Cement-based tough water-stop mortar suitable for underwater repair of concrete joints and rapid construction process of cement-based tough water-stop mortar

Abstract

The invention discloses cement-based tough water-stop mortar suitable for underwater repair of concrete joints and a rapid construction process of the cement-based tough water-stop mortar. The cement-based tough water-stop mortar is prepared from three materials, namely a powder material, a polymer emulsion and water, wherein the powder material is prepared by mixing cement, glass beads, modified fibers, modified rubber particles, quartz sand, a water reducing agent, a defoaming agent and an anti-dispersing agent. The cement-based tough water-stop mortar material is based on a cement-based material, through multi-component optimization and synergistic effect, the cement-based tough water-stop mortar material is pasty after being mixed, joints do not flow, the viscosity is low, the underwater dispersion resistance is excellent, and the cement-based tough water-stop mortar material is suitable for long-distance pipeline pressurized conveying and underwater extrusion forming; the underwater interface bonding strength is high, and the characteristics of low elastic modulus, high elasticity and high toughness are achieved after hardening; the underwater construction technology of caulking repair is provided, a pressing spatula is adopted to press the upper edge of the joint, discharging and plastering construction are conducted at the same time, and the underwater repair technology is suitable for underwater rapid and long-acting repair of the joint defects of the hydraulic concrete structure.

Description

Technical Field

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

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

[0003] At present, the commonly used repair method is to create a dry environment during the water outage and maintenance by means of cofferdam isolation and emptying, clean the original materials at the joint position, set a water stop strip on the water-facing surface of the structure, and inject organic repair materials such as polyurethane or epoxy resin into the joint position to achieve repair. However, the joint position is often in a humid, seeping or even underwater environment, which cannot achieve a dry base construction environment, and it needs to be quickly drained after the construction is completed. Different from dry construction conditions, underwater joint repair materials must have the following characteristics: (1) good anti-dispersion performance to prevent the repair material from dispersing and segregating underwater; (2) high underwater bonding strength, which must have a certain degree of hydrophilicity to ensure bonding with the concrete water-based surface; (3) fast coagulation and hardening to prevent the repair material from being washed away by water flow; (4) strong deformation ability and a certain degree of deformation adaptability.

[0004] Cement is a common hydraulic cementitious material, widely used in civil engineering, water conservancy, national defense and other projects. It can solidify and harden normally in the presence of water and bond other materials. However, when it is formed underwater, it is easy to disperse and fluidize, which affects the bonding strength. At present, the main underwater repair cement-based materials include underwater non-dispersible cement-based materials and polymer-modified cement-based materials. Underwater non-dispersible cement-based materials are ordinary cement-based materials with anti-dispersants added. The long-chain molecules in the anti-dispersants attract and overlap each other to form a network structure, which ensures that the various components of the cement-based materials are bonded together when encountering water. Polymer-modified cement-based materials refer to organic-inorganic composite materials obtained by adding polymers to cement mortar or concrete. The polymer can form a film with high bonding strength between aggregate and cement slurry, fill the pores in the mortar, and improve the density of the hardened mortar. Affected by the material's own properties and construction process factors, joint repair still has problems such as cement-based repair materials being easily dispersed, slow hardening speed, low bonding strength on wet or underwater bases, large shrinkage deformation and easy cracking after hardening, poor water-stopping effect and material elastic deformation ability, making it difficult to guarantee the repair effect.

[0005] The Chinese patent with publication number CN112341140A discloses an interface agent for wet joint concrete of prefabricated buildings and a preparation method thereof. The interface agent is composed of two components, a powder and a liquid. The powder is composed of ultrafine cement and fly ash microbeads, and the polymer emulsion used is one or two of styrene acrylic emulsion and pure acrylic emulsion. The interface agent for wet joint concrete of prefabricated buildings provided by the invention has high fluidity, good operability, and is easy to apply and construct. After using the interface agent provided by the present invention, the interface bonding strength of the old concrete-interface agent-new concrete composite structure is greatly improved, and the impermeability of the wet joint interface is significantly improved. However, the invention can only be used as an interface agent, and is not suitable for filling and repairing concrete joints. It needs to be applied on a dry interface and the interface usually needs to be roughened.

[0006] The Chinese patent with publication number CN110423073A discloses a super early strength shrinkage compensating wet joint concrete dry mix and preparation method. The invention product uses the expansion effect of expansion components (calcium oxide, calcium sulfoaluminate, magnesium oxide or calcium oxide-calcium sulfoaluminate) to compensate for the shrinkage deformation of concrete, and uses mixed fibers (steel fibers and synthetic organic fibers) to achieve high ductility. It only relies on the bonding strength of cement and the old interface, and does not improve the bonding effect of the interface, especially the wet interface.

[0007] The Chinese patent with publication number CN114057439A discloses an elastic mortar for building exterior walls and its preparation process. Through the reaction of 2,4-toluene diisocyanate and polyether diol, the carbon-carbon double bonds at both ends of the monomer can be polymerized with the double bonds of the acrylate monomer to produce micro-crosslinking, and a waterproof elastic emulsion with the advantages of both polyurethane and acrylate emulsion is prepared. However, the invention ① is only used for thermal insulation and waterproofing of building exterior walls and roof decoration, and does not explain the bonding effect on the wet or underwater interface of hydraulic structures. ② The mortar performance only mentions the tensile bonding strength in a dry environment, and the deformation performance of the mortar is unknown.

[0008] The Chinese patent with publication number 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 amino-terminated water-soluble hyperbranched polyamide, the introduction of hyperbranched structure and silicone rubber structure makes the concrete have better toughness and elasticity, which can overcome the defects of adding rubber materials to ordinary concrete, low adhesion between rubber particles and cement paste, poor concrete strength, impermeability and compactness. The disclosed elastic concrete has high compressive strength and elastic modulus, but does not explain the deformation performance of the material, interface bonding strength, etc., and is not suitable for underwater repair of hydraulic concrete joints.

[0009] The Chinese patent with publication number CN107867814A discloses an elastic mortar, which is composed of organic and inorganic materials, has high elasticity and good flexibility. The invention utilizes the elasticity of polysulfide rubber powder, and reacts with the thiol group at the end of polysulfide rubber through water-based epoxy resin, introduces flexible segments into the epoxy resin molecules, and increases the plastic deformation capacity of the matrix. It is mainly used in the ground of entertainment venues. However, the raw materials contain emulsified asphalt and water-based epoxy resin emulsion, and the interface bonding performance will be affected in a humid environment, which is not suitable for repairing wet joints.

[0010] The Chinese patent with publication number CN110204836A discloses a waterproof joint material for tunnel concrete structure joints. It is composed of a base material composed of a closed-cell rubber foam board and a self-adhesive layer applied to the side of the base material for bonding with the concrete surface. The double-sided self-adhesive rubber waterproof material is used for joints, and the self-adhesive strip is attached to the concrete. The material needs to be heated and insulated during construction, and the construction process is complicated. The raw materials may cause pollution to the environment.

[0011] The Chinese patent with publication number CN101684643A discloses the application of a fly ash synthetic channel joint anti-seepage material for construction at a wet interface or in water. Fly ash is synthesized with raw materials such as polyether polyurethane prepolymer, curing agent, catalyst, antioxidant, ultraviolet absorber, etc. The invention ① contains a large amount of organic matter such as polyether polyurethane prepolymer, petroleum asphalt, thin oil, toluene, etc. in the material composition, and the preparation process is complicated; ② although the bonding strength of the joint anti-seepage material constructed at a wet interface or in water reaches more than 80% of the bonding strength at a dry interface, the bonding strength of the dry basis and wet interface is relatively low, not exceeding 1.1MPa; ③ the material's underwater construction performance and deformation performance are not mentioned.

[0012] The Chinese patent with publication number CN109305789A discloses a cement-based elastic grouting material suitable for deep-water concrete crack repair and its preparation method. With cement, slag powder and rubber powder as the base materials, silicon powder, gypsum powder, polyester fiber, water reducer, water-based latex and water-based curing agent are added in a certain proportion, and water is added and mixed to form an underwater non-dispersible plastic body that can be grouted, and after solidification, an elastic solid that is firmly bonded to the concrete crack interface is formed. By adding water-based acrylic emulsion and water-based epoxy curing agent, the bonding strength of the elastic consolidation body in water is improved; the water-based epoxy curing agent can effectively promote the curing and film formation of acrylic latex; the polyester fiber and rubber powder are used to make the consolidation body have elastic deformation ability. However, the invention ① uses the mortar flexural strength to characterize the bonding strength, which is not accurate; ② the material is mainly used for the repair of cracks of about 2mm in hydraulic concrete buildings, and the corresponding effect of repairing concrete joints with a larger width is unknown; ③ the underwater anti-dispersion effect of the material and the corresponding underwater construction process are not proposed.

[0013] The Chinese patent with publication number CN102674779A discloses a modified expansive water-stopping mortar and its preparation method. A mixed lightweight aggregate composed of waste rubber powder and waste polyurethane is used as the anti-cracking component of the mortar, which significantly improves the flexibility and elasticity of the mortar. However, the invention ① The addition of waste polyurethane particles and rubber particles reduces the material compression ratio and elastic modulus, but the elastic deformation capacity and wet interface bonding performance are not mentioned. ② It is applied to the waterproof treatment of door and window openings and overhanging structures in construction projects, and the effect on underwater repair of concrete joints is unknown.

[0014] The Chinese patent with publication number CN111362646A discloses a low elastic modulus flexible ultra-high toughness mortar concrete system and its preparation method. It adopts sulphoaluminate cement, rubber powder, mixed with different fibers, calcium oxide expansion agent and other methods to solve the problems of low early strength, high elastic modulus, insufficient flexibility, large shrinkage deformation and other problems of existing ultra-high toughness mortar concrete. The fiber content is as high as 10~40kg / m 3 , the rubber powder has a larger particle size of 200-300 mesh, and the fiber is a new type of polyoxymethylene fiber. Although the mortar concrete has low elastic modulus and high uniaxial tensile deformation properties, its shrinkage deformation and interface bonding properties are not mentioned. It can be used for earthquake-resistant, impact-resistant or anti-collision concrete structures, but is not suitable for repairing concrete defects in humid or underwater environments.

[0015] The Chinese patent with publication number CN108585700A discloses a joint mortar and its preparation method, which solves the shortcomings of easy cracking and weak bonding of building mortar by adding vermiculite to improve the compressive strength and bonding strength of the mortar, styrene-butadiene emulsion to improve the compactness, and acetyl tributyl citrate to improve the water retention. However, the invention ① the 28d compressive strength of the mortar does not exceed 30MPa, and the 28d bonding strength under the dry interface is less than 1.5MPa, and there is no data support for the crack resistance and shrinkage deformation performance; ② it is applied to the wall joints of construction projects, and the effect of underwater repair of concrete joints is unknown.

[0016] The Chinese patent with publication number CN110357521A discloses a lightweight, high-strength, high-ductility mortar and its preparation method, which uses slag powder, silica fume, and recycled powder as active mineral admixtures, cement as a cementitious material, fly ash beads, glass beads, and recycled rubber powder as lightweight fillers, and combines water reducers and reinforcing fibers. Through appropriate component composition, the mortar material has lightweight, high compressive strength, high tensile strength, and high tensile ductility characteristics. Among them, fly ash beads, glass beads, and recycled rubber powder are used to reduce the density of the mortar, and by reducing the sand ratio and preferably selecting ultra-high molecular weight polyethylene fibers and polyester fibers, fiber bridging is achieved to achieve a toughening effect. However, the invention has high requirements on raw materials, component ratios, preparation and curing conditions for the mortar, and mainly emphasizes lightness and high ductility, and does not mention the material interface bonding performance.

[0017] The Chinese patent with publication number CN110357521A discloses a rubber powder ultra-high ductility mortar for architectural 3D printing, which solves the problem that ordinary 3D printing mortar materials have poor tensile properties and cannot be completely free from the constraints of steel bars. Silica fume is used as an active admixture to improve the long-term strength of the material, and rubber powder is added to adjust the strength of the matrix and improve the tensile strength and elongation. However, the order of adding raw materials and the mixing quality of the invention have a great influence on the subsequent printing performance and mechanical properties of the mortar, and it needs to be prepared according to a specified mixing method.

[0018] In summary, there is currently little research on cement-based tough water-stop mortar for underwater repair of hydraulic concrete joints. The present invention is based on cement-based materials, improves the underwater bonding performance and deformation performance, proposes a new idea for underwater repair materials for concrete joints and a corresponding rapid construction process, and provides a reference for underwater reinforcement of concrete structures. Summary of the invention

[0019] In order to improve the level of underwater disease treatment of hydraulic structures and solve the problems of difficulty in underwater repair of concrete structure joints, easy dispersion of repair materials underwater, low bonding strength with the base surface, poor deformation adaptability after hardening, the present invention has developed a cement-based tough water-stop mortar with the performance characteristics of no underwater dispersion, high underwater bonding strength, low elastic modulus and high toughness, and proposed its underwater rapid construction process.

[0020] The cement-based tough water-stopping mortar suitable for underwater repair of concrete joints and its rapid construction process described in the present invention include the following contents: The cement-based tough water-stopping mortar for underwater repair of concrete joints described in the present invention is prepared from three parts of materials: powder, polymer emulsion and water, wherein the mass ratio of powder, polymer emulsion and water is (83-90):(1-6):(9-11).

[0021] The polymer emulsion is one or two of acrylic copolymer emulsion, styrene-butadiene emulsion, ethylene-vinyl acetate copolymer emulsion, styrene-acrylic emulsion, chloroprene rubber emulsion and polyvinyl acetate emulsion.

[0022] The type and amount of polymer emulsion directly affect the underwater interface bonding strength of mortar materials, by reducing the width of the transition zone of the bonding interface between mortar and substrate, improving density, reducing interface microcracks, and increasing the mechanical bite force and chemical bond with the old interface.

[0023] 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); More preferably, the polymer emulsion is a combination of ethylene-vinyl acetate copolymer emulsion and polyvinyl acetate emulsion, and the combination ratio of the two emulsions is (3-5):1.

[0024] Further preferably, the polymer emulsion is a combination of ethylene-vinyl acetate copolymer emulsion and polyvinyl acetate emulsion in a mass ratio of 5:1; The powder is prepared by mixing 850-950 parts of cement, 50-150 parts of vitrified microspheres, 2-4 parts of modified fibers, 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 defoaming agent and 1-2 parts of anti-dispersant.

[0025] The cement is general-purpose Portland cement with a strength grade of ≥42.5; The vitrified microspheres are made of ore sand with a silicon dioxide content of more than 90% as raw material, finely ground to 100-300 meshes, and put into a high-speed mixer after granulation, calcination, and cooling. 1%-2% of γ-aminopropyl silane coupling agent is evenly added during stirring at a speed of 500-1000 r / min. After all the silane coupling agent is added, hot air at 60-80° C. is introduced into the mixer. The reaction time is 30-60 minutes. Finally, the microspheres are naturally cooled to room temperature and sieved to obtain a balling rate of ≥90%, a closed porosity of ≥85%, and a specific surface area of ​​≥1200 m 2 / kg, vitrified microspheres with 28d activity index ≥100%; The anti-dispersant is one of polyacrylamide, hydroxypropyl methylcellulose ether and polyacrylamide; The water reducing agent is one of melamine-based high-efficiency water reducing agent and polycarboxylic acid-based high-performance water reducing agent, in powder form, with a water reduction rate of not less than 25%; The defoamer is one of an amino polyether defoamer and a polyether modified silicone defoamer; The quartz sand has a particle size range of 0.315-1.25 mm and an apparent density of not less than 2500 kg / m 3 .

[0026] The modified fiber is obtained by dipping the fiber into a mixed solution of gamma-aminopropylsilane coupling agent and then drying it.

[0027] Further preferably, the modified fiber is obtained by immersing the selected fiber in a γ-aminopropylsilane coupling agent mixed solution at 40-60°C for 60-90 minutes and then drying; 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.

[0028] The γ-aminopropylsilane coupling agent mixed solution 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.

[0029] The fiber modified by γ-aminopropyl silane coupling agent has better effect than other modification methods, greatly improving the bonding strength between fiber and hardened cement paste and improving synergistic performance.

[0030] The type and amount of modified fibers directly affect the tensile deformation properties of mortar materials. Increasing the amount of modified fibers can increase the ultimate tensile value of mortar, and the performance of the combination of the two fibers is better than that of a single fiber at the same dosage.

[0031] The modified fiber is preferably a mixture of polypropylene fiber PP and polyoxymethylene fiber POM in a mass ratio of (2-4):(0-2); More preferably, the modified fiber is preferably a mixture of polypropylene fiber PP and polyoxymethylene fiber POM in a mass ratio of 3:1.

[0032] The modified rubber particles have a fineness range of 16 to 60 meshes; The modified rubber particles are composed of two particle sizes of 16-30 mesh and 30-60 mesh in a mass ratio of 3:1, and the density is 0.85-1.20 kg / m 3 .

[0033] The mass ratio of the two sizes of rubber particles will directly affect the state of the mortar mixture, as well as the probability of interface defects in the mortar after hardening and the tensile deformation performance of the mortar. In the present invention, the two sizes of 16-30 mesh and 30-60 mesh are preferably composed of a mass ratio of 3:1.

[0034] The rubber particles were first washed with water and dried naturally; then immersed in a 5% NaOH aqueous solution for 20-30 minutes, washed with water until neutral, and then dried at a low temperature of 30-40°C; then placed in a 1% c The rubber particles are immersed in an ethanol solution of -(methacryloyloxy)propyltrimethoxysilane coupling agent for 30-40 minutes, and finally dried at a low temperature of 30-40°C to obtain the desired modified rubber particles.

[0035] The "rolling effect" of vitrified microspheres in the powder combined with high-performance water reducers can improve the workability of the repair mortar and increase the fluidity of long-distance pipeline pressurized transportation; the anti-dispersant is selected to improve the underwater anti-dispersion of the repair mortar. After mixing, the cement-based tough water-stop mortar is paste-like and has high underwater anti-dispersion. The viscosity is ≤5Pa·s, and the setting and hardening time is adjustable in the range of 1~5h. It is suitable for long-distance pipeline pressurized transportation and underwater extrusion molding.

[0036] The "rolling effect" of vitrified microspheres can reduce the viscosity of the mortar mixture. As the amount of vitrified microspheres increases, the viscosity of the mortar gradually decreases.

[0037] Selecting the appropriate type of anti-dispersant and increasing the amount of anti-dispersant can improve the underwater anti-dispersibility of the mixture. Polyacrylamide has the best effect at the same dosage. Although increasing the amount of anti-dispersant will significantly reduce the underwater anti-dispersibility turbidity of the mixture, it will also cause the plastic viscosity of the mixture to increase and affect the underwater interface adhesion of the material.

[0038] The present invention has found through experiments that by adjusting the amount of glass beads and anti-dispersant so that the viscosity of the cement-based mortar mixture is ≤5Pa·s and the underwater anti-dispersion turbidity is ≤50NTU, the repair mortar has the fluidity required for long-distance pipeline pressurized transportation and the anti-dispersion required for underwater extrusion molding.

[0039] As the amount of modified rubber particles increases, the tensile elastic modulus of cement-based mortar gradually decreases, but the increase in the amount of rubber particles will increase the probability of weak interfaces in the material, thereby reducing the tensile deformation performance and bending toughness of the mortar. The optimal range of modified rubber particles is 300~750 parts (14%~32% of the total mass of added sand), and the optimal value is 550 parts.

[0040] The synergistic effect of modified rubber particles and hybrid fibers can make the cement-based mortar have the characteristics of low elastic modulus, high elasticity, high toughness, and adaptability to large deformation after hardening. The 28d tensile modulus is <4.0GPa, and the ultimate tensile value is ≥400×10 -6 , bending toughness index I 5>4.0.

[0041] The mass ratio of powder, polymer emulsion and water in the cement-based tough water-stop mortar for underwater repair of concrete joints is preferably 85:(4-6):(9-11).

[0042] The polymer emulsion is preferably ethylene-vinyl acetate copolymer emulsion and polyvinyl acetate emulsion, and the mixing ratio of the two emulsions is 5:1.

[0043] In the powder of the present invention, it is further preferred that 850-900 parts of cement, 100-150 parts of glass beads, 2-4 parts of modified fibers, 550-650 parts of modified rubber particles, 1600-1850 parts of quartz sand, 2-4 parts of water reducing agent, 1 part of defoaming agent, and 1-2 parts of anti-dispersant are mixed; More preferably, the powder is mixed by 850 parts of cement, 150 parts of glass beads, 4 parts of modified fiber, 550 parts of modified rubber particles, 1600 parts of quartz sand, 3-4 parts of water reducer, 1 part of defoamer, and 1.5-2 parts of anti-dispersant.

[0044] The preparation method of the cement-based tough water-stopping mortar for underwater repair of concrete joints of the present invention comprises the following steps: firstly adding weighed polymer emulsion and water into a mixing tank, stirring at a speed of 300-500 r / min for 10-15 min; then adding pre-mixed uniform powder, stirring at a speed of 1000-1200 r / min for 3-5 min to obtain the mortar.

[0045] The prepared cement-based tough water-stop mortar is paste-like after mixing, with plastic viscosity ≤5Pa·s, underwater anti-dispersion turbidity ≤50NTU, underwater forming 1d bonding strength with concrete ≥1.0MPa, 28d bonding strength ≥2.5MPa, 28d tensile modulus <4.0GPa after hardening, ultimate tensile value ≥400×10 -6 , bending toughness index I 5>4.0, meeting the needs of rapid and long-term underwater repair of materials.

[0046] The invention discloses a rapid construction process of cement-based tough waterproof mortar for underwater repair of concrete joints. The process adopts the idea of ​​"caulking repair". The cement-based tough waterproof mortar is prepared on shore and transported to an underwater operation platform through a pipeline by extrusion. A diver or underwater robot operates a pressure spatula with a reserved discharge port to press on the joint while discharging the material while moving to perform repair construction. The specific steps are as follows: ① Use professional equipment to mix cement-based tough water-stop mortar on shore and store it; ② Connect the material outlet of the storage container and the pressure spatula through a high-pressure pipe, move to the underwater joint repair work surface, and press the pressure spatula on the joint; ③ The material is discharged through the grouting machine, and the material is squeezed into the joint through the reserved holes of the trowel; ④ The diver or underwater robot carries a pressure spatula and moves forward along the joint defect position. When moving, a certain pressure is maintained on the pressure spatula, and the material is discharged while moving to complete the filling and plastering repair of the joint defect.

[0047] The present invention is based on cement-based materials. Through multi-component optimization and synergistic effects, the viscosity of the mixture, underwater bonding performance and elastic deformation performance are improved. The cement-based tough water-stop mortar material is in a paste state after mixing, the joints do not flow, the viscosity is low, and the underwater anti-dispersion performance is excellent. It is suitable for long-distance pipeline pressurized transportation and underwater extrusion molding; the underwater interface bonding strength is high, and after hardening, it has low elastic modulus, high elasticity and high toughness characteristics; an underwater construction process of "caulking repair" is proposed, and a pressure trowel is used to press on the joints while discharging and plastering the surface. It is suitable for underwater rapid and long-term repair of joint defects in hydraulic concrete structures.

[0048] The cement-based tough water-stopping mortar for underwater repair of concrete joints and its rapid construction process described in the present invention can be applied to underwater repair projects of concrete structure defects. Compared with the prior art, the present invention has the following beneficial effects: ①Through the "rolling effect" of vitrified microspheres and the combined action of high-performance water reducers, the workability of the repair mortar is improved and the fluidity of long-distance pipeline pressurized transportation is increased; the anti-dispersant is selected to improve the underwater anti-dispersion of the repair mortar. After mixing, the cement-based tough water-stop mortar is paste-like and has high underwater anti-dispersion. The viscosity is ≤5Pa·s, and the setting and hardening time is adjustable in the range of 1~5h. It is suitable for long-distance pipeline pressurized transportation and underwater extrusion molding.

[0049] ② The addition of polymer emulsion significantly reduces the width of the transition zone between the mortar and the base surface, improves the compactness, reduces interface microcracks, increases the mechanical bite force and chemical bond with the old interface, and greatly improves the underwater bonding strength of the repair mortar. The bonding strength with concrete after underwater curing for 1 day is ≥1.0MPa, the bonding strength after 28 days is ≥2.5MPa, and the water-to-land compressive strength ratio is ≥90%, which is suitable for rapid and long-term repair of underwater defects.

[0050] ③Through modification, the interfacial bonding between rubber particles, fibers and cement-based materials is enhanced. Among them, rubber particles reduce the elastic modulus of the repair material and give the material elasticity; the coordinated effect of rubber particles and hybrid fibers improves the tensile deformation performance of cement-based repair materials, reduces energy dissipation during material deformation, and significantly enhances the toughness of the repair material. After hardening, the cement-based tough water-stop mortar has the characteristics of low elastic modulus, high elasticity, high toughness, and adaptability to large deformation. The 28d tensile modulus is <4.0GPa, and the ultimate tensile value is ≥400×10 -6 , bending toughness index I 5>4.0.

[0051] ④ Based on the characteristics of repair mortar materials, a "caulking repair" construction process with simultaneous mortar preparation on shore, pipeline transportation, and extrusion and plastering is proposed, which can solve the problem of carrying repair materials and rapid forming and plastering under the action of flowing water. Combined with underwater disease detection technology and equipment, it can be expanded to be applied to the operation and maintenance of underwater structures and emergency rescue of major projects, reservoirs and dams, water transfer projects, wading bridges, municipal pipelines, etc., with significant economic and social benefits.

[0052] ⑤ The raw materials of cement-based tough water-stop mortar are mostly cement-based materials such as cement and fly ash. It not only has the characteristics of water hardness, but also has the advantages of wide material source and low cost. It also uses a large amount of waste recycled raw material rubber particles. Compared with the currently commonly used organic repair products such as epoxy resin and polyurethane, the cost of the repair mortar material of the present invention is greatly reduced. DETAILED DESCRIPTION

[0053] In order to more clearly describe the technical solution of the present invention, the present invention is further described below in conjunction with a specific embodiment. This embodiment is only used to better explain the content of the present invention, but does not limit the present invention. All similar embodiments listed based on the present invention should belong to the protection scope of the present invention.

[0054] The raw materials described in the present invention can all be obtained through public channels.

[0055] Example 1

[0056] 1) Cement-based tough water-stop mortar for underwater repair of concrete joints is prepared from three parts of materials: powder, polymer emulsion and water, wherein the mass ratio of powder, emulsion and water is 85:4:11. The polymer emulsion is an acrylic copolymer emulsion; the powder is mixed with 950 parts of cement, 50 parts of glass beads, 2 parts of modified fiber, 300 parts of rubber particles, 1850 parts of quartz sand, 2 parts of water reducer, 0.5 parts of defoamer and 1 part of anti-dispersant. The cement is P∙O 42.5 ordinary Portland cement; the balling rate of glass beads is ≥90%, the closed porosity is ≥95%, and the specific surface area is ≥1200m 2 / kg, 28d activity index ≥100%; rubber particles are unmodified, and are composed of two particle sizes of 16~30 mesh and 30~60 mesh in a mass ratio of 3:1, with a density of 0.85~1.20kg / m 3 ; The anti-dispersant is hydroxypropyl methylcellulose ether; the water reducer is a polycarboxylic acid-based high-performance water reducer, powder; the defoamer is a polyether-modified silicone defoamer; the quartz sand particle size range is 0.315~1.25mm, and the apparent density is not less than 2500kg / m 3 .

[0057] 2) The modified fiber is polyvinyl alcohol fiber PVA, with an equivalent diameter of 200µm and a length of 6mm. The γ-aminopropyl silane coupling agent is hydrolyzed in a water: anhydrous ethanol = 3:7 solution in advance, and the pH is adjusted to 3-5, and then the selected fiber is immersed in the 60°C mixed solution for 60 minutes and then dried.

[0058] 3) First, add the weighed polymer emulsion and water into the stirring tank, and stir at 500r / min for 10 minutes; then add the pre-mixed powder, and stir at 1000r / min for 5 minutes to obtain.

[0059] Example 2

[0060] 1) Cement-based tough water-stop mortar for underwater repair of concrete joints is prepared from three parts of materials: powder, polymer emulsion and water, wherein the mass ratio of powder, emulsion and water is 85:4:11. The polymer emulsion is an acrylic copolymer emulsion; the powder is mixed with 950 parts of cement, 50 parts of glass beads, 2 parts of fiber, 300 parts of modified rubber particles, 1850 parts of quartz sand, 2 parts of water reducer, 0.5 parts of defoamer and 1 part of anti-dispersant. The cement is P∙O 42.5 ordinary Portland cement; the balling rate of glass beads is ≥90%, the closed porosity is ≥95%, and the specific surface area is ≥1200m 2 / kg, 28d activity index ≥100%; the fiber is unmodified, and polyvinyl alcohol fiber PVA with an equivalent diameter of 200µm and a length of 6mm is selected. The anti-dispersant is hydroxypropyl methylcellulose ether; the water reducer is a polycarboxylic acid high-performance water reducer, powder; the defoamer is a polyether modified silicone defoamer; the quartz sand particle size range is 0.315~1.25mm, and the apparent density is not less than 2500kg / m 3 .

[0061] 2) The modified rubber particles have a particle size range of 16-60 mesh, and the two particle sizes of 16-30 mesh and 30-60 mesh are composed of a mass ratio of 3:1, and a density of 0.85-1.20 kg / m 3 The rubber particles were first washed with water and dried naturally; then immersed in a 5% NaOH aqueous solution for 30 minutes, washed with water until neutral, and then dried at 30°C; then placed in a 1% c The obtained product is immersed in an ethanol solution of -(methacryloyloxy)propyltrimethoxysilane coupling agent for 30 minutes and finally dried at 30°C.

[0062] 3) First, add the weighed polymer emulsion and water into the stirring tank, and stir at 500r / min for 10 minutes; then add the pre-mixed powder, and stir at 1000r / min for 5 minutes to obtain.

[0063] Example 3

[0064] 1) Cement-based tough water-stop mortar for underwater repair of concrete joints is prepared from three parts of materials: powder, polymer emulsion and water, wherein the mass ratio of powder, emulsion and water is 85:4:11. The polymer emulsion is an acrylic copolymer emulsion; the powder is mixed with 950 parts of cement, 50 parts of glass beads, 2 parts of modified fiber, 300 parts of modified rubber particles, 1850 parts of quartz sand, 2 parts of water reducer, 0.5 parts of defoamer and 1 part of anti-dispersant. The cement is P∙O 42.5 ordinary Portland cement; the balling rate of glass beads is ≥90%, the closed porosity is ≥95%, and the specific surface area is ≥1200m 2 / kg, 28d activity index ≥100%; anti-dispersant is hydroxypropyl methylcellulose ether; water reducer is polycarboxylic acid high-performance water reducer, powder; defoamer is polyether modified silicone defoamer; quartz sand particle size range is 0.315~1.25mm, apparent density is not less than 2500kg / m 3 .

[0065] 2) The modified fiber is polyvinyl alcohol fiber PVA, with an equivalent diameter of 200µm and a length of 6mm. The γ-aminopropyl silane coupling agent is hydrolyzed in a water: anhydrous ethanol = 3:7 solution in advance, and the pH is adjusted to 3-5, and then the selected fiber is immersed in the 60°C mixed solution for 60 minutes and then dried.

[0066] 3) The modified rubber particles have a particle size range of 16-60 mesh, and the two particle sizes of 16-30 mesh and 30-60 mesh are composed of a mass ratio of 3:1, and a density of 0.85-1.20 kg / m 3 The rubber particles were first washed with water and dried naturally; then immersed in a 5% NaOH aqueous solution for 30 minutes, washed with water until neutral, and then dried at 30°C; then placed in a 1% c The obtained product is immersed in an ethanol solution of -(methacryloyloxy)propyltrimethoxysilane coupling agent for 30 minutes and finally dried at 30°C.

[0067] 4) First, add the weighed polymer emulsion and water into the stirring tank, and stir at 500r / min for 10 minutes; then add the pre-mixed powder, and stir at 1000r / min for 5 minutes to obtain.

[0068] Example 4

[0069] 1) The cement-based tough water-stop mortar for underwater repair of concrete joints is prepared from three parts of materials: powder, polymer emulsion and water, wherein the mass ratio of powder, emulsion and water is 85:4:11. The polymer emulsion is styrene-butadiene emulsion; the powder is mixed with 900 parts of cement, 100 parts of glass beads, 4 parts of modified fiber, 300 parts of modified rubber particles, 1850 parts of quartz sand, 2 parts of water reducer, 1 part of defoamer and 1 part of anti-dispersant. The cement is P∙O 42.5 ordinary Portland cement; the balling rate of glass beads is ≥90%, the closed porosity is ≥95%, and the specific surface area is ≥1200m 2 / kg, 28d activity index ≥100%; anti-dispersant is polyacrylamide; water reducer is polycarboxylic acid high performance water reducer, powder; defoamer is amino polyether defoamer; quartz sand particle size range is 0.315~1.25mm, apparent density is not less than 2500kg / m 3 .

[0070] 2) The modified fiber is polyacrylonitrile fiber PAN, with an equivalent diameter of 5-200µm and a length of 12mm. The γ-aminopropyl silane coupling agent is hydrolyzed in a solution of water: anhydrous ethanol = 3:7 in advance, and the pH is adjusted to 3-5, and then the selected fiber is immersed in the mixed solution at 40°C for 90 minutes and then dried to obtain the obtained fiber.

[0071] 3) The modified rubber particles have a particle size range of 16-60 mesh, and the two particle sizes of 16-30 mesh and 30-60 mesh are composed of a mass ratio of 3:1, and a density of 0.85-1.20 kg / m 3 The rubber particles were first washed with water and dried naturally; then immersed in a 5% NaOH aqueous solution for 20-30 minutes, washed with water until neutral, and then dried at 30°C; then placed in a 1% cThe obtained product is immersed in an ethanol solution of -(methacryloyloxy)propyltrimethoxysilane coupling agent for 30 minutes and finally dried at 30°C.

[0072] 4) First, add the weighed polymer emulsion and water into the stirring tank, and stir at 500r / min for 10 minutes; then add the pre-mixed powder, and stir at 1000r / min for 5 minutes to obtain.

[0073] Example 5

[0074] 1) The cement-based tough water-stop mortar for underwater repair of concrete joints is prepared from three parts of materials: powder, polymer emulsion and water, wherein the mass ratio of powder, emulsion and water is 85:4:11. The polymer emulsion is ethylene-vinyl acetate copolymer emulsion; the powder is mixed with 850 parts of cement, 150 parts of glass beads, 4 parts of modified fiber, 650 parts of modified rubber particles, 1500 parts of quartz sand, 3 parts of water reducer, 1 part of defoamer and 1 part of anti-dispersant. The cement is P∙O 42.5 ordinary Portland cement; the balling rate of glass beads is ≥90%, the closed porosity is ≥95%, and the specific surface area is ≥1200m 2 / kg, 28d activity index ≥100%; anti-dispersant is polyacrylamide; water reducer is polycarboxylic acid series high performance water reducer, powder; defoamer is amino polyether defoamer; quartz sand particle size range is 0.315~1.25mm, apparent density is not less than 2500kg / m 3 .

[0075] 2) The modified fiber is selected from polypropylene fiber PP, with an equivalent diameter of 200µm and a length of 12mm. The γ-aminopropyl silane coupling agent is hydrolyzed in a water: anhydrous ethanol = 3:7 solution in advance, and the pH is adjusted to 3-5, and then the selected fiber is immersed in the mixed solution at 40°C for 90 minutes and then dried.

[0076] 3) The modified rubber particles have a particle size range of 16-60 mesh, and the two particle sizes of 16-30 mesh and 30-60 mesh are composed of a mass ratio of 3:1, and a density of 0.85-1.20 kg / m 3 The rubber particles were first washed with water and dried naturally; then immersed in a 5% NaOH aqueous solution for 30 minutes, washed with water until neutral, and then dried at 40°C; then placed in a 1% c The obtained product is immersed in an ethanol solution of -(methacryloyloxy)propyltrimethoxysilane coupling agent for 30 minutes and finally dried at 40°C.

[0077] 4) First, add the weighed polymer emulsion and water into the stirring tank, and stir at 500r / min for 10 minutes; then add the pre-mixed powder, and stir at 1000r / min for 5 minutes to obtain.

[0078] Example 6

[0079] 1) The cement-based tough water-stop mortar for underwater repair of concrete joints is prepared from three parts of materials: powder, polymer emulsion and water, wherein the mass ratio of powder, emulsion and water is 85:6:9. The polymer emulsion is ethylene-vinyl acetate copolymer emulsion and polyvinyl acetate emulsion, and the mixing ratio of the two emulsions is 5:1. The powder is mixed with 850 parts of cement, 150 parts of glass beads, 4 parts of modified fibers, 550 parts of modified rubber particles, 1600 parts of quartz sand, 4 parts of water reducer, 1 part of defoamer and 2 parts of anti-dispersant. The cement is P∙II 52.5 silicate cement; the balling rate of glass beads is ≥90%, the closed porosity is ≥95%, and the specific surface area is ≥1200m 2 / kg, 28d activity index ≥100%; anti-dispersant is polyacrylamide; water reducer is polycarboxylic acid series high performance water reducer, powder; defoamer is amino polyether defoamer; quartz sand particle size range is 0.315~1.25mm, apparent density is not less than 2500kg / m 3 .

[0080] 2) The modified fiber is selected from polypropylene fiber PP, with an equivalent diameter of 200µm and a length of 12mm. The γ-aminopropyl silane coupling agent is hydrolyzed in a water: anhydrous ethanol = 3:7 solution in advance, and the pH is adjusted to 3-5, and then the selected fiber is immersed in the 60°C mixed solution for 60 minutes and then dried.

[0081] 3) The modified rubber particles have a particle size range of 16-60 mesh, and the two particle sizes of 16-30 mesh and 30-60 mesh are composed of a mass ratio of 3:1, and a density of 0.85-1.20 kg / m 3 The rubber particles were first washed with water and dried naturally; then immersed in a 5% NaOH aqueous solution for 30 minutes, washed with water until neutral, and then dried at 40°C; then placed in a 1% c The obtained product is immersed in an ethanol solution of -(methacryloyloxy)propyltrimethoxysilane coupling agent for 30 minutes and finally dried at 40°C.

[0082] 4) First, add the weighed polymer emulsion and water into the stirring tank, and stir at 300r / min for 15 minutes; then add the pre-mixed powder, and stir at 1000r / min for 5 minutes to obtain.

[0083] Example 7

[0084] 1) The cement-based tough water-stop mortar for underwater repair of concrete joints is prepared from three parts of materials: powder, polymer emulsion and water, wherein the mass ratio of powder, emulsion and water is 85:6:9. The polymer emulsion is ethylene-vinyl acetate copolymer emulsion and polyvinyl acetate emulsion, and the mixing ratio of the two emulsions is 5:1; the powder is mixed with 850 parts of cement, 150 parts of glass beads, 4 parts of modified fibers, 550 parts of modified rubber particles, 1600 parts of quartz sand, 3 parts of water reducer, 1 part of defoamer, and 1.5 parts of anti-dispersant. The cement is P∙II 52.5 silicate cement; the balling rate of glass beads is ≥90%, the closed porosity is ≥95%, and the specific surface area is ≥1200m 2 / kg, 28d activity index ≥100%; anti-dispersant is polyacrylamide; water reducer is polycarboxylic acid series high performance water reducer, powder; defoamer is amino polyether defoamer; quartz sand particle size range is 0.315~1.25mm, apparent density is not less than 2500kg / m 3 .

[0085] 2) The modified fibers are selected from polypropylene fiber PP and polyoxymethylene fiber POM, with an equivalent diameter of 200µm, a length of 12mm, and a doping ratio of 3:1. The γ-aminopropylsilane coupling agent is hydrolyzed in a solution of water: anhydrous ethanol = 3:7 in advance, and the pH is adjusted to 3-5, and then the selected fiber is immersed in a 60°C mixed solution for 60 minutes and then dried.

[0086] 3) The modified rubber particles have a particle size range of 16-60 mesh, and the two particle sizes of 16-30 mesh and 30-60 mesh are composed of a mass ratio of 3:1, and a density of 0.85-1.20 kg / m 3 The rubber particles were first washed with water and dried naturally; then immersed in a 5% NaOH aqueous solution for 30 minutes, washed with water until neutral, and then dried at 40°C; then placed in a 1% c The obtained product is immersed in an ethanol solution of -(methacryloyloxy)propyltrimethoxysilane coupling agent for 30 minutes and finally dried at 40°C.

[0087] 4) First, add the weighed polymer emulsion and water into the stirring tank, and stir at 500r / min for 15 minutes; then add the pre-mixed powder, and stir at 1000r / min for 5 minutes to obtain.

[0088] In order to facilitate comparison of the actual effect of the cement-based tough water-stopping mortar suitable for underwater repair of concrete joints in the embodiments, several groups of comparison examples are set as follows: Comparative Example 1 Use P∙II 52.5 cement, standard mortar, and anti-dispersant (hydroxypropyl methylcellulose ether), weigh the materials according to the mortar-sand ratio of 1:3, water-cement ratio of 0.45, and anti-dispersant dosage of 0.4%, mix them evenly and then use.

[0089] Comparative Example 2 Add polymer waterproof mortar produced by a Shandong company and sold on the market. Weigh the materials according to the ratio of water: powder = 1:10 and mix them evenly before use.

[0090] Comparative Example 3 Add underwater non-dispersible repair mortar produced by a Jiangsu company and sold on the market, weigh the materials according to the ratio of water: powder = 1:11, mix them evenly and then use.

[0091] The temperature in the laboratory was controlled at (20±2)℃ and the relative humidity was not less than 50%. The raw materials were weighed according to the ratio of the joint toughness water-stopping sealing materials, and the mortar mixer was used to mix and slurry, and the state of the mixed materials was observed. Two glass plates were placed in parallel to set as "narrow gaps", and the slurry was squeezed into the joints, and then stood upright to observe whether the slurry flowed or deformed. The Brookfield RST-SST rheometer was used to control the speed of the rotor to test the plastic viscosity of the mortar. In the test, the shear rate was increased from 0 s to 10 s within 60 s. -1 Increase linearly to 60s -1 Then within 60 seconds, -1 Down to 0 s -1 The turbidity method was used to evaluate the underwater anti-dispersion property of the mortar. About 150 ml of the mixed mortar material was poured into 500 ml of water. After 30 seconds, 20 ml of water sample was randomly drawn from a depth of 5 cm below the water surface. The turbidity of the water sample (unit: NTU) was tested using a WGZ-1A scattered light turbidity meter. The smaller the turbidity, the better the anti-dispersion property of the mortar.

[0092] Referring to SL / T 352-2020, pre-formed "8"-shaped mortar specimens with a compressive strength of not less than 40MPa are sawn from the middle of the specimen after wet curing for 28 days, and the dust and powder on the end face are removed with a brush; 6 and a half "8"-shaped specimens together with the test mold are placed in 20℃ water and left to stand for 8h. The slurry is poured into the test mold by underwater extrusion molding method, and the test mold is taken out and cured in water to the specified age to measure its bonding strength; another batch of "8"-shaped mortar specimens formed on land are placed in a (20±1)℃ standard curing room with the mold and cured to the specified age, and then taken out to measure its bonding strength, and the water-to-land compressive strength ratio is calculated. Referring to SL / T 352-2020, a dumbbell-shaped test mold (straight section length 100mm, width (25±0.10)mm, thickness (25±0.25)mm) was placed in 20℃ water for 2h in advance, and the slurry was poured into the test mold by underwater extrusion molding. After curing in water for 28 days, it was taken out; after the strain gauge was pasted, a tensile test was carried out on a microcomputer-controlled hydraulic servo testing machine to determine the ultimate tensile value and tensile elastic modulus of the mortar. Referring to the "Fiber Concrete Test Method Standard" CECS 13-2009, a 100mm×100mm×400mm prism test block was prepared, and a servo-type hydraulic testing machine was used to carry out the bending toughness test. The loading speed before the first crack was 0.06MPa / s, and the loading speed after the first crack was 0.1mm / min. The deflection was collected by LVDT with an accuracy of 0.0001mm. Three specimens were tested in each group of tests.

[0093] The relevant test results are shown in Table 1. As can be seen from Table 1, 0.4% hydroxypropyl methylcellulose ether is added to the mortar of Comparative Example 1. Although it has a certain underwater anti-dispersion property, the viscosity of the mixture is large, the underwater molding interface bonding strength is low, and the elastic deformation and bending toughness are poor; Comparative Example 2 commercially available polymer waterproof mortar is compounded with a certain amount of microfibers, which mainly plays an anti-cracking role, and the extreme tensile tensile value is slightly improved, but the elastic deformation and bending toughness are still poor. In addition, the anti-dispersion turbidity of the mixture exceeds 650NTU, and the underwater interface bonding strength does not exceed 0.4MPa; Comparative Example 3 commercially available underwater non-dispersible repair mortar 28d underwater interface bonding strength does not exceed 1.2MPa, and the water-land ratio is only 50%. In addition, the viscosity of the mixture, underwater anti-dispersion, elastic deformation and bending toughness still need to be improved.

[0094] Compared with the comparative example, the cement-based repair mortars of Examples 1 to 7 do not flow in the joints after mixing, have excellent underwater anti-dispersion properties, and have improved underwater interface bonding properties, elastic deformation capacity, and toughness to varying degrees.

[0095] Comparing Examples 1 to 3, it can be seen that ① compared with ordinary rubber particles, the addition of rubber particles modified by the method of the present invention can significantly reduce the elastic modulus of cement-based mortar and give the material elasticity. Under the same dosage conditions, the mortar elastic modulus decreases by more than 35%, and the modified rubber particles have obvious effects. ② Compared with ordinary fibers, the addition of fibers modified by the method of the present invention can significantly improve the tensile deformation capacity and toughness of cement-based mortar, with the 28d ultimate tensile value increased by 11% and the bending toughness index increased by 37%. ③ Through the modification of the method of the present invention, the interfacial bonding force between rubber particles, fibers and cement-based materials can be significantly enhanced, thereby synergistically exerting the performance advantages of each component.

[0096] Comparing Examples 3 to 7, it can be seen that ① the "rolling effect" of adding vitrified microspheres can reduce the viscosity of the mortar mixture, and the viscosity of the mortar gradually decreases as the amount of vitrified microspheres increases. ② The type of anti-dispersant and the increase in the amount of anti-dispersant can improve the underwater anti-dispersion of the mixture, and polyacrylamide has the best effect at the same dosage; although increasing the amount of anti-dispersant will significantly reduce the underwater anti-dispersion turbidity of the mixture, it will also increase the plastic viscosity of the mixture and affect the underwater interface adhesion of the material. The applicant found through experiments that when the viscosity of the cement-based mortar mixture is ≤5Pa·s and the underwater anti-dispersion turbidity is ≤50NTU, the repair mortar can have the fluidity required for long-distance pipeline pressurized transportation and the anti-dispersion required for underwater extrusion molding. ③ As the amount of modified rubber particles increases, the tensile elastic modulus of the cement-based mortar gradually decreases, but the increase in the amount of rubber particles will increase the probability of the existence of weak interfaces in the material, thereby reducing the tensile deformation performance and bending toughness of the mortar. There is an optimal value for the amount of modified rubber particles. ④ The type and amount of modified fiber directly affect the tensile deformation properties of mortar materials. Increasing the amount of modified fiber 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 at the same dosage; among them, the best effect is achieved when polypropylene fiber PP and polyoxymethylene fiber POM are mixed in 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 make the cement-based mortar have the characteristics of low elastic modulus, high elasticity, high toughness, and adaptability to large deformation after hardening. The 28d tensile modulus is <4.0GPa, and the ultimate tensile value is ≥400×10 -6 , bending toughness index I5>4.0. ⑥ The type and amount of polymer emulsion directly affect the underwater interface bonding strength of mortar materials, by reducing the width of the transition zone of the mortar and substrate bonding interface, improving the compactness, and increasing the mechanical bite force and chemical bond with the old interface. The applicant found through experiments that the effect is best when ethylene-vinyl acetate copolymer emulsion and its combination with polyvinyl acetate emulsion are selected, and the mixing ratio of the two is (4~6):(0~2). Among them, the bonding strength of the cement-based repair mortars in Examples 6 and 7 formed underwater with concrete at 1d is ≥1.4MPa, and the bonding strength at 28d is ≥2.6MPa, with significant improvement. The bonding strength at 28d formed on land also exceeds 2.9MPa, and the water-to-land strength ratio exceeds 90%, meeting the requirements for rapid and long-term underwater repair of materials. 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 interface bonding performance of the material. The polymer emulsion and anti-dispersant work synergistically to make the cement-based tough water-stop mortar paste-like after mixing, with a plastic viscosity of ≤5Pa·s, an underwater anti-dispersion turbidity of ≤50NTU, and a bonding strength with concrete of ≥1.0MPa after 1d of underwater molding and ≥2.5MPa after 28d of bonding.

[0097] Table 1 Performance of cement-based tough water-stop mortar for underwater repair of concrete joints

[0098] In summary, the present invention discloses a cement-based tough water-stopping mortar suitable for underwater repair of concrete joints and its rapid construction process. After mixing, the material is in a paste-like state, has low viscosity, and has high underwater anti-dispersion, and is suitable for long-distance pipeline pressurized transportation and underwater extrusion molding; it has high underwater bonding strength, and has low elastic modulus, high elasticity, and high toughness characteristics after hardening. An underwater construction process is proposed, which is suitable for underwater rapid and long-term repair of joint defects in hydraulic concrete structures, and provides a new idea for underwater defect treatment of concrete structures.

[0099] Example 8

[0100] A rapid construction process for cement-based tough water-stopping mortar suitable for underwater repair of concrete joints According to the methods of Examples 5 to 7, cement-based tough water-stop mortar for underwater repair of concrete joints is prepared. The mixing state of the prepared cement-based tough water-stop mortar is: it is mixed into a viscous paste, and the joints do not flow. The construction process of cement-based tough water-stop mortar adopts the idea of ​​"caulking repair". The cement-based tough water-stop mortar is prepared on shore and transported to the underwater operating platform through pipelines by extrusion. Divers or underwater robots operate the pressure spatula with a reserved discharge port, press on the joints, and discharge the material while moving to perform repair construction. The specific demonstration application of underwater joint repair is shown in the following steps: ① Use professional equipment to mix cement-based tough water-stop mortar on shore and store it; ② Connect the material outlet of the storage container and the pressure spatula through a high-pressure pipe, move to the underwater joint repair work surface, and press the pressure spatula on the joint; ③ The material is discharged through the grouting machine, and the material is squeezed into the joint through the reserved holes of the trowel; ④ The diver or underwater robot carries a pressure spatula and moves forward along the joint defect position. When moving, a certain pressure is maintained on the pressure spatula, and the material is discharged while moving to complete the filling and plastering repair of the joint defect.

[0101] The above embodiments are only for illustrating the better performance of the present invention and do not constitute a limitation on the present invention. It should be pointed out that any changes made by technicians in this professional field without departing from the core concept of the present invention and the obvious changes derived therefrom are all within the protection scope of the present invention.

Claims

1. A cement-based tough water-stopping mortar suitable for underwater repair of concrete joints, characterized by: The cement-based tough water-stop mortar is prepared from three materials: powder, polymer emulsion and water, wherein the mass ratio of powder, polymer emulsion and water is (83-90):(1-6):(9-11); The powder is mixed by the following components in the following mass proportions: 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 parts of defoaming agent, and 1-2 parts of anti-dispersant; The modified fiber is obtained by dipping the fiber into a mixed solution of γ-aminopropyl silane coupling agent and then drying it; The modified rubber particles are obtained by dipping the rubber particles in an alkaline solution and drying them, and then placing them in a γ The obtained product is immersed in an ethanol solution of -(methacryloyloxy)propyltrimethoxysilane coupling agent for 30-40 minutes, and finally dried at a low temperature of 30-40°C.

2. The cement-based tough water-stopping mortar suitable for underwater repair of concrete joints according to claim 1, characterized in that: The polymer emulsion is one or two of acrylic copolymer emulsion, styrene-butadiene emulsion, ethylene-vinyl acetate copolymer emulsion, styrene-acrylic emulsion, chloroprene rubber emulsion and polyvinyl acetate emulsion.

3. The cement-based tough water-stopping mortar suitable for underwater repair of concrete joints according to claim 1, characterized in that: The modified fiber is obtained by dipping the fiber into a γ-aminopropylsilane coupling agent mixed solution at 40-60° C. for 60-90 minutes and then drying it; The fiber can be selected from one or two of polyvinyl alcohol fiber PVA, polypropylene fiber PP, polyoxymethylene fiber POM, and polyacrylonitrile fiber PAN.

4. The cement-based tough water-stopping mortar suitable for underwater repair of concrete joints according to claim 1, characterized in that: The anti-dispersion agent is one of polyacrylamide, hydroxypropyl methylcellulose ether and polyacrylamide; the water reducer is one of melamine-based high-efficiency water reducer and polycarboxylic acid-based high-performance water reducer.

5. The cement-based tough water-stopping mortar suitable for underwater repair of concrete joints according to claim 2, characterized in that: The polymer emulsion is a combination of ethylene-vinyl acetate copolymer emulsion and polyvinyl acetate emulsion in the following weight parts: 4-6 parts of ethylene-vinyl acetate copolymer emulsion and 0-2 parts of polyvinyl acetate emulsion.

6. The cement-based tough water-stopping mortar suitable for underwater repair of concrete joints according to claim 3, characterized in that: The fibers are a mixture of polypropylene fibers PP and polyoxymethylene fibers POM in parts by mass, wherein the polypropylene fibers PP account for 2 to 4 parts and the polyoxymethylene fibers POM account for 0 to 2 parts.

7. Use of the cement-based tough water-stop mortar according to any one of claims 1 to 6 in underwater repair of concrete joints.

8. The method for preparing the cement-based tough water-stop mortar according to any one of claims 1 to 6, characterized in that: The steps include: 1) Add weighed polymer emulsion and water into a stirring tank and stir at 300-500 r / min for 10-15 min; 2) 850-950 parts of cement, 50-150 parts of vitrified microspheres, 2-4 parts of modified fibers, 300-650 parts of modified rubber particles, 1500-1850 parts of quartz sand, 2-4 parts of water reducing agent, 0.5-1 parts of defoaming agent, and 1-2 parts of anti-dispersant are mixed uniformly by mass to obtain a powder; 3) Add the powder into a mixing tank and stir at a speed of 1000-1200 r / min for 3-5 minutes.

9. A rapid construction process using the cement-based tough water-stopping mortar for underwater repair of concrete joints as claimed in claim 1, characterized in that: Cement-based tough water-stop mortar is prepared on shore and then squeezed and transported to the underwater operating platform through a high-pressure pipeline. The trowel with a reserved discharge port is pressed on the defective position of the joint, and the joint is filled and repaired while moving and discharging the material.

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