Fiber reinforced asphalt mixture and method of making same

Abstract

The application discloses a kind of fiber reinforced asphalt mixture and preparation method thereof, it is related to bitumen technical field.The asphalt mixture preparation method includes the steps of preparing modified polyester fiber, preparing modified lignin fiber, fiber compounding, preparing asphalt mixture;Preparation modified polyester fiber uses raw material including polyester fiber, NaOH, tannic acid solution, butyl acrylate, ammonium persulfate, silane coupling agent;Preparation modified lignin fiber uses raw material including lignin fiber, NaOH, maleic anhydride, benzoyl peroxide;The raw material of asphalt mixture includes matrix asphalt, coarse aggregate, fine aggregate, limestone powder, compound fiber.The product of the application is excellent in low-temperature crack resistance, strong in anti-rutting performance, and good in water stability.

Description

Technical Field

[0001] This invention relates to the field of asphalt technology, and more specifically to a fiber-reinforced asphalt mixture and its preparation method. Background Technology

[0002] Asphalt mixtures are widely used as core materials for infrastructure such as roads and airport runways due to their good adhesion and construction adaptability. However, traditional asphalt mixtures are susceptible to the effects of traffic loads and extreme weather during their service life, resulting in problems such as high-temperature rutting, low-temperature cracking, water damage, and fatigue failure, which seriously affect the service life of roads and driving safety.

[0003] In existing technologies, fiber is commonly used to modify asphalt mixtures. Fibers, through adsorption of asphalt and the formation of a spatial network structure, can improve the tensile strength, deformation resistance, and stability of the mixture. However, existing fiber-reinforced asphalt mixtures still have significant shortcomings: some fibers have poor compatibility with asphalt, easily agglomerating and unevenly dispersing in the mixture, leading to unstable reinforcement effects; some fibers have poor aging resistance, easily degrading and failing after long-term use, making it difficult to maintain the long-term service quality of roads. Existing technology CN120829269A discloses a fiber-reinforced asphalt mixture and its preparation method. This prior art uses a combination of modified coconut shell fibers and modified polyester fibers to improve the strength and rutting resistance of asphalt mixtures. However, this prior art is not designed for application scenarios in cold or rainy regions.

[0004] In summary, although the existing technical solutions have improved some properties of asphalt mixtures to a certain extent, the following technical problems still exist: poor low-temperature cracking resistance, insufficient rutting resistance, and poor water stability. Summary of the Invention

[0005] In order to solve the above-mentioned problems in the prior art, the present invention provides a fiber-reinforced asphalt mixture and its preparation method, and achieves the following objectives: to prepare an asphalt mixture with excellent low-temperature crack resistance, strong rutting resistance and good water stability.

[0006] To achieve the above objectives, the following technical solution is adopted: A fiber-reinforced asphalt mixture, by weight, comprises: 6-8 parts base asphalt, 50-60 parts coarse aggregate, 30-35 parts fine aggregate, 4-6 parts limestone powder, and 0.4-0.5 parts compounded fiber.

[0007] The coarse aggregate is basalt or granite.

[0008] The fine aggregate is manufactured sand or natural sand.

[0009] The present invention also provides a method for preparing fiber-reinforced asphalt mixture, comprising the steps of preparing modified polyester fiber, preparing modified lignin fiber, fiber compounding, and obtaining asphalt mixture; The modified polyester fiber is prepared as follows: Dry polyester fiber is immersed in NaOH solution, heated to 40-45℃, and stirred for 30-40 minutes at a stirring speed of 100-200 rpm. Then, it is washed with deionized water until neutral and dried to obtain pretreated polyester fiber. The pH of the tannic acid solution is adjusted to 4-5 with acetic acid, and then the pretreated polyester fiber is immersed in it at 40-50℃, stirred for 1.5-2 hours at a stirring speed of 150-200 rpm. After removal, it is washed 2-3 times with deionized water and dried to obtain tannic acid-coated polyester fiber. Butyl acrylate and silane coupling agent solutions are mixed evenly and immersed in the tannic acid-coated polyester fiber. Nitrogen gas is purged for 10-15 minutes to remove oxygen. Ammonium persulfate is added, the temperature is raised to 80-90℃, and the reaction is stirred for 2-3 hours at a stirring speed of 150-200 rpm. After the reaction, the fiber is collected by filtration, washed 3-4 times with deionized water, and vacuum dried to obtain modified polyester fiber.

[0010] From the appendix Figure 1 As can be seen, after alkali etching, tannic acid coating, and butyl acrylate grafting modification, a uniform and dense textured modified layer was formed on the originally smooth polyester fiber surface, with no exposed smooth fibril areas, indicating that the modified layer completely covered the fiber surface; the fiber monofilaments were well dispersed, and no fiber adhesion or agglomeration caused by modification was observed. The increased surface roughness can enhance the mechanical interlocking between the fiber and the asphalt mastic, while the grafted flexible polymer layer can improve the compatibility and wettability between the fiber and the asphalt, ensuring the efficiency of interfacial stress transfer, and together with the three-dimensional reinforcing network, improve the deformation resistance and crack resistance of the mixture.

[0011] The concentration of the NaOH solution is 0.5 mol / L.

[0012] The drying process involves a temperature of 80-90℃ and a drying time of 2-3 hours.

[0013] The tannic acid solution has a mass fraction of 0.5-1%.

[0014] The mass ratio of butyl acrylate to silane coupling agent solution is (0.8-1.2):1.

[0015] The amount of ammonium persulfate used is 0.5-1% of the mass of butyl acrylate.

[0016] The mass fraction of the silane coupling agent solution is 1-3%, and the silane coupling agent selected is KH570.

[0017] The vacuum drying process involves a temperature of 60-70℃, a vacuum degree of -0.08MPa to -0.09MPa, and a drying time of 2-3 hours.

[0018] The preparation of modified lignin fibers involves immersing dried lignin fibers in a NaOH solution, heating to 50-55°C, stirring for 40-50 minutes at a stirring rate of 100-200 rpm, then washing with deionized water until neutral, and drying to obtain pretreated lignin fibers. Maleic anhydride and benzoyl peroxide are then mixed uniformly with the pretreated lignin fibers, protected by nitrogen gas, heated to 95-100°C, and reacted under sealed conditions for 4-5 hours, with intermittent stirring to ensure uniform material distribution. After the reaction, the mixture is cooled to room temperature, washed 4-5 times with deionized water, and vacuum dried to obtain modified lignin fibers.

[0019] From the appendix Figure 2 It is evident that after alkali pretreatment and maleic anhydride grafting modification, the surface of lignin fibers exhibits abundant longitudinal grooves and a rough, uneven structure. A flocculent grafted modification layer is uniformly attached to the surface, while the fiber body maintains its complete skeletal morphology without significant breakage or damage. This rough morphology enhances the interfacial bonding force between the fiber and the asphalt mastic through mechanical interlocking. Furthermore, it increases the specific surface area of ​​the fiber, fully exposing the carboxyl active sites grafted onto the surface. This strengthens the interfacial interaction between the fiber and the polar components of asphalt and the aggregate surface, providing a structural basis for improving the water stability of the mixture.

[0020] The concentration of the NaOH solution is 0.3 mol / L.

[0021] The drying process involves a temperature of 80-100℃ and a drying time of 2-3 hours.

[0022] The amount of maleic anhydride used is 10-15% of the mass of the pretreated lignin fiber.

[0023] The amount of benzoyl peroxide used is 0.5-1% of the mass of the pretreated lignin fiber.

[0024] The vacuum drying process involves a temperature of 60-70℃, a vacuum degree of -0.08MPa to -0.09MPa, and a drying time of 2-3 hours.

[0025] The fiber blending process involves mixing modified polyester fiber and modified lignin fiber evenly, adding calcium stearate, and stirring evenly to obtain the blended fiber. Furthermore, the mass ratio of the modified polyester fiber to the modified lignin fiber is (3-3.5):(1.5-2); the amount of calcium stearate used is 0.5-1% of the mass of the modified polyester fiber.

[0026] The asphalt mixture is prepared by heating the base asphalt to 160-170℃; heating the dry coarse aggregate, fine aggregate, and limestone powder to 170-180℃, stirring evenly, adding the compound fiber and dry mixing, and then pouring in the heated base asphalt and wet mixing to obtain the asphalt mixture.

[0027] The beneficial effects of this invention are as follows: (1) This invention constructs a multi-component composite organic interface transition layer on the surface of polyester fibers by alkaline etching, tannic acid coating, and composite modification with butyl acrylate / silane coupling agent. This transition layer, on the one hand, increases the surface roughness of the fibers through alkaline etching, enhancing the mechanical interlocking force between the fibers and the asphalt mastic; on the other hand, the introduction of flexible butyl acrylate segments and the silane coupling agent significantly improves the compatibility and wettability of the modified polyester fibers with asphalt, allowing the asphalt mastic to more tightly encapsulate the fibers and improve interfacial bonding strength. The modified polyester fibers and modified lignin fibers together form a stable three-dimensional reinforcing network in the asphalt matrix, optimizing the stress transmission path, thereby significantly improving the integrity, rutting resistance, and durability of the mixture.

[0028] The modified lignin fiber in this invention undergoes maleic anhydride esterification treatment, which significantly enhances the interfacial bonding strength of the three-phase system of fiber, asphalt, and aggregate, thereby effectively preventing water intrusion along the interface and greatly improving the water stability and long-term water damage resistance of the mixture.

[0029] Modified lignin fibers can quickly adsorb free asphalt during mixing to form high-viscosity slurry, which improves the suspension and dispersion of modified polyester fibers, effectively preventing the polyester fibers from entangled and agglomerated at high dosages, and making the fiber distribution more uniform.

[0030] (2) The fiber-reinforced asphalt mixture of the present invention has excellent low-temperature crack resistance. The flexural tensile strength of the prepared asphalt mixture is 19.9-20.8 MPa, and the maximum flexural tensile strain is 5325-5382 με.

[0031] (3) The fiber-reinforced asphalt mixture of the present invention has excellent rutting resistance. The asphalt mixture prepared therefrom exhibits a dynamic stability of 6205-6586 cycles / mm in the rutting resistance test.

[0032] (4) The fiber-reinforced asphalt mixture of the present invention has excellent water stability. The prepared asphalt mixture has a residual stability of 90.7-92.8% in the immersion Marshall test. Attached Figure Description

[0033] Figure 1 A scanning electron microscope (SEM) image of the modified polyester fiber prepared in step one.

[0034] Figure 2This is a scanning electron microscope (SEM) image of the modified lignin fibers obtained in step two. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0036] Example 1: A fiber-reinforced asphalt mixture and its preparation method A fiber-reinforced asphalt mixture, by weight, comprises: 6 parts base asphalt, 60 parts coarse aggregate, 30 parts fine aggregate, 6 parts limestone powder, and 0.4 parts compounded fiber.

[0037] A method for preparing fiber-reinforced asphalt mixture includes the following steps: Step 1: Preparation of modified polyester fibers Dry polyester fibers were immersed in NaOH solution, heated to 40℃, and stirred for 40 min at a stirring speed of 100 rpm. They were then washed with deionized water until neutral and dried to obtain pretreated polyester fibers. The pH of the tannic acid solution was adjusted to 4 with acetic acid; the pretreated polyester fibers were then immersed in the solution at 40℃ and stirred for 1.5 h at a stirring speed of 150 rpm. After removal, the fibers were washed twice with deionized water and dried to obtain tannic acid-coated polyester fibers. A mixture of butyl acrylate and silane coupling agent solution was thoroughly mixed and immersed in the tannic acid-coated polyester fibers. Nitrogen gas was purged for 10 min to remove oxygen. Ammonium persulfate was added, the temperature was raised to 80℃, and the reaction was stirred for 3 h at a stirring speed of 150 rpm. After the reaction, the fibers were collected by filtration, washed three times with deionized water, and dried under vacuum to obtain modified polyester fibers.

[0038] The concentration of the NaOH solution is 0.5 mol / L.

[0039] The drying process involves a temperature of 80°C and a drying time of 3 hours.

[0040] The tannic acid solution has a mass fraction of 0.5%.

[0041] The mass ratio of the butyl acrylate to the silane coupling agent solution is 0.8:1.

[0042] The amount of ammonium persulfate used is 0.5% of the mass of butyl acrylate.

[0043] The mass fraction of the silane coupling agent solution is 1%, and the silane coupling agent selected is KH570.

[0044] The vacuum drying process involves a temperature of 60°C, a vacuum level of -0.08 MPa, and a drying time of 3 hours.

[0045] Step 2: Preparation of modified lignin fibers Dry lignin fibers were immersed in NaOH solution, heated to 50°C, and stirred for 50 minutes at a stirring rate of 100 rpm. They were then washed with deionized water until neutral and dried to obtain pretreated lignin fibers. Maleic anhydride and benzoyl peroxide were mixed evenly with the pretreated lignin fibers, and the mixture was heated to 95°C under nitrogen protection and reacted under sealed conditions for 5 hours. Intermittent stirring was performed during the reaction to ensure uniform material distribution. After the reaction, the mixture was cooled to room temperature, washed four times with deionized water, and vacuum dried to obtain modified lignin fibers.

[0046] The concentration of the NaOH solution is 0.3 mol / L.

[0047] The drying process involves a temperature of 80°C and a drying time of 3 hours.

[0048] The amount of maleic anhydride used is 10% of the mass of the pretreated lignin fiber.

[0049] The amount of benzoyl peroxide used is 0.5% of the mass of the pretreated lignin fiber.

[0050] The vacuum drying process involves a temperature of 60°C, a vacuum level of -0.08 MPa, and a drying time of 3 hours.

[0051] Step 3: Fiber compounding The modified polyester fiber and modified lignin fiber were mixed evenly, and then calcium stearate was added. The mixture was stirred for 15 minutes at a stirring speed of 300 rpm to obtain the composite fiber.

[0052] The mass ratio of the modified polyester fiber to the modified lignin fiber is 3:1.5.

[0053] The amount of calcium stearate used is 0.5% of the mass of the modified polyester fiber.

[0054] Step 4: Obtaining asphalt mixture Heat the base asphalt to 160°C; heat the dried coarse aggregate, fine aggregate, and limestone powder to 170°C, stir evenly, add the compound fiber and dry mix, pour in the heated base asphalt and wet mix to obtain the asphalt mixture.

[0055] Example 2: A fiber-reinforced asphalt mixture and its preparation method A fiber-reinforced asphalt mixture, by weight, comprises: 7 parts base asphalt, 55 parts coarse aggregate, 32 parts fine aggregate, 5 parts limestone powder, and 0.5 parts compounded fiber.

[0056] A method for preparing fiber-reinforced asphalt mixture includes the following steps: Step 1: Preparation of modified polyester fibers Dry polyester fibers were immersed in NaOH solution, heated to 42℃, and stirred for 35 minutes at a stirring speed of 150 rpm. They were then washed with deionized water until neutral and dried to obtain pretreated polyester fibers. The pH of the tannic acid solution was adjusted to 4.5 with acetic acid. The pretreated polyester fibers were then immersed in the solution at 45℃ and stirred for 2 hours at a stirring speed of 200 rpm. After removal, the fibers were washed three times with deionized water and dried to obtain tannic acid-coated polyester fibers. A mixture of butyl acrylate and silane coupling agent solution was thoroughly mixed and immersed in the tannic acid-coated polyester fibers. Nitrogen gas was purged for 15 minutes to remove oxygen. Ammonium persulfate was added, and the solution was heated to 88℃ and stirred for 2 hours at a stirring speed of 200 rpm. After the reaction, the fibers were collected by filtration, washed four times with deionized water, and dried under vacuum to obtain modified polyester fibers.

[0057] The concentration of the NaOH solution is 0.5 mol / L.

[0058] The drying process involves a temperature of 85°C and a drying time of 2.5 hours.

[0059] The tannic acid solution has a mass fraction of 0.8%.

[0060] The mass ratio of butyl acrylate to silane coupling agent solution is 1:1.

[0061] The amount of ammonium persulfate used is 0.8% of the mass of butyl acrylate.

[0062] The mass fraction of the silane coupling agent solution is 2%, and the silane coupling agent selected is KH570.

[0063] The vacuum drying process involves a temperature of 65°C, a vacuum degree of -0.09 MPa, and a drying time of 2.5 hours.

[0064] Step 2: Preparation of modified lignin fibers Dry lignin fibers were immersed in NaOH solution, heated to 52°C, and stirred for 45 minutes at a stirring rate of 150 rpm. They were then washed with deionized water until neutral and dried to obtain pretreated lignin fibers. Maleic anhydride and benzoyl peroxide were mixed evenly with the pretreated lignin fibers, and the mixture was heated to 100°C under nitrogen protection and reacted under sealed conditions for 4.5 hours. Intermittent stirring was performed during the reaction to ensure uniform material distribution. After the reaction, the mixture was cooled to room temperature, washed five times with deionized water, and vacuum dried to obtain modified lignin fibers.

[0065] The concentration of the NaOH solution is 0.3 mol / L.

[0066] The drying process involves a temperature of 90°C and a drying time of 2.5 hours.

[0067] The amount of maleic anhydride used is 12% of the mass of the pretreated lignin fiber.

[0068] The amount of benzoyl peroxide used is 0.8% of the mass of the pretreated lignin fiber.

[0069] The vacuum drying process involves a temperature of 65°C, a vacuum degree of -0.09 MPa, and a drying time of 2.5 hours.

[0070] Step 3: Fiber compounding The modified polyester fiber and modified lignin fiber were mixed evenly, and then calcium stearate was added. The mixture was stirred for 12 minutes at a stirring speed of 400 rpm to obtain the composite fiber.

[0071] The mass ratio of the modified polyester fiber to the modified lignin fiber is 3:2.

[0072] The amount of calcium stearate used is 0.8% of the mass of the modified polyester fiber.

[0073] Step 4: Obtaining asphalt mixture Heat the base asphalt to 165°C; heat the dried coarse aggregate, fine aggregate, and limestone powder to 175°C, stir evenly, add the compound fiber and dry mix, then pour in the heated base asphalt and wet mix to obtain the asphalt mixture.

[0074] Example 3: A fiber-reinforced asphalt mixture and its preparation method A fiber-reinforced asphalt mixture, by weight, comprises: 8 parts base asphalt, 50 parts coarse aggregate, 35 parts fine aggregate, 4 parts limestone powder, and 0.5 parts compounded fiber.

[0075] A method for preparing fiber-reinforced asphalt mixture includes the following steps: Step 1: Preparation of modified polyester fibers Dry polyester fibers were immersed in NaOH solution, heated to 45°C, and stirred for 30 minutes at a stirring speed of 200 rpm. They were then washed with deionized water until neutral and dried to obtain pretreated polyester fibers. The pH of the tannic acid solution was adjusted to 5 with acetic acid. The pretreated polyester fibers were then immersed in the solution at 50°C and stirred for 2 hours at a stirring speed of 200 rpm. After removal, the fibers were washed three times with deionized water and dried to obtain tannic acid-coated polyester fibers. A mixture of butyl acrylate and silane coupling agent solution was thoroughly mixed and immersed in the tannic acid-coated polyester fibers. Nitrogen gas was purged for 15 minutes to remove oxygen. Ammonium persulfate was added, the temperature was raised to 90°C, and the reaction was stirred for 2 hours at a stirring speed of 200 rpm. After the reaction, the fibers were collected by filtration, washed four times with deionized water, and dried under vacuum to obtain modified polyester fibers.

[0076] The concentration of the NaOH solution is 0.5 mol / L.

[0077] The drying process involves a temperature of 90°C and a drying time of 2 hours.

[0078] The tannic acid solution has a mass fraction of 1%.

[0079] The mass ratio of butyl acrylate to silane coupling agent solution is 1.2:1.

[0080] The amount of ammonium persulfate used is 1% of the mass of butyl acrylate.

[0081] The mass fraction of the silane coupling agent solution is 3%, and the silane coupling agent selected is KH570.

[0082] The vacuum drying process involves a temperature of 70°C, a vacuum degree of -0.09 MPa, and a drying time of 2 hours.

[0083] Step 2: Preparation of modified lignin fibers Dry lignin fibers were immersed in NaOH solution, heated to 55°C, and stirred for 40 minutes at a stirring rate of 200 rpm. They were then washed with deionized water until neutral and dried to obtain pretreated lignin fibers. Maleic anhydride and benzoyl peroxide were mixed evenly with the pretreated lignin fibers, and the mixture was heated to 100°C under nitrogen protection and reacted under sealed conditions for 4 hours. Intermittent stirring was performed during the reaction to ensure uniform material distribution. After the reaction, the mixture was cooled to room temperature, washed five times with deionized water, and vacuum dried to obtain modified lignin fibers.

[0084] The concentration of the NaOH solution is 0.3 mol / L.

[0085] The drying process involves a temperature of 100℃ and a drying time of 2 hours.

[0086] The amount of maleic anhydride used is 15% of the mass of the pretreated lignin fiber.

[0087] The amount of benzoyl peroxide used is 1% of the mass of the pretreated lignin fiber.

[0088] The vacuum drying process involves a temperature of 70°C, a vacuum degree of -0.09 MPa, and a drying time of 2 hours.

[0089] Step 3: Fiber compounding The modified polyester fiber and modified lignin fiber were mixed evenly, and then calcium stearate was added. The mixture was stirred for 10 minutes at a stirring speed of 500 rpm to obtain the composite fiber.

[0090] The mass ratio of the modified polyester fiber to the modified lignin fiber is 3.5:2.

[0091] The amount of calcium stearate used is 1% of the mass of the modified polyester fiber.

[0092] Step 4: Obtaining asphalt mixture Heat the base asphalt to 170°C; heat the dried coarse aggregate, fine aggregate, and limestone powder to 180°C, stir evenly, add the compound fiber and dry mix, then pour in the heated base asphalt and wet mix to obtain the asphalt mixture.

[0093] Comparative Example 1 A fiber-reinforced asphalt mixture, by weight, comprises: 7 parts base asphalt, 55 parts coarse aggregate, 32 parts fine aggregate, 5 parts limestone powder, and 0.5 parts fiber admixture.

[0094] A method for preparing fiber-reinforced asphalt mixture includes the following steps: Step 1: Preparation of modified lignin fibers This step is the same as the "Preparation of Modified Lignin Fibers" step in Example 2.

[0095] Step 2: Fiber compounding Modified lignin fibers were mixed with calcium stearate and stirred for 10-15 minutes at a stirring speed of 400 rpm to obtain fiber admixture.

[0096] The amount of calcium stearate used is 0.6% of the mass of the modified lignin fiber.

[0097] Step 3: Obtaining asphalt mixture This step is the same as the "preparation of asphalt mixture" step in Example 2.

[0098] Comparative Example 2 A fiber-reinforced asphalt mixture, by weight, comprises: 7 parts base asphalt, 55 parts coarse aggregate, 32 parts fine aggregate, 5 parts limestone powder, and 0.5 parts fiber admixture.

[0099] A method for preparing fiber-reinforced asphalt mixture includes the following steps: Step 1: Preparation of modified polyester fibers This step is the same as the "Preparation of Modified Polyester Fiber" step in Example 2.

[0100] Step 2: Fiber compounding Modified polyester fiber was mixed with calcium stearate and stirred for 10-15 minutes at a stirring speed of 400 rpm to obtain fiber admixture.

[0101] The amount of calcium stearate used is 0.6% of the mass of the modified polyester fiber.

[0102] Step 3: Obtaining asphalt mixture This step is the same as the "preparation of asphalt mixture" step in Example 2.

[0103] Example 4 Performance Testing (a) The asphalt mixtures prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to low-temperature cracking resistance tests according to the test methods specified in T0715 of JTGE20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering". The flexural tensile strength and maximum flexural tensile strain of the asphalt mixtures were calculated. The specific test results are shown in Table 1.

[0104] Table 1 As shown in Table 1, the asphalt mixtures prepared in Examples 1-3 exhibit flexural tensile strengths of 19.9-20.8 MPa and maximum flexural tensile strains of 5325-5382 με, significantly higher than those in the comparative examples. This demonstrates the excellent low-temperature crack resistance of the asphalt mixtures prepared in this invention.

[0105] (ii) The asphalt mixtures prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to rutting resistance tests according to the test methods specified in T0719 of JTGE20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering". The dynamic stability of the asphalt mixtures was calculated. The specific test results are shown in Table 2.

[0106] Table 2 As shown in Table 2, the asphalt mixtures prepared in Examples 1-3 exhibited a dynamic stability of 6205-6586 cycles / mm in the rutting resistance test. This demonstrates the excellent rutting resistance of the asphalt mixtures prepared according to this invention.

[0107] (III) The asphalt mixtures prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to water stability tests according to the test methods specified in T0709 of JTGE20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering". The residual stability of the asphalt mixtures was calculated using the immersion Marshall test method. The specific test results are shown in Table 3.

[0108] Table 3 As shown in Table 3, the asphalt mixtures prepared in Examples 1-3 exhibited a residual stability of 90.7-92.8% in the Marshall water immersion test. This demonstrates that the asphalt mixtures prepared in this invention possess excellent water stability.

[0109] The specific parameters of the raw materials used in this invention are as follows: The polyester fiber has a length of 6-12 mm.

[0110] The length of the lignin fiber is 1-5 mm.

[0111] The coarse aggregate is basalt or granite with a particle size range of 4.75-19 mm.

[0112] The fine aggregate is manufactured sand or natural sand, with a particle size range of 0-4.75 mm.

[0113] The limestone powder has a particle size ≤0.075mm and a specific surface area ≥2500cm². 2 / g.

[0114] The base asphalt is 70# asphalt.

[0115] Obviously, there are many other possible implementation methods under the concept of this invention. It should be stated here that any changes made under the inventive concept of this invention will fall within the protection scope of this invention.

Claims

1. A method for preparing fiber-reinforced asphalt mixture, characterized in that: The process includes steps such as preparing modified polyester fibers, preparing modified lignin fibers, fiber blending, and obtaining asphalt mixtures; the raw materials used include: base asphalt, coarse aggregate, fine aggregate, limestone powder, and blended fibers; The preparation of modified polyester fibers involves: immersing dried polyester fibers in NaOH solution, stirring, washing, and drying to obtain pretreated polyester fibers; adjusting the pH value of a tannic acid solution, immersing the pretreated polyester fibers in it, stirring, washing, and drying to obtain tannic acid-coated polyester fibers; mixing butyl acrylate and silane coupling agent solutions evenly, immersing the tannic acid-coated polyester fibers in the mixture, purging with nitrogen, adding ammonium persulfate, heating, and stirring to react; and finally filtering, washing, and vacuum drying to obtain modified polyester fibers. The preparation of modified lignin fiber involves: immersing dried lignin fiber in NaOH solution, stirring, washing, and drying to obtain pretreated lignin fiber; mixing maleic anhydride and benzoyl peroxide with the pretreated lignin fiber evenly, purging with nitrogen for protection, heating, and conducting a closed-loop constant-temperature reaction; after the reaction is complete, cooling, washing, and vacuum drying to obtain modified lignin fiber. The fiber blending process involves mixing modified polyester fiber and modified lignin fiber evenly, adding calcium stearate, and stirring to obtain the blended fiber.

2. The method for preparing fiber-reinforced asphalt mixture according to claim 1, characterized in that: The raw materials used are composed of the following parts by weight: 6-8 parts of base asphalt, 50-60 parts of coarse aggregate, 30-35 parts of fine aggregate, 4-6 parts of limestone mineral powder, and 0.4-0.5 parts of compound fiber.

3. The method for preparing fiber-reinforced asphalt mixture according to claim 1, characterized in that: In the step of preparing modified polyester fiber, the mass ratio of butyl acrylate to silane coupling agent solution is (0.8-1.2):

1.

4. The method for preparing fiber-reinforced asphalt mixture according to claim 1, characterized in that: In the step of preparing modified polyester fiber, the mass fraction of the silane coupling agent solution is 1-3%, and the silane coupling agent selected is KH570; the mass fraction of the tannic acid solution is 0.5-1%.

5. The method for preparing fiber-reinforced asphalt mixture according to claim 1, characterized in that: In the step of preparing modified polyester fiber, the amount of ammonium persulfate is 0.5-1% of the mass of butyl acrylate.

6. The method for preparing fiber-reinforced asphalt mixture according to claim 1, characterized in that: In the step of preparing modified lignin fibers, the amount of maleic anhydride used is 10-15% of the mass of the pretreated lignin fibers.

7. The method for preparing fiber-reinforced asphalt mixture according to claim 1, characterized in that: In the step of preparing modified lignin fibers, the amount of benzoyl peroxide used is 0.5-1% of the mass of the pretreated lignin fibers.

8. The method for preparing fiber-reinforced asphalt mixture according to claim 1, characterized in that: In the fiber compounding step, the mass ratio of modified polyester fiber to modified lignin fiber is (3-3.5):(1.5-2).

9. The method for preparing fiber-reinforced asphalt mixture according to claim 8, characterized in that: In the fiber compounding step, the amount of calcium stearate used is 0.5-1% of the mass of the modified polyester fiber.

10. The method for preparing fiber-reinforced asphalt mixture according to claim 1, characterized in that: The asphalt mixture is prepared by heating the base asphalt to 160-170℃; heating the dry coarse aggregate, fine aggregate, and limestone powder to 170-180℃, stirring evenly, adding the compound fiber and dry mixing, and then pouring in the heated base asphalt and wet mixing to obtain the asphalt mixture.

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