Asphalt mixture and preparation method thereof

Abstract

The invention relates to the field of asphalt, in particular to an asphalt mixture and a preparation method thereof. The asphalt mixture is prepared from the following components in parts by weight: 93.5 to 94.5 parts of mineral aggregate, 0.32 to 0.40 part of composite fiber material and 5 parts of asphalt, the composite fiber material is formed by compounding 1 part of basalt fiber, 0.8-1.2 parts of modified polyester fiber, 0.3-0.5 part of lignin fiber and 6-8 parts of polystyrene; the modified polyester fibers are obtained by dipping polyester fibers in a modifier, and the modifier is at least one of sodium cocoyl glutamate, cocamidopropyl betaine and sorbitan fatty acid ester. According to the invention, the polyester fibers are subjected to dipping treatment through modifiers such as sodium cocoyl glutamate, cocamidopropyl betaine, sorbitan fatty acid ester and the like, so that the compatibility of the polyester fibers and asphalt is enhanced; meanwhile, the polystyrene can be matched with other fibers to jointly form a fiber network with excellent performance, so that the overall performance of the asphalt mixture is finally enhanced.

Description

Technical Field

[0001] The present application relates to the field of asphalt, and in particular to an asphalt mixture and a preparation method thereof. Background Art

[0002] Asphalt pavement is widely used in the construction of highways, airport roads, and other areas due to its high strength, excellent durability, good elastic-plastic deformation capacity, high driving comfort, relatively simple maintenance, and environmentally friendly and recyclable properties. However, with the increase in application scenarios, asphalt pavement has also encountered problems in actual use, such as a shorter-than-expected service life, rutting during high summer temperatures, and cracking in humid winter areas, which have affected the normal use of roads. To adapt to the rapid development of my country's road transportation industry, higher requirements must be placed on the performance of asphalt pavements.

[0003] Currently, the three most common methods for addressing pavement problems are gradation improvement, asphalt modification, and the addition of fibers to asphalt concrete. The addition of fibers effectively improves asphalt concrete's resistance to rutting and water damage, while also facilitating and expediting construction. Currently, the main fibers used for asphalt modification include lignin fibers and polyester fibers. However, while polyester fibers have a high elongation, their smooth surface prevents them from adhering well to asphalt, limiting their application. Summary of the Invention

[0004] In order to solve the problem of poor compatibility between polyester fiber and asphalt, the present application provides an asphalt mixture, in which the polyester fiber is impregnated with modifiers such as sodium cocoyl glutamate, cocamidopropyl betaine and sorbitan fatty acid esters to enhance the compatibility between the polyester fiber and asphalt; at the same time, polystyrene can cooperate with other fibers to form a fiber network with superior performance, thereby ultimately enhancing the overall performance of the asphalt mixture.

[0005] In a first aspect, the present application provides an asphalt mixture, which adopts the following technical solution: An asphalt mixture comprises the following components in parts by weight: 93.5-94.5 parts of mineral material, 0.32-0.40 parts of composite fiber material, and 5 parts of asphalt; The composite fiber material is composed of 1 part of basalt fiber, 0.8-1.2 parts of modified polyester fiber, 0.3-0.5 parts of lignin fiber and 6-8 parts of polystyrene; The modified polyester fiber is obtained by immersing the polyester fiber in a modifier, wherein the modifier is at least one of sodium cocoyl glutamate, cocamidopropyl betaine and sorbitan fatty acid ester.

[0006] By adopting the above technical solution, polyester fiber is a common reinforcing material in asphalt mixtures, but due to its limited compatibility with asphalt, it will affect the overall performance of the mixture. In order to improve the compatibility of polyester fiber with asphalt, the formula uses modifiers such as sodium cocoyl glutamate, cocamidopropyl betaine and dehydrated sorbitan fatty acid ester to impregnate the polyester fiber. These modifiers are surfactants with dual properties of lipophilicity and hydrophilicity. When combined with polyester fiber, they can give the fiber surface lipophilic groups, thereby enhancing the interaction between the fiber and asphalt. This modification process allows the polyester fiber to be better dispersed in the asphalt, forming a more compact and stable structure, thereby improving the performance of the entire asphalt mixture, such as strength, durability and crack resistance.

[0007] In addition, the polystyrene in the composite fiber can further enhance the mechanical properties of the mixture due to its own certain elastic modulus and strength. Secondly, polystyrene and asphalt have good compatibility, which can form a more uniform mixture system. Therefore, polystyrene and other fiber components (such as basalt fiber, modified polyester fiber and lignin fiber) cooperate with each other to form a fiber network with superior performance. This network can effectively disperse and transfer stress, thereby improving the overall bearing capacity of the mixture. At the same time, polystyrene can also play a filling and sealing role, reducing the porosity in the mixture and improving its density and water damage resistance.

[0008] This application impregnates polyester fibers with modifiers such as sodium cocoyl glutamate, cocamidopropyl betaine, and sorbitan fatty acid esters to enhance the compatibility of polyester fibers with asphalt. At the same time, polystyrene can cooperate with other fibers to form a fiber network with superior performance, thereby ultimately enhancing the overall performance of the asphalt mixture.

[0009] Preferably, the modifier is sodium cocoyl glutamate, and the mass ratio of the polyester fiber to sodium cocoyl glutamate is 1:0.5-0.8.

[0010] By adopting the above technical solution, sodium cocoyl glutamate is a surfactant with dual lipophilic and hydrophilic properties. If the dosage is too small, it may not fully cover the surface of the polyester fiber, resulting in poor compatibility between the fiber and asphalt. This can affect the uniformity and stability of the mixture, thereby reducing its overall performance. The main function of sodium cocoyl glutamate is to impart lipophilic groups to the polyester fiber, thereby improving its compatibility with asphalt. If the dosage is insufficient, the modification effect will be less significant, and the dispersion and stability of the polyester fiber in the asphalt will also be affected. Although sodium cocoyl glutamate can improve the compatibility of polyester fiber with asphalt, excessive use may interfere with the adhesion and fluidity of the asphalt, thereby affecting the workability and final quality of the mixture.

[0011] Preferably, the modifier is cocamidopropyl betaine, and the mass ratio of the polyester fiber to cocamidopropyl betaine is 1:0.4-0.7.

[0012] When using the above technical solution, if the content of cocamidopropyl betaine in the modifier is too low, it may not fully cover the surface of the polyester fiber, resulting in a less significant modification effect. This can affect the compatibility of the polyester fiber with asphalt, reducing the overall performance of the mixture. In addition, cocamidopropyl betaine may enhance the stability of the mixture, while too little content may cause the asphalt mixture to crack at low temperatures. Although cocamidopropyl betaine can improve the compatibility of polyester fiber with asphalt, excessive use may interfere with the adhesion and fluidity of the asphalt, thereby affecting the workability and final quality of the mixture.

[0013] Preferably, the modifier is sorbitan fatty acid ester, and the mass ratio of the polyester fiber to the sorbitan fatty acid ester is 1:0.3-0.6.

[0014] By adopting the above technical solution, sorbitan fatty acid ester is an important surfactant with excellent emulsifying, dispersing, and lubricating properties. When its content in the modifier is too low, it may not fully cover the surface of the polyester fiber, resulting in a less significant modification effect. This can affect the compatibility of the polyester fiber with asphalt, reducing the dispersion and stability of the fiber in the asphalt, thereby affecting the overall performance of the mixture. Sorbitan fatty acid ester not only has emulsifying properties but also has a certain degree of stability. It can improve the stability of the mixture to a certain extent, preventing stratification and segregation during storage and construction. If its content is insufficient, the stability of the mixture may be affected, which in turn affects the construction quality and the service life of the road.

[0015] Although sorbitan fatty acid esters can improve the compatibility of polyester fiber with asphalt, excessive use may interfere with the adhesion and fluidity of asphalt, thereby affecting the construction performance and final quality of the mixture.

[0016] Preferably, the method for preparing the composite fiber material comprises the following steps: Fiber composite: add the formulated amount of basalt fiber, modified polyester fiber and lignin fiber to the trehalose aqueous solution, then add tin tetrachloride catalyst, heat and stir, and separate, wash and dry to obtain composite coarse material; Extrusion granulation: the composite coarse material is stirred and mixed with a formulated amount of polystyrene, and then extruded and granulated to obtain a composite fiber material.

[0017] By adopting the above technical solution, basalt fiber, modified polyester fiber, and lignin fiber are added to a trehalose aqueous solution and heated and stirred with the addition of a tin tetrachloride catalyst. This process promotes uniform mixing and interpenetration between the fibers, forming a more compact and stable fiber network structure. Basalt fiber, with its high strength, high modulus, and good heat resistance, provides excellent mechanical properties and thermal stability to the composite material. Modified polyester fiber, through a specific modification treatment, enhances its compatibility and adhesion with asphalt or other matrix materials, helping to improve the overall performance of the composite material. Lignin fiber, with its good hygroscopicity and dispersibility, helps improve the processing properties of the composite material and the performance of the final product.

[0018] Trehalose, a natural sugar, possesses excellent biocompatibility and stability. During the fiber composite process, the trehalose aqueous solution acts as a binder between the fibers, promoting close bonding. Trehalose also helps improve the composite's water and weather resistance, extending its service life. The addition of polystyrene improves the composite's fluidity, making it easier to flow and form during processing.

[0019] Preferably, the content of trehalose in the trehalose aqueous solution is 1.3-1.7 times the total weight of the basalt fiber, the modified polyester fiber and the lignin fiber.

[0020] By adopting the above technical solution, trehalose can form a certain viscosity in the aqueous solution, which helps to tightly bind the basalt fiber, modified polyester fiber and lignin fiber together. If the trehalose content is too low, its viscosity may not be enough to completely wrap and bond these fibers, resulting in a weakening of the bonding force between the fibers and affecting the overall performance of the composite fiber material. The trehalose aqueous solution also acts as a dispersant, which can help the fibers to be evenly dispersed in the solution. Low trehalose content may lead to uneven fiber dispersion, some fibers may agglomerate together, while some areas may lack fibers, which will affect the uniformity and consistency of the composite fiber material.

[0021] Excessive trehalose may cover the fiber surface and form an overly thick film layer, which may hinder the direct contact and bonding between the fiber and asphalt or other matrix materials, thereby affecting the overall performance of the composite fiber material.

[0022] Preferably, the polyester fibers have an average length of 3-6 mm and an average diameter of 15-25 μm.

[0023] By employing this technical solution, polyester fibers maintain excellent strength and toughness within this length and diameter range. Shorter fiber lengths facilitate even fiber distribution within the matrix, enhancing the overall strength of the composite. Furthermore, an appropriate fiber diameter ensures that the fibers are less susceptible to breakage under stress, improving the toughness of the composite.

[0024] Within the above range, the fiber length is moderate and will not cause entanglement and knotting problems during processing due to excessive length. At the same time, the appropriate fiber diameter also helps to improve the fluidity of the composite material, making it easier to shape and solidify during processing.

[0025] Within the aforementioned length and diameter ranges, polyester fibers maintain relatively stable chemical properties. The fiber surface is less susceptible to chemical attack, thus ensuring the composite's longevity in harsh environments. Appropriate fiber length and diameter contribute to the polyester fiber's heat resistance. In high-temperature environments, the fiber is less likely to deform or melt, thus ensuring the composite's stability and reliability.

[0026] Preferably, the mineral material is composed of the following components in weight percentage: 30-35 parts of 1# crushed stone, 36-40 parts of 2# crushed stone, 4-7 parts of 3# crushed stone, 12-15 parts of 4# crushed stone, and 8-13 parts of mineral powder; The 1# crushed stone is basalt with an average particle size of 11mm≤x<16mm, the 2# crushed stone is basalt with an average particle size of 5mm≤x<11mm, the 3# crushed stone is basalt with an average particle size of 3mm≤x<5mm, and the 4# crushed stone is basalt with an average particle size of 0.1mm≤x<3mm.

[0027] In a second aspect, the present application provides a method for preparing an asphalt mixture, which adopts the following technical solution: A method for preparing an asphalt mixture, for preparing the above-mentioned asphalt mixture, comprises the following steps: Material preheating: The mineral material, composite fiber material and asphalt are heated separately to obtain fluidized asphalt, fluidized fiber material and dry mineral material respectively; Mixing raw materials: pouring flowing asphalt into the flowing fiber material, stirring evenly, then adding mineral material, continuing to stir, and after mixing evenly, the asphalt mixture is obtained.

[0028] In summary, this application has the following beneficial effects: Since the polyester fiber is impregnated with modifiers such as sodium cocoyl glutamate, cocamidopropyl betaine and sorbitan fatty acid esters in this application, the compatibility of the polyester fiber with asphalt is enhanced; at the same time, polystyrene can cooperate with other fibers to form a fiber network with superior performance, thereby ultimately enhancing the overall performance of the asphalt mixture. DETAILED DESCRIPTION

[0029] The raw materials in this application include the following parts: Basalt crushed stone: the commercial product produced in Xinchang, Shaoxing, Zhejiang Province is used; Mineral powder: The commercially available product is produced by Tianyi in Huzhou, Zhejiang Province; Asphalt: Use commercially available products; Basalt fiber: commercially available product from Qifeng Mineral Fiber Co., Ltd. Polyester fiber: commercially available product from Qifeng Mineral Fiber Co., Ltd. Lignin fiber: commercially available product from Qifeng Mineral Fiber Co., Ltd. Polystyrene: a commercially available product with CAS number 9003-53-6 was used; Sodium cocoyl glutamate: a commercially available product with CAS number 68187-32-6; Cocamidopropyl betaine: a commercially available product with CAS number 61789-40-0; Sorbitan fatty acid ester: a commercial product named Span-20 produced by Hebei Kelongduo Biotechnology Co., Ltd. Trehalose: a commercial product with CAS number 99-20-7 was used; Tin tetrachloride: a commercially available product with CAS number 7646-78-8; The present application is further described in detail below with reference to the following examples and comparative examples.

[0030] Example 1 A method for preparing modified polyester fiber comprises the following steps: 1000 g of polyester fiber was immersed in 700 g of sodium cocoyl glutamate, and modified polyester fiber was obtained after 30 minutes; the average length of the polyester fiber was 4 mm (within 3-6 mm), and the average diameter was 20 μm (within 15-20 μm).

[0031] A method for preparing a composite fiber comprises the following steps: Fiber composite: add 100g of basalt fiber, 100g of modified polyester fiber (within 80g-120g) and 40g of lignin fiber (within 30g-50g) to 1L of trehalose aqueous solution (trehalose content 360g), then add 18g of tin tetrachloride catalyst, heat to 75°C in a water bath, stir for 4h, and filter, separate, wash and dry to obtain a composite coarse material; extrusion granulation: stir and mix the composite coarse material with 700g of polystyrene (within 600g-800g), then extrude and granulate to obtain a composite fiber material.

[0032] A method for preparing an asphalt mixture comprises the following steps: The mineral material consists of 320g of 1# crushed stone (within 300g-350g), 380g of 2# crushed stone (within 360g-400g), 60g of 3# crushed stone (within 40g-70g), 140g of 4# crushed stone (within 120g-150g), and 100g of mineral powder (within 80g-130g).

[0033] Among them, 1# crushed stone is basalt with an average particle size of 11mm≤x<16mm, 2# crushed stone is basalt with an average particle size of 5mm≤x<11mm, 3# crushed stone is basalt with an average particle size of 3mm≤x<5mm, and 4# crushed stone is basalt with an average particle size of 0.1mm≤x<3mm.

[0034] Material preheating: 940g of mineral material, 3.8g of composite fiber material, and 50g of asphalt were heated separately, wherein the mineral material was heated to 180°C, the composite fiber material was heated to 160°C, and the asphalt was heated to 175°C to obtain fluidized asphalt, fluidized fiber material, and dried mineral material, respectively; Mixing raw materials: pouring flowing asphalt into the flowing fiber material, stirring evenly, then adding mineral material, continuing to stir, and after mixing evenly, the asphalt mixture is obtained.

[0035] Example 2-3 In Example 2-3, based on the preparation method of Example 1, the content of each component of the asphalt mixture was adjusted. The specific adjustments are shown in Table 1.

[0036] Comparative Example 1-2 In Comparative Example 1, 100 g of modified polyester fiber was not added to the composite fiber. When the fibers were composited, the content of trehalose was 210 g, and other conditions remained unchanged.

[0037] Comparative Example 2 is to replace 100 g of modified polyester fiber with 100 g of ordinary polyester fiber, while other conditions remain unchanged.

[0038] Table 1 Content of each component of asphalt mixture of Examples 1-3 and performance test table of Comparative Examples 1-2 project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Mineral material / g 940 935 945 940 940 Composite fiber material / g 3.8 3.0 4.0 3.8 3.8 Asphalt / g 50 50 50 50 50 Dynamic stability / (times / mm) 10811 9924 10736 8216 9648 MSO / % 98.3 94.8 98.1 92.6 93.2 TSR / % 97.4 93.2 97.0 90.7 91.5 Performance testing The following performance tests were performed on Examples 1-3 and Comparative Examples 1-2. The test results are shown in Table 1.

[0039] 1. Dynamic stability Asphalt mixture specimens with a diameter of 10±0.2mm and a thickness of 2±0.1mm were tested for the number of times the asphalt mixture could withstand a standard axle load for every 1mm of deformation at high temperature (60°C). The higher the dynamic stability value, the better the asphalt mixture's high-temperature thermal stability.

[0040] 2. Water immersion residual stability MSO Asphalt mixture specimens with a diameter of 101.6 ± 0.2 mm and a height of 63.5 ± 1.3 mm were prepared and placed in a 60°C constant-temperature water bath for 48 hours. The higher the MSO value, the better the asphalt mixture's resistance to water damage.

[0041] 3. Freeze-thaw splitting strength ratio TSR Asphalt mixture specimens with a diameter of 101.6±0.2mm and a height of 63.5±1.3mm were randomly divided into two groups. The first group was stored at room temperature for later use; the second group was subjected to a water retention test method, whereby the specimens were vacuum-saturated with water at a vacuum of 98kPa for 15 minutes. The vacuum was then restored to normal pressure, and the specimens were placed in the water for 0.5 hours. The specimens were then removed and placed in a plastic bag, 10mL of water was added, and the bag was sealed. The bag was then placed in a constant-temperature refrigerator at 18±2°C for 16 hours. The specimens were then removed and immediately placed in a constant-temperature water bath maintained at 60±0.5°C. The plastic bag was removed and the temperature was maintained for 24 hours. All specimens in the first and second groups were immersed in a constant-temperature water bath at 25±0.5°C for 3 hours. The specimens were then removed and subjected to a splitting test at a loading rate of 50 mm / min. The maximum load was obtained and TSR was calculated as (average splitting tensile strength of the second group of valid specimens after freeze-thaw cycles / average splitting tensile strength of the first group of valid specimens without freeze-thaw cycles) × 100%. The higher the freeze-thaw splitting strength ratio (TSR), the better the asphalt mixture's low-temperature resistance.

[0042] Referring to Table 1, by comparing Examples 1-3 and Comparative Example 1-2, it can be seen that the dynamic stability, MSO, and TSR of Examples 1-3 are much greater than those of Comparative Example 1-2, indicating that the addition of polyester fibers modified with sodium cocoyl glutamate can enhance the interaction between the fibers and asphalt, thereby improving the overall performance of the asphalt mixture.

[0043] In comparison, the performance of Example 1 is the best, and Example 1 is preferred.

[0044] Examples 4-7 In Examples 4-7, based on the preparation method of Example 1, the amount of sodium cocoyl glutamate added was adjusted. The specific adjustments are shown in Table 2.

[0045] The asphalt mixtures of Examples 4-7 were subjected to the above performance tests, and the test results are shown in Table 2.

[0046] Table 2 Addition amount and performance test table of sodium cocoyl glutamate of Example 1 and Examples 4-7 project Example 1 Example 4 Example 5 Example 6 Example 7 Sodium cocoyl glutamate / g 700 400 500 800 900 Dynamic stability / (times / mm) 10811 10104 10478 10737 10621 MSO / % 98.3 95.5 97.4 98.0 97.8 TSR / % 97.4 94.1 95.6 97.0 96.4 As shown in Table 2, comparing Example 1 with Examples 4-7, the dynamic stability, MSO, and TSR of the asphalt mixture first increase and then decrease with increasing sodium cocoyl glutamate addition. This is likely because as the amount of sodium cocoyl glutamate added increases, it continuously covers the surface of the polyester fiber, improving the compatibility between the fiber and asphalt, enhancing the uniformity and stability of the mixture, and thus improving its overall performance. Exceeding a certain range may interfere with the adhesion and fluidity of the asphalt, thereby reducing the overall performance of the asphalt mixture.

[0047] Examples 8-12 Example 8 Based on the preparation method of Example 8, 700g of sodium cocoyl glutamate was replaced with 600g of cocamidopropyl betaine, and the other conditions remained unchanged.

[0048] In Examples 9-12, based on the preparation method of Example 8, the amount of cocamidopropyl betaine added was adjusted, and the specific adjustments are shown in Table 3.

[0049] The asphalt mixtures of Examples 8-12 were subjected to the above performance tests, and the test results are shown in Table 3.

[0050] Table 3 Addition amount and performance test table of cocamidopropyl betaine in Example 1 and Examples 8-12 Referring to Table 3, a comparison of Example 1 and Examples 8-12 shows that as the amount of cocamidopropyl betaine added increases, the dynamic stability, MSO, and TSR of the asphalt mixture first increase and then decrease. This may be because as the amount of cocamidopropyl betaine added increases, the cocamidopropyl betaine continuously covers the surface of the polyester fiber, improving the compatibility between the fiber and asphalt, improving the uniformity and stability of the mixture, and thus improving its overall performance. When the amount exceeds a certain range, it may interfere with the adhesion and fluidity of the asphalt, and instead reduce the overall performance of the asphalt mixture.

[0051] Examples 13-17 Example 13 Based on the preparation method of Example 8, 700g of sodium cocoyl glutamate was replaced with 500g of sorbitan fatty acid ester, and the other conditions remained unchanged.

[0052] In Examples 14-17, based on the preparation method of Example 13, the amount of sorbitan fatty acid ester added was adjusted. The specific adjustments are shown in Table 4.

[0053] The asphalt mixtures of Examples 13-17 were subjected to the above performance tests, and the test results are shown in Table 4.

[0054] Table 4 Addition amount and performance test table of sorbitan fatty acid esters of Example 1 and Examples 13-17 As shown in Table 4, a comparison of Example 1 and Examples 13-17 shows that as the amount of sorbitan fatty acid ester added increases, the dynamic stability, MSO, and TSR of the asphalt mixture first increase and then decrease. This is likely because as the amount of sorbitan fatty acid ester added increases, the sorbitan fatty acid ester continuously covers the surface of the polyester fiber, improving the compatibility between the fiber and asphalt, enhancing the uniformity and stability of the mixture, and thus improving its overall performance. Exceeding a certain range may interfere with the adhesion and fluidity of the asphalt, thereby reducing the overall performance of the asphalt mixture.

[0055] Examples 18-21 In Examples 18-21, based on the preparation method of Example 1, the amount of trehalose added was adjusted. The specific adjustments are shown in Table 5.

[0056] The asphalt mixtures of Examples 18-21 were subjected to the above performance tests, and the test results are shown in Table 5.

[0057] Table 5: Addition amount of trehalose and performance test table of Example 1 and Examples 18-21 project Example 1 Example 18 Example 19 Example 20 Example 21 Trehalose / g 360 264 312 408 456 Dynamic stability / (times / mm) 10811 10612 10725 10763 10687 MSO / % 98.3 97.5 98.1 98.1 98.0 TSR / % 97.4 96.5 96.9 97.2 96.7 As shown in Table 5, a comparison of Example 1 and Examples 18-21 shows that as the amount of trehalose added increases, the dynamic stability, MSO, and TSR of the asphalt mixture first increase and then decrease. This is likely because as the amount of trehalose added increases, the trehalose continuously coats and bonds the basalt fibers, modified polyester fibers, and lignin fibers, increasing the bonding strength between the fibers and thereby improving their overall performance. When the amount exceeds a certain range, the excess trehalose may coat the fiber surface, forming an excessively thick film. This film may hinder direct contact and bonding between the fibers and the asphalt or other matrix materials, thereby reducing the overall performance of the asphalt mixture.

[0058] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. An asphalt mixture, characterized in that: The invention comprises the following components in parts by weight: 93.5-94.5 parts of mineral material, 0.32-0.40 parts of composite fiber material, and 5 parts of asphalt; The composite fiber material is composed of 1 part of basalt fiber, 0.8-1.2 parts of modified polyester fiber, 0.3-0.5 parts of lignin fiber and 6-8 parts of polystyrene; The modified polyester fiber is obtained by immersing the polyester fiber in a modifier, wherein the modifier is at least one of sodium cocoyl glutamate, cocamidopropyl betaine and sorbitan fatty acid ester.

2. The asphalt mixture according to claim 1, characterized in that: The modifier is sodium cocoyl glutamate, and the mass ratio of the polyester fiber to sodium cocoyl glutamate is 1:0.5-0.

8.

3. The asphalt mixture according to claim 1, characterized in that: The modifier is cocamidopropyl betaine, and the mass ratio of the polyester fiber to cocamidopropyl betaine is 1:0.4-0.

7.

4. The asphalt mixture according to claim 1, characterized in that: The modifier is sorbitan fatty acid ester, and the mass ratio of the polyester fiber to the sorbitan fatty acid ester is 1:0.3-0.

6.

5. The asphalt mixture according to claim 1, characterized in that: The preparation method of the composite fiber material comprises the following steps: Fiber composite: add the formulated amount of basalt fiber, modified polyester fiber and lignin fiber to the trehalose aqueous solution, then add tin tetrachloride catalyst, heat and stir, and separate, wash and dry to obtain composite coarse material; Extrusion granulation: the composite coarse material is stirred and mixed with a formulated amount of polystyrene, and then extruded and granulated to obtain a composite fiber material.

6. The asphalt mixture according to claim 5, characterized in that: The content of trehalose in the trehalose aqueous solution is 1.3-1.7 times the total weight of the basalt fiber, the modified polyester fiber and the lignin fiber.

7. The asphalt mixture according to claim 1, characterized in that: The polyester fibers have an average length of 3-6 mm and an average diameter of 15-25 μm.

8. The asphalt mixture according to claim 1, characterized in that: The mineral material is composed of the following components in weight percentage: 30-35 parts of 1# crushed stone, 36-40 parts of 2# crushed stone, 4-7 parts of 3# crushed stone, 12-15 parts of 4# crushed stone, and 8-13 parts of mineral powder; The 1# crushed stone is basalt with an average particle size of 11mm≤x<16mm, the 2# crushed stone is basalt with an average particle size of 5mm≤x<11mm, the 3# crushed stone is basalt with an average particle size of 3mm≤x<5mm, and the 4# crushed stone is basalt with an average particle size of 0.1mm≤x<3mm.

9. The method for preparing an asphalt mixture according to any one of claims 1 to 8, characterized in that: The following steps are involved: Material preheating: The mineral material, composite fiber material and asphalt are heated separately to obtain fluidized asphalt, fluidized fiber material and dry mineral material respectively; Mixing raw materials: pouring flowing asphalt into the flowing fiber material, stirring evenly, then adding mineral material, continuing to stir, and after mixing evenly, the asphalt mixture is obtained.

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