrified microspheres have a sphericity rate ≥90%, a closed-cell rate ≥95%, and a specific surface area ≥1200 m². 2 / kg, 28-day activity index ≥100%; unmodified fiber, selected as polyvinyl alcohol fiber (PVA) with an equivalent diameter of 200µm and a length of 6mm. Anti-dispersant is hydroxypropyl methylcellulose ether; water-reducing agent is a polycarboxylate-based high-performance water-reducing agent (powder); defoamer is a polyether-modified silicone defoamer; quartz sand particle size range 0.315~1.25mm, apparent density not less than 2500kg / m³. 3 .

[0077] 2) The modified rubber particles have a fineness range of 16-60 mesh, and are composed of two particle sizes, 16-30 mesh and 30-60 mesh, in a mass ratio of 3:1, with a density of 0.85-1.20 kg / m³. 3 The rubber granules are first washed with water and air-dried; then soaked in a 5% NaOH aqueous solution for 30 minutes, washed with water until neutral, and dried at 30℃; then placed in a solution containing 1% NaOH... c The 1-(methacryloyloxy)propyltrimethoxysilane coupling agent was immersed in an ethanol solution for 30 minutes and then dried at 30°C.

[0078] 3) First, add the weighed polymer emulsion and water to the mixing tank and stir at 500 r / min for 10 min; then add the pre-mixed powder and stir at 1000 r / min for 5 min to obtain the final product.

[0079] Example 3

[0080] 1) Cement-based tough water-stopping mortar for underwater repair of concrete joints is composed of three parts: powder, polymer emulsion, and water, with a mass ratio of 85:4:11. The polymer emulsion is an acrylic copolymer emulsion; the powder is composed of 950 parts cement, 50 parts vitrified microspheres, 2 parts modified fiber, 300 parts modified rubber particles, 1850 parts quartz sand, 2 parts water-reducing agent, 0.5 parts defoamer, and 1 part anti-dispersant. The cement is P∙O 42.5 ordinary Portland cement; the vitrified microspheres have a sphericity rate ≥90%, a closed-cell rate ≥95%, and a specific surface area ≥1200 m². 2 / kg, 28d activity index ≥100%; anti-dispersant is hydroxypropyl methylcellulose ether; water-reducing agent is polycarboxylate-based high-performance water-reducing agent, powder; defoamer is polyether-modified silicone defoamer; quartz sand particle size range 0.315~1.25mm, apparent density not less than 2500kg / m³ 3 .

[0081] 2) The modified fiber is polyvinyl alcohol (PVA) fiber with an equivalent diameter of 200µm and a length of 6mm. The γ-aminopropylsilane coupling agent is pre-hydrolyzed in a solution of water:anhydrous ethanol = 3:7, and the pH is adjusted to 3-5. The selected fiber is then immersed in the mixture at 60℃ for 60 minutes and dried.

[0082] 3) The modified rubber particles have a fineness range of 16-60 mesh, and are composed of two particle sizes, 16-30 mesh and 30-60 mesh, in a mass ratio of 3:1, with a density of 0.85-1.20 kg / m³. 3 The rubber granules are first washed with water and air-dried; then soaked in a 5% NaOH aqueous solution for 30 minutes, washed with water until neutral, and dried at 30℃; then placed in a solution containing 1% NaOH... c The 1-(methacryloyloxy)propyltrimethoxysilane coupling agent was immersed in an ethanol solution for 30 minutes and then dried at 30°C.

[0083] 4) First, add the weighed polymer emulsion and water to the mixing tank and stir at 500 r / min for 10 min; then add the pre-mixed powder and stir at 1000 r / min for 5 min to obtain the final product.

[0084] Example 4

[0085] 1) The cement-based tough water-stopping mortar for underwater repair of concrete joints is composed of three parts: powder, polymer emulsion, and water, with a mass ratio of 85:4:11. The polymer emulsion is a styrene-butadiene emulsion; the powder is composed of 900 parts cement, 100 parts vitrified microspheres, 4 parts modified fiber, 300 parts modified rubber particles, 1850 parts quartz sand, 2 parts water-reducing agent, 1 part defoamer, and 1 part anti-dispersant agent. The cement is P∙O 42.5 ordinary Portland cement; the vitrified microspheres have a sphericity rate ≥90%, a closed-cell rate ≥95%, and a specific surface area ≥1200 m². 2 / kg, 28d activity index ≥100%; anti-dispersant is polyacrylamide; water-reducing agent is polycarboxylate-based high-performance water-reducing agent (powder); defoamer is amine polyether defoamer; quartz sand particle size range 0.315~1.25mm, apparent density not less than 2500kg / m³ 3 .

[0086] 2) The modified fiber is polyacrylonitrile fiber (PAN) with an equivalent diameter of 5-200µm and a length of 12mm. The γ-aminopropylsilane coupling agent is pre-hydrolyzed in a solution of water:anhydrous ethanol = 3:7, and the pH is adjusted to 3-5. The selected fiber is then immersed in the mixture at 40℃ for 90 minutes and dried.

[0087] 3) The modified rubber particles have a fineness range of 16-60 mesh, and are composed of two particle sizes, 16-30 mesh and 30-60 mesh, in a mass ratio of 3:1, with a density of 0.85-1.20 kg / m³. 3 The rubber granules are first washed with water and air-dried; then soaked in a 5% NaOH aqueous solution for 20-30 minutes, washed with water until neutral, and dried at a low temperature of 30℃; then placed in a solution containing 1% NaOH... c The 1-(methacryloyloxy)propyltrimethoxysilane coupling agent was immersed in an ethanol solution for 30 minutes and then dried at 30°C.

[0088] 4) First, add the weighed polymer emulsion and water to the mixing tank and stir at 500 r / min for 10 min; then add the pre-mixed powder and stir at 1000 r / min for 5 min to obtain the final product.

[0089] Example 5

[0090] 1) The cement-based tough water-stopping mortar for underwater repair of concrete joints is composed of three parts: powder, polymer emulsion, and water, with a mass ratio of 85:4:11. The polymer emulsion is an ethylene-vinyl acetate copolymer emulsion; the powder is composed of 850 parts cement, 150 parts vitrified microspheres, 4 parts modified fiber, 650 parts modified rubber particles, 1500 parts quartz sand, 3 parts water-reducing agent, 1 part defoamer, and 1 part anti-dispersant agent. The cement is P∙O 42.5 ordinary Portland cement; the vitrified microspheres have a sphericity rate ≥90%, a closed-cell rate ≥95%, and a specific surface area ≥1200 m². 2 / kg, 28d activity index ≥100%; anti-dispersant is polyacrylamide; water-reducing agent is polycarboxylate-based high-performance water-reducing agent, powder; defoamer is amine polyether defoamer; quartz sand particle size range 0.315~1.25mm, apparent density not less than 2500kg / m³ 3 .

[0091] 2) The modified fiber is selected from polypropylene (PP) fiber with an equivalent diameter of 200µm and a length of 12mm. The γ-aminopropylsilane coupling agent is hydrolyzed in a solution of water:anhydrous ethanol = 3:7 beforehand, and the pH is adjusted to 3~5. Then, the selected fiber is immersed in the mixed solution at 40℃ for 90min and then dried.

[0092] 3) The modified rubber particles have a fineness range of 16-60 mesh, and are composed of two particle sizes, 16-30 mesh and 30-60 mesh, in a mass ratio of 3:1, with a density of 0.85-1.20 kg / m³. 3 The rubber granules are first washed with water and air-dried; then soaked in a 5% NaOH aqueous solution for 30 minutes, washed with water until neutral, and dried at a low temperature of 40℃; then placed in a solution containing 1% NaOH... c The 1-(methacryloyloxy)propyltrimethoxysilane coupling agent was immersed in an ethanol solution for 30 minutes and then dried at a low temperature of 40°C.

[0093] 4) First, add the weighed polymer emulsion and water to the mixing tank and stir at 500 r / min for 10 min; then add the pre-mixed powder and stir at 1000 r / min for 5 min to obtain the final product.

[0094] Example 6

[0095] 1) The cement-based tough water-stopping mortar for underwater repair of concrete joints is composed of three parts: powder, polymer emulsion, and water, with a mass ratio of 85:6:9. The polymer emulsion is an ethylene-vinyl acetate copolymer emulsion and a polyvinyl acetate emulsion, mixed in a ratio of 5:1. The powder is composed of 850 parts cement, 150 parts vitrified microspheres, 4 parts modified fiber, 550 parts modified rubber particles, 1600 parts quartz sand, 4 parts water-reducing agent, 1 part defoamer, and 2 parts anti-dispersant agent. The cement is P∙II 52.5 silicate cement; the vitrified microspheres have a sphericity rate ≥90%, a closed-cell rate ≥95%, and a specific surface area ≥1200 m². 2 / kg, 28d activity index ≥100%; anti-dispersant is polyacrylamide; water-reducing agent is polycarboxylate-based high-performance water-reducing agent, powder; defoamer is amine polyether defoamer; quartz sand particle size range 0.315~1.25mm, apparent density not less than 2500kg / m³ 3 .

[0096] 2) The modified fiber is selected from polypropylene (PP) fiber with an equivalent diameter of 200µm and a length of 12mm. The γ-aminopropylsilane coupling agent is hydrolyzed in a solution of water:anhydrous ethanol = 3:7 beforehand, and the pH is adjusted to 3~5. Then, the selected fiber is immersed in the mixed solution at 60℃ for 60min and then dried.

[0097] 3) The modified rubber particles have a fineness range of 16-60 mesh, and are composed of two particle sizes, 16-30 mesh and 30-60 mesh, in a mass ratio of 3:1, with a density of 0.85-1.20 kg / m³. 3 The rubber granules are first washed with water and air-dried; then soaked in a 5% NaOH aqueous solution for 30 minutes, washed with water until neutral, and dried at a low temperature of 40℃; then placed in a solution containing 1% NaOH... c The 1-(methacryloyloxy)propyltrimethoxysilane coupling agent was immersed in an ethanol solution for 30 minutes and then dried at a low temperature of 40°C.

[0098] 4) First, add the weighed polymer emulsion and water to the mixing tank and stir at 300 r / min for 15 min; then add the pre-mixed powder and stir at 1000 r / min for 5 min to obtain the final product.

[0099] Example 7

[0100] 1) The cement-based tough water-stopping mortar for underwater repair of concrete joints is composed of three parts: powder, polymer emulsion, and water, with a mass ratio of 85:6:9. The polymer emulsion is a mixture of ethylene-vinyl acetate copolymer emulsion and polyvinyl acetate emulsion, with a mixing ratio of 5:1. The powder is composed of 850 parts cement, 150 parts vitrified microspheres, 4 parts modified fiber, 550 parts modified rubber particles, 1600 parts quartz sand, 3 parts water-reducing agent, 1 part defoamer, and 1.5 parts anti-dispersant agent. The cement is P∙II 52.5 silicate cement; the vitrified microspheres have a sphericity rate ≥90%, a closed-cell rate ≥95%, and a specific surface area ≥1200 m². 2 / kg, 28d activity index ≥100%; anti-dispersant is polyacrylamide; water-reducing agent is polycarboxylate-based high-performance water-reducing agent, powder; defoamer is amine polyether defoamer; quartz sand particle size range 0.315~1.25mm, apparent density not less than 2500kg / m³ 3 .

[0101] 2) The modified fibers selected are polypropylene (PP) fiber and polyoxymethylene (POM) fiber, with an equivalent diameter of 200µm and a length of 12mm, and a blending ratio of 3:1. The γ-aminopropylsilane coupling agent is hydrolyzed in a solution of water:anhydrous ethanol = 3:7 beforehand, and the pH is adjusted to 3-5. Then, the selected fibers are immersed in the mixed solution at 60℃ for 60 minutes and then dried.

[0102] 3) The modified rubber particles have a fineness range of 16-60 mesh, and are composed of two particle sizes, 16-30 mesh and 30-60 mesh, in a mass ratio of 3:1, with a density of 0.85-1.20 kg / m³. 3 The rubber granules are first washed with water and air-dried; then soaked in a 5% NaOH aqueous solution for 30 minutes, washed with water until neutral, and dried at a low temperature of 40℃; then placed in a solution containing 1% NaOH... c The 1-(methacryloyloxy)propyltrimethoxysilane coupling agent was immersed in an ethanol solution for 30 minutes and then dried at a low temperature of 40°C.

[0103] 4) First, add the weighed polymer emulsion and water to the mixing tank and stir at 500 r / min for 15 min; then add the pre-mixed powder and stir at 1000 r / min for 5 min to obtain the final product.

[0104] To facilitate comparison of the actual effects of cement-based tough waterproofing mortar suitable for underwater repair of concrete joints in the examples, several sets of comparative examples are set as follows:

[0105] Comparative Example 1

[0106] Select P∙II 52.5 cement, standard mortar, and anti-dispersant agent (hydroxypropyl methylcellulose ether). Weigh the materials and mix them evenly according to the mortar-to-binder ratio of 1:3, the water-to-binder ratio of 0.45, and the anti-dispersant dosage of 0.4%.

[0107] Comparative Example 2

[0108] Add polymer waterproof mortar produced by a Shandong company and sell it on the market. Weigh the materials according to the ratio of water to powder of 1:10, mix them evenly and then use.

[0109] Comparative Example 3

[0110] Add an underwater non-dispersible repair mortar produced by a company in Jiangsu Province that is sold on the market. Weigh the materials according to the ratio of water to powder of 1:11, mix them evenly, and then use.

[0111] The laboratory temperature was controlled at (20±2)℃ and the relative humidity at no less than 50%. Raw materials were weighed according to the proportion of the joint toughness sealing material, and a mortar mixer was used to mix and prepare the slurry. The state of the mixed material was observed. Two parallel glass plates were placed to form a "narrow joint," and the slurry was squeezed into the joint. The plate was then stood upright to observe whether the slurry flowed or deformed. A Bollerfeld RST-SST rheometer was used to test the plastic viscosity of the mortar by controlling the rotor speed. During the test, the shear rate changed from 0 s⁻¹ to 0 s⁻¹ within 60 seconds. -1 linearly increased to 60s -1 Then within 60 seconds -1 Reduced to 0 s -1 The underwater anti-dispersion property of mortar was evaluated using the turbidity method. Approximately 150 ml of the mixed mortar material was poured into 500 ml of water. After 30 seconds, 20 ml of water sample was randomly taken from a depth of 5 cm below the water surface. The turbidity of the water sample (unit: NTU) was measured using a WGZ-1A type scattering light turbidity meter. The lower the turbidity, the better the anti-dispersion property of the mortar.

[0112] Referring to SL / T 352-2020, pre-formed figure-eight mortar specimens with a compressive strength of not less than 40 MPa were cured in moisture for 28 days and then sawn in the middle. The dust and powder on the end face were removed with a brush. Six and a half figure-eight specimens, along with the mold, were placed in water at 20℃ and left to stand for 8 hours. The mortar was then filled into the mold using an underwater extrusion molding method. After water curing to the specified age, the specimens were removed and their bond strength was measured. Another batch of figure-eight mortar specimens were formed on land and placed in a standard curing room at (20±1)℃ with the mold in place. After curing to the specified age, the specimens were removed and their bond strength was measured. The ratio of compressive strength between water and land was calculated. Referring to SL / T 352-2020, dumbbell-shaped test molds (straight section length 100mm, width (25±0.10)mm, thickness (25±0.25)mm) were pre-immersed in 20℃ water for 2 hours. The slurry was then poured into the mold using an underwater extrusion molding method. After water curing for 28 days, the molds were removed. Strain gauges were then attached, and tensile tests were conducted on a computer-controlled hydraulic servo testing machine to determine the ultimate tensile strength and tensile modulus of elasticity of the mortar. Referring to the "Standard for Test Methods of Fiber Reinforced Concrete" CECS 13-2009, 100mm×100mm×400mm prism specimens were prepared. Bending toughness tests were conducted using a servo hydraulic testing machine. The loading rate before initial cracking was 0.06MPa / s, and the loading rate after initial cracking was 0.1mm / min. Deflection was collected using an LVDT with an accuracy of 0.0001mm. Three specimens were tested in each group of tests.

[0113] The relevant test results are shown in Table 1. Table 1 shows that Comparative Example 1 mortar, which incorporated 0.4% hydroxypropyl methylcellulose ether, exhibited some underwater anti-dispersion properties, but the mixture had high viscosity, low underwater interfacial bonding strength, and poor elastic deformation and flexural toughness. Comparative Example 2, a commercially available polymer waterproof mortar with a certain amount of microfiber, primarily served to prevent cracking, and its extreme tensile strength was slightly improved, but its elastic deformation and flexural toughness remained poor. Furthermore, the mixture's anti-dispersion turbidity exceeded 650 NTU, and its underwater interfacial bonding strength did not exceed 0.4 MPa. Comparative Example 3, a commercially available underwater non-dispersion repair mortar, had an underwater interfacial bonding strength of less than 1.2 MPa after 28 days and a water-to-land ratio of only 50%. Additionally, the mixture's viscosity, underwater anti-dispersion properties, elastic deformation, and flexural toughness still need improvement.

[0114] Compared with the comparative examples, the cement-based repair mortars in Examples 1-7 showed no flow at the joints after mixing, excellent underwater anti-dispersion properties, and varying degrees of improvement in underwater interfacial bonding performance, elastic deformation capacity, and toughness.

[0115] Comparing Examples 1-3, it can be seen that: ① Compared with ordinary rubber particles, the use of rubber particles modified by the method of this invention can significantly reduce the elastic modulus of cement-based mortar and impart elasticity to the material. Under the same dosage conditions, the elastic modulus of the mortar decreases by more than 35%, demonstrating the significant effect of the modified rubber particles. ② Compared with ordinary fibers, the use of fibers modified by the method of this invention can significantly improve the tensile deformation capacity and toughness of cement-based mortar, with an increase of 11% in the 28-day ultimate tensile value and a 37% increase in the flexural toughness index. ③ Through the modification method of this invention, the interfacial adhesion between rubber particles, fibers, and cement-based materials can be significantly enhanced, thereby synergistically leveraging the performance advantages of each component.

[0116] Comparing Examples 3-7, it can be seen that: ① The "ball effect" of vitrified microspheres can reduce the viscosity of the mortar mixture; the viscosity gradually decreases with increasing vitrified microsphere dosage. ② Optimizing the type of anti-dispersant and increasing the dosage of anti-dispersant can improve the underwater anti-dispersibility of the mixture; polyacrylamide shows the best effect at the same dosage. While increasing the dosage of anti-dispersant significantly reduces the underwater anti-dispersibility turbidity of the mixture, it also increases the plastic viscosity of the mixture and affects the underwater interfacial adhesion of the material. The applicant's experiments found that when the viscosity of the cement-based mortar mixture is ≤5 Pa·s and the underwater anti-dispersibility turbidity is ≤50 NTU, the repair mortar can possess the fluidity required for long-distance pipeline pressurized transportation and the anti-dispersibility required for underwater extrusion molding. ③ As the dosage of modified rubber particles increases, the tensile elastic modulus of the cement-based mortar gradually decreases; however, increasing the dosage of rubber particles increases the probability of weak interfaces in the material, thus reducing the tensile deformation performance and flexural toughness of the mortar. There is an optimal value for the dosage of modified rubber particles. ④ The type and amount of modified fibers directly affect the tensile deformation performance of mortar materials. Increasing the amount of modified fibers can increase the ultimate tensile value of the mortar, and the performance of the combination of two fibers is better than that of a single fiber at the same dosage. Among them, polypropylene fiber (PP) and polyoxymethylene fiber (POM) have the best effect when mixed at a mass ratio of (2~4):(0~2). ⑤ There is a matching relationship between the type and amount of modified rubber particles and modified fibers. The synergistic effect of modified rubber particles and hybrid fibers can enable cement-based mortar to have characteristics such as low elastic modulus, high elasticity, high toughness, and adaptability to large deformation after hardening. The 28-day tensile modulus is <4.0GPa and the ultimate tensile value is ≥400×10 -6 Flexural toughness index I5 > 4.0. ⑥ The type and amount of polymer emulsion directly affect the underwater interfacial bonding strength of mortar materials. By reducing the width of the transition zone between the mortar and the substrate, improving compactness, and increasing the mechanical interlocking force and chemical bonding with the old interface, the applicant's experiments found that the optimal effect was achieved when using ethylene-vinyl acetate copolymer emulsion and its combination with polyvinyl acetate emulsion in a mixing ratio of (4~6):(0~2). Among them, the cement-based repair mortars in Examples 6 and 7 showed a bonding strength with concrete ≥1.4MPa after 1 day of underwater molding and ≥2.6MPa after 28 days, with significant improvement. The bonding strength after 28 days of onshore molding also exceeded 2.9MPa, and the water-to-land strength ratio exceeded 90%, meeting the needs of rapid and long-term underwater repair. ⑦ There is a matching relationship between the type and amount of polymer emulsion and anti-dispersant. Increasing the amount of polymer emulsion and anti-dispersant will increase the plastic viscosity of the mixture. In addition, increasing the amount of anti-dispersant will also affect the underwater interfacial bonding performance of the material. The synergistic effect of polymer emulsion and anti-dispersant agent can make cement-based tough water-stopping mortar into a paste after mixing, with a plastic viscosity ≤5Pa·s, underwater anti-dispersibility turbidity ≤50NTU, and underwater molding bond strength with concrete ≥1.0MPa after 1 day and ≥2.5MPa after 28 days.

[0117] Table 1. Performance of Cement-Based Tough Water-Stopping Mortar for Underwater Repair of Concrete Joints

[0118]

[0119] In summary, this invention presents a cement-based tough water-stopping mortar suitable for underwater repair of concrete joints and its rapid construction process. The material, after mixing, is a paste with low viscosity and high anti-dispersion properties underwater, making it suitable for long-distance pressurized pipeline transportation and underwater extrusion molding. It exhibits high underwater bonding strength and, after hardening, possesses low modulus of elasticity, high elasticity, and high toughness. Furthermore, an underwater construction process is proposed, applicable to the rapid and long-term underwater repair of joint defects in hydraulic concrete structures, providing a new approach to underwater defect treatment of concrete structures.

[0120] Example 8

[0121] A rapid construction process for cement-based tough water-stopping mortar suitable for underwater repair of concrete joints.

[0122] Cement-based tough water-stopping mortar for underwater repair of concrete joints was prepared according to the methods in Examples 5-7. The prepared cement-based tough water-stopping mortar had a viscous paste-like consistency when mixed and did not flow into the joint. The construction process of the cement-based tough water-stopping mortar adopted the "joint caulking repair" approach. The cement-based tough water-stopping mortar was prepared on land and transported to the underwater operating platform by extrusion through pipelines. Divers or underwater robots operated a trowel with a pre-reserved discharge port, pressing it onto the joint and discharging it while moving to perform the repair work. The specific underwater joint repair demonstration application is shown in the following steps:

[0123] ① Use specialized equipment to mix and store cement-based tough water-stopping mortar on the shore;

[0124] ② Connect the material container outlet and the trowel through the high-pressure pipe, move it to the underwater joint repair work surface, and press the trowel onto the joint;

[0125] ③ The material is extruded through a grouting machine and squeezed into the joint through the pre-drilled holes in the trowel.

[0126] ④ A diver or underwater robot carrying a trowel moves forward along the joint defect location, maintaining a certain pressure on the trowel while moving and discharging material to complete the filling and repair of the joint defect.

[0127] The above embodiments are merely illustrative of the preferred embodiments of the present invention and do not constitute a limitation on the present invention. It should be noted that any modifications made by those skilled in the art without departing from the core concept of the present invention, and any obvious variations derived therefrom, are within the scope of protection of the present invention.

Claims

1. A cement-based tough water-stopping mortar suitable for underwater repair of concrete joints, characterized in that: Cement-based tough water-stopping mortar is formulated from three parts: powder, polymer emulsion, and water, with a mass ratio of powder, polymer emulsion, and water of 85:(4~6):(9~11). The polymer emulsion is a combination of ethylene-vinyl acetate copolymer emulsion and polyvinyl acetate emulsion, with a ratio of 5:

1. The powder is composed of the following components in the indicated mass proportions: 850~900 parts of general-purpose silicate cement, 100~150 parts of vitrified microspheres, 2~4 parts of modified fiber, 550~650 parts of modified rubber particles, 1600~1850 parts of quartz sand, 2~4 parts of water-reducing agent, 1 part of defoamer, and 1~2 parts of anti-dispersant agent. The vitrified microspheres are made from mineral sand with a silica content of over 90%, finely ground to 100~300 g / L. After granulation, calcination, and cooling, the sample is placed in a high-speed mixer. While stirring at 500-1000 rpm, 1%-2% of γ-aminopropylsilane coupling agent is added evenly. After all the silane coupling agent is added, hot air at 60-80℃ is introduced into the mixer. The reaction time is 30-60 minutes. Finally, the sample is naturally cooled to room temperature and sieved to obtain a pelletizing rate ≥90%, a closed-cell rate ≥85%, and a specific surface area ≥1200 m². 2 / kg, 28d activity index ≥100% vitrified microspheres; The modified fiber is obtained by immersing the fiber in a γ-aminopropylsilane coupling agent mixture at 40-60℃ for 60-90 minutes and then drying it; the fiber is a mixture of polypropylene fiber (PP) and polyoxymethylene fiber (POM) with an equivalent diameter of 5-200μm and a length of 6-12mm, in parts by mass, wherein the polypropylene fiber (PP) comprises 2-4 parts and the polyoxymethylene fiber (POM) comprises 0-2 parts; the γ-aminopropylsilane coupling agent mixture is obtained by hydrolyzing the γ-aminopropylsilane coupling agent in a solution of water:anhydrous ethanol = (1-3):(7-9) and adjusting the pH to 3-5; the modified rubber granules are obtained by washing the rubber granules with water and then air-drying them naturally; Then, it is immersed in 5% NaOH solution for 20-30 minutes, washed with water until neutral, and dried at a low temperature of 30-40℃; it is then immersed in an ethanol solution containing 1% γ-(methacryloyloxy)propyltrimethoxysilane coupling agent for 30-40 minutes, and finally dried at a low temperature of 30-40℃ to obtain the modified rubber particles; the modified rubber particles are composed of two particle sizes, 16-30 mesh and 30-60 mesh, in a mass ratio of 3:1, with a density of 0.85-1.20 g / cm³. 3 .

2. The cement-based toughening waterproof mortar for underwater repair of concrete joints according to claim 1, characterized in that: The anti-dispersant is one of polyacrylamide and hydroxypropyl methylcellulose ether; the water-reducing agent is one of melamine-based high-efficiency water-reducing agent and polycarboxylate-based high-performance water-reducing agent.

3. The application of the cement-based tough water-stopping mortar of claim 1 in underwater repair of concrete joints.

4. The method for preparing the cement-based tough water-stopping mortar according to claim 1, characterized in that, The process includes the following steps: 1) Add the weighed polymer emulsion and water to a mixing tank and stir at 300-500 r / min for 10-15 min; 2) Mix 850-900 parts of cement, 100-150 parts of vitrified microspheres, 2-4 parts of modified fiber, 550-650 parts of modified rubber granules, 1600-1850 parts of quartz sand, 2-4 parts of water-reducing agent, 1 part of defoamer, and 1-2 parts of anti-dispersant agent evenly to obtain a powder; 3) Add the powder to a mixing tank and stir at 1000-1200 r / min for 3-5 min to obtain the final product.

5. A rapid construction process for using the cement-based tough water-stopping mortar for underwater repair of concrete joints as described in claim 1, characterized in that: The "caulking and repair" approach involves preparing cement-based tough water-stopping mortar on land, then extruding it through a high-pressure pipeline to an underwater operating platform. A trowel with a pre-drilled outlet is used to press the mortar onto the joint defect, discharging material as it moves to complete the caulking and repair work. The specific steps include: 1) Mixing and storing the cement-based tough water-stopping mortar on land using specialized equipment; 2) Connecting the outlet of the storage container to the trowel via a high-pressure pipeline, moving it to the underwater joint repair work surface, and pressing the trowel onto the joint; 3) Extruding the material through a grouting machine, squeezing it into the joint through the pre-drilled hole in the trowel; 4) A diver or underwater robot carries the trowel forward along the joint defect location, maintaining pressure on the trowel while discharging material, completing the caulking and repair of the joint defect.

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