A high-performance polymer-cement based composite repair material and its preparation method

Abstract

This invention relates to a high-performance polymer-cement-based composite repair material and its preparation method. The high-performance polymer-cement-based composite repair material, by mass fraction, comprises the following components: 690-710 parts cement; 130-150 parts fly ash; 45-55 parts silica fume; 200-210 parts mixing water; 950-1050 parts fine aggregate; 21-23 parts modified polymer; 9-10 parts expansion agent; 4-5 parts water-reducing agent; 5-6 parts modified fiber; and 0.16-0.18 parts defoamer. This invention utilizes nano-toughened modified polymer and modified fiber. The nano-modified polymer improves the microstructure of the repair material, while the modified fiber limits shrinkage and enhances the crack resistance of the matrix. The synergistic effect of both effectively improves the toughness and mechanical properties of the repair material, ensuring that early cracking does not occur.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a high-performance polymer-cement-based composite repair material and its preparation method. Background Technology

[0002] Reinforced concrete structures are widely used in civil engineering due to their excellent mechanical properties, durability, fire resistance, and earthquake resistance. However, after long-term use, the load-bearing capacity of the structure decreases due to material aging, corrosion, load, and the effects of natural disasters such as fires and earthquakes. From a safety and economic perspective, repairing and reinforcing damaged structures can not only restore their load-bearing capacity and durability to a certain extent, but also avoid the high costs associated with demolition and reconstruction, facilitating the renovation and reuse of old structures. Therefore, developing high-performance repair materials and improving the durability of repaired structures are crucial for effectively extending the service life of reinforced concrete structures.

[0003] In recent years, cement-based repair materials have been widely used for repairing and reinforcing reinforced concrete structures due to their compatibility and long-term durability. A common method for repairing damaged reinforced concrete structures to maintain structural function is to apply repair materials to the existing concrete surface. However, differences in properties such as the modulus of elasticity, shrinkage rate, and coefficient of thermal expansion between the repair material and the old concrete can create weak points at the interface. Furthermore, the effectiveness of traditional repair materials is limited by defects in the old concrete, such as cracks, surface contamination, and reduced strength.

[0004] Commonly used repair materials mainly include inorganic and organic repair materials. Inorganic repair materials are primarily cement-based. While cement-based repair materials have advantages such as high compressive strength and good durability, they also suffer from poor ductility, brittle fracture, large shrinkage, and poor adhesion, reducing the safety and lifespan of the repaired road. Organic repair materials are represented by epoxy resin. Although epoxy resin has excellent adhesion and impermeability, it is prone to aging and strength loss over time, and its excessive viscosity makes it difficult to apply. Some researchers have attempted to combine inorganic and organic materials to form organic-inorganic composite repair materials. Organic-inorganic repair materials, to some extent, compensate for the large shrinkage and poor adhesion of cement-based repair materials. However, organic-inorganic repair materials still have many shortcomings. For example, their crack resistance remains poor, and the poor compatibility between organic and inorganic materials leads to a decrease in compressive strength after mixing. Summary of the Invention

[0005] The present invention aims to address the shortcomings of the prior art by providing a high-performance polymer-cement-based composite repair material and its preparation method.

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

[0007] A high-performance polymer-cement-based composite repair material, formulated by mass fraction, consists of the following components:

[0008] 690-710 parts cement;

[0009] 130-150 parts fly ash;

[0010] 45-55 parts silica fume;

[0011] Mix 200-210 parts water;

[0012] 950-1050 parts fine aggregate;

[0013] 21-23 parts of modified polymer;

[0014] 9-10 parts of expanding agent;

[0015] 4-5 parts water-reducing agent;

[0016] 5-6 parts of modified fiber;

[0017] 0.16-0.18 parts of defoamer.

[0018] Specifically, the cement is composed of sulfoaluminate cement and ordinary silicate cement, and both sulfoaluminate cement and ordinary silicate cement have a strength grade of 42.5. The mass ratio of sulfoaluminate cement to ordinary silicate cement is 1:0.3.

[0019] Specifically, the fly ash is either Grade I fly ash or Grade II fly ash.

[0020] Specifically, the specific surface area of ​​silica fume is not less than 15000 m². 2 / kg.

[0021] Specifically, the fine aggregate is quartz sand or river sand, with a particle size distribution range of 0.15-2.35 mm.

[0022] Specifically, the water-reducing agent is a high-efficiency polycarboxylate water-reducing agent.

[0023] Specifically, the modified polymer is obtained by nano-toughening of ethylene-vinyl acetate copolymer powder, and its preparation steps are as follows:

[0024] S1. Add 9g of cetyltrimethylammonium bromide to 100ml of deionized water, heat the solution to 45℃, and stir the solution with a magnetic stirrer for 10-15min to obtain solution A.

[0025] S2. Add 1g of pyrene to solution A and stir the solution with a magnetic stirrer for 2 hours at room temperature until the pyrene is fully dispersed to obtain solution B.

[0026] S3. Add 3.6g of hydrochloric acid solution with pH=3 to 11.5g of tetramethyl silicate, stir continuously for 5-6 minutes, and use an ultrasonic probe to sonicate the mixed solution for 10-15 minutes to obtain solution C.

[0027] S4. Mix solutions B and C at 40°C and stir for 4-5 minutes. After the mixture has completely turned into a sol-gel state, place the gel in an oven at 90°C and dry for 24 hours to obtain composite material D.

[0028] S5. Place the D composite material into a ceramic boat, heat the ceramic boat in nitrogen gas, heat it to 900℃ at a heating rate of 2℃ / min, maintain it at 900℃ for 120-130min, and then grind the heated composite material into powder to obtain E powder.

[0029] S6. Add 200mg of E powder to 60ml of deionized water and stir continuously for 5-6 minutes. Use an ultrasonic probe to sonicate the mixture for 10-15 minutes to obtain solution F.

[0030] S7. Add 200 mg of magnesium chloride hexahydrate and 1600 mg of ammonium chloride to 60 ml of deionized water and stir for 3-4 min to obtain solution G.

[0031] S8. Mix solution F and solution G and stir for 60-65 min to obtain solution H. Transfer solution H to an autoclave and heat at 150℃ for 24 h to synthesize nanoproducts. Centrifuge the nanoproducts generated by the reaction, wash them with deionized water 5-6 times, and dry them in an oven at 60℃ for 12 h to obtain nano-toughened composite materials.

[0032] S9. Pour the nano-toughened composite material and ethylene-vinyl acetate copolymer powder into a stirrer at a ratio of 3:1000 and mix for 10-12 minutes to obtain the nano-toughened polymer, i.e., the modified polymer.

[0033] Specifically, the modified fiber is obtained by modifying polypropylene fiber, and its preparation steps are as follows:

[0034] P1. Add 30g of polypropylene fiber to 500ml of ethanol solution of γ-aminopropyltriethoxysilane, and use an ultrasonic probe to sonicate the mixed solution for 30-35 minutes to disperse the fiber in the solution, thus obtaining fiber I.

[0035] P2. Thoroughly rinse I fiber with anhydrous ethanol, and dry the cleaned fiber at 65°C for 24 hours to obtain modified J fiber.

[0036] P3. Dissolve 10g of nano-silica in 1000ml of ethanol, and sonicate the solution at 30℃ for 30-35min using an ultrasonic probe to obtain solution K.

[0037] P4. Place the modified J fiber into solution K, and then use an ultrasonic probe to sonicate the solution for 3 hours to obtain the modified L fiber.

[0038] P5. Thoroughly rinse the modified L fiber and dry the cleaned fiber at 65℃ for 24 hours to obtain the modified M fiber, i.e., the modified fiber.

[0039] Specifically, the polypropylene fiber has a length of 19-22 mm, a diameter of 0.12-0.16 mm, and a tensile strength greater than 950 MPa.

[0040] A method for preparing a high-performance polymer-cement-based composite repair material includes the following steps:

[0041] N1. Weigh the following components by weight: 690-710 parts cement, 130-150 parts fly ash, 45-55 parts silica fume, 200-210 parts mixing water, 950-1050 parts fine aggregate, 21-23 parts modified polymer, 9-10 parts expanding agent, 4-5 parts water-reducing agent, 5-6 parts modified fiber, and 0.16-0.18 parts defoamer.

[0042] N2. Add cement, fly ash, silica fume, fine aggregate, and modified polymer to a mixer and mix evenly for 3-4 minutes. The resulting mixture is denoted as N mixture.

[0043] N3. Add the expanding agent, water reducing agent and defoamer to the mixing water and stir evenly for 1-2 minutes. The resulting mixture is called mixture O.

[0044] N4. Add the O mixture evenly to the N mixture and stir until homogeneous. Stir for 3-4 minutes. The resulting mixture is the P mixture.

[0045] N5. Slowly and evenly add the modified fiber to the P mixture and stir until the fiber is fully dispersed. The stirring time is 3-4 minutes to obtain fresh concrete.

[0046] N6. Pour the fresh concrete from N5 into the mold for curing. Curing is carried out for 24 hours at a temperature of 22±2℃ and a humidity of 99%. After demolding, it is cured to a fixed age to obtain a cured high-performance polymer-cement-based composite repair material.

[0047] The beneficial effects of this invention are:

[0048] 1. Compared with traditional polymer-cement composite repair materials, this invention uses nano-toughened modified polymers and modified fibers. The nano-modified polymers can improve the microstructure of the repair material, and the modified fibers can limit the shrinkage of the repair material and enhance the crack resistance of the matrix. The synergistic effect of the two can effectively improve the toughness and mechanical properties of the repair material, ensuring that the repair material does not crack in the early stage.

[0049] 2. The modified polymer used in this invention has good mechanical properties and dispersibility. The modified polymer and cement can play a better synergistic role, which solves the technical defects of poor bonding between polymer and cement and significant reduction in the compressive strength of cement concrete caused by the incorporation of polymer.

[0050] 3. The repair material prepared by this invention has good impact resistance and wear resistance.

[0051] 4. This invention can achieve ultra-high mechanical properties in a short time, shortening the curing time. Its maximum compressive strength can reach more than 100MPa, and it can be widely applied in the field of engineering repair. Detailed Implementation

[0052] The present invention will be further described below with reference to embodiments:

[0053] A high-performance polymer-cement-based composite repair material, formulated by mass fraction, consists of the following components:

[0054] 690-710 parts cement;

[0055] 130-150 parts fly ash;

[0056] 45-55 parts silica fume;

[0057] Mix 200-210 parts water;

[0058] 950-1050 parts fine aggregate;

[0059] 21-23 parts of modified polymer;

[0060] 9-10 parts of expanding agent;

[0061] 4-5 parts water-reducing agent;

[0062] 5-6 parts of modified fiber;

[0063] 0.16-0.18 parts of defoamer.

[0064] The cement is composed of sulfoaluminate cement and ordinary Portland cement, both with a strength grade of 42.5, and a mass ratio of sulfoaluminate cement to ordinary Portland cement of 1:0.3. This composite cement offers the following advantages: Balance between early and long-term strength: A significant characteristic of sulfoaluminate cement is its ability to achieve high early strength in a short time, which is highly advantageous for work requiring rapid construction or repair; while ordinary Portland cement does not have as high an early strength as sulfoaluminate cement, its later strength development is excellent, and it exhibits superior durability; the combined use allows the concrete to have both rapid hardening and good long-term performance. Enhanced freeze-thaw resistance: Because sulfoaluminate cement promotes earlier completion of the hydration reaction, it improves the concrete's adaptability to cold environments, reducing the risk of damage caused by moisture freezing and expansion; simultaneously, the stable structure provided by ordinary Portland cement further enhances the overall freeze-thaw resistance of the material. Improved workability: In some cases, by adjusting the ratio of the two cements, the workability of the mixture, such as fluidity and plasticity, can be adjusted, making construction more convenient and faster.

[0065] Fly ash is classified as Grade I or Grade II fly ash. Due to its high activity and fineness, fly ash plays the following roles in cement-based repair materials: Improving workability: The spherical particle shape of fly ash acts as a lubricant, increasing the fluidity of concrete mixtures, thus improving workability and pumpability. Enhancing durability: Fly ash fills pores in cement paste, reducing the penetration pathways of harmful ions (such as chloride ions), thereby improving the impermeability and corrosion resistance of concrete. It also reacts with cement hydration products to generate more CSH gel, further densifying the concrete structure and improving its long-term durability. Reducing the risk of thermal cracking: In large-volume concrete construction, fly ash slows down the generation of heat of hydration, helping to reduce early temperature peaks and reducing cracks caused by temperature differences. Cost savings: By partially replacing cement, fly ash can reduce raw material costs, and due to its lower density, it can also reduce the mass of concrete per unit volume. Improving later-stage strength: Although fly ash may slightly delay early strength development, it participates in secondary hydration reactions over time, promoting the growth of later-stage concrete strength. Environmentally friendly: Using fly ash as a partial substitute for cement helps reduce the environmental impact of industrial waste and lowers the energy consumption and CO2 emissions required to produce cement.

[0066] The specific surface area of ​​silica fume is not less than 15000 m². 2 / kg; Silica fume is typically obtained through the collection and processing of byproducts generated during the production of metallic silicon or ferroalloys. Its main component is amorphous silica, which has an extremely high specific surface area, giving it a unique role in cement-based repair materials: Increased Strength: Silica fume can significantly increase the compressive strength, tensile strength, and modulus of elasticity of concrete because the active silica in it reacts with calcium hydroxide in cement hydration products to generate more CSH gel, which is the main load-bearing phase of the hardened cement. Improved Durability: Due to its extremely small particle size, silica fume can fill the tiny pores in cement paste, reducing porosity and thus increasing the density of concrete. This helps improve the concrete's impermeability, freeze-thaw resistance, and resistance to chemical attack. Silica fume can also reduce the risk of alkali-aggregate reaction because the silica in it consumes some of the calcium hydroxide, reducing the alkali content inside the concrete. Enhanced Bond Strength: In repair materials, silica fume provides a better interfacial transition zone, enhancing the bond between new and old concrete, which is particularly important for repair projects. Controlling early cracking: By optimizing the mix proportions, silica fume can help control early shrinkage and reduce cracking, which is crucial for ensuring the effectiveness and long-term performance of repair materials. Improving abrasion and erosion resistance: Due to its increased hardness and density, silica fume can improve the abrasion and erosion resistance of concrete surfaces, which is very important for certain specialized applications.

[0067] The chemical composition of ordinary silicate cement, sulfoaluminate cement and silica fume is shown in Table 1.

[0068] Table 1 Chemical composition of ordinary Portland cement (PC), sulfoaluminate cement (CSA), and silica fume (SF)

[0069] Material <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> MgO CaO <![CDATA[Na2O]]> <![CDATA[K2O]]> <![CDATA[SO3]]> <![CDATA[TiO2]]> Others PC 23.22 5.21 4.56 2.85 60.21 0.77 0.54 1.13 1.27 0.24 CSA 8.31 33.42 2.12 1.74 43.91 0.12 0.33 7.81 1.45 0.79 SF 98.68 0.22 0.13 0.12 0.17 0.04 0.09 0.11 0.16 0.28

[0070] The fine aggregate is quartz sand or river sand, with a particle size distribution range of 0.15-2.35 mm.

[0071] The water-reducing agent is a high-efficiency polycarboxylate water-reducing agent.

[0072] Before formulating the composite repair material, the ethylene-vinyl acetate copolymer powder and polypropylene fibers were modified. The ethylene-vinyl acetate copolymer powder had an average particle size of 0.4 mm and a solid content of 99±1%. The polypropylene fibers had a length of 19-22 mm, a diameter of 0.12-0.16 mm, and a tensile strength greater than 950 MPa.

[0073] The modified polymer is obtained by nano-toughening ethylene-vinyl acetate copolymer powder. The nano-toughening technique involves carbonizing and derivatizing the organic molecule pyrene to form graphene with a three-dimensional carbon network, followed by a series of optimization reactions on the graphene nanosheets to form the nano-toughened material. The nano-toughened material is then further mixed with the ethylene-vinyl acetate copolymer to form a modified polymer with high thermal stability, high strength, and high dispersibility. The preparation steps are as follows:

[0074] S1. Add 9g of hexadecyltrimethylammonium bromide to 100ml of deionized water, heat the solution to 45℃, and stir the solution with a magnetic stirrer for 10-15min to obtain solution A; hexadecyltrimethylammonium bromide is a light yellow powder;

[0075] S2. Add 1g of pyrene to solution A and stir the solution with a magnetic stirrer for 2 hours at room temperature until the pyrene is fully dispersed to obtain solution B; pyrene is a pale yellow powder.

[0076] S3. Add 3.6g of hydrochloric acid solution with pH=3 to 11.5g of tetramethyl silicate, stir continuously for 5-6 minutes, and use an ultrasonic probe to sonicate the mixture for 10-15 minutes to obtain solution C; tetramethyl silicate is an organic compound and is a colorless liquid;

[0077] S4. Mix solutions B and C at 40°C and stir for 4-5 minutes. After the mixture has completely turned into a sol-gel state, place the gel in an oven at 90°C and dry for 24 hours to obtain composite material D.

[0078] S5. Place the D composite material into a ceramic boat, heat the ceramic boat in nitrogen gas, heat it to 900℃ at a heating rate of 2℃ / min, maintain it at 900℃ for 120-130min, and then grind the heated composite material into powder to obtain E powder.

[0079] S6. Add 200mg of E powder to 60ml of deionized water and stir continuously for 5-6 minutes. Use an ultrasonic probe to sonicate the mixture for 10-15 minutes to obtain solution F.

[0080] S7. Add 200 mg of magnesium chloride hexahydrate and 1600 mg of ammonium chloride to 60 ml of deionized water and stir for 3-4 min to obtain solution G; magnesium chloride hexahydrate and ammonium chloride are white powders.

[0081] S8. Mix solution F and solution G and stir for 60-65 min to obtain solution H. Transfer solution H to an autoclave and heat at 150℃ for 24 h to synthesize nanoproducts. Centrifuge the nanoproducts generated by the reaction, wash them with deionized water 5-6 times, and dry them in an oven at 60℃ for 12 h to obtain nano-toughened composite materials.

[0082] S9. Pour the nano-toughened composite material and ethylene-vinyl acetate copolymer powder into a stirrer at a ratio of 3:1000 and mix for 10-12 minutes to obtain the nano-toughened polymer, i.e., the modified polymer. The ethylene-vinyl acetate copolymer powder is a white powder.

[0083] The modified fiber is obtained by modifying polypropylene fiber, and its preparation steps are as follows:

[0084] P1. Add 30g of polypropylene fiber to 500ml of ethanol solution of γ-aminopropyltriethoxysilane, and use an ultrasonic probe to sonicate the mixed solution for 30-35 minutes to disperse the fiber in the solution, thus obtaining fiber I.

[0085] P2. Thoroughly rinse I fiber with anhydrous ethanol, and dry the cleaned fiber at 65°C for 24 hours to obtain modified J fiber.

[0086] P3. Dissolve 10g of nano-silica in 1000ml of ethanol, and sonicate the solution at 30℃ for 30-35min using an ultrasonic probe to obtain solution K.

[0087] P4. Place the modified J fiber into solution K, and then use an ultrasonic probe to sonicate the solution for 3 hours to obtain the modified L fiber.

[0088] P5. Thoroughly rinse the modified L fiber and dry the cleaned fiber at 65℃ for 24 hours to obtain the modified M fiber, i.e., the modified fiber.

[0089] A method for preparing a high-performance polymer-cement-based composite repair material includes the following steps:

[0090] N1. Weigh the following components by weight: 690-710 parts cement, 130-150 parts fly ash, 45-55 parts silica fume, 200-210 parts mixing water, 950-1050 parts fine aggregate, 21-23 parts modified polymer, 9-10 parts expanding agent, 4-5 parts water-reducing agent, 5-6 parts modified fiber, and 0.16-0.18 parts defoamer.

[0091] N2. Add cement, fly ash, silica fume, fine aggregate, and modified polymer to a mixer and mix evenly for 3-4 minutes. The resulting mixture is denoted as N mixture.

[0092] N3. Add the expanding agent, water reducing agent and defoamer to the mixing water and stir evenly for 1-2 minutes. The resulting mixture is called mixture O.

[0093] N4. Add the O mixture evenly to the N mixture and stir until homogeneous. Stir for 3-4 minutes. The resulting mixture is the P mixture.

[0094] N5. Slowly and evenly add the modified fiber to the P mixture and stir until the fiber is fully dispersed. The stirring time is 3-4 minutes to obtain fresh concrete.

[0095] N6. Pour the fresh concrete from N5 into the mold for curing. Curing is carried out for 24 hours at a temperature of 22±2℃ and a humidity of 99%. After demolding, it is cured to a fixed age to obtain a cured high-performance polymer-cement-based composite repair material.

[0096] Example 1

[0097] A high-performance polymer-cement-based composite repair material, formulated by mass fraction, consists of the following components:

[0098] 690 parts cement, 130 parts fly ash, 55 parts silica fume, 210 parts mixing water, 1050 parts fine aggregate, 21 parts modified polymer, 9 parts expanding agent, 4 parts water-reducing agent, 5 parts modified fiber, and 0.16 parts defoamer.

[0099] The cement is composed of sulfoaluminate cement and ordinary Portland cement, both with a strength grade of 42.5, and a mass ratio of sulfoaluminate cement to ordinary Portland cement of 1:0.3. The fly ash is grade I fly ash with a specific surface area of ​​453 m². 2 / kg. The specific surface area of ​​silica fume is 19000 m². 2 / g. The fine aggregate is washed river sand with a fineness modulus of 2.65, a particle size distribution range of 0-2.35mm, and a mud content of less than 3%. The water-reducing agent is a high-efficiency polycarboxylate water-reducing agent.

[0100] The modified polymer was obtained by nano-toughening of ethylene-vinyl acetate copolymer powder, and its preparation steps are as follows:

[0101] S1. Add 9g of hexadecyltrimethylammonium bromide to 100ml of deionized water, heat the solution to 45℃, and stir the solution with a magnetic stirrer for 10-15min to obtain solution A; hexadecyltrimethylammonium bromide is a light yellow powder;

[0102] S2. Add 1g of pyrene to solution A and stir the solution with a magnetic stirrer for 2 hours at room temperature until the pyrene is fully dispersed to obtain solution B; pyrene is a pale yellow powder.

[0103] S3. Add 3.6g of hydrochloric acid solution with pH=3 to 11.5g of tetramethyl silicate, stir continuously for 5-6 minutes, and use an ultrasonic probe to sonicate the mixture for 10-15 minutes to obtain solution C; tetramethyl silicate is an organic compound and is a colorless liquid;

[0104] S4. Mix solutions B and C at 40°C and stir for 4-5 minutes. After the mixture has completely turned into a sol-gel state, place the gel in an oven at 90°C and dry for 24 hours to obtain composite material D.

[0105] S5. Place the D composite material into a ceramic boat, heat the ceramic boat in nitrogen gas, heat it to 900℃ at a heating rate of 2℃ / min, maintain it at 900℃ for 120-130min, and then grind the heated composite material into powder to obtain E powder.

[0106] S6. Add 200mg of E powder to 60ml of deionized water and stir continuously for 5-6 minutes. Use an ultrasonic probe to sonicate the mixture for 10-15 minutes to obtain solution F.

[0107] S7. Add 200 mg of magnesium chloride hexahydrate and 1600 mg of ammonium chloride to 60 ml of deionized water and stir for 3-4 min to obtain solution G; magnesium chloride hexahydrate and ammonium chloride are white powders.

[0108] S8. Mix solution F and solution G and stir for 60-65 min to obtain solution H. Transfer solution H to an autoclave and heat at 150℃ for 24 h to synthesize nanoproducts. Centrifuge the nanoproducts generated by the reaction, wash them with deionized water 5-6 times, and dry them in an oven at 60℃ for 12 h to obtain nano-toughened composite materials.

[0109] S9. Pour the nano-toughened composite material and ethylene-vinyl acetate copolymer powder into a stirrer at a ratio of 3:1000 and mix for 10-12 minutes to obtain the nano-toughened polymer, i.e., the modified polymer. The ethylene-vinyl acetate copolymer powder is a white powder.

[0110] The modified fiber is obtained by modifying polypropylene fiber, and its preparation steps are as follows:

[0111] P1. Add 30g of polypropylene fiber to 500ml of ethanol solution of γ-aminopropyltriethoxysilane, and use an ultrasonic probe to sonicate the mixed solution for 30-35 minutes to disperse the fiber in the solution, thus obtaining fiber I.

[0112] P2. Thoroughly rinse I fiber with anhydrous ethanol, and dry the cleaned fiber at 65°C for 24 hours to obtain modified J fiber.

[0113] P3. Dissolve 10g of nano-silica in 1000ml of ethanol, and sonicate the solution at 30℃ for 30-35min using an ultrasonic probe to obtain solution K.

[0114] P4. Place the modified J fiber into solution K, and then use an ultrasonic probe to sonicate the solution for 3 hours to obtain the modified L fiber.

[0115] P5. Thoroughly rinse the modified L fiber and dry the cleaned fiber at 65℃ for 24 hours to obtain the modified M fiber, i.e., the modified fiber.

[0116] A method for preparing a high-performance polymer-cement-based composite repair material includes the following steps:

[0117] N1. Weigh the following components according to the above-mentioned mass proportions: 690 parts cement, 130 parts fly ash, 55 parts silica fume, 210 parts mixing water, 1050 parts fine aggregate, 21 parts modified polymer, 9 parts expanding agent, 4 parts water-reducing agent, 5 parts modified fiber, and 0.16 parts defoamer.

[0118] N2. Add cement, fly ash, silica fume, fine aggregate, and modified polymer to a mixer and mix evenly for 3-4 minutes. The resulting mixture is denoted as N mixture.

[0119] N3. Add the expanding agent, water reducing agent and defoamer to the mixing water and stir evenly for 1-2 minutes. The resulting mixture is called mixture O.

[0120] N4. Add the O mixture evenly to the N mixture and stir until homogeneous. Stir for 3-4 minutes. The resulting mixture is the P mixture.

[0121] N5. Slowly and evenly add the modified fiber to the P mixture and stir until the fiber is fully dispersed. The stirring time is 3-4 minutes to obtain fresh concrete.

[0122] N6. Pour the fresh concrete from N5 into the mold for curing. Curing is carried out for 24 hours at a temperature of 22±2℃ and a humidity of 99%. After demolding, it is cured to a fixed age to obtain a cured high-performance polymer-cement-based composite repair material.

[0123] Example 2

[0124] A high-performance polymer-cement-based composite repair material, formulated by mass fraction, consists of the following components:

[0125] 700 parts cement, 140 parts fly ash, 50 parts silica fume, 200 parts mixing water, 1000 parts fine aggregate, 22 parts modified polymer, 9 parts expanding agent, 5 parts water-reducing agent, 6 parts modified fiber, and 0.17 parts defoamer.

[0126] The cement is composed of sulfoaluminate cement and ordinary Portland cement, both with a strength grade of 42.5, and a mass ratio of sulfoaluminate cement to ordinary Portland cement of 1:0.3. The fly ash is grade I fly ash with a specific surface area of ​​453 m². 2 / kg. The specific surface area of ​​silica fume is 19000 m². 2 / g. The fine aggregate is washed river sand with a fineness modulus of 2.65, a particle size distribution range of 0-2.35 mm, and a mud content of less than 3%. The water-reducing agent is a high-efficiency polycarboxylate water-reducing agent. The preparation steps of the modified polymer and modified fiber are the same as in Example 1.

[0127] The preparation method of a high-performance polymer-cement-based composite repair material is the same as that in Example 1.

[0128] Example 3

[0129] A high-performance polymer-cement-based composite repair material, formulated by mass fraction, consists of the following components:

[0130] 710 parts cement, 150 parts fly ash, 45 parts silica fume, 200 parts mixing water, 950 parts fine aggregate, 23 parts modified polymer, 10 parts expanding agent, 5 parts water-reducing agent, 6 parts modified fiber, and 0.18 parts defoamer.

[0131] The cement is composed of sulfoaluminate cement and ordinary Portland cement, both with a strength grade of 42.5, and a mass ratio of sulfoaluminate cement to ordinary Portland cement of 1:0.3. The fly ash is grade I fly ash with a specific surface area of ​​453 m². 2 / kg. The specific surface area of ​​silica fume is 19000 m². 2 / g. The fine aggregate is washed river sand with a fineness modulus of 2.65, a particle size distribution range of 0-2.35 mm, and a mud content of less than 3%. The water-reducing agent is a high-efficiency polycarboxylate water-reducing agent. The preparation steps of the modified polymer and modified fiber are the same as in Example 1.

[0132] The preparation method of a high-performance polymer-cement-based composite repair material is the same as that in Example 1.

[0133] Comparative Example 1

[0134] Compared to Example 1, no modified polymer was added in Comparative Example 1.

[0135] A high-performance polymer-cement-based composite repair material, by mass fraction, is composed of the following components: 690 parts cement, 130 parts fly ash, 55 parts silica fume, 210 parts mixing water, 1050 parts fine aggregate, 9 parts expansion agent, 4 parts water-reducing agent, 5 parts modified fiber, and 0.16 parts defoamer.

[0136] The cement is composed of sulfoaluminate cement and ordinary Portland cement, both with a strength grade of 42.5, and a mass ratio of sulfoaluminate cement to ordinary Portland cement of 1:0.3. The fly ash is grade I fly ash with a specific surface area of ​​453 m². 2 / kg. The specific surface area of ​​silica fume is 19000 m². 2 / g. The fine aggregate is washed river sand with a fineness modulus of 2.65, a particle size distribution range of 0-2.35 mm, and a mud content of less than 3%. The water-reducing agent is a high-efficiency polycarboxylate water-reducing agent. The modified fiber preparation steps are the same as in Example 1.

[0137] The preparation method of a high-performance polymer-cement-based composite repair material is the same as that in Example 1.

[0138] Comparative Example 2

[0139] Compared to Example 1, no modification was made to the polymer in Comparative Example 1; only ethylene-vinyl acetate copolymer powder was added.

[0140] A high-performance polymer-cement-based composite repair material, by mass fraction, is composed of the following components: 690 parts cement, 130 parts fly ash, 55 parts silica fume, 210 parts mixing water, 1050 parts fine aggregate, 21 parts ethylene-vinyl acetate copolymer powder, 9 parts expansion agent, 4 parts water-reducing agent, 5 parts modified fiber, and 0.16 parts defoamer.

[0141] The cement is composed of sulfoaluminate cement and ordinary Portland cement, both with a strength grade of 42.5, and a mass ratio of sulfoaluminate cement to ordinary Portland cement of 1:0.3. The fly ash is grade I fly ash with a specific surface area of ​​453 m².2 / kg. The specific surface area of ​​silica fume is 19000 m². 2 / g. The fine aggregate is washed river sand with a fineness modulus of 2.65, a particle size distribution range of 0-2.35 mm, and a mud content of less than 3%. The water-reducing agent is a high-efficiency polycarboxylate water-reducing agent. The modified fiber preparation steps are the same as in Example 1.

[0142] The preparation method of a high-performance polymer-cement-based composite repair material is the same as that in Example 1.

[0143] Comparative Example 3

[0144] Compared to Example 1, no modified fibers were added in Comparative Example 1.

[0145] A high-performance polymer-cement-based composite repair material, by mass fraction, is composed of the following components: 690 parts cement, 130 parts fly ash, 55 parts silica fume, 210 parts mixing water, 1050 parts fine aggregate, 21 parts modified polymer, 9 parts expansion agent, 4 parts water-reducing agent, and 0.16 parts defoamer.

[0146] The cement is composed of sulfoaluminate cement and ordinary Portland cement, both with a strength grade of 42.5, and a mass ratio of sulfoaluminate cement to ordinary Portland cement of 1:0.3. The fly ash is grade I fly ash with a specific surface area of ​​453 m². 2 / kg. The specific surface area of ​​silica fume is 19000 m². 2 / g. The fine aggregate is washed river sand with a fineness modulus of 2.65, a particle size distribution range of 0-2.35 mm, and a mud content of less than 3%. The water-reducing agent is a high-efficiency polycarboxylate water-reducing agent. The preparation steps of the modified polymer are the same as in Example 1.

[0147] The preparation method of a high-performance polymer-cement-based composite repair material is the same as that in Example 1.

[0148] Comparative Example 4

[0149] Compared to Example 1, Comparative Example 1 did not modify the polypropylene fibers; only unmodified polypropylene fibers were added.

[0150] A high-performance polymer-cement-based composite repair material, by mass fraction, is composed of the following components: 690 parts cement, 130 parts fly ash, 55 parts silica fume, 210 parts mixing water, 1050 parts fine aggregate, 21 parts modified polymer, 9 parts expansion agent, 4 parts water-reducing agent, 5 parts polypropylene fiber, and 0.16 parts defoamer.

[0151] The cement is composed of sulfoaluminate cement and ordinary Portland cement, both with a strength grade of 42.5, and a mass ratio of sulfoaluminate cement to ordinary Portland cement of 1:0.3. The fly ash is grade I fly ash with a specific surface area of ​​453 m². 2 / kg. The specific surface area of ​​silica fume is 19000 m². 2 / g. The fine aggregate is washed river sand with a fineness modulus of 2.65, a particle size distribution range of 0-2.35 mm, and a mud content of less than 3%. The water-reducing agent is a high-efficiency polycarboxylate water-reducing agent. The preparation steps of the modified polymer are the same as in Example 1.

[0152] The preparation method of a high-performance polymer-cement-based composite repair material is the same as that in Example 1.

[0153] Table 2 shows the dosage of each component in the high-performance polymer-cement-based composite repair materials of Examples 1-3 and Comparative Examples 1-4.

[0154] Table 2 shows the amount of raw materials used in specific embodiments 1-3 and comparative examples 1-4.

[0155]

[0156] According to the standards GB / T 2419-2005 "Test Method for Flowability of Cement Mortar", GB / T 17671-2021 "Test Method for Strength of Cement Mortar", DL / T 5126-2001 "Test Procedure for Polymer Modified Cement Mortar", ASTM C882 / C882M "Standard Test Method for Determining Bond Strength of Epoxy Resin Adhesives for Concrete by Oblique Shear Method", and GB / T 3810.6-2016 "Test Methods for Ceramic Tiles Part 6: Determination of Abrasion Depth of Unglazed Tiles", the flowability, 4-hour compressive strength, 28-day flexural strength, 28-day compressive strength, tensile bond strength, compressive-oblique-shear bond strength, and wear mass of the high-performance polymer-cement-based composite repair materials in Examples 1-3 and Comparative Examples 1-4 were tested respectively. The test results are shown in Table 3.

[0157] Table 3. Performance of high-performance polymer-cement-based composite remediation materials in Examples 1-3 and Comparative Examples 1-4

[0158]

[0159] By comparing the performance results of Examples 1-3 and Comparative Examples 1-4 in Table 3, it can be found that the high-performance polymer-cement-based composite repair material prepared by mixing modified polymer and modified fiber has better overall performance in all aspects (flowability, compressive strength, flexural strength, tensile bond strength, incised bond strength, wear quality and impact strength) than the repair material without modified polymer or modified fiber.

[0160] In particular, when modified polymers were added to cement-based composite repair materials (by comparing Example 1 and Comparative Example 1), the repair materials did not experience a decrease in compressive strength or fluidity. Instead, the flexural strength, tensile bond strength, compressive bond strength, and impact strength of the repair materials were significantly improved, and the wear resistance was significantly enhanced. This means that the repaired structure has good safety and durability, which is of great significance for improving the road repair effect and can avoid the need for repeated repairs of the repaired road.

[0161] Comparing Example 1, Comparative Example 1, and Comparative Example 2, it can be found that compared with adding unmodified polymer, adding modified polymer has a more significant effect on improving the flexural strength, tensile bond strength, compressive bond strength, wear quality, and impact strength of cement-based repair materials. Moreover, the effect of adding modified polymer on the compressive strength and flowability of repair materials is negligible. In contrast, adding unmodified polymer (ethylene-vinyl acetate copolymer powder) has a limited effect on improving the flexural strength, tensile bond strength, compressive bond strength, wear quality, and impact strength of repair materials, and it will significantly reduce the compressive strength and flowability of repair materials.

[0162] Comparing Example 1, Comparative Example 3, and Comparative Example 4, it can be found that adding modified fibers can significantly improve the flexural strength, wear quality, and impact strength of cement-based repair materials, but the effect on improving the tensile bond strength and compressive bond strength is not significant. This indicates that adding modified fibers can further improve the overall mechanical properties of cement-based repair materials, making them safer.

[0163] In summary, by comparing the performance results of Examples 1-3 and Comparative Examples 1-4, it can be found that the high-performance polymer-cement-based composite repair material of the present invention has good working performance, mechanical properties and repair performance. It solves to a certain extent the technical problem of the decline in mechanical properties of repair materials caused by the incorporation of polymers into cement-based repair materials, and can be widely used in the field of road structure and building structure repair.

[0164] Compared to traditional polymer-cement composite repair materials, this invention utilizes nano-toughened modified polymers and modified fibers. The nano-modified polymers improve the microstructure of the repair material, while the modified fibers limit shrinkage and enhance the crack resistance of the matrix. Their synergistic effect effectively improves the toughness and mechanical properties of the repair material, ensuring that it does not crack in its early stages. The modified polymers used in this invention possess excellent mechanical properties and dispersibility. The modified polymers and cement exhibit a better synergistic effect, overcoming the technical defects of poor polymer-cement bonding and significant reduction in the compressive strength of cement concrete due to polymer incorporation. The repair material prepared by this invention exhibits excellent impact resistance and abrasion resistance. This invention achieves ultra-high mechanical properties in a short time, shortens curing time, and its maximum compressive strength can reach over 100 MPa, making it widely applicable in engineering repair fields.

[0165] The present invention has been described above by way of example. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any improvements made using the inventive concept and technical solution of the present invention, or direct application to other situations without modification, are all within the protection scope of the present invention. Furthermore, the endpoint values ​​and any values ​​given in the present invention are not limited to these precise ranges or values; these ranges or values ​​should be values ​​close to these ranges or values.

Claims

1. A high performance polymer-cement based composite repair material, characterized in that, According to the mass fraction ratio, it consists of the following components: Cement 690-710 parts; fly ash 130-150 parts; silica fume 45-55 parts; mixing water 200-210 parts; fine aggregate 950-1050 parts; modified polymer 21-23 parts; expanding agent 9-10 parts; water-reducing agent 4-5 parts; modified fiber 5-6 parts; defoamer 0.16-0.18 parts; The cement is composed of sulfoaluminate cement and ordinary silicate cement, and both sulfoaluminate cement and ordinary silicate cement have a strength grade of 42.

5. The mass ratio of sulfoaluminate cement to ordinary silicate cement is 1:0.

3. The modified polymer was obtained by nano-toughening of ethylene-vinyl acetate copolymer powder, and its preparation steps are as follows: S1. Add 9g of cetyltrimethylammonium bromide to 100ml of deionized water, heat the solution to 45℃, and stir the solution with a magnetic stirrer for 10-15min to obtain solution A. S2. Add 1g of pyrene to solution A and stir the solution with a magnetic stirrer for 2 hours at room temperature until the pyrene is fully dispersed to obtain solution B. S3. Add 3.6g of hydrochloric acid solution with pH=3 to 11.5g of tetramethyl silicate, stir continuously for 5-6 minutes, and use an ultrasonic probe to sonicate the mixture for 10-15 minutes to obtain solution C. S4. Mix solutions B and C at 40°C and stir for 4-5 minutes. After the mixture has completely turned into a sol-gel state, place the gel in an oven at 90°C and dry for 24 hours to obtain composite material D. S5. Place the D composite material into a ceramic boat, heat the ceramic boat in nitrogen gas, heat it to 900℃ at a heating rate of 2℃ / min, maintain it at 900℃ for 120-130min, and then grind the heated composite material into powder to obtain E powder. S6. Add 200mg of E powder to 60ml of deionized water and stir continuously for 5-6 minutes. Use an ultrasonic probe to sonicate the mixture for 10-15 minutes to obtain solution F. S7. Add 200 mg of magnesium chloride hexahydrate and 1600 mg of ammonium chloride to 60 ml of deionized water and stir for 3-4 min to obtain solution G; S8. Mix solution F and solution G and stir for 60-65 min to obtain solution H. Transfer solution H to an autoclave and heat at 150℃ for 24 h to synthesize nanoproducts. Centrifuge the nanoproducts generated by the reaction, wash them with deionized water 5-6 times, and dry them in an oven at 60℃ for 12 h to obtain nano-toughened composite materials. S9. Pour the nano-toughened composite material and ethylene-vinyl acetate copolymer powder into a stirrer at a ratio of 3:1000 and mix for 10-12 minutes to obtain the nano-toughened polymer, i.e., the modified polymer. The modified fiber is obtained by modifying polypropylene fiber, and its preparation steps are as follows: P1. Add 30g of polypropylene fiber to 500ml of ethanol solution of γ-aminopropyltriethoxysilane, and use an ultrasonic probe to sonicate the mixed solution for 30-35 minutes to disperse the fiber in the solution, thus obtaining fiber I. P2. Thoroughly rinse I fiber with anhydrous ethanol, and dry the cleaned fiber at 65°C for 24 hours to obtain modified J fiber. P3. Dissolve 10g of nano-silica in 1000ml of ethanol, and sonicate the solution at 30℃ for 30-35min using an ultrasonic probe to obtain solution K. P4. Place the modified J fiber into solution K, and then use an ultrasonic probe to sonicate the solution for 3 hours to obtain the modified L fiber. P5. Thoroughly rinse the modified L fiber and dry the cleaned fiber at 65℃ for 24 hours to obtain the modified M fiber, i.e., the modified fiber.

2. The high performance polymer-cement based composite repair material according to claim 1, characterized in that, The fly ash is either Grade I fly ash or Grade II fly ash.

3. The high performance polymer-cement based composite repair material according to claim 1, characterized in that, The specific surface area of the silica ash is not less than 15000 m 2 / kg.

4. The high performance polymer-cement based composite repair material according to claim 1, characterized in that, The fine aggregate is quartz sand or river sand, with a particle size distribution range of 0.15-2.35 mm.

5. The high performance polymer-cement based composite repair material according to claim 1, characterized in that, The water-reducing agent is a high-efficiency polycarboxylate water-reducing agent.

6. The high-performance polymer-cement-based composite repair material according to claim 1, characterized in that, The polypropylene fibers are 19-22 mm in length, 0.12-0.16 mm in diameter, and have a tensile strength greater than 950 MPa.

7. A method for preparing a high-performance polymer-cement-based composite repair material according to any one of claims 1-6, characterized in that, Includes the following steps: N1. Weigh the following components by weight: 690-710 parts cement, 130-150 parts fly ash, 45-55 parts silica fume, 200-210 parts mixing water, 950-1050 parts fine aggregate, 21-23 parts modified polymer, 9-10 parts expanding agent, 4-5 parts water-reducing agent, 5-6 parts modified fiber, and 0.16-0.18 parts defoamer. N2. Add cement, fly ash, silica fume, fine aggregate, and modified polymer to a mixer and mix evenly for 3-4 minutes. The resulting mixture is denoted as N mixture. N3. Add the expanding agent, water reducing agent and defoamer to the mixing water and stir evenly for 1-2 minutes. The resulting mixture is called mixture O. N4. Add the O mixture evenly to the N mixture and stir until homogeneous. Stir for 3-4 minutes. The resulting mixture is the P mixture. N5. Slowly and evenly add the modified fiber to the P mixture and stir until the fiber is fully dispersed. The stirring time is 3-4 minutes to obtain fresh concrete. N6. Pour the fresh concrete from N5 into the mold for curing. Curing is carried out for 24 hours at a temperature of 22±2℃ and a humidity of 99%. After demolding, it is cured to a fixed age to obtain a cured high-performance polymer-cement-based composite repair material.

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