Modified recycled fiber asphalt, preparation method thereof and application in road engineering

Abstract

The present invention discloses a modified regenerated fiber asphalt, a preparation method thereof, and its application in road engineering, belonging to the technical field of modified asphalt. The modified regenerated fiber asphalt is prepared by the following method: heating the base asphalt until it dissolves, then adding the modified regenerated fiber and shearing at a constant temperature; then adding a flame retardant and continuing the constant temperature shearing to obtain the modified regenerated fiber asphalt. The modified regenerated fiber asphalt prepared by the present invention overcomes the disadvantage of the prior art that the fiber and asphalt are difficult to mechanically engage. It has excellent properties such as softening point, needle penetration, ductility, rutting factor, low-temperature performance, electrical healing performance, and fatigue life, thus showing good application prospects in the field of road engineering.

Description

Technical Field

[0001] The present invention belongs to the technical field of modified asphalt, and in particular relates to a modified recycled fiber asphalt, a preparation method thereof and an application in road engineering. Background Art

[0002] Asphalt is a vital road engineering material due to its excellent road performance and long service life. However, with the rapid development of the road transportation industry, traffic loads on asphalt pavements are becoming increasingly heavier, and more and more asphalt pavements are nearing the end of their service life. Especially on roads subject to harsh weather conditions, heavy loads, and overloaded vehicles, asphalt pavements often face problems such as cracking and rutting. These issues not only impact road safety but also increase road maintenance costs.

[0003] The preparation of fiber-based asphalt has become an important approach to improving the comprehensive pavement performance of asphalt mixtures. However, due to the smooth surface of the fiber, its mechanical interaction with asphalt is weak, resulting in limited interfacial bonding. Furthermore, the chemical inertness of the fiber limits its adsorption capacity, resulting in a primary reliance on physical adsorption for bonding with asphalt, with limited chemical bonding. This results in poor dispersion and stability of the fiber in the asphalt, and the modification effect is less than ideal. While fiber-modified asphalt improves rutting resistance to some extent, under high and long-term loads, the fiber may detach from the asphalt matrix, and the rutting factor exhibits an unstable trend. The low interfacial bonding strength between the fiber and asphalt makes it difficult for the fiber to effectively share the load, leading to fatigue cracks initiating and propagating at the interface, thereby reducing the fatigue life of the asphalt. The chemical inertness and insufficient adsorption capacity of the fiber limit the material's electrical conductivity and electrical healing properties. This is particularly true in the field of self-healing technology, where it is difficult to rapidly heal cracks in fiber-based asphalt using an applied electromagnetic field, limiting the development and utilization of its self-healing capabilities.

[0004] Therefore, it is of great significance to improve the interfacial bonding strength between the fiber and the asphalt matrix through modification technology, increase the softening point and rutting factor of the asphalt, enhance its high-temperature rheological properties, reduce the risk of rutting deformation under high temperature conditions, and ultimately provide a modified fiber asphalt with excellent comprehensive road performance. Summary of the Invention

[0005] The present invention provides a fiber asphalt for road engineering, wherein the fiber asphalt is a modified recycled fiber asphalt, and the modified recycled fiber asphalt is a modified recycled polyester fiber asphalt, a modified recycled lignin fiber asphalt or a modified recycled PAN fiber asphalt.

[0006] The present invention provides a method for preparing the modified regenerated fiber asphalt, comprising the following steps:

[0007] The matrix asphalt is heated until dissolved, and then the modified recycled fiber is added and sheared at a constant temperature; then the flame retardant is added and the constant temperature shearing is continued to obtain the modified recycled fiber asphalt.

[0008] In the above-mentioned method for preparing the modified regenerated fiber asphalt, the raw materials are selected from the following weights:

[0009] 50-200 parts of matrix asphalt, 1-4 parts of modified recycled fiber, 5-20 parts of flame retardant;

[0010] When the component is a solid component, the portion number represents grams; when the component is a liquid component, the portion number represents milliliters; in actual application, the portion number can be enlarged or reduced in proportion to the portion number.

[0011] In a specific embodiment, each raw material is selected from the following parts:

[0012] 50 parts of base asphalt, 1 part of modified recycled fiber, 5 parts of flame retardant;

[0013] When the component is a solid component, the portion number represents grams; when the component is a liquid component, the portion number represents milliliters; in actual application, the portion number can be enlarged or reduced in proportion to the portion number.

[0014] In the above-mentioned preparation method of modified regenerated fiber asphalt, the constant temperature shearing conditions are selected from: shearing at 2000-3000 rpm at 150-180°C for 1-2 hours; preferably: shearing at 2000 rpm at 150°C for 1 hour.

[0015] In the above-mentioned preparation method of modified regenerated fiber asphalt, the matrix asphalt is selected from one or more of coke asphalt, rock asphalt, petroleum asphalt, and bio-asphalt; preferably, petroleum asphalt.

[0016] In the above-mentioned method for preparing modified regenerated fiber asphalt, the modified regenerated fiber is prepared by the following method:

[0017] The carbon nanotubes are mixed with an organic solvent and ultrasonically dispersed to obtain a carbon nanotube dispersion; the regenerated fibers are added, followed by a promoter, and the mixture is allowed to react; after the reaction is completed, the reaction product is washed and dried to obtain a modified regenerated fiber.

[0018] In the above-mentioned method for preparing modified regenerated fiber, each raw material is selected from the following parts:

[0019] 1-4 parts of carbon nanotubes, 50-200 parts of organic solvent, 1-4 parts of regenerated fiber, 0.05-0.2 parts of accelerator;

[0020] When the component is a solid component, the portion number represents grams; when the component is a liquid component, the portion number represents milliliters; in actual application, the portion number can be enlarged or reduced in proportion to the portion number.

[0021] In a specific embodiment, each raw material is selected from the following parts:

[0022] 1 part of carbon nanotubes, 50 parts of organic solvent, 1 part of regenerated fiber, 0.05 parts of accelerator;

[0023] When the component is a solid component, the portion number represents grams; when the component is a liquid component, the portion number represents milliliters; in actual application, the portion number can be enlarged or reduced in proportion to the portion number.

[0024] In the above-mentioned preparation method of modified regenerated fibers, the carbon nanotubes are selected from surface-functionalized multi-walled carbon nanotubes, specifically hydroxyl-functionalized multi-walled carbon nanotubes, amino-functionalized multi-walled carbon nanotubes or carboxyl-functionalized multi-walled carbon nanotubes; the organic solvent is selected from one or more of sodium lauryl sulfate, hexadecyltrimethylammonium bromide, polyoxyethylene sorbitan monooleate, polyvinyl pyrrolidone, and polyethylene glycol; the regenerated fiber is epoxy-functionalized regenerated fiber, specifically epoxy-functionalized regenerated polyester fiber, epoxy-functionalized regenerated lignin fiber or epoxy-functionalized regenerated PAN fiber; the promoter is selected from one or more of triethylamine, potassium hydroxide, stannous octoate, and benzyltriethylammonium chloride.

[0025] In the above-mentioned method for preparing modified regenerated fiber, the ultrasonic dispersion time is selected from 1 to 3 hours, preferably 2 hours.

[0026] In the above-mentioned method for preparing modified regenerated fiber, the conditions for the static reaction are selected from: static reaction at 50-80° C. for 6-12 hours; preferably: static reaction at 50° C. for 6 hours.

[0027] In the above-mentioned method for preparing modified regenerated fibers, the hydroxyl-functionalized multi-walled carbon nanotubes are prepared by the following method:

[0028] Multi-walled carbon nanotubes are placed in a modifier under reflux conditions at 70-80°C, mixed and reacted for 3-4 hours to obtain a suspension; the suspension is filtered and washed with water, and dried at 90-100°C for 24-36 hours to obtain oxidized multi-walled carbon nanotubes; a hydroxyl modifier and a catalyst are mixed, and then an organic solvent and oxidized multi-walled carbon nanotubes are added, and the mixture is stirred at 200-500 rpm at room temperature under nitrogen protection for 24-48 hours to obtain a mixed solution; the mixed solution is filtered and the reaction product is washed, and dried at 100-110°C for 24-36 hours to obtain hydroxyl-functionalized multi-walled carbon nanotubes.

[0029] In the above-mentioned method for preparing hydroxyl-functionalized multi-walled carbon nanotubes, the raw materials are selected from the following weights:

[0030] 0.5-2 parts of multi-walled carbon nanotubes, 20-40 parts of modifier, 1-4 parts of hydroxyl modifier, 0.5-4 parts of catalyst, 25-50 parts of organic solvent, and 0.5-2 parts of oxidized multi-walled carbon nanotubes;

[0031] When the component is a solid component, the portion number represents grams; when the component is a liquid component, the portion number represents milliliters; in actual application, the portion number can be enlarged or reduced in proportion to the portion number.

[0032] In a specific embodiment, each raw material is selected from the following parts:

[0033] 1 part of multi-walled carbon nanotubes, 20 parts of modifier, 1.6 parts of hydroxyl modifier, 1 part of catalyst, 25 parts of organic solvent, 1 part of oxidized multi-walled carbon nanotubes;

[0034] When the component is a solid component, the portion number represents grams; when the component is a liquid component, the portion number represents milliliters; in actual application, the portion number can be enlarged or reduced in proportion to the portion number.

[0035] In the above-mentioned preparation method of hydroxyl-functionalized multi-walled carbon nanotubes, the modifier is selected from one or more of concentrated sulfuric acid and concentrated nitric acid (mixed acid), concentrated sulfuric acid and chlorosulfonic acid (mixed acid), concentrated sulfuric acid and phosphoric acid (mixed acid), and concentrated sulfuric acid and perchloric acid (mixed acid), and the mixed acid ratio is 1:(3-4); the hydroxyl modifier is selected from one or more of pentaerythritol, polyethylene glycol, glycerol, xylitol, inositol, mercaptoethanol, triethylene glycol, 1,4-butanediol, 2,3-butanediol, and polypropylene glycol; the catalyst The agent is selected from one or more of N,N'-diisopropylcarbodiimide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, triethylamine, 4-pyrrolidinopyridine, N-hydroxybenzotriazole, N-hydroxysuccinimide, dicyclohexylurea, hexamethylenetetramine, scandium trifluoromethanesulfonate, and cuprous oxide; the organic solvent is selected from one or more of toluene, chloroform, cyclohexanone, acetone, pyridine, acetonitrile, N,N-dimethylformamide, tetrahydrofuran, dimethyl sulfoxide, and 1,2-dichloroethane.

[0036] In the above-mentioned method for preparing modified regenerated fibers, the amino-functionalized multi-walled carbon nanotubes are prepared by the following method:

[0037] The dispersant and water are mixed, and then an amino modifier is added, and the mixture is stirred at 1000-1200 rpm at room temperature for 1-2 hours to obtain a mixed solution; then multi-walled carbon nanotubes are placed in the mixed solution, and stirred at 1500-1600 rpm at 60-65°C for 6-8 hours; then the reaction product is washed with water and dried at 100-110°C for 24-36 hours to obtain amino-functionalized multi-walled carbon nanotubes.

[0038] In the above-mentioned method for preparing amino-functionalized multi-walled carbon nanotubes, the raw materials are selected from the following weights:

[0039] 10-20 parts of dispersant, 4-10 parts of water, 1.5-2 parts of amino modifier, 0.5-2 parts of multi-walled carbon nanotubes;

[0040] When the component is a solid component, the portion number represents grams; when the component is a liquid component, the portion number represents milliliters; in actual application, the portion number can be enlarged or reduced in proportion to the portion number.

[0041] In a specific embodiment, each raw material is selected from the following parts:

[0042] 10 parts of dispersant, 4 parts of water, 1.5 parts of amino modifier, 1 part of multi-walled carbon nanotubes;

[0043] When the component is a solid component, the portion number represents grams; when the component is a liquid component, the portion number represents milliliters; in actual application, the portion number can be enlarged or reduced in proportion to the portion number.

[0044] In the above-mentioned preparation method of amino-functionalized multi-walled carbon nanotubes, the dispersant is selected from one or more of ethanol, methanol, isopropanol, toluene, and acetone; the amino modifier is selected from N-phenyl-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropyl(diethoxy)methylsilane, 3-(2-aminoethylamino)propylmethyldimethoxysilane, N-aminoethyl-γ-aminopropyltrimethoxysilane , bis[3-(trimethoxysilyl)propyl]amine, 3-aminopropyldimethylmethoxysilane, 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane, γ-diethylenetriaminepropylmethyldimethoxysilane, diethylaminomethyltriethoxysilane, N-[3-(trimethoxysilyl)propyl]butan-1-amine, trimethoxy[3-(phenylamino)propyl]silane, anilinemethyltriethoxysilane, 3-(N-cyclohexylamino)propylmethyldimethoxysilane.

[0045] In the above-mentioned method for preparing modified regenerated fibers, the carboxyl-functionalized multi-walled carbon nanotubes are prepared by the following method:

[0046] The multi-walled carbon nanotubes are evenly dispersed in the reaction chamber of the plasma equipment; gas is introduced to make the gas pressure in the chamber reach the pressure setting value; then the plasma treatment parameters are adjusted, the plasma equipment is started, and the multi-walled carbon nanotubes are treated to obtain carboxyl functionalized multi-walled carbon nanotubes.

[0047] In the above-mentioned preparation method of carboxyl-functionalized multi-walled carbon nanotubes, the gas is selected from one or more of oxygen, carbon dioxide, argon, water vapor, ozone, nitrogen, helium, and neon; the pressure setting value is selected from 10 to 100 Pa; and the plasma parameters are selected from: power 50 to 200 W, and treatment time 5 to 60 min.

[0048] In the above-mentioned method for preparing modified regenerated fiber, the epoxy-functionalized regenerated fiber is prepared by the following method:

[0049] The alkaline compound is added to the organic solvent and stirred to obtain a mixed solution; then the catalyst is added and stirred; then the epoxy modifier is slowly added dropwise; finally, the regenerated fiber is added and stirred for reaction; after the reaction is completed, the reaction product is washed and dried to obtain the epoxy functionalized regenerated fiber.

[0050] In the above-mentioned method for preparing epoxy-functionalized regenerated fiber, the raw materials are selected from the following weights:

[0051] 0.5-0.7 parts of alkaline compound, 10-20 parts of organic solvent, 0.05-0.1 parts of catalyst, 1.5-3 parts of epoxy modifier, 0.5-2 parts of regenerated fiber;

[0052] When the component is a solid component, the portion number represents grams; when the component is a liquid component, the portion number represents milliliters; in actual application, the portion number can be enlarged or reduced in proportion to the portion number.

[0053] In a specific embodiment, each raw material is selected from the following parts:

[0054] 0.5 parts of basic compound, 10 parts of organic solvent, 0.05 parts of catalyst, 1.7 parts of epoxy modifier, 1 part of regenerated fiber;

[0055] When the component is a solid component, the portion number represents grams; when the component is a liquid component, the portion number represents milliliters; in actual application, the portion number can be enlarged or reduced in proportion to the portion number.

[0056] In the preparation method of the above-mentioned epoxy-functional regenerated fiber, the alkaline compound is selected from one or more of sodium ethoxide, potassium methoxide, sodium amide, sodium hydride, 1,1,3,3-tetramethylguanidine, 1,8-diazabicyclo[5.4.0]undec-7-ene, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene; the organic solvent is selected from one or more of γ-butyrolactone, cyclopentane, propylene carbonate, caprolactam, N-ethylpyrrolidone, ethylene glycol dimethyl ether, diethylene glycol monobutyl ether, formamide, hexamethylphosphoramide, and isophorone; the catalyst is selected from one or more of polyethylene glycol monomethyl ether, didodecyldimethylammonium chloride, trioctylmethylammonium chloride, benzyltriethylammonium chloride, tetraoctylammonium bromide, polyoxyethylene sorbitan fatty acid ester, N-hexadecyl-N,N-dimethyl-3-aminopropyl One or more of trimethoxysilane ammonium chloride, bis-(2-diethylaminoethyl) ether, alkyl glycoside quaternary ammonium salt, and 1-(3-sulfonic acid)propyl-3-methylimidazolium salt; the epoxy modifier is selected from one or more of allyl glycidyl ether, butyl glycidyl ether, isooctyl glycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, epoxy fatty acid methyl ester, 4-vinyl-1-cyclohexene diepoxide, and polyethylene glycol diglycidyl ether; the regenerated fiber is selected from one or more of regenerated polyester fiber, regenerated carbon fiber, regenerated ceramic fiber, regenerated polypropylene fiber, regenerated PVA fiber, regenerated lignin fiber, regenerated PAN fiber, regenerated aramid fiber, regenerated basalt fiber, regenerated polyvinyl alcohol fiber, regenerated polyacrylonitrile fiber, regenerated PBO fiber, and regenerated bamboo fiber.

[0057] In the above-mentioned preparation method of epoxy-functional regenerated fiber, the stirring time is selected from 20 to 40 minutes, preferably 30 minutes; the slow dripping time is selected from 30 to 60 minutes, preferably 40 minutes.

[0058] In the above-mentioned preparation method of epoxy-functionalized regenerated fiber, the stirring reaction conditions are selected from: stirring reaction at 50-80°C and 200-300 rpm for 4-8 hours; preferably: stirring reaction at 60°C and 200 rpm for 6 hours.

[0059] In the above-mentioned preparation method of modified regenerated fiber asphalt, the flame retardant is an inorganic flame retardant modified by an ester modifier, and its preparation method is as follows:

[0060] The inorganic flame retardant is placed in a dispersant and stirred in an oil bath to form a suspension; then an ester modifier is added and stirred for reaction; after the reaction is completed, the reaction product is washed and dried to obtain an ester modifier-modified inorganic flame retardant.

[0061] In the preparation method of the ester modifier-modified inorganic flame retardant, the raw materials are selected from the following parts:

[0062] 5-10 parts of inorganic flame retardant, 20-40 parts of dispersant, 0.1-0.2 parts of ester modifier;

[0063] When the component is a solid component, the portion number represents grams; when the component is a liquid component, the portion number represents milliliters; in actual application, the portion number can be enlarged or reduced in proportion to the portion number.

[0064] In a specific embodiment, each raw material is selected from the following parts:

[0065] 5 parts of inorganic flame retardant, 20 parts of dispersant, 0.1 parts of ester modifier;

[0066] When the component is a solid component, the portion number represents grams; when the component is a liquid component, the portion number represents milliliters; in actual application, the portion number can be enlarged or reduced in proportion to the portion number.

[0067] In the preparation method of the above-mentioned ester modifier modified inorganic flame retardant, the inorganic flame retardant is selected from one or more of nano-montmorillonite, ammonium polyphosphate, wollastonite, zinc oxide, tin dioxide, aluminum hydroxide, magnesium hydroxide, zinc borate, calcium borate, and titanium dioxide; the dispersant is selected from one or more of ethanol, toluene, xylene, petroleum ether, cumene, cyclohexane, n-hexane, and n-heptane; the ester modifier is selected from one or more of alkyl phosphate, trimethyl phosphate, One or more of tripropyl borate, tetrabutyl zirconate, trilauryl phosphite, triphenyl phosphite, pentaerythritol, γ-aminopropyl triethoxysilane phosphate, bis(dioctyl pyrophosphoryloxy) oxo ester titanium, tetraisopropyl bis(dioctyl phosphite) titanate, tetra-n-butyl titanate, isopropyl tri(dioctyl pyrophosphate acyloxy) titanate, isopropyl dioleyloxy (dioctyl phosphate acyloxy) titanate, and isopropyl triisostearate titanate.

[0068] In the preparation method of the ester modifier-modified inorganic flame retardant, the oil bath stirring conditions are selected from: stirring at 300-800 rpm in a 40-60°C oil bath for 10-20 min; preferably: stirring at 400 rpm in a 50°C oil bath for 15 min.

[0069] In the above-mentioned method for preparing the inorganic flame retardant modified by the ester modifier, the stirring reaction time is selected from 1 to 3 hours, preferably 2 hours.

[0070] In the preparation method of the ester modifier-modified inorganic flame retardant, the washing is to wash the reaction product with an organic solvent; the organic solvent is selected from one or more of ethanol, toluene, xylene, petroleum ether, cumene, cyclohexane, n-hexane, and n-heptane.

[0071] The present invention provides the application of the modified recycled fiber asphalt in road engineering; the road engineering includes but is not limited to micro-surfacing, sealing, covering and other engineering fields related to road asphalt.

[0072] The beneficial effects of the present invention are:

[0073] The present invention introduces carbon nanotubes on the surface of regenerated fibers. The unique nanostructure has a large specific surface area, which can increase the adsorption points between the regenerated fibers and the asphalt. It can also serve as an effective reinforcing phase, connecting the regenerated fibers and the asphalt through the carbon nanotubes, forming an effective strain transfer network. This structure can prevent the expansion of microcracks inside the asphalt and improve the mechanical properties of the asphalt.

[0074] The epoxy-functionalized regenerated fibers grafted with hydroxyl-functionalized carbon nanotubes in the present invention undergo a ring-opening addition reaction between the epoxy groups on the surface of the regenerated fibers and the hydroxyl groups on the surface of the carbon nanotubes. This results in a high and stable chemical bond energy, making the connection between these chemical bonds more secure and improving the poor dispersion and easy agglomeration of the carbon nanotubes. Furthermore, the carbon nanotubes themselves possess extremely high electrical conductivity, current carrying capacity, and thermal conductivity. Their unique structure effectively conducts electrons, forming pathways within the material. In this process, the regenerated fibers act as a connecting matrix, providing a support and connection foundation for the carbon nanotubes. This more effectively constructs a continuous conductive pathway within the asphalt, imparting its conductive properties. Furthermore, the formation of this conductive pathway provides a foundation for the asphalt's electrical self-healing properties.

[0075] The modified asphalt is prepared by grafting hydroxyl-functionalized carbon nanotubes onto epoxy-functionalized regenerated fibers. Two crosslinking reactions occur within the system: esterification and etherification crosslinking reactions between the hydroxyl groups carried by the hydroxyl-functionalized carbon nanotubes and the carboxyl groups and active hydrogen atoms in the asphalt. The other reaction involves the epoxy groups reacting with active groups in the asphalt, such as the carboxyl groups, to form a crosslinked structure containing ester bonds and hydrocarbon groups. This creates a crosslinked network within the modified system, increasing the number of connection points between asphalt molecules, boosting the asphalt's molecular weight and intermolecular forces, and improving the asphalt's fatigue resistance, as well as its high- and low-temperature properties.

[0076] The use of recycled fiber in this invention allows for the reuse of waste fiber materials, reducing the demand for virgin fiber materials and lowering energy consumption and environmental pollution during resource extraction and processing. This aligns with the concept of sustainable development, helps promote the development of a circular economy, alleviates the pressure of waste disposal to a certain extent, and achieves the effective recycling of resources.

[0077] In order to solve the problem of poor compatibility and easy precipitation between inorganic flame retardants and asphalt, the present invention adopts an ester modifier modification method. The ester modifier is anchored on the surface of the inorganic flame retardant by chemical bonding. At the same time, the organic long chain part in its molecule extends outward, thereby changing the surface properties of the inorganic flame retardant and improving its lipophilic properties, which helps to better play a flame retardant role in the asphalt flame retardant system.

[0078] In response to the problem of insufficient flexibility of the existing technology under low temperature conditions, the present invention optimizes the surface properties of the fiber and its compatibility with asphalt, improves the ductility and low-temperature flexibility of the material, and effectively improves the low-temperature crack resistance. The mechanical meshing and chemical adsorption capacity of the fiber and asphalt are improved through modification, fundamentally improving its fatigue resistance and extending the service life of the road surface. In response to the shortcomings of fiber asphalt in self-repair of cracks, the present invention introduces conductive materials to give the modified asphalt good electrical healing ability, so that cracks can be quickly repaired through an external energy field after they are formed. The problem of uneven distribution of fibers in asphalt mixtures is solved, the dispersion and stability of fibers are improved, and thus the homogeneity and consistency of material properties are ensured.

[0079] In summary, the modified recycled fiber asphalt prepared by the present invention overcomes the disadvantage of the existing technology that the fiber and asphalt are difficult to mechanically engage with each other. It has excellent properties such as softening point, needle penetration, ductility, rutting factor, low temperature performance, electrical healing performance and fatigue life, thus showing good application prospects in the field of road engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 This is the SEM photo of the modified recycled polyester fiber;

[0081] Figure 2 Softening point, penetration and ductility of various modified asphalts;

[0082] Figure 3 is the rutting factor of various modified asphalts;

[0083] Figure 4 Fatigue life of various modified asphalts;

[0084] Figure 5 Low temperature rheological properties of various modified asphalts;

[0085] Figure 6 The electrical healing properties of various modified asphalts;

[0086] Figure 7 The flame retardant properties of the modified asphalt described in Example 1 and Comparative Example 4. DETAILED DESCRIPTION

[0087] In the present invention, the multi-walled carbon nanotubes were purchased from Shandong Dazhan Nanomaterials Co., Ltd.; the recycled polyester fiber was purchased from Shandong Yingke Environmental Protection Recycling Resources Co., Ltd.; the recycled lignin fiber was purchased from Shandong Langwang New Materials Co., Ltd.; and the recycled PAN fiber was purchased from Shandong Langwang New Materials Co., Ltd.

[0088] The matrix asphalt used in the following embodiments of the present invention is 70# matrix asphalt produced by Hebei Dejia Company, and its relevant technical indicators are shown in Table 1.

[0089] Table 1

[0090]

[0091] The other materials used in the present invention, unless otherwise stated, can be obtained through commercial channels. Unless otherwise specified, other terms used in the present invention generally have the meanings commonly understood by those of ordinary skill in the art. The present invention will be further described in detail below with reference to specific examples and data. The following examples are merely for illustration of the present invention and are not intended to limit the scope of the present invention in any way.

[0092] Example 1

[0093] The steps for preparing modified recycled fiber asphalt are as follows:

[0094] Heat 50g of base asphalt to 150℃ to obtain a uniform liquid, then add 1g of modified regenerated fiber, and shear at a constant temperature of 150℃ for 1h with a shear rate of 2000rpm; then add 5g of flame retardant, continue shearing for 1h, and keep the shear rate and temperature unchanged to obtain modified regenerated fiber asphalt.

[0095] In this embodiment, the modified regenerated fiber is a modified regenerated polyester fiber, and its preparation method is as follows:

[0096] 1 g of hydroxyl-functionalized multi-walled carbon nanotubes and 50 mL of sodium dodecyl sulfate were mixed and ultrasonically dispersed at room temperature for 2 hours to obtain a hydroxyl-functionalized multi-walled carbon nanotube dispersion; 1 g of epoxy-functionalized regenerated polyester fiber was added to the hydroxyl-functionalized multi-walled carbon nanotube dispersion, followed by adding 0.05 g of triethylamine and standing at 50°C for 6 hours; the filtered and washed product was then placed in a 70°C oven and dried for 24 hours to obtain a modified regenerated polyester fiber.

[0097] The hydroxyl-functionalized multi-walled carbon nanotubes are prepared by the following method:

[0098] 1 g of multi-walled carbon nanotubes and 20 mL of concentrated sulfuric acid and concentrated nitric acid (mixed acid, including 5 mL of concentrated sulfuric acid and 15 mL of concentrated nitric acid) were mixed and reacted at 70°C for 3 hours to obtain a multi-walled carbon nanotube suspension. After the reaction, the multi-walled carbon nanotube suspension was filtered and washed. The washed product was then placed in a 90°C oven and dried for 24 hours to obtain oxidized multi-walled carbon nanotubes.

[0099] 1.6 mL of polyethylene glycol, 0.5 mL of N,N'-diisopropylcarbodiimide and 0.5 mL of 4-pyrrolidinopyridine were mixed, followed by the addition of 25 mL of N,N-dimethylformamide and finally the addition of 1 g of oxidized multi-walled carbon nanotubes. The mixture was mechanically stirred at room temperature under nitrogen protection for 24 hours at a speed of 300 rpm to obtain a mixed solution. The product obtained after filtering and washing the mixed solution was placed in an oven at 100°C and dried for 24 hours to obtain hydroxyl-functionalized multi-walled carbon nanotubes.

[0100] The epoxy-functionalized regenerated polyester fiber is prepared by the following method:

[0101] 0.5 g of 1,1,3,3-tetramethylguanidine was added to 10 mL of N-ethylpyrrolidone and stirred at room temperature for 30 min to obtain a mixed solution; then 0.05 g of tetraoctylammonium bromide was added and stirring continued for 30 min; then 1.7 mL of 1,6-hexanediol diglycidyl ether was slowly added dropwise for 40 min; finally, 1 g of regenerated polyester fiber was added and stirred at 60 ° C for 6 h at a speed of 200 rpm; after the reaction was completed, the mixed solution was filtered and washed to obtain the product, which was placed in a 60 ° C oven and dried for 12 h to obtain epoxy functionalized regenerated polyester fiber.

[0102] The SEM photos of the modified recycled polyester fiber are as follows: Figure 1 As shown:

[0103] Depend on Figure 1 The surface of the recycled polyester fiber is uniformly distributed and free of agglomeration. This indicates that the ring-opening addition reaction between the epoxy groups on the recycled fiber surface and the hydroxyl groups on the carbon nanotubes creates a high and stable chemical bond. This stronger bond improves the poor dispersion and agglomeration of the carbon nanotubes. Furthermore, the unique nanostructure has a large specific surface area, which improves the surface roughness of the recycled polyester fiber and facilitates the bonding of the fiber with the asphalt.

[0104] In this embodiment, the flame retardant is an inorganic flame retardant modified with an ester modifier, and its preparation method is as follows:

[0105] 5 g of nano-montmorillonite was placed in 20 mL of petroleum ether and stirred at 400 rpm in a 50°C oil bath for 15 minutes to form a suspension; 0.1 g of trilauryl phosphite was then added to the suspension and stirred for 2 hours; the suspension was then filtered and washed with a small amount of n-heptane, and then dried in a 90°C oven for 2 hours to obtain an ester modifier-modified inorganic flame retardant.

[0106] Example 2

[0107] In this embodiment, a modified regenerated fiber asphalt is prepared, and its preparation method is as shown in the above-mentioned embodiment 1; different from embodiment 1, in this embodiment, when preparing the modified regenerated fiber, the amount of hydroxyl-functionalized multi-walled carbon nanotubes used is 2g.

[0108] Example 3

[0109] In this embodiment, a modified regenerated fiber asphalt is prepared, and its preparation method is as shown in the above-mentioned embodiment 1; different from embodiment 1, in this embodiment, when preparing the modified regenerated fiber, the amount of hydroxyl-functionalized multi-walled carbon nanotubes used is 3g.

[0110] Comparative Example 1

[0111] This comparative example provides the above-mentioned unmodified 70# matrix asphalt produced by Hebei Dejia Company, and its relevant index tests are shown in Table 1.

[0112] Comparative Example 2

[0113] In this comparative example, a modified regenerated fiber asphalt is prepared, and its preparation method is as shown in the above-mentioned Example 1; different from Example 1, in this comparative example, when preparing the modified regenerated fiber, the amount of hydroxyl-functionalized multi-walled carbon nanotubes used is 0g.

[0114] Comparative Example 3

[0115] In this comparative example, a modified regenerated fiber asphalt is prepared, and its preparation method is as shown in the above-mentioned Example 1; different from Example 1, in this comparative example, unmodified multi-walled carbon nanotubes are used when preparing the modified regenerated fiber.

[0116] Comparative Example 4

[0117] In this comparative example, a modified regenerated fiber asphalt is prepared, and the preparation method thereof is as shown in the above-mentioned Example 1. Different from Example 1, in this comparative example, an unmodified inorganic flame retardant is used.

[0118] 1. Modified asphalt performance test

[0119] 1. Softening point, needle penetration, and elongation

[0120] The softening point of asphalt is measured using the ring and ball method. This softening point reflects the asphalt's high-temperature stability, specifically whether it will soften excessively or deform under high-temperature conditions. Asphalt with a higher softening point generally indicates better resistance to high-temperature rutting.

[0121] Asphalt penetration is measured at 25°C using a standard penetration tester. Penetration primarily reflects the asphalt's hardness at standard temperature. Higher penetrations generally indicate softer asphalt, while lower penetrations indicate harder asphalt. Low penetrations indicate greater stability at high temperatures and resistance to softening.

[0122] Asphalt ductility is measured at 5°C using standard ductility testing equipment. Ductility reflects asphalt's flexibility and ductility, specifically its ability to stretch without cracking at low temperatures or under deformation stress. Higher ductility indicates better low-temperature crack resistance and flexibility.

[0123] The test results are as follows Figure 2 As shown:

[0124] Depend on Figure 2 It can be seen that the modified asphalts prepared in Comparative Examples 2 and 3 have poor softening point, penetration, and ductility compared to Examples 1 to 3 due to the lack of hydroxyl-functionalized multi-walled carbon nanotubes or the use of unmodified multi-walled carbon nanotubes, but have improved compared to Comparative Example 1 (base asphalt). As can be seen from Examples 1 to 3, as the amount of hydroxyl-functionalized multi-walled carbon nanotubes increases, the modified asphalts prepared therefrom show a downward trend in properties such as softening point, penetration, and ductility. This is because the reaction between the hydroxyl groups carried by the carbon nanotubes and the epoxy groups carried by the regenerated polyester fibers is excessive, resulting in the carbon nanotubes being unable to be grafted onto the regenerated polyester fibers in the form of stable chemical bonds, causing shedding or agglomeration, thereby leading to a decline in its performance.

[0125] 2. Rutting factor

[0126] The rutting factor of asphalt is measured using a dynamic shear rheometer (DSR) temperature sweep test at temperatures ranging from 58°C to 94°C, with each step being 6°C. The rutting factor reflects asphalt's resistance to rutting under high temperatures and traffic loads. Rutting deformation is permanent deformation caused by asphalt softening at high temperatures and under load. A larger rutting factor indicates that asphalt maintains its rigidity at high temperatures, resists flow deformation, and exhibits better rutting resistance.

[0127] The test results are as follows Figure 3 As shown:

[0128] Depend on Figure 3It can be seen that the change curve of the rutting factor decreases in the form of a parabola. Compared with Comparative Example 1, the rutting factors of Comparative Examples 2 and 3 increase slightly. The rutting factors of Examples 1 to 3 decrease with the increase of the content of hydroxyl-functionalized multi-walled carbon nanotubes. As the temperature increases, the difference in rutting factors between the comparative examples and the examples becomes smaller and smaller, but the trend of change does not change. The rutting factor of Comparative Example 1 is the smallest at all temperatures, and its high-temperature rheological properties are the worst, followed by Comparative Examples 2 and 3. The high-temperature rheological properties of Examples 1 to 3 are good, which can indicate that both hydroxyl-functionalized multi-walled carbon nanotubes and epoxy-functionalized regenerated polyester fibers have the ability to improve the high-temperature rheological properties of asphalt. The formation of the cross-linking reaction network structure in the asphalt and the larger comparative area of ​​the multi-walled carbon nanotubes can enable the regenerated polyester fiber to form a more effective network structure in the asphalt, further enhancing the high-temperature rheological properties of the modified asphalt.

[0129] 3. Fatigue life

[0130] The fatigue life of asphalt is tested using the LAS in a dynamic shear rheometer (DSR) at a test temperature of 25°C. Fatigue life reflects the ability of asphalt to resist fatigue damage during long-term use. It refers to the number of repeated loading cycles that asphalt can withstand under repeated stresses (such as traffic loads) until the asphalt cracks or fails. A longer fatigue life means that the asphalt can maintain good performance under repeated loads and reduce cracking and damage caused by fatigue damage. This type of asphalt is more suitable for areas with high traffic volume and changeable climate, and can provide a longer service life and less maintenance requirements.

[0131] The test results are as follows Figure 4 As shown:

[0132] Depend on Figure 4 It can be seen that the fatigue life of Comparative Examples 2 and 3 at the two strain levels of 2.5% and 5% are both lower than that of Examples 1 to 3, but are both higher than that of Comparative Example 1. The fatigue life of Examples 1 to 3 has been significantly improved. This is because the epoxy groups on the surface of the epoxy-functionalized regenerated polyester fibers have strong reactivity and can react chemically with certain components in the asphalt to form chemical bonds. At the same time, the hydroxyl groups of the hydroxyl-functionalized multi-walled carbon nanotubes can also produce hydrogen bonds or physical adsorption with the polar groups in the asphalt. This chemical bonding and physical action form a good interface between the recycled polyester fibers, the multi-walled carbon nanotubes and the asphalt, effectively transferring stress, improving the overall performance of the asphalt, delaying the generation and expansion of fatigue cracks, and thus improving the fatigue life of the modified asphalt.

[0133] 4. Low temperature rheological properties

[0134] The low-temperature rheological properties of asphalt are measured using the low-temperature bending stress test (BBR) at test temperatures of -6°C, -12°C, and -18°C. Low-temperature rheological properties reflect asphalt's crack resistance and ductility at low temperatures. Asphalt can become brittle at low temperatures, leading to cracks or fractures. Therefore, its low-temperature performance directly impacts the durability and service life of roads. When the creep stiffness (S) value is too high, asphalt becomes more rigid at low temperatures and is prone to cracking or brittle fracture. A higher m value generally indicates better ductility at low temperatures, allowing it to adapt to temperature changes and prevent cracking.

[0135] The test results are as follows Figure 5 As shown:

[0136] Depend on Figure 5 It can be seen that as the temperature decreases, the creep stiffness of the modified asphalt increases and the creep rate decreases. The creep stiffness of Comparative Examples 2 and 3 is lower than that of Comparative Example 1, and the creep rate is increased, indicating that multi-walled carbon nanotubes and epoxy-functionalized regenerated polyester fibers can effectively improve the low-temperature performance of asphalt. Examples 1-3 have the best low-temperature performance. After the epoxy-functionalized polyester fibers are grafted with hydroxyl-functionalized carbon nanotubes, stronger intermolecular forces are formed between the epoxy-functionalized polyester fibers and the asphalt molecules. At low temperatures, they can limit the excessive shrinkage and aggregation of asphalt molecules, allowing the asphalt molecular chains to maintain a certain degree of mobility, thereby improving the flexibility and crack resistance of the asphalt, and lowering the glass transition temperature of the asphalt, so that the temperature range of the asphalt transition from the high elastic state to the glass state moves toward the low temperature direction. This means that under the same low-temperature environment, the asphalt with the grafted composite material is less likely to enter the brittle glass state, thereby maintaining better low-temperature performance.

[0137] 5. Electrical healing performance

[0138] The complex shear modulus of asphalt before and after electrical healing was measured using a dynamic shear rheometer (DSR) at 64°C. The evaluation metric, the complex modulus healing index (HI), was calculated. The HI measures the asphalt's ability to recover its rheological properties after electrical healing. A higher HI indicates better recovery after electrical healing and a higher healing capacity. A high HI value indicates the asphalt's ability to self-repair and restore its mechanical properties after damage through the electrical healing process. Therefore, asphalt with a high HI value generally exhibits greater durability and improved self-healing capabilities.

[0139] The calculation formula is as follows:

[0140]

[0141] Where: H I is the complex modulus healing index; G ais the initial modulus after 40 minutes of power-on; G0 is the initial modulus after 40 minutes of storage at room temperature.

[0142] The test results are as follows Figure 6 As shown:

[0143] Figure 6 The electrical healing properties of various modified asphalts are demonstrated. Comparative Example 3 shows a significant improvement in electrical healing performance after the addition of multi-walled carbon nanotubes compared to Comparative Example 2, demonstrating that the addition of multi-walled carbon nanotubes can effectively improve the electrical conductivity of asphalt. The electrical healing properties of Examples 1-3 further increase, but decrease with increasing the dosage of hydroxyl-functionalized carbon nanotubes. This is because the increased dosage leads to aggregation of the hydroxyl-functionalized carbon nanotubes, requiring more energy to overcome intermolecular forces, which in turn leads to a decrease in electrical healing performance. The data from the above examples demonstrate that epoxy-functionalized polyester fibers grafted with hydroxyl-functionalized carbon nanotubes can effectively enhance the electrical healing properties of asphalt.

[0144] 6. Flame retardant properties

[0145] Oxygen index testing is typically performed using an oxygen index meter (LOI tester). The test determines the minimum oxygen concentration required for asphalt to burn under certain conditions by controlling the mixing ratio of oxygen and nitrogen. A higher oxygen index indicates less flammable asphalt and greater fire resistance. It is typically expressed as the percentage of oxygen in the mixed gas. The calculation formula is as follows:

[0146]

[0147] Where: L OI is the oxygen index; O is the oxygen flow rate at the critical condition, L / min; N is the nitrogen flow rate at the critical condition, L / min.

[0148] The test results are as follows Figure 7 As shown:

[0149] The oxygen index of Example 1 and Comparative Example 4 was both greater than 23%, meeting the modified asphalt requirements of the "Petrochemical Industry Standard of the People's Republic of China" (NB / SH / T 0821-2010) at a 10% dosage. The oxygen index of Example 1 was greater than that of Comparative Example 4, demonstrating that the use of an ester modifier altered the surface properties of the inorganic flame retardant, improving its oleophilicity and contributing to its enhanced flame retardant performance within the asphalt flame retardant system.

[0150] The present invention also provides other feasible embodiments, as shown below:

[0151] Example 4

[0152] The steps for preparing modified recycled fiber asphalt are as follows:

[0153] Heat 50g of base asphalt to 150℃ to obtain a uniform liquid, then add 1g of modified regenerated fiber, and shear at a constant temperature of 150℃ for 1h with a shear rate of 2000rpm; then add 5g of flame retardant, continue shearing for 1h, and keep the shear rate and temperature unchanged to obtain modified regenerated fiber asphalt.

[0154] In this embodiment, the modified regenerated fiber is modified regenerated lignin fiber, and its preparation method is as follows:

[0155] 1 g of amino-functionalized multi-walled carbon nanotubes was mixed with 50 mL of sodium dodecyl sulfate and ultrasonically dispersed at room temperature for 2 h to obtain an amino-functionalized multi-walled carbon nanotube dispersion; 1 g of epoxy-functionalized regenerated lignin fiber was added to the amino-functionalized multi-walled carbon nanotube dispersion, followed by addition of 0.05 g of triethylamine and allowed to react at 50 °C for 6 h; the filtered and washed product was then placed in an oven at 70 °C and dried for 24 h to obtain modified regenerated lignin fiber.

[0156] The amino-functionalized multi-walled carbon nanotubes are prepared by the following method:

[0157] 10 mL of methanol and 4 mL of deionized water were mixed, and then 1.5 mL of 3-aminopropylmethyldimethoxysilane was added. The mixture was mechanically stirred at 1000 rpm at room temperature for 1 hour to obtain a mixed solution. Then, 1 g of multi-walled carbon nanotubes was placed in the mixed solution and mechanically stirred at 1500 rpm at 60°C for 6 hours. The mixture was then rinsed with deionized water and dried in an oven at 100°C for 24 hours to obtain amino-functionalized multi-walled carbon nanotubes.

[0158] The epoxy-functionalized regenerated lignin fiber is prepared by the following method:

[0159] 0.5 mL of 1,1,3,3-tetramethylguanidine was added to 10 mL of N-ethylpyrrolidone and stirred at room temperature for 30 minutes to obtain a mixed solution; then 0.05 g of tetraoctylammonium bromide was added and stirring continued for 30 minutes; then 1.7 mL of 1,6-hexanediol diglycidyl ether was slowly added dropwise for 40 minutes; finally, 1 g of regenerated lignin fiber was added and stirred at 60°C for 6 hours at a speed of 200 rpm; after the reaction was completed, the mixed solution was filtered and washed to obtain the product, which was placed in a 60°C oven and dried for 12 hours to obtain epoxy-functionalized regenerated lignin fiber.

[0160] In this embodiment, the flame retardant is an inorganic flame retardant modified with an ester modifier, and its preparation method is as follows:

[0161] 5 g of nano-montmorillonite was placed in 20 mL of petroleum ether and stirred at 400 rpm in a 50°C oil bath for 15 minutes to form a suspension; 0.1 g of trilauryl phosphite was then added to the suspension and stirred for 2 hours; the suspension was then filtered and washed with a small amount of n-heptane, and then dried in a 90°C oven for 2 hours to obtain an ester modifier-modified inorganic flame retardant.

[0162] Example 5

[0163] The steps for preparing modified recycled fiber asphalt are as follows:

[0164] Heat 50g of base asphalt to 150℃ to obtain a uniform liquid, then add 1g of modified regenerated fiber, and shear at a constant temperature of 150℃ for 1h with a shear rate of 2000rpm; then add 5g of flame retardant, continue shearing for 1h, and keep the shear rate and temperature unchanged to obtain modified regenerated fiber asphalt.

[0165] In this embodiment, the modified regenerated fiber is modified regenerated PAN fiber, and its preparation method is as follows:

[0166] 1 g of carboxyl-functionalized multi-walled carbon nanotubes and 50 mL of sodium dodecyl sulfate were mixed and ultrasonically dispersed at room temperature for 2 hours to obtain a carboxyl-functionalized multi-walled carbon nanotube dispersion; 1 g of epoxy-functionalized regenerated PAN fiber was added to the carboxyl-functionalized multi-walled carbon nanotube dispersion, followed by adding 0.05 g of triethylamine and allowing to react at 50°C for 6 hours; the filtered and washed product was then placed in a 70°C oven and dried for 24 hours to obtain modified regenerated PAN fiber.

[0167] The carboxyl functionalized multi-walled carbon nanotubes are prepared by the following method:

[0168] The multi-walled carbon nanotubes were evenly dispersed in the reaction chamber of the plasma equipment; ozone was introduced to make the gas pressure in the chamber reach 40Pa; then the plasma treatment parameters were adjusted to 70W power and 30min treatment time, and the plasma equipment was started to treat the multi-walled carbon nanotubes to obtain carboxyl-functionalized multi-walled carbon nanotubes.

[0169] The epoxy-functionalized regenerated PAN fiber is prepared by the following method:

[0170] 0.5 mL of 1,1,3,3-tetramethylguanidine was added to 10 mL of N-ethylpyrrolidone and stirred at room temperature for 30 minutes to obtain a mixed solution; then 0.05 g of tetraoctylammonium bromide was added and stirring continued for 30 minutes; then 1.7 mL of 1,6-hexanediol diglycidyl ether was slowly added dropwise for 40 minutes; finally, 1 g of regenerated PAN fiber was added and stirred at 60°C for 6 hours at a speed of 200 rpm; after the reaction was completed, the mixed solution was filtered and washed to obtain the product, which was placed in a 60°C oven and dried for 12 hours to obtain epoxy-functionalized regenerated PAN fiber.

[0171] In this embodiment, the flame retardant is an inorganic flame retardant modified with an ester modifier, and its preparation method is as follows:

[0172] 5 g of nano-montmorillonite was placed in 20 g of petroleum ether and stirred at 400 rpm in a 50°C oil bath for 15 minutes to form a suspension; 0.1 g of trilauryl phosphite was then added to the suspension and stirred for 2 hours; the suspension was then filtered and washed with a small amount of n-heptane, and then dried in a 90°C oven for 2 hours to obtain an ester modifier-modified inorganic flame retardant.

[0173] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above-disclosed technical content to modify or modify the present invention into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present invention and are based on the technical essence of the present invention remain within the scope of protection of the present invention.

Claims

1. A fiber asphalt for road engineering, characterized in that: The fiber asphalt is modified recycled fiber asphalt; The preparation method of the modified regenerated fiber asphalt comprises the following steps: Heat 50-200 parts of base asphalt until dissolved, then add 1-4 parts of modified regenerated fiber and shear at constant temperature; then add 5-20 parts of flame retardant and continue shearing at constant temperature to obtain modified regenerated fiber asphalt; The constant temperature shearing condition is selected from: shearing at 2000-3000 rpm at 150-180°C for 1-2 hours; and / or, the matrix asphalt is selected from one or more of coke asphalt, rock asphalt, petroleum asphalt, and bio-asphalt; The modified regenerated fiber is prepared by the following method: 1-4 parts of carbon nanotubes are mixed with 50-200 parts of an organic solvent and ultrasonically dispersed to obtain a carbon nanotube dispersion; 1-4 parts of regenerated fiber are added, followed by 0.05-0.2 parts of a promoter, and the mixture is allowed to react; after the reaction is completed, the reaction product is washed and dried to obtain a modified regenerated fiber; The carbon nanotubes are surface-functionalized multi-walled carbon nanotubes, specifically hydroxyl-functionalized multi-walled carbon nanotubes, amino-functionalized multi-walled carbon nanotubes, or carboxyl-functionalized multi-walled carbon nanotubes; the organic solvent is selected from one or more of sodium lauryl sulfate, hexadecyltrimethylammonium bromide, polyoxyethylene sorbitan monooleate, polyvinyl pyrrolidone, and polyethylene glycol; the regenerated fiber is epoxy-functionalized regenerated fiber; and the accelerator is selected from one or more of triethylamine, potassium hydroxide, stannous octoate, and benzyltriethylammonium chloride. The epoxy-functionalized regenerated fiber is prepared by the following method: Add 0.5-0.7 parts of a basic compound to 10-20 parts of an organic solvent and stir to obtain a mixed solution; then add 0.05-0.1 parts of a catalyst and stir; Then, 1.5 to 3 parts of epoxy modifier are slowly added dropwise; finally, 0.5 to 2 parts of regenerated fiber are added and stirred for reaction; after the reaction is completed, the reaction product is washed and dried to obtain epoxy functionalized regenerated fiber.

2. The fiber asphalt for road engineering according to claim 1, characterized in that: The hydroxyl-functionalized multi-walled carbon nanotubes are prepared by the following method: Add 0.5-2 parts of multi-walled carbon nanotubes to 20-40 parts of the modifier under reflux at 70-80°C, mix and react for 3-4 hours to obtain a suspension; The suspension is filtered, washed with water, and dried at 90-100° C. for 24-36 hours to obtain oxidized multi-walled carbon nanotubes; 1-4 parts of a hydroxyl modifier and 0.5-4 parts of a catalyst are mixed, followed by adding 25-50 parts of an organic solvent and 0.5-2 parts of oxidized multi-walled carbon nanotubes, and the mixture is stirred at 200-500 rpm under nitrogen protection for 24-48 hours to obtain a mixed solution; the mixed solution is filtered, the reaction product is washed, and dried at 100-110° C. for 24-36 hours to obtain hydroxyl-functionalized multi-walled carbon nanotubes; The modifier is selected from one or more of concentrated sulfuric acid and concentrated nitric acid, concentrated sulfuric acid and chlorosulfonic acid, concentrated sulfuric acid and phosphoric acid, and concentrated sulfuric acid and perchloric acid; the hydroxyl modifier is selected from one or more of pentaerythritol, polyethylene glycol, glycerol, xylitol, inositol, mercaptoethanol, triethylene glycol, 1,4-butanediol, 2,3-butanediol, and polypropylene glycol.

3. The fiber asphalt for road engineering according to claim 1, characterized in that: The amino-functionalized multi-walled carbon nanotubes are prepared by the following method: Mix 10-20 parts of dispersant and 4-10 parts of water, then add 1.5-2 parts of amino modifier, and stir at 1000-1200 rpm at room temperature for 1-2 hours to obtain a mixed solution; then add 0.5-2 parts of multi-walled carbon nanotubes into the mixed solution, and stir at 1500-1600 rpm at 60-65°C for 6-8 hours; then rinse the reaction product with water and dry it at 100-110°C for 24-36 hours to obtain amino-functionalized multi-walled carbon nanotubes.

4. The fiber asphalt for road engineering according to claim 1, characterized in that: The carboxyl functionalized multi-walled carbon nanotubes are prepared by the following method: The multi-walled carbon nanotubes are uniformly dispersed in a reaction chamber of a plasma device; gas is introduced to make the gas pressure in the chamber reach a set pressure value; then the plasma treatment parameters are adjusted, the plasma device is started, and the multi-walled carbon nanotubes are treated to obtain carboxyl-functionalized multi-walled carbon nanotubes; The gas is selected from oxygen or ozone; the pressure setting value is selected from 10~100Pa; the plasma parameters are selected from: power 50~200w, processing time 5~60min.

5. The fiber asphalt for road engineering according to claim 1, characterized in that: The flame retardant is an inorganic flame retardant modified by an ester modifier, and its preparation method is as follows: 5-10 parts of an inorganic flame retardant are added to 20-40 parts of a dispersant and stirred in an oil bath to form a suspension; then 0.1-0.2 parts of an ester modifier are added and stirred for reaction; after the reaction is completed, the reaction product is washed and dried to obtain an ester modifier-modified inorganic flame retardant.

6. Use of the fiber asphalt according to any one of claims 1 to 5 in road engineering.

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