Low-temperature-resistant and crack-resistant epoxy asphalt concrete for anti-seepage face plate of pumped storage reservoir and preparation method thereof

Abstract

The application discloses a low-temperature-resistant and crack-resistant epoxy asphalt concrete for seepage prevention panels of pumped storage reservoirs and a preparation method thereof. The concrete comprises 300-350 parts of fine aggregate, 520-650 parts of coarse aggregate, 100-150 parts of mineral powder, 45-55 parts of base asphalt, 5-7 parts of rubber powder, 6-10 parts of epoxy resin, 4.5-6.5 parts of curing agent and 1.5-3 parts of modified composite fiber. The modified composite fiber is prepared through a multi-stage synergistic modification process, i.e., first, a silane coupling agent is modified by EMCA, 2-MeTHF and DBU, and then, the modified silane coupling agent is reacted with a mercapto ionic liquid. Basalt fibers are etched by mercaptoacetic acid, and polypropylene fibers are subjected to oxidation treatment. Finally, the fibers are modified through nanocomposite modification of graphene oxide and molybdenum disulfide. Through the external modified fiber reinforcement technology, the low-temperature crack resistance of the epoxy asphalt concrete is significantly improved, the problem that the traditional asphalt concrete material for seepage prevention panels of pumped storage reservoirs is prone to brittle cracking in a low-temperature environment is solved, and meanwhile, the excellent mechanical properties and durability are maintained, and the application is especially suitable for seepage prevention panels of pumped storage power stations.

Description

Technical Field

[0001] This invention relates to the field of asphalt preparation technology, and in particular to low-temperature resistant and crack-resistant epoxy asphalt concrete for the seepage-proof panels around pumped storage reservoirs and its preparation method. Background Technology

[0002] During operation, the asphalt concrete lining panels around pumped-storage power station reservoirs are exposed to the natural environment for extended periods. When faced with sudden drops in winter temperatures, shrinkage stress develops within the asphalt concrete. Currently used asphalt concrete generally lacks sufficient flexibility, making it prone to micro-cracks that gradually expand and eventually form through-cracks. These cracks not only compromise the integrity of the reservoir panel structure but also accelerate hydraulic erosion and freeze-thaw cycle damage, severely impacting the reservoir's seepage prevention performance and service life.

[0003] Existing technologies modify asphalt concrete by adding external additives such as fiber-reinforced materials to enhance its toughness. The main fiber-reinforced materials used include mineral fibers and plant fibers. However, the fiber-reinforced materials used in existing technologies still have the following problems:

[0004] 1. Although plant fibers have advantages such as low cost and wide availability, their mechanical strength is insufficient and cannot meet the engineering mechanical requirements of the seepage prevention panels around the reservoir of pumped storage power stations.

[0005] 2. Mineral fibers have good mechanical properties, but ordinary mineral fibers do not fully demonstrate their crack resistance at low temperatures and cannot be well applied to complex hydraulic environments. Summary of the Invention

[0006] The technical problem this invention aims to solve is to address the shortcomings of existing technologies by providing a low-temperature resistant and crack-resistant epoxy asphalt concrete for seepage prevention panels around pumped storage reservoirs, and its preparation method. This concrete comprises fine aggregate, coarse aggregate, mineral powder, base asphalt, rubber powder, epoxy resin, curing agent, and modified composite fibers. The modified composite fibers are prepared through a multi-stage synergistic modification process. This invention significantly improves the low-temperature crack resistance of epoxy asphalt concrete, solving the problem of brittle cracking of traditional asphalt concrete materials used for seepage prevention panels around pumped storage reservoirs in low-temperature, hydraulic environments.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A low-temperature resistant and crack-resistant epoxy asphalt concrete for the seepage prevention panel around a pumped storage reservoir, wherein the low-temperature resistant and crack-resistant epoxy asphalt concrete comprises, by weight, 300-350 parts fine aggregate, 520-650 parts coarse aggregate, 100-150 parts mineral powder, 45-55 parts base asphalt, 5-7 parts rubber powder, 6-10 parts epoxy resin, 4.5-6.5 parts curing agent, and 1.5-3 parts modified composite fiber.

[0009] The preparation process of a low-temperature resistant and crack-resistant epoxy asphalt concrete is as follows:

[0010] The base asphalt and rubber powder are mixed and preheated to 165°C until the asphalt is completely melted. The temperature is maintained at around 150°C. The mixture of epoxy resin and curing agent is added to the mixing pot. Then, the coarse aggregate, fine aggregate, and mineral powder are baked and preheated to 160°C and added to the preheated base asphalt. The stirring speed is controlled at around 60 rpm. When the temperature reaches around 160°C, the modified composite fiber is added and mixed. After discharge, the low-temperature resistant and crack-resistant epoxy asphalt concrete for the seepage prevention panel around the pumping reservoir is obtained.

[0011] A method for preparing modified composite fibers, comprising the following steps:

[0012] Step 1: Mix epoxy cyclohexyl methacrylate (EMCA), 2-methyltetrahydrofuran (2-MeTHF), and 1,8-diazabicycloundec-7-ene (DBU) evenly, and simultaneously introduce nitrogen gas to protect the reagents. Raise the temperature to 50-60℃, and use a magnetic stirrer set to 90-100 rpm. Add silane coupling agent KH560 and stir to react fully for 3-4 hours to obtain the intermediate for later use.

[0013] The ratio of EMCA, 2-MeTHF, and DBU is 0.2 mol: 0.5 mol-0.6 mol: 0.05-0.1 mol: 45-55 mol. EMCA and DBU catalyze the ring-opening reaction of epoxy groups.

[0014] Step 2: Take the intermediate, 1-mercaptoethyl-3-methylimidazolium bromide, and anhydrous acetone and mix them evenly. Purge with nitrogen gas and keep the temperature at 60℃-65℃. Use a magnetic stirrer and set the speed to 70-90 rpm to stir thoroughly for 30 minutes. Then slowly add boron trifluoride diethyl ether solution and react for 2 hours. Then remove the acetone by low-temperature distillation to obtain the modified silane coupling agent.

[0015] The ratio of the intermediate, 1-mercaptoethyl-3-methylimidazolium bromide, anhydrous acetone, and boron trifluoride diethyl ether solution is 0.1 mol: 0.1-0.12 mol: 100-125 mL: 0.05-0.1 mol, introducing thiol groups to react with epoxy groups.

[0016] Step 3: Dry the basalt fiber at a constant temperature of 200℃. After removing and allowing it to cool naturally, soak it in anhydrous ethanol until fully immersed to remove surface oil and impurities. Rinse with deionized water and then dry thoroughly in an oven at 70℃. Alternatively, soak the basalt fiber in a 5% mercaptoacetic acid solution for 0.5-1 hour, rinse with deionized water, and then dry thoroughly in an oven at 70℃ to obtain the basalt fiber intermediate.

[0017] The ratio of mercaptoacetic acid solution to basalt fiber is 800ml:80g-120g. After etching with mercaptoacetic acid solution, the number of fiber generation sites is increased.

[0018] Step 4: Place benzoyl peroxide powder into an acetone solution to prepare a 20% benzoyl peroxide solution. Then, place the solution in a heatable magnetic stirrer and control the temperature at 70℃ to ensure the benzoyl peroxide is fully dissolved. Place the polypropylene fiber into the prepared benzoyl peroxide solution and place it in a constant temperature device at 65℃ for 0.5-1 hour. Remove the soaked polypropylene fiber, let it air dry in a ventilated place, rinse it with deionized water, and then dry it thoroughly in an oven at 75℃ to obtain the polypropylene fiber intermediate.

[0019] In this case, the ratio of benzoyl peroxide solution to polypropylene fiber is 1L:150g-300g, which reduces the contact angle of polypropylene fiber and increases its surface energy.

[0020] Step 5: Add the modified silane coupling agent and ethanol solution and mix well. Add dilute hydrochloric acid to adjust the pH value to 4-5, maintain the temperature at 45-55℃, and mix thoroughly for 1-1.5 hours. Add basalt fiber intermediate and polypropylene fiber intermediate, stir thoroughly, remove and dry to obtain modified fiber intermediate.

[0021] The ratio of modified silane coupling agent, basalt fiber intermediate, and polypropylene fiber intermediate is 60g:80g-120g:150g-300g, which improves the interfacial bonding strength of the fibers.

[0022] Step 6: Take graphene oxide and molybdenum disulfide powder, disperse the powder in a 3% sodium polyacrylate (PAAS) solution, and simultaneously sonicate at 500W. During sonication, add 5% FeCl3 solution dropwise using a microsyringe for 30-60 minutes to obtain a mixture. Completely immerse the modified fiber intermediate in the mixture and simultaneously sonicate in a water bath at 50-150W for 10-30 minutes to utilize the cavitation effect to promote the directional adsorption and uniform distribution of nanomaterials on the fiber surface. After drying, the modified composite fiber is obtained.

[0023] The ratio of graphene oxide, molybdenum disulfide powder, sodium polyacrylate solution, FeCl3 solution, basalt fiber intermediate, and polypropylene fiber intermediate is 2.1g-4.2g: 2.1g-8.4g: 100mL: 50mL: 80g-120g: 150g-300g. The two-dimensional layered structure of graphene oxide significantly improves the tensile strength and modulus of the fiber through physical interpenetration and chemical bonding. At the same time, the layered structure of molybdenum disulfide can disperse stress, prevent crack propagation, and improve the fatigue resistance and toughness of the fiber.

[0024] Low-temperature resistant and crack-resistant epoxy asphalt concrete can be used in the seepage prevention panels around pumped storage power stations.

[0025] The present invention has the following beneficial effects:

[0026] 1. This invention prepares a low-temperature resistant and crack-resistant epoxy asphalt concrete by adding modified composite fibers. The graphene oxide in the modified composite fibers forms a three-dimensional thermally conductive network in the asphalt, inhibiting low-temperature brittle cracking. Molybdenum disulfide absorbs shrinkage strain through interlayer slip. The polar groups of polypropylene fibers enhance the bonding with epoxy resin, and the thiol modification of basalt fibers improves asphalt compatibility. Fe... 3+ Cross-linking stabilizes material distribution. This multi-scale synergistic effect enables the material to maintain excellent interfacial strength, stress dispersion, and crack resistance at low temperatures, effectively solving the problems of low-temperature shrinkage stress and brittle fracture in epoxy asphalt concrete. Simultaneously, the low-temperature elasticity of the rubber powder effectively inhibits the propagation of thermal shrinkage cracks in epoxy asphalt concrete.

[0027] 2. The modified composite fiber preparation method of this invention is a multi-stage synergistic modification process. An active siloxane intermediate is constructed through the ring-opening reaction of EMCA and KH560 epoxy groups, increasing the number of reaction sites. Then, 1-mercaptoethyl-3-methylimidazolium bromide is introduced, and an ionic liquid structure is introduced into the molecular chain through a mercapto-epoxy group addition reaction, enhancing the structural stability. Basalt fibers undergo mercapto etching and polypropylene fiber peroxidation treatment to enhance surface activity, forming a stable covalent bond interface with the modified silane coupling agent. The two-dimensional layered structure of graphene oxide significantly improves the tensile strength and modulus of the fiber through physical interpenetration and chemical bonding. Simultaneously, the layered structure of molybdenum disulfide disperses stress, prevents crack propagation, and synergistically improves the fatigue resistance and toughness of the fiber material under low-temperature conditions.

[0028] 3. The modification process of this invention, from molecular bonding to macroscopic network construction, realizes the optimized design of the fiber-asphalt interface, enabling the composite material to maintain good performance in harsh low-temperature environments. It is especially suitable for complex hydraulic environments and is applicable as a seepage prevention panel around the reservoir of a pumped storage power station. Detailed Implementation

[0029] The present invention will be further illustrated by the following embodiments, but the scope of protection of the claims of the present invention is not limited by the embodiments.

[0030] Example 1

[0031] (1) Preparation of modified composite fibers

[0032] Step 1: Epoxycyclohexyl methacrylate (EMCA), 2-methyltetrahydrofuran (2-MeTHF), and 1,8-diazabicycloundec-7-ene (DBU) are mixed thoroughly while nitrogen gas is introduced to protect the reagents. The temperature is raised to 50-60℃, and a magnetic stirrer is used at 90 rpm. Silane coupling agent KH560 is added, and the mixture is stirred for 3 hours to obtain an intermediate for later use. The ratio of EMCA, 2-MeTHF, and DBU is 0.2 mol: 0.5 mol: 0.05 mol: 45 mL.

[0033] Step 2: Mix the intermediate, 1-mercaptoethyl-3-methylimidazolium bromide, and anhydrous acetone thoroughly. Purge with nitrogen gas and maintain the temperature at 60°C. Use a magnetic stirrer at 70 rpm and stir for 30 minutes. Then, slowly add boron trifluoride diethyl ether solution. React for 2 hours, then remove the acetone by low-temperature distillation to obtain the modified silane coupling agent. The ratio of the intermediate, 1-mercaptoethyl-3-methylimidazolium bromide, anhydrous acetone, and boron trifluoride diethyl ether solution is 0.1 mol: 0.1 mol: 100 mL: 0.05 mol.

[0034] Step 3: Dry the basalt fiber at a constant temperature of 200℃. After removing and allowing it to cool naturally, soak it in anhydrous ethanol until fully immersed to remove surface oil and impurities. Rinse with deionized water and then dry thoroughly in an oven at 70℃. Alternatively, soak the basalt fiber in a 5% mercaptoacetic acid solution for 0.5 hours, rinse with deionized water, and then dry thoroughly in an oven at 70℃ to obtain the basalt fiber intermediate. The ratio of mercaptoacetic acid solution to basalt fiber is 800ml:80g.

[0035] Step 4: Dissolve benzoyl peroxide powder in acetone to prepare a 20% (w / w) benzoyl peroxide solution. Place the solution in a heatable magnetic stirrer at 70°C to ensure complete dissolution of the benzoyl peroxide. Add the polypropylene fiber to the prepared benzoyl peroxide solution and place it in a thermostat at 65°C for 0.5 hours. Remove the soaked polypropylene fiber, allow it to air dry in a ventilated area, rinse with deionized water, and then dry it thoroughly in an oven at 75°C to obtain the polypropylene fiber intermediate. The ratio of benzoyl peroxide solution to polypropylene fiber is 1L:150g.

[0036] Step 5: Add the modified silane coupling agent and ethanol solution and mix well. Add dilute hydrochloric acid to adjust the pH to 4, maintain the temperature at 45℃, and mix thoroughly for 1 hour. Add basalt fiber intermediate and polypropylene fiber intermediate, stir thoroughly, remove and dry to obtain the modified fiber intermediate. The ratio of modified silane coupling agent, basalt fiber intermediate, and polypropylene fiber intermediate is 60g:80g:150g.

[0037] Step 6: Take graphene oxide and molybdenum disulfide powder, disperse the powder in a 3% sodium polyacrylate (PAAS) solution, and simultaneously perform ultrasonic treatment at a power of 500W. During the ultrasonic treatment, add 5% FeCl3 solution dropwise using a microsyringe. Treat for 0.5 hours to obtain a mixed solution. Completely immerse the modified fiber intermediate in the mixed solution and simultaneously perform water bath ultrasonic treatment at a power of 50W for 10 minutes. After drying, obtain the modified composite fiber. The ratio of graphene oxide, molybdenum disulfide powder, sodium polyacrylate solution, FeCl3 solution, basalt fiber intermediate, and polypropylene fiber intermediate is 2.1g:2.1g:100mL:50mL:80g:150g.

[0038] (2) Preparation of epoxy asphalt concrete

[0039] In this embodiment, the low-temperature crack-resistant epoxy asphalt concrete is made from the following raw materials in parts by weight: 45 parts base asphalt, 300 parts fine aggregate, 520 parts coarse aggregate, 100 parts mineral powder, 6 parts epoxy resin, 4.5 parts curing agent, 1.5 parts composite fiber, and 5 parts rubber powder.

[0040] The preparation process of epoxy asphalt concrete in this embodiment is as follows:

[0041] The base asphalt and rubber powder are mixed and preheated to 165℃ until the asphalt is completely melted. The temperature is maintained at around 150℃. The epoxy resin and curing agent are mixed and added to the mixing pot. Coarse aggregate, fine aggregate, and mineral powder are baked and preheated to 160℃ and then added to the preheated base asphalt. The stirring speed is controlled at around 60 rpm. When the temperature reaches around 160℃, the modified composite fiber is added and mixed. After discharge, the low-temperature resistant and crack-resistant epoxy asphalt concrete for the seepage prevention panel around the pumping reservoir is obtained.

[0042] Example 2

[0043] (1) Preparation of modified composite fibers

[0044] Step 1: Epoxycyclohexyl methacrylate (EMCA), 2-methyltetrahydrofuran (2-MeTHF), and 1,8-diazabicycloundec-7-ene (DBU) are mixed thoroughly, and nitrogen gas is introduced to protect the reagents. The temperature is raised to 50-60℃, and a magnetic stirrer is used at 100 rpm. Silane coupling agent KH560 is added, and the mixture is stirred until fully reacted for 3.5 hours to obtain an intermediate for later use. The ratio of EMCA, 2-MeTHF, and DBU is 0.2 mol: 0.6 mol: 0.1 mol: 55 mL.

[0045] Step 2: Mix the intermediate, 1-mercaptoethyl-3-methylimidazolium bromide, and anhydrous acetone thoroughly. Purge with nitrogen and maintain the temperature at 60°C. Use a magnetic stirrer at 75 rpm and stir for 30 minutes. Then, slowly add boron trifluoride diethyl ether solution. Raise the temperature to 60°C and react for 2 hours. Remove the acetone by low-temperature distillation to obtain the modified silane coupling agent. The ratio of the intermediate, 1-mercaptoethyl-3-methylimidazolium bromide, anhydrous acetone, and boron trifluoride diethyl ether solution is 0.1 mol: 0.1 mol: 125 mL: 0.075 mol.

[0046] Step 3: Dry the basalt fiber at a constant temperature of 200℃. After removing and allowing it to cool naturally, soak it in anhydrous ethanol until fully immersed to remove surface oil and impurities. Rinse with deionized water and then dry thoroughly in an oven at 70℃. Alternatively, soak the basalt fiber in a 5% mercaptoacetic acid solution for 1 hour, rinse with deionized water, and then dry thoroughly in an oven at 70℃ to obtain the basalt fiber intermediate. The ratio of mercaptoacetic acid solution to basalt fiber is 800ml:80g.

[0047] Step 4: Dissolve benzoyl peroxide powder in acetone to prepare a 20% benzoyl peroxide solution. Place the solution in a heatable magnetic stirrer at 70°C to ensure complete dissolution of the benzoyl peroxide. Add the polypropylene fiber to the prepared benzoyl peroxide solution and place it in a thermostat at 65°C for 1 hour. Remove the soaked polypropylene fiber, allow it to air dry in a ventilated area, rinse with deionized water, and then dry it thoroughly in an oven at 75°C to obtain the polypropylene fiber intermediate. The ratio of benzoyl peroxide solution to polypropylene fiber is 1L:200g.

[0048] Step 5: Add the modified silane coupling agent and ethanol solution and mix well. Add dilute hydrochloric acid to adjust the pH to 4, maintain the temperature at 50℃, and mix thoroughly for 1 hour. Add basalt fiber intermediate and polypropylene fiber intermediate, stir thoroughly, remove and dry to obtain the modified fiber intermediate. The ratio of modified silane coupling agent, basalt fiber intermediate, and polypropylene fiber intermediate is 60g:80g:200g.

[0049] Step 6: Take graphene oxide and molybdenum disulfide powder, disperse the powder in a 3% sodium polyacrylate (PAAS) solution, and simultaneously perform ultrasonic treatment at a power of 500W. During the ultrasonic treatment, add 5% FeCl3 solution dropwise using a microsyringe. Treat for 45 minutes to obtain a mixed solution. Completely immerse the modified fiber intermediate in the mixed solution and simultaneously perform water bath ultrasonic treatment at a power of 100W for 10 minutes. After drying, the modified composite fiber is obtained. The ratio of graphene oxide, molybdenum disulfide powder, sodium polyacrylate solution, FeCl3 solution, basalt fiber intermediate, and polypropylene fiber intermediate is 2.1g:4.2g:100mL:50mL:80g:200g.

[0050] (2) Preparation of epoxy asphalt concrete

[0051] In this embodiment, the low-temperature cracking epoxy asphalt concrete is made from the following raw materials by weight: 48 parts base asphalt, 330 parts fine aggregate, 580 parts coarse aggregate, 130 parts mineral powder, 8 parts epoxy resin, 5.5 parts curing agent, 2 parts composite fiber, and 5.5 parts rubber powder.

[0052] The preparation process of epoxy asphalt concrete in this embodiment is as follows:

[0053] The base asphalt and modified rubber powder are mixed and preheated to 175℃ until the asphalt is completely melted. The temperature is maintained at around 150℃. The epoxy resin and curing agent are mixed and added to the mixing pot. Coarse aggregate, fine aggregate, and mineral powder are baked and preheated to 160℃ and then added to the preheated base asphalt. The stirring speed is controlled at around 80 rpm. When the temperature reaches around 150℃, the modified composite fiber and graphene are added and mixed. After discharge, the low-temperature resistant and crack-resistant epoxy asphalt concrete for the seepage prevention panel around the pumping reservoir is obtained.

[0054] Example 3

[0055] (1) Preparation of modified composite fibers

[0056] Step 1: Epoxycyclohexyl methacrylate (EMCA), 2-methyltetrahydrofuran (2-MeTHF), and 1,8-diazabicycloundec-7-ene (DBU) are mixed thoroughly, and nitrogen gas is introduced to protect the reagents. The temperature is raised to 60°C, and a magnetic stirrer is used at 100 rpm. Silane coupling agent KH560 is added, and the mixture is stirred for 3-4 hours to obtain an intermediate for later use. The ratio of EMCA, 2-MeTHF, and DBU is 0.2 mol: 0.6 mol: 0.1 mol: 55 mL. EMCA and DBU catalyze the ring-opening reaction of the epoxy groups, enhancing stability.

[0057] Step 2: Mix the intermediate, 1-mercaptoethyl-3-methylimidazolium bromide, and anhydrous acetone thoroughly. Purge with nitrogen and maintain the temperature at 65°C. Use a magnetic stirrer at 90 rpm and stir for 30 minutes. Then, slowly add boron trifluoride diethyl ether solution. Raise the temperature to 60°C and react for 2 hours. Remove the acetone by low-temperature distillation to obtain the modified silane coupling agent. The ratio of the intermediate, 1-mercaptoethyl-3-methylimidazolium bromide, anhydrous acetone, and boron trifluoride diethyl ether solution is 0.1 mol: 0.12 mol: 100 mL: 0.1 mol.

[0058] Step 3: Dry the basalt fiber at a constant temperature of 200℃. After removing and allowing it to cool naturally, soak it in anhydrous ethanol until fully immersed to remove surface oil and impurities. Rinse with deionized water and then dry thoroughly in an oven at 70℃. Alternatively, soak the basalt fiber in a 5% mercaptoacetic acid solution for 1 hour, rinse with deionized water, and then dry thoroughly in an oven at 70℃ to obtain the basalt fiber intermediate. The ratio of mercaptoacetic acid solution to basalt fiber is 800ml:120g.

[0059] Step 4: Dissolve benzoyl peroxide powder in acetone to prepare a 20% benzoyl peroxide solution. Place the solution in a heatable magnetic stirrer at 70°C to ensure complete dissolution of the benzoyl peroxide. Add the polypropylene fiber to the prepared benzoyl peroxide solution and place it in a thermostat at 65°C for 1 hour. Remove the soaked polypropylene fiber, allow it to air dry in a ventilated area, rinse with deionized water, and then dry it thoroughly in an oven at 75°C to obtain the polypropylene fiber intermediate. The ratio of benzoyl peroxide solution to polypropylene fiber is 1L:150g.

[0060] Step 5: Add the modified silane coupling agent and ethanol solution and mix well. Add dilute hydrochloric acid to adjust the pH to 5, maintain the temperature at 55℃, and mix thoroughly for 1.5 hours. Add basalt fiber intermediate and polypropylene fiber intermediate, stir thoroughly, remove and dry to obtain the modified fiber intermediate. The ratio of modified silane coupling agent, basalt fiber intermediate, and polypropylene fiber intermediate is 60g:120g:150g.

[0061] Step 6: Take graphene oxide and molybdenum disulfide powder, disperse the powder in a 3% sodium polyacrylate (PAAS) solution, and simultaneously perform ultrasonic treatment at a power of 500W. During the ultrasonic treatment, add 5% FeCl3 solution dropwise using a microsyringe. Treat for 1 hour to obtain a mixed solution. Completely immerse the modified fiber intermediate in the mixed solution and simultaneously perform ultrasonic treatment in a water bath at a power of 150W for 0.5 hours. After drying, the modified composite fiber is obtained. The ratio of graphene oxide, molybdenum disulfide powder, sodium polyacrylate solution, FeCl3 solution, basalt fiber intermediate, and polypropylene fiber intermediate is 4.2g:2.1g:100mL:50mL:120g:150g.

[0062] (2) Preparation of epoxy asphalt concrete

[0063] In this embodiment, the low-temperature crack-resistant epoxy asphalt concrete is made from the following raw materials in parts by weight: 52 parts base asphalt, 300 parts fine aggregate, 600 parts coarse aggregate, 140 parts mineral powder, 9 parts epoxy resin, 6 parts curing agent, 2 parts composite fiber, and 5 parts rubber powder.

[0064] The preparation process of epoxy asphalt concrete in this embodiment is as follows:

[0065] The base asphalt and modified rubber powder are mixed and preheated to 160℃ until the asphalt is completely melted. The temperature is maintained at around 150℃. The epoxy resin and curing agent are mixed and added to the mixing pot. Coarse aggregate, fine aggregate, and mineral powder are baked and preheated to 160℃ and then added to the preheated base asphalt. The stirring speed is controlled at around 70 rpm. When the temperature reaches around 160℃, the modified composite fiber and graphene are added and mixed. After discharge, the low-temperature resistant and crack-resistant epoxy asphalt concrete for the seepage prevention panel around the pumped storage reservoir is obtained.

[0066] Example 4

[0067] (1) Preparation of modified composite fibers

[0068] Step 1: Epoxycyclohexyl methacrylate (EMCA), 2-methyltetrahydrofuran (2-MeTHF), and 1,8-diazabicycloundec-7-ene (DBU) are mixed thoroughly, and nitrogen gas is introduced to protect the reagents. The temperature is raised to 60°C, and a magnetic stirrer is used at 100 rpm. Silane coupling agent KH560 is added, and the mixture is stirred for 4 hours to obtain an intermediate for later use. The ratio of EMCA, 2-MeTHF, and DBU is 0.2 mol: 0.6 mol: 0.1 mol: 55 mL.

[0069] Step 2: Mix the intermediate, 1-mercaptoethyl-3-methylimidazolium bromide, and anhydrous acetone thoroughly. Purge with nitrogen and maintain the temperature at 65°C. Use a magnetic stirrer at 90 rpm and stir for 0.5 hours. Then, slowly add boron trifluoride diethyl ether solution. Raise the temperature to 60°C and react for 2 hours. Remove the acetone by low-temperature distillation to obtain the modified silane coupling agent. The ratio of the intermediate, 1-mercaptoethyl-3-methylimidazolium bromide, anhydrous acetone, and boron trifluoride diethyl ether solution is 0.1 mol: 0.12 mol: 125 mL: 0.1 mol, introducing thiol groups to react with epoxy groups.

[0070] Step 3: Dry the basalt fiber at a constant temperature of 200℃. After removing and allowing it to cool naturally, soak it in anhydrous ethanol until fully immersed to remove surface oil and impurities. Rinse with deionized water and then dry thoroughly in an oven at 70℃. Alternatively, soak the basalt fiber in a 5% mercaptoacetic acid solution for 1 hour, rinse with deionized water, and then dry thoroughly in an oven at 70℃ to obtain the basalt fiber intermediate. The ratio of mercaptoacetic acid solution to basalt fiber is 800ml:120g.

[0071] Step 4: Dissolve benzoyl peroxide powder in acetone to prepare a 20% benzoyl peroxide solution. Place the solution in a heatable magnetic stirrer at 70°C to ensure complete dissolution of the benzoyl peroxide. Add the polypropylene fiber to the prepared benzoyl peroxide solution and place it in a thermostat at 65°C for 1 hour. Remove the soaked polypropylene fiber, allow it to air dry in a ventilated area, rinse with deionized water, and then dry it thoroughly in an oven at 75°C to obtain the polypropylene fiber intermediate. The ratio of benzoyl peroxide solution to polypropylene fiber is 1L:300g.

[0072] Step 5: Add the modified silane coupling agent and ethanol solution and mix well. Add dilute hydrochloric acid to adjust the pH to 5, maintain the temperature at 55℃, and mix thoroughly for 1.5 hours. Add basalt fiber intermediate and polypropylene fiber intermediate, stir thoroughly, remove and dry to obtain the modified fiber intermediate. The ratio of modified silane coupling agent, basalt fiber intermediate, and polypropylene fiber intermediate is 60g:120g:300g.

[0073] Step 6: Take graphene oxide and molybdenum disulfide powder, disperse the powder in a 3% sodium polyacrylate (PAAS) solution, and simultaneously perform ultrasonic treatment at a power of 500W. During the ultrasonic treatment, add 5% FeCl3 solution dropwise using a microsyringe. Treat for 1 hour to obtain a mixed solution. Completely immerse the modified fiber intermediate in the mixed solution and simultaneously perform water bath ultrasonic treatment at a power of 150W for 0.5 hours. After drying, obtain the modified composite fiber. The ratio of graphene oxide, molybdenum disulfide powder, sodium polyacrylate solution, FeCl3 solution, basalt fiber intermediate, and polypropylene fiber intermediate is 2.1g:8.4g:100mL:50mL:120g:300g.

[0074] (2) Preparation of epoxy asphalt concrete

[0075] In this embodiment, the low-temperature crack-resistant epoxy asphalt concrete is made from the following raw materials in parts by weight: 55 parts base asphalt, 350 parts fine aggregate, 650 parts coarse aggregate, 150 parts mineral powder, 10 parts epoxy resin, 6.5 parts curing agent, 3 parts composite fiber, and 7 parts rubber powder.

[0076] The preparation process of epoxy asphalt concrete in this embodiment is as follows:

[0077] The base asphalt and modified rubber powder are mixed and preheated to 170℃ until the asphalt is completely melted. The temperature is maintained at around 150℃. The epoxy resin and curing agent are mixed and added to the mixing pot. Coarse aggregate, fine aggregate, and mineral powder are baked and preheated to 160℃ and then added to the preheated base asphalt. The stirring speed is controlled at around 90 rpm. When the temperature reaches around 150℃, the modified composite fiber and graphene are added and mixed. After discharge, the low-temperature resistant and crack-resistant epoxy asphalt concrete for the seepage prevention panel around the pumping reservoir is obtained.

[0078] Comparative Example 1

[0079] The only difference between the low-temperature resistant and crack-resistant epoxy asphalt concrete used for the seepage prevention panel around the pumped storage reservoir in this comparative example and Example 4 is that no modification treatment was made to the basalt fiber and polypropylene fiber.

[0080] Comparative Example 2

[0081] The difference between the low-temperature resistant and crack-resistant epoxy asphalt concrete for the seepage prevention panel around the pumped storage reservoir given in this comparative example and Example 4 is only that: the silane coupling agent KH560 was not treated with epoxy cyclohexyl methacrylate (EMCA), 2-methyltetrahydrofuran (2-MeTHF), and 1,8-diazabicycloundec-7-ene (DBU).

[0082] Comparative Example 3

[0083] The only difference between the low-temperature resistant and crack-resistant epoxy asphalt concrete used for the seepage prevention panel around the pumped storage reservoir in this comparative example and Example 4 is that graphene oxide and molybdenum disulfide powder were not used.

[0084] Comparative Example 4

[0085] The only difference between the low-temperature resistant and crack-resistant epoxy asphalt concrete used for the seepage prevention panel around the pumped storage reservoir given in this comparative example and Example 4 is that rubber powder was not used.

[0086] Performance testing:

[0087] To verify the low-temperature splitting resistance and flexural strength of the low-temperature crack-resistant epoxy asphalt concrete used for the seepage prevention panel around the pumped storage reservoir of this invention, extreme engineering environments were simulated according to the "Test Procedure for Hydraulic Asphalt Concrete" (DL / T5362-2018). Control groups at -10℃ and -20℃ were set up, and standard specimens of epoxy asphalt concrete were made. The results of splitting and flexural properties of the asphalt concrete are shown in Table 1.

[0088] Table 1 Splitting and Flexural Properties of Asphalt Concrete

[0089] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Unfrozen splitting strength / MPa 5.29 5.37 5.45 5.52 5.17 4.99 5.02 5.21 Splitting strength after freeze-thaw cycles / MPa 4.91 4.95 5.12 5.19 4.80 4.39 4.56 4.51 Splitting strength at -10℃ / MPa 5.59 5.69 5.81 5.87 5.27 5.04 5.22 5.32 -20℃ splitting strength / MPa 6.03 6.14 6.26 6.35 5.79 5.51 5.66 5.92 Unfrozen tensile strength in bending / MPa 43.92 44.81 45.27 46.03 43.89 43.24 43.72 44.91 Flexural tensile strength after freeze-thaw cycles / MPa 41.73 42.17 42.11 42.86 40.24 38.67 38.91 40.41 Bending tensile strength at -10℃ / MPa 46.81 47.22 47.93 48.27 45.21 44.68 45.47 46.27 -20℃ flexural strength / MPa 48.68 49.10 49.88 51.06 45.66 45.55 45.92 47.63

[0090] According to the test results in Table 1, the epoxy asphalt concrete with added composite fibers showed a significant improvement in low-temperature splitting strength and low-temperature flexural strength. Both the splitting strength and flexural strength exceeded the relevant requirements in the "Specifications for Construction of Hydraulic Asphalt Concrete" (SL514-2013) and "Test Procedures for Hydraulic Asphalt Concrete" (DL / T5362-2018). By adding modified composite fibers and rubber powder, the low-temperature crack resistance of asphalt concrete was significantly improved. This asphalt concrete is expected to become an ideal hydraulic material for seepage prevention panels around pumped storage reservoirs.

[0091] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A method for preparing modified composite fibers, characterized in that: Includes the following steps: Step 1: Preparation of intermediate: Glycidyl methacrylate, 2-methyltetrahydrofuran, and 1,8-diazabicycloundec-7-ene are mixed, protected by nitrogen gas, and the temperature is set to 50-60℃. Silane coupling agent KH560 is added, and the reaction is stirred to obtain the intermediate. Step 2: Preparation of modified silane coupling agent: Take the intermediate, 1-mercaptoethyl-3-methylimidazolium bromide, and anhydrous acetone, mix them, purge with nitrogen, set the temperature to 60℃-65℃, stir and slowly add boron trifluoride diethyl ether solution, and remove acetone by low-temperature distillation after the reaction to obtain the modified silane coupling agent. Step 3: Preparation of basalt fiber intermediate: Soak basalt fibers in anhydrous ethanol, rinse with deionized water and dry; soak basalt fibers in mercaptoacetic acid solution, rinse and dry to obtain basalt fiber intermediate; Step 4: Preparation of polypropylene fiber intermediate: Immerse polypropylene fibers in benzoyl peroxide solution, then remove, rinse and dry to obtain polypropylene fiber intermediate; Step 5: Preparation of modified fiber intermediate: Mix the modified silane coupling agent and ethanol solution, adjust the pH value to 4-5, and set the temperature to 45-55℃; Basalt fiber intermediate and polypropylene fiber intermediate were added, stirred, and then dried to obtain modified fiber intermediate; Step 6: Preparation of modified composite fibers: Dissolve graphene oxide and molybdenum disulfide powder in sodium polyacrylate solution, sonicate the solution, and add FeCl3 solution dropwise to obtain a mixed solution; add the modified fiber intermediate to the mixed solution, sonicate it, and then take it out and dry it to obtain the modified composite fibers.

2. The method for preparing modified composite fibers according to claim 1, characterized in that: In step 1, the ratio of the amounts of epoxycyclohexyl methacrylate, 2-methyltetrahydrofuran, 1,8-diazabicycloundec-7-ene, and KH560 silane coupling agent is 0.2mol:0.5mol-0.6mol:0.05mol-0.1mol:45-55ml.

3. The method for preparing modified composite fibers according to claim 1, characterized in that: In step 2, the ratio of the intermediate, 1-mercaptoethyl-3-methylimidazolium bromide, anhydrous acetone, and boron trifluoride diethyl ether solution is 0.1 mol: 0.1-0.12 mol: 100-125 mL: 0.05-0.1 mol.

4. The method for preparing the modified composite fiber according to claim 1, characterized in that: In step 3, the ratio of mercaptoacetic acid solution to basalt fiber is 800ml:80g-120g.

5. The method for preparing modified composite fibers according to claim 1, characterized in that: In step 4, the ratio of benzoyl peroxide solution to polypropylene fiber is 1L:150g-300g.

6. The method for preparing modified composite fibers according to claim 1, characterized in that: In step 5, the ratio of the amount of modified silane coupling agent, basalt fiber intermediate, and polypropylene fiber intermediate is 60g:80g-120g:150g-300g.

7. The method for preparing modified composite fibers according to claim 1, characterized in that: The ratio of the amounts of graphene oxide, molybdenum disulfide powder, sodium polyacrylate solution, FeCl3 solution, basalt fiber intermediate, and polypropylene fiber intermediate is 2.1g-4.2g: 2.1g-8.4g: 100mL: 50mL: 80g-120g: 150g-300g.

8. The method for preparing modified composite fibers according to claim 1, characterized in that: In step 6, the concentration of sodium polyacrylate is 3%, and the concentration of FeCl3 solution is 5%.

9. Low-temperature resistant and crack-resistant epoxy asphalt concrete for the seepage-proof panel around the pumped storage reservoir, characterized in that: The modified composite fiber prepared according to claim 1; The low-temperature resistant and crack-resistant epoxy asphalt concrete comprises, by weight, 300-350 parts fine aggregate, 520-650 parts coarse aggregate, 100-150 parts mineral powder, 45-55 parts base asphalt, 5-7 parts rubber powder, 6-10 parts epoxy resin, 4.5-6.5 parts curing agent, and 1.5-3 parts modified composite fiber.

10. The method for preparing low-temperature resistant and crack-resistant epoxy asphalt concrete according to claim 9, characterized in that: Includes the following steps: Preheat the base asphalt and rubber powder until completely melted, and then keep them at that temperature. Add epoxy resin and curing agent, and mix thoroughly. After preheating the coarse aggregate, fine aggregate, and mineral powder, add them to the base asphalt and mix them. Modified composite fibers are added, and after mixing and discharging, low-temperature resistant and crack-resistant epoxy asphalt concrete is obtained.