Preparation method of modified basalt fiber, modified basalt fiber and application

Abstract

The invention belongs to the technical field of fiber reinforced composite materials, and relates to a preparation method of modified basalt fibers, the modified basalt fibers and application, the preparation method comprises the following steps: S1, placing the basalt fibers in a reactor, and introducing silicon tetrafluoride gas for etching treatment to obtain etched basalt fibers; s2, performing radio frequency magnetron sputtering treatment by taking the etched basalt fiber as a substrate and titanium dioxide or zirconium dioxide as a target material, and then performing annealing treatment to obtain surface coating basalt fiber; and S3, immersing the surface-coated basalt fiber into an impregnating compound, taking out the surface-coated basalt fiber, and drying and curing the surface-coated basalt fiber to obtain the modified basalt fiber. According to the method, after the modified basalt fiber is applied to the asphalt concrete, the key performance indexes of the asphalt concrete can be remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of fiber-reinforced composite materials technology, and relates to the preparation method of modified basalt fiber, modified basalt fiber and its application. Background Technology

[0002] In the field of road engineering, asphalt concrete is widely used due to its good driving comfort and maintainability. However, under temperature changes and long-term vehicle loads, it is prone to defects such as temperature cracks, fatigue cracks, and rutting, which seriously affect the service life of roads and driving safety. To improve the performance of asphalt concrete, adding fibers has become an effective means of strengthening and toughening. Among them, basalt fiber, as an inorganic fiber made from the melting and drawing of natural basalt ore, has advantages such as high strength, high temperature resistance, corrosion resistance, and good compatibility with asphalt, and is regarded as a highly promising asphalt concrete reinforcing material.

[0003] Theoretically, the addition of basalt fibers can improve the toughness of asphalt mastic through bridging and crack-inhibiting effects, disperse stress, thereby inhibiting crack initiation and propagation, and enhancing the high-temperature rutting resistance and low-temperature crack resistance of the mixture. However, in practical applications, it has been found that the interfacial bond between untreated basalt fibers and the asphalt concrete matrix is ​​often weak. This is mainly due to two reasons: firstly, the surface of basalt fibers is smooth and inert, resulting in insufficient wettability and adhesion to asphalt; secondly, the internal environment of asphalt concrete is weakly alkaline during service, which may slowly erode the fiber surface, further weakening the interfacial strength. In addition, during the high-temperature mixing and construction of asphalt mixtures, fibers are prone to agglomeration or breakage due to friction and static electricity, leading to uneven dispersion in the matrix and making it difficult to fully exert their reinforcing effect.

[0004] In existing technologies, basalt fibers are typically surface-treated with sizing agents to improve their bundle structure, dispersion, and adhesion to asphalt concrete. However, conventional sizing agent treatments primarily focus on physical encapsulation and electrostatic elimination, offering limited alteration to the fiber surface's physicochemical properties. The resulting interfacial bonding layer exhibits insufficient long-term stability under complex stress and alkaline environments, making it difficult to significantly improve key road performance indicators (durability under freeze-thaw conditions, low-temperature flexibility, and high-temperature stability). Some studies have attempted to increase surface roughness or activity through single chemical etching or physical coating treatments, but these methods are often complex, offer limited modification effects, or fail to guarantee the fiber's intrinsic strength. Consequently, their application in asphalt concrete fails to significantly improve the key performance indicators of asphalt concrete (durability under freeze-thaw conditions, low-temperature flexibility, and high-temperature stability).

[0005] Therefore, developing a method to improve the surface properties of basalt fibers so that the modified basalt fibers can significantly improve the key performance indicators of asphalt concrete (durability under freeze-thaw conditions, low-temperature flexibility, and high-temperature stability) is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing modified basalt fibers, the modified basalt fibers themselves, and their application in asphalt concrete. This method involves sequentially subjecting basalt fibers to silicon tetrafluoride etching, titanium dioxide or zirconium dioxide magnetron sputtering, and wetting treatments to construct a composite structure on the fiber surface consisting of a "rough etched layer - inorganic coating - organic functional film." When applied to asphalt concrete, the modified basalt fibers can significantly improve the key performance indicators of asphalt concrete (durability under freeze-thaw conditions, asphalt exudation rate during construction, low-temperature flexibility, and high-temperature stability).

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing modified basalt fibers, comprising the following steps: S1: Surface etching treatment: Basalt fiber is placed in a reactor and silicon tetrafluoride gas is introduced for etching treatment to obtain etched basalt fiber. S2: Surface sputtering coating treatment: Using the etched basalt fiber as a substrate and titanium dioxide or zirconium dioxide as a target, radio frequency magnetron sputtering treatment is performed, followed by annealing treatment to obtain basalt fiber with surface coating. S3: Immersion treatment: Immerse the surface-coated basalt fiber in an impregnating agent, remove it, and then dry and cure it to obtain modified basalt fiber.

[0008] This invention utilizes silicon tetrafluoride (SiF4) for vapor-phase etching of basalt fiber surfaces. The etching significantly improves the surface roughness of the basalt fibers, increasing their specific surface area and surface energy. This provides stronger mechanical anchoring points for subsequent coatings and wetting agents, thereby enhancing the physical interlocking between the fibers and the asphalt matrix and contributing to improved overall road performance of asphalt concrete (e.g., durability under freeze-thaw conditions, asphalt exudation rate during construction). A uniform titanium dioxide (TiO2) or zirconium dioxide (ZrO2) nano-coating is deposited on the etched fiber surface using radio frequency magnetron sputtering. This coating is chemically stable and alkali-resistant, effectively isolating the alkaline environment inside the asphalt concrete from erosion of the basalt fiber matrix and improving the fiber's chemical durability. Simultaneously, the coating... The abundant hydroxyl groups (-OH) on the surface of the layer can form chemical bonds with the subsequent impregnating agent, enhancing the interfacial bonding strength. After annealing, the TiO2 or ZrO2 coating crystallizes, resulting in a more stable structure and stronger adhesion, further ensuring the durability of the fiber under high temperature and complex stress. This has a positive effect on improving the stability of movement in rutting tests and long-term performance stability. Through impregnation, a flexible and dense organic composite film is formed on the fiber surface, which can improve the fiber's bundle properties, antistatic properties, and wear resistance. Furthermore, the impregnating agent can act as a "molecular bridge" to connect the inorganic coating and the asphalt matrix, enhancing the chemical bonding of the fiber-asphalt interface, thereby significantly improving the fiber-asphalt interfacial bonding strength and improving the overall road performance of asphalt mixtures (e.g., low-temperature flexibility and high-temperature stability).

[0009] This invention employs a three-step composite modification process—chemical etching, physical sputtering, and organic wetting—to sequentially construct a synergistic system on the fiber surface, consisting of a micro / nano-scale rough structure, a highly stable titanium dioxide or zirconium dioxide inorganic coating, and a functionalized organic composite film. This structure achieves a strong, multi-layered bond with the asphalt matrix through physical interlocking, chemical bonding, and molecular wetting, thereby comprehensively improving the bond strength and stress transfer efficiency of the fiber-asphalt interface. When the resulting modified basalt fiber is applied to asphalt concrete, it significantly improves key performance indicators of asphalt concrete (durability under freeze-thaw conditions, asphalt exudation rate during construction, low-temperature flexibility, and high-temperature stability).

[0010] Furthermore, in step S1, the etching temperature is 130℃~140℃, and the processing time is 40~60min.

[0011] Furthermore, in step S1, the flow rate of the silicon tetrafluoride gas is 100–150 mL / min.

[0012] Furthermore, after step S1, the method further includes rinsing the etched basalt fiber with deionized water 2 to 3 times.

[0013] Furthermore, in step S2, the power of the radio frequency magnetron sputtering is 150-200W, and the sputtering time is 30-60min.

[0014] Furthermore, in step S2, the annealing temperature is 500℃~600℃, and the annealing time is 1~2h.

[0015] Furthermore, in step S2, the thickness of the titanium dioxide or zirconium dioxide nanocoating formed on the surface of the etched basalt fiber after the radio frequency magnetron sputtering and annealing treatment is 200-300 nm.

[0016] Furthermore, in step S2, the thickness of the titanium dioxide or zirconium dioxide nanocoating formed on the surface of the etched basalt fiber after the radio frequency magnetron sputtering and annealing treatment is 220-250 nm.

[0017] Furthermore, in step S3, the immersion time for the soaking treatment is 12 to 15 hours.

[0018] Furthermore, in step S3, the drying and curing temperature is 100℃~150℃, and the time is 10~15h.

[0019] Furthermore, the mass ratio of basalt fiber raw material to the impregnating agent is 1:(5-10).

[0020] Furthermore, in step S3, the wetting agent comprises the following components by weight percentage: 3%–6% film-forming agent 1, 2%–5% film-forming agent 2, 5%–8% polyvinyl acetate, 0.1%–1% surfactant, 0.2%–1.2% silane coupling agent, 1%–2% pH adjuster, 0.2%–0.4% antistatic agent, 0.2%–0.5% lubricant, and the balance being deionized water.

[0021] Furthermore, the solid content of film-forming agent 1 is 40-50 wt%; the solid content of film-forming agent 2 is 25-35 wt%; and the mass concentration of pH adjuster is 25-30%.

[0022] Furthermore, the film-forming agent 1 is an epoxy resin emulsion.

[0023] Furthermore, the film-forming agent 2 is an acrylate emulsion.

[0024] Furthermore, the silane coupling agent is an aminosilane coupling agent or an epoxy-based silane coupling agent.

[0025] Furthermore, the silane coupling agent is one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

[0026] Furthermore, the pH adjuster is an organic amine or ammonia.

[0027] Furthermore, the antistatic agent is a polyquaternary ammonium salt or ammonium chloride.

[0028] Furthermore, the polyquaternary ammonium salt is selected from dodecyl dimethyl benzyl ammonium chloride, octadecyl trimethyl ammonium chloride, or hexadecyl trimethyl ammonium bromide.

[0029] Furthermore, the surfactant is a mixture of fatty alcohol polyoxyethylene ether and sodium octadecyl sulfate or a polypropylene-polyethylene (PO-EO) block copolymer.

[0030] Furthermore, the lubricant is an organosilicon lubricant.

[0031] Furthermore, the preparation method of the wetting agent includes: first, adding the pH adjuster and silane coupling agent to a portion of deionized water and stirring evenly; then adding the film-forming agent 1, film-forming agent 2 and polyvinyl acetate, stirring for 15-20 minutes; then adding the antistatic agent, lubricant, surfactant and the remaining deionized water, continuing to stir for 15-20 minutes, and then ultrasonically vibrating for 20-30 minutes; wherein, the pH value of the wetting agent is 7-8.

[0032] In a second aspect, the present invention provides a modified basalt fiber, which is prepared by the preparation method described in the first aspect.

[0033] Furthermore, the modified basalt fiber surface has, from the inside out, a roughened etching layer formed by silicon tetrafluoride etching, a titanium dioxide or zirconium dioxide nano-coating deposited by radio frequency magnetron sputtering and annealed, and an organic composite film layer formed by curing the wetting agent.

[0034] Thirdly, the present invention provides an application of modified basalt fiber as described in the second aspect in asphalt concrete.

[0035] Furthermore, the modified basalt fiber is added to the asphalt concrete in a short-cut form, with a fiber length of 6-12 mm, and the dosage in the asphalt concrete is 0.2%-0.5% of the total mass of the asphalt mixture.

[0036] Compared with the prior art, the beneficial effects of the present invention include at least one of the following: 1) This invention uses silicon tetrafluoride (SiF4) to perform vapor phase etching on the surface of basalt fibers. After etching, the surface roughness of the basalt fibers is significantly improved, increasing the specific surface area and surface energy of the fibers. This provides stronger mechanical anchoring points for subsequent coatings and wetting agents, thereby enhancing the physical interlocking between the fibers and the asphalt matrix. This helps to improve the overall road performance of asphalt concrete (e.g., durability under freeze-thaw conditions, asphalt exudation rate during construction). 2) This invention deposits a uniform titanium dioxide (TiO2) or zirconium dioxide (ZrO2) nano-coating on the etched fiber surface through radio frequency magnetron sputtering of titanium dioxide or zirconium dioxide. This coating is chemically stable and alkali-resistant, effectively isolating the alkaline environment inside asphalt concrete from erosion of the basalt fiber body and improving the chemical durability of the fiber. At the same time, the abundant hydroxyl groups (-OH) on the coating surface can form chemical bonds with the subsequent wetting agent, enhancing the interfacial bonding strength. After annealing, the TiO2 or ZrO2 coating crystallizes, resulting in a more stable structure and stronger adhesion, further ensuring the durability of the fiber under high temperature and complex stress, and playing a positive role in improving the movement stability in rutting tests and long-term performance stability. 3) This invention forms a flexible and dense organic composite film on the fiber surface through impregnation treatment. This film can improve the fiber's bundle properties, antistatic properties, and wear resistance. Furthermore, the impregnating agent can act as a "molecular bridge" to connect the inorganic coating and the asphalt matrix, enhancing the chemical bonding at the fiber-asphalt interface, thereby significantly improving the fiber-asphalt interface bond strength and improving the overall road performance of asphalt concrete (e.g., low-temperature flexibility and high-temperature stability). 4) This invention employs a three-step composite modification process—chemical etching, physical sputtering, and organic wetting—to sequentially construct a synergistic system on the fiber surface, consisting of a micro / nano-scale rough structure, a highly stable titanium dioxide or zirconium dioxide inorganic coating, and a functionalized organic composite film. This structure achieves a strong, multi-layered bond with the asphalt matrix through physical interlocking, chemical bonding, and molecular wetting, thereby comprehensively improving the bond strength and stress transfer efficiency of the fiber-asphalt interface. Applying the resulting modified basalt fiber to asphalt concrete significantly enhances key performance indicators of asphalt concrete (durability under freeze-thaw conditions, asphalt exudation rate during construction, low-temperature flexibility, and high-temperature stability). Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Those skilled in the art should understand that the embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Process parameters not specifically specified in the following embodiments are generally performed under conventional conditions.

[0038] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0039] In a first aspect, the present invention provides a method for preparing modified basalt fibers, comprising the following steps: S1: Surface etching treatment: Basalt fiber is placed in a reactor and silicon tetrafluoride gas is introduced for etching treatment to obtain etched basalt fiber. S2: Surface sputtering coating treatment: Using the etched basalt fiber as a substrate and titanium dioxide or zirconium dioxide as a target, radio frequency magnetron sputtering treatment is performed, followed by annealing treatment to obtain basalt fiber with surface coating. S3: Immersion treatment: Immerse the surface-coated basalt fiber in an impregnating agent, remove it, and then dry and cure it to obtain modified basalt fiber.

[0040] This invention utilizes silicon tetrafluoride (SiF4) for vapor-phase etching of basalt fiber surfaces. The etching significantly improves the surface roughness of the basalt fibers, increasing their specific surface area and surface energy. This provides stronger mechanical anchoring points for subsequent coatings and wetting agents, thereby enhancing the physical interlocking between the fibers and the asphalt matrix and contributing to improved overall road performance of asphalt concrete (e.g., durability under freeze-thaw conditions, asphalt exudation rate during construction). A uniform titanium dioxide (TiO2) or zirconium dioxide (ZrO2) nano-coating is deposited on the etched fiber surface using radio frequency magnetron sputtering. This coating is chemically stable and alkali-resistant, effectively isolating the alkaline environment inside the asphalt concrete from erosion of the basalt fiber matrix and improving the fiber's chemical durability. Simultaneously, the coating... The abundant hydroxyl groups (-OH) on the surface can form chemical bonds with the subsequent impregnating agent, enhancing the interfacial bonding strength. After annealing, the TiO2 or ZrO2 coating crystallizes, resulting in a more stable structure and stronger adhesion, further ensuring the durability of the fiber under high temperature and complex stress. This has a positive effect on improving the movement stability in rutting tests and long-term performance stability. The impregnation treatment forms a flexible and dense organic composite film on the fiber surface, which can improve the fiber's bundle properties, antistatic properties, and wear resistance. Furthermore, the impregnating agent can act as a "molecular bridge" to connect the inorganic coating and the asphalt matrix, enhancing the chemical bonding at the fiber-asphalt interface, thereby significantly improving the fiber-asphalt interfacial bond strength. This is beneficial for improving the comprehensive road performance of asphalt concrete (e.g., low-temperature flexibility and high-temperature stability).

[0041] This invention employs a three-step composite modification process—chemical etching, physical sputtering, and organic wetting—to sequentially construct a synergistic system on the fiber surface, consisting of a micro / nano-scale rough structure, a highly stable titanium dioxide or zirconium dioxide inorganic coating, and a functionalized organic composite film. This structure achieves a strong, multi-layered bond with the asphalt matrix through physical interlocking, chemical bonding, and molecular wetting, thereby comprehensively improving the bond strength and stress transfer efficiency of the fiber-asphalt interface. When the resulting modified basalt fiber is applied to asphalt concrete, it significantly improves key performance indicators of asphalt concrete (durability under freeze-thaw conditions, asphalt exudation rate during construction, low-temperature flexibility, and high-temperature stability).

[0042] As an optional implementation, in step S1, the etching temperature is 130℃~140℃, for example, 130℃, 135℃ or 140℃, and the processing time is 40~60min, for example, 40min, 50min or 60min.

[0043] As an optional implementation, in step S1, the flow rate of the silicon tetrafluoride gas is 100-150 mL / min, for example, it can be 100 mL / min, 110 mL / min, 120 mL / min, 130 mL / min, 140 mL / min or 150 mL / min.

[0044] As an optional implementation, step S1 is followed by rinsing the etched basalt fiber with deionized water 2 to 3 times.

[0045] This invention utilizes silicon tetrafluoride gas for vapor-phase etching, primarily targeting the silicon-oxygen network. The etching method is controllable, minimizing damage to the fiber's main structure and preventing excessive etching that could lead to a sharp drop in fiber strength. The reaction occurs at the gas-solid interface, easily forming a uniform, isotropic micro / nanoscale rough structure, unlike acid / alkali etching which may result in localized over-erosion. Reaction byproducts are mainly volatile gases, easily removed by simple water washing, resulting in high surface cleanliness and activity, providing excellent chemical bonding sites for TiO2 or ZrO2 sputtering coatings. Further optimization of etching reaction conditions (etching temperature, processing time, and etching gas flow rate) enables efficient and controllable generation of suitable micro / nanoscale rough structures while ensuring the fiber's mechanical properties. Rinsing removes residual acidic substances and reactants from the surface, providing a clean and active substrate for subsequent sputtering coatings, thus ensuring the bonding quality between functional layers.

[0046] As an optional implementation, in step S2, the power of the radio frequency magnetron sputtering is 150 to 200 W, for example, 150 W, 160 W, 180 W or 200 W, and the sputtering time is 30 to 60 min, for example, 30 min, 40 min, 45 min, 50 min or 60 min.

[0047] As an optional implementation, in step S2, the annealing temperature is 500℃~600℃, for example, 500℃, 520℃, 550℃ or 600℃, and the annealing time is 1~2h, for example, 1h, 1.5h or 2h.

[0048] This invention further determines the power and time of sputtering coating and the temperature of annealing treatment, solving the problems of uneven coating and poor adhesion caused by improper sputtering power or time, and poor coating crystallinity or mismatch between thermal expansion and fiber substrate caused by improper annealing temperature. It ensures that titanium dioxide or zirconium dioxide coating can be uniformly and densely deposited on the etched fiber surface, and form a structurally stable and firmly bonded nanocrystalline coating after annealing.

[0049] As an optional implementation, in step S2, the thickness of the titanium dioxide or zirconium dioxide nanocoating formed on the surface of the etched basalt fiber after the radio frequency magnetron sputtering and annealing treatment is 200-300 nm, for example, it can be 200 nm, 220 nm, 230 nm, 240 nm, 250 nm, 280 nm or 300 nm, preferably 220-250 nm.

[0050] As an optional implementation, in step S3, the immersion time of the soaking treatment is 12 to 15 hours, for example, 12 hours, 13 hours, 14 hours or 15 hours.

[0051] As an optional implementation, in step S3, the drying and curing temperature is 100℃~150℃, for example, 100℃, 110℃, 120℃ or 150℃, and the time is 10~15h, for example, 10h, 12h, 14h or 15h.

[0052] The present invention further selects reasonable curing conditions (curing temperature and time) to enable the impregnating agent to fully cross-link into a film, forming a strong and flexible organic composite protective layer, thereby better cooperating with other functional layers to maximize the performance of each functional layer.

[0053] As an optional implementation, in step S3, the mass ratio of basalt fiber raw material to the impregnating agent is 1:(5-10), for example, it can be 1:5, 1:6, 1:6.7, 1:7, 1:8, 1:9 or 1:10.

[0054] As an optional implementation, in step S3, the wetting agent comprises the following components by weight percentage: 3%–6% film-forming agent 1, 2%–5% film-forming agent 2, 5%–8% polyvinyl acetate, 0.1%–1% surfactant, 0.2%–1.2% silane coupling agent, 1%–2% pH adjuster, 0.2%–0.4% antistatic agent, 0.2%–0.5% lubricant, and the balance being deionized water.

[0055] This invention, through the synergistic effect of its components, enables the final cured organic film layer to possess excellent adhesion, flexibility, abrasion resistance, alkali resistance, and antistatic properties. It effectively "locks in" the sputtered coating, further enhancing the integrity of the fibers and ensuring that they do not break or fracture during asphalt mixture mixing, and are uniformly dispersed.

[0056] As an optional implementation, in step S3, the film-forming agent 1 can be 3%, 4%, 5% or 6%.

[0057] As an optional implementation, in step S3, the film-forming agent 2 can be 2%, 3%, 4% or 5%.

[0058] As an optional implementation, in step S3, the polyvinyl acetate can be 5%, 6%, 7% or 8%.

[0059] As an optional implementation, in step S3, the surfactant can be 0.1%, 0.2%, 0.3%, 0.5%, 0.6%, 0.8%, or 1%.

[0060] As an optional implementation, in step S3, the silane coupling agent can be 0.2%, 0.3%, 0.5%, 0.6%, 0.8%, 1%, or 1.2%.

[0061] As an optional implementation, in step S3, the pH adjuster can be 1%, 1.2%, 1.5%, 1.8%, or 2%.

[0062] As an optional implementation, in step S3, the antistatic agent can be 0.2%, 0.25%, 0.3%, 0.35%, or 0.4%.

[0063] As an optional implementation, in step S3, the lubricant can be 0.2%, 0.3%, 0.4%, or 0.5%.

[0064] As an optional embodiment, the solid content of the film-forming agent 1 is 40-50 wt%, for example, it can be 40 wt%, 45 wt%, 48 wt% or 50 wt%; the solid content of the film-forming agent 2 is 25-35 wt%, for example, it can be 25 wt%, 28 wt%, 30 wt% or 35 wt%; and the mass concentration of the pH adjuster is 25-30%, for example, it can be 25%, 28% or 30%.

[0065] As an optional implementation, the film-forming agent 1 is an epoxy resin emulsion.

[0066] As an optional embodiment, the film-forming agent 2 is an acrylate emulsion.

[0067] As an optional implementation, the silane coupling agent is an aminosilane coupling agent or an epoxy-based silane coupling agent.

[0068] As an optional implementation, the silane coupling agent is one or more of γ-aminopropyltriethoxysilane (KH-550), γ-glycidoxypropyltrimethoxysilane (KH-560), and γ-methacryloyloxypropyltrimethoxysilane (KH-570).

[0069] As an optional implementation, the pH adjuster is an organic amine.

[0070] As an optional implementation, the pH adjuster is ammonia.

[0071] As an optional implementation, the antistatic agent is a polyquaternary ammonium salt or ammonium chloride.

[0072] As an alternative embodiment, the polyquaternary ammonium salt is selected from dodecyl dimethyl benzyl ammonium chloride, octadecyl trimethyl ammonium chloride, or hexadecyl trimethyl ammonium bromide.

[0073] As an optional embodiment, the surfactant is a mixture of fatty alcohol polyoxyethylene ether and sodium octadecyl sulfate or a polypropylene-polyethylene (PO-EO) block copolymer.

[0074] As an optional implementation, the mass ratio of the fatty alcohol polyoxyethylene ether to the sodium octadecyl sulfate is 1:(1-2), for example, it can be 1:1, 1:1.5 or 1:2.

[0075] The lubricant is an organosilicon lubricant.

[0076] In this invention, the detailed functions of each component in the wetting agent are as follows: First, film-forming agent 1 is an epoxy resin emulsion, which is more effective in bundling and bonding basalt fibers, maintaining good elasticity, wear resistance, and adhesion of the fibers, preventing them from fraying before being added to asphalt concrete. Film-forming agent 2 is an acrylic emulsion, which provides flexibility, weather resistance, and film-forming properties, improving the toughness and durability of the coating. The combination of the two achieves a "rigid-flexible" coating structure, ensuring both strength and improved toughness, preventing brittleness. Polyvinyl acetate, as an auxiliary film-forming agent, improves the bundling of basalt fibers, preventing them from agglomerating and ensuring uniform dispersion of basalt fibers in asphalt concrete. This enhances the overall continuity and density of the film, further improving the mechanical protective effect of the coating. Second, after hydrolysis under alkaline conditions, the silane coupling agent's silanol groups combine with the -OH groups of the titanium dioxide-coated basalt fibers, while the organic groups (such as amino and epoxy groups) at the other end react with the active groups of the asphalt matrix to form a strong chemical bond layer. Silane coupling agents act as "molecular bridges," connecting the inorganic fiber surface to the asphalt matrix, enhancing interfacial chemical bonding, and improving adhesion and water resistance. Mixtures of fatty alcohol polyoxyethylene ether and sodium octadecyl sulfate, or PO-EO block copolymers, act as surfactants, promoting the uniform spreading of silane coupling agents and film-forming agents on the fiber surface and enhancing interfacial contact. Third, polyquaternary ammonium salts or ammonium chloride act as antistatic agents, preventing fiber agglomeration during processing and improving its dispersibility; organosilicon lubricants act as lubricants, reducing inter-fiber friction, protecting coating integrity, and improving processing performance. Together, they reduce fiber friction, electrostatic agglomeration, and breakage during mixing and construction, ensuring uniform fiber dispersion in asphalt concrete. Organic amines or ammonia water act as pH adjusters, providing a stable hydrolytic environment for the silane coupling agent, preventing its self-polymerization failure, and maintaining system stability. After curing, the above components form a dense, flexible, highly adhesive, alkali-resistant, and antistatic composite film layer, which not only protects the fibers from alkaline erosion inside the asphalt concrete, but also significantly improves the interfacial bonding strength and long-term durability between the fibers and the asphalt.

[0077] As an optional embodiment, the preparation method of the wetting agent includes: first, adding the pH adjuster and silane coupling agent to a portion of deionized water and stirring evenly; then adding the film-forming agent 1, film-forming agent 2 and polyvinyl acetate, stirring for 15-20 minutes, for example, 15 minutes, 18 minutes or 20 minutes; then adding the antistatic agent, lubricant, surfactant and the remaining deionized water, continuing to stir for 15-20 minutes, for example, 15 minutes, 18 minutes or 20 minutes; and then ultrasonically vibrating for 20-30 minutes, for example, 20 minutes, 25 minutes or 30 minutes; wherein, the pH value of the wetting agent is 7-8.

[0078] The preparation method of this invention ensures that the silane coupling agent is fully hydrolyzed and stable at a pH of 7-8, and then uniformly mixed with film-forming agents, etc., and finally ultrasonically processed to obtain a highly homogeneous and stable sizing agent emulsion. This guarantees the stable performance of each batch of sizing agent, thereby ensuring the reliability of the fiber treatment effect.

[0079] In a second aspect, the present invention provides a modified basalt fiber, which is prepared by the preparation method described in the first aspect.

[0080] As an alternative embodiment, the modified basalt fiber surface has, from the inside out, a roughened etching layer formed by silicon tetrafluoride etching, a titanium dioxide or zirconium dioxide nanocoating deposited by radio frequency magnetron sputtering and annealed, and an organic composite film layer formed by curing the wetting agent.

[0081] The modified basalt fiber of this invention possesses a specific composite structure (etched layer + TiO2 or ZrO2 coating + organic film layer). These three layers each perform their respective functions while synergistically enhancing each other: the roughening layer increases specific surface area and mechanical interlocking; the TiO2 or ZrO2 nanolayer provides a chemically inert barrier and establishes chemical bonds with the fiber and wetting agent respectively; the organic film layer provides final protection and functionalization. These structural features are the fundamental reason why the fiber achieves excellent properties (high interfacial adhesion and durability).

[0082] Thirdly, the application of a modified basalt fiber as described in the second aspect in asphalt concrete.

[0083] As an optional implementation, the modified basalt fiber is added to the asphalt concrete in a chopped form, with a fiber length of 6 to 12 mm, for example, 6 mm, 8 mm, 9 mm, 10 mm or 12 mm, and the dosage in the asphalt concrete is 0.2% to 0.5% of the total mass of the asphalt mixture, for example, 0.2%, 0.25%, 0.3%, 0.35%, 0.4% or 0.5%.

[0084] This invention, by limiting the fiber morphology (chopped), length, and dosage range, has found a balance between achieving optimal bridging and reinforcement effects in asphalt concrete while ensuring workability and economy. This gives the technical solution of this invention clear and repeatable engineering guidance value.

[0085] The present invention will now be described in further detail with reference to specific embodiments and comparative examples.

[0086] Example 1 This embodiment provides a method for preparing modified basalt fibers, the specific steps of which are as follows: S1: Surface etching process 100g of commercially available basalt fiber (13-15μm in diameter) was placed in a tubular reactor, and silicon tetrafluoride (SiF4) gas was introduced at a flow rate of 120 mL / min. Etching was performed at 135℃ for 50 min, resulting in etched basalt fiber with a roughened surface. The etched fiber was then rinsed three times with deionized water to remove residual reactants and acidic substances such as hydrofluoric acid (HF) and fluorosilicic acid (H2SiF6). After washing, the fiber was dried at 80℃ for later use.

[0087] S2: Surface sputtering coating treatment The etched and dried basalt fibers were used as a substrate and fixed on the sample stage of an RF magnetron sputtering apparatus. Titanium dioxide (TiO2) was used as the target material. The sputtering power was set to 180 W and the sputtering time to 45 min, depositing a titanium dioxide nano-coating on the fiber surface. After sputtering, the sample was placed in a muffle furnace and annealed at 550 °C for 1.5 h to crystallize the titanium dioxide coating, obtaining surface-coated basalt fibers. The thickness of the titanium dioxide nano-coating was measured to be approximately 250 nm.

[0088] S3: Preparation of wetting agent Accurately weigh the following components by weight percentage to prepare a total of 1000g of wetting agent emulsion: Film-forming agent 1 (epoxy resin emulsion, solid content approximately 48wt%): 50g; Film-forming agent 2 (acrylate emulsion, solid content approximately 30wt%): 30g; Polyvinyl acetate: 60g; Surfactant (polypropylene-polyethylene block copolymer): 3g; Silane coupling agent (KH560): 5g; pH adjuster (ammonia water, 25% mass concentration): 20g; Antistatic agent (ammonium chloride): 3g; Organosilicon lubricant (polysiloxane Dow XIAMETER™ PMX-200 series): 2g; Deionized water: 827g.

[0089] The preparation process is as follows: First, ammonia water (20g) and silane coupling agent KH560 (5g) were added to a portion of deionized water (about 200g) and stirred evenly. Then, epoxy resin emulsion (50g), acrylate emulsion (30g) and polyvinyl acetate (60g) were added and stirred for 18 minutes. Then, ammonium chloride (3g), polysiloxane (2g), polypropylene oxide-ethylene oxide block copolymer (3g) and the remaining deionized water (627g) were added and stirred for another 18 minutes. Finally, the mixture was ultrasonically vibrated for 25 minutes to obtain a uniform and stable wetting agent emulsion with a pH value controlled at around 7.5.

[0090] S4: Immersion Treatment The surface-coated basalt fibers obtained in step S2 were immersed in the aforementioned sizing agent, ensuring complete sizing. After 12 hours of immersion, the fibers were removed and excess droplets were drained. Subsequently, the fibers were placed in an oven and dried and cured at 120°C for 12 hours, allowing the sizing agent to form a dense and flexible organic composite film on the fiber surface, ultimately yielding the modified basalt fibers.

[0091] This embodiment utilizes a three-step composite process of "etching-sputtering-wetting" to produce basalt fibers. The surface of these fibers sequentially exhibits a micro-nano-scale roughened etched layer, a titanium dioxide nano-coating, and a functionalized organic composite film. While maintaining the inherent high strength of basalt fibers, this significantly improves interfacial adhesion, alkali resistance, and durability with the asphalt matrix. When these fibers are chopped (9 mm in length) and incorporated into asphalt concrete at 0.35% of the total asphalt mixture mass, they significantly improve key performance indicators of asphalt concrete (durability under freeze-thaw conditions, asphalt exudation rate during construction, low-temperature flexibility, and high-temperature stability). Specific enhancement effects are shown in Table 1.

[0092] Example 2 This embodiment provides another method for preparing modified basalt fibers, the specific steps of which are as follows: S1: Surface etching process 150g of commercially available basalt fiber (fiber diameter 13~15μm) was placed in a tubular reactor. Silicon tetrafluoride (SiF4) gas was introduced into the reactor at a flow rate of 100 mL / min. Etching was performed at 130℃ for 60 min, resulting in etched basalt fiber with a roughened surface. The etched fiber was then rinsed twice with deionized water to remove residual reactants and acidic substances such as hydrofluoric acid (HF) and fluorosilicic acid (H2SiF6). After washing, the fiber was dried at 80℃ for later use.

[0093] S2: Surface sputtering coating treatment The etched and dried basalt fibers were used as a substrate and fixed on the sample stage of an RF magnetron sputtering apparatus. Titanium dioxide (TiO2) was used as the target material. The sputtering power was set to 160 W and the sputtering time to 50 min, depositing a titanium dioxide nano-coating on the fiber surface. After sputtering, the sample was placed in a muffle furnace and annealed at 520℃ for 1.5 h to crystallize the titanium dioxide coating, obtaining surface-coated basalt fibers. The thickness of the titanium dioxide nano-coating was measured to be approximately 230 nm.

[0094] S3: Preparation of wetting agent Accurately weigh the following components by weight percentage to prepare a total of 1000g of wetting agent emulsion: Film-forming agent 1 (epoxy resin emulsion, solid content approximately 45wt%): 40g; Film-forming agent 2 (acrylate emulsion, solid content approximately 28wt%): 40g; Polyvinyl acetate: 70g; Surfactant (a mixture of fatty alcohol polyoxyethylene ether and sodium octadecyl sulfate in a mass ratio of 1:2): 5g; Silane coupling agent (KH550): 8g; pH adjuster (ammonia water, mass concentration 28%): 15g; Antistatic agent (dodecyl dimethyl benzyl ammonium chloride): 3.5g; Silicone lubricant (polysiloxane Dow XIAMETER™ PMX-200 series): 3g; Deionized water: 815.5g.

[0095] The preparation process is as follows: First, ammonia water (15g) and silane coupling agent KH550 (8g) were added to a portion of deionized water (about 200g) and stirred evenly. Then, epoxy resin emulsion (40g), acrylate emulsion (40g) and polyvinyl acetate (70g) were added and stirred for another 20 minutes. Next, dodecyl dimethyl benzyl ammonium chloride (3.5g), polysiloxane (3g), a mixture of fatty alcohol polyoxyethylene ether and sodium octadecyl sulfate (5g) and the remaining deionized water (615.5g) were added and stirred for another 15 minutes. Finally, the mixture was ultrasonically vibrated for 30 minutes to obtain a uniform and stable wetting agent emulsion with a pH value controlled at around 7.8.

[0096] S4: Immersion Treatment All the surface-coated basalt fibers obtained in S2 were immersed in the prepared sizing agent to ensure complete sizing. After immersion for 12 hours, the fibers were removed and excess droplets were drained. The fibers were then placed in an oven and dried and cured at 110°C for 14 hours to allow the sizing agent to form a dense and flexible organic composite film on the fiber surface, thus obtaining the modified basalt fibers.

[0097] The fibers obtained in this embodiment are chopped (8 mm in length) and added to asphalt concrete at 0.25% of the total mass of the asphalt mixture. This can also significantly improve the key performance indicators of asphalt concrete (durability under freeze-thaw conditions, asphalt exudation rate during construction, low-temperature flexibility and high-temperature stability). For specific enhancement effects, please refer to Table 1.

[0098] Example 3 This embodiment provides another method for preparing modified basalt fibers, the specific steps of which are as follows: S1: Surface etching process 200g of commercially available basalt fiber (fiber diameter 13~15μm) was placed in a tubular reactor. Silicon tetrafluoride (SiF4) gas was introduced into the reactor at a flow rate of 140 mL / min. Etching was performed at 140℃ for 40 min, resulting in etched basalt fiber with a roughened surface. The etched fiber was then rinsed twice with deionized water to remove residual reactants and acidic substances such as hydrofluoric acid (HF) and fluorosilicic acid (H2SiF6). After washing, the fiber was dried at 80℃ for later use.

[0099] S2: Surface sputtering coating treatment The etched and dried basalt fibers were used as a substrate and fixed on the sample stage of an RF magnetron sputtering apparatus. Titanium dioxide (TiO2) was used as the target. The sputtering power was set to 200 W and the sputtering time to 30 min, depositing a titanium dioxide nano-coating on the fiber surface. After sputtering, the sample was placed in a muffle furnace and annealed at 600℃ for 1.5 h to crystallize the titanium dioxide coating, obtaining surface-coated basalt fibers. The thickness of the titanium dioxide nano-coating was measured to be approximately 300 nm.

[0100] S3: Preparation of wetting agent Accurately weigh the following components by weight percentage to prepare a total of 1000g of wetting agent emulsion: Film-forming agent 1 (epoxy resin emulsion, solid content approximately 40wt%): 30g; Film-forming agent 2 (acrylate emulsion, solid content approximately 35wt%): 50g; Polyvinyl acetate: 80g; Surfactant (polypropylene-polyethylene block copolymer): 1g; Silane coupling agent (KH570): 2g; pH adjuster (ammonia water, 30% concentration): 10g; Antistatic agent (ammonium chloride): 4g; Silicone lubricant (polysiloxane Dow XIAMETER™ PMX-200 series): 5g; Deionized water: 818g.

[0101] The preparation process is as follows: First, ammonia water (10g) and silane coupling agent KH570 (2g) were added to a portion of deionized water (about 200g) and stirred evenly. Then, epoxy resin emulsion (30g), acrylate emulsion (50g) and polyvinyl acetate (80g) were added and stirred for 15 minutes. Then, ammonium chloride (4g), polysiloxane (5g), polypropylene oxide-ethylene oxide block copolymer (1g) and the remaining deionized water (618g) were added and stirred for another 20 minutes. Finally, the mixture was ultrasonically vibrated for 20 minutes to obtain a uniform and stable wetting agent emulsion with a pH value controlled at about 7.2.

[0102] S4: Immersion Treatment All the surface-coated basalt fibers obtained in S2 were immersed in the prepared sizing agent to ensure complete sizing. After 12 hours of immersion, the fibers were removed and excess droplets were drained. The fibers were then placed in an oven and dried and cured at 150°C for 10 hours to allow the sizing agent to form a dense and flexible organic composite film on the fiber surface, thus obtaining the modified basalt fibers.

[0103] The fibers obtained in this embodiment were chopped (12 mm in length) and added to asphalt concrete at 0.5% of the total mass of the asphalt mixture. Tests showed that this could significantly improve the key performance indicators of asphalt concrete (durability under freeze-thaw conditions, asphalt exudation rate during construction, low-temperature flexibility and high-temperature stability). The specific enhancement effect is shown in Table 1.

[0104] Example 4 This embodiment provides another method for processing basalt fibers. The difference from Embodiment 1 is that the etching time in step S1 of Embodiment 1 is extended from 50 min to 100 min, while the parameters and dosage of all other steps (S2 surface sputtering coating treatment, S3 wetting agent preparation, and S4 wetting treatment) are completely consistent with those of Embodiment 1.

[0105] Example 5 This embodiment provides another method for preparing modified basalt fibers. The difference between Example 5 and Example 1 is that the weight percentage of each component in the sizing agent (step S3) was adjusted. The specific steps are as follows: S3: Preparation of wetting agent Accurately weigh the following components by weight percentage to prepare a total of 1000g of wetting agent emulsion: Film-forming agent 1 (epoxy resin emulsion, solid content approximately 48wt%): 20g (2%); Film-forming agent 2 (acrylate emulsion, solid content approximately 30wt%): 20g (2%); Polyvinyl acetate: 80g (8%); Surfactant (polypropylene-polyethylene block copolymer): 6g (0.6%); Silane coupling agent (KH560): 15g (1.5%); pH adjuster (ammonia water, mass concentration 25%): 20g (2%); Antistatic agent (ammonium chloride): 3g (0.3%); Silicone lubricant (polysiloxane Dow XIAMETER™ PMX-200 series): 2g (0.2%); Deionized water: 834g (balance).

[0106] The preparation process is the same as in Example 1: First, ammonia water (20g) and silane coupling agent KH560 (15g) are added to a portion of deionized water (about 200g) and stirred evenly; then epoxy resin emulsion (20g), acrylate emulsion (20g) and polyvinyl acetate (80g) are added, and stirring is continued for 18 min; then ammonium chloride (3g), polysiloxane (2g), polypropylene oxide-ethylene oxide block copolymer (6g) and the remaining deionized water (634g) are added, and stirring is continued for 18 min; finally, the mixture is ultrasonically vibrated for 25 min to obtain a uniform wetting agent emulsion with a pH value of about 7.5.

[0107] Comparative Example 1 This comparative example provides a method for processing basalt fibers, for comparison with the embodiments of the present invention. The difference from Example 1 is that this comparative example completely omits the surface etching treatment (S1) and surface sputtering coating treatment (S2) steps, and only performs the same wetting treatment (S3) on the original basalt fibers as in Example 1.

[0108] Comparative Example 2 This comparative example provides a method for processing basalt fibers, for comparison with the embodiments of the present invention. The difference from Example 1 is that this comparative example completely omits the surface etching treatment (S1) step, and only performs the same surface sputtering coating treatment (S2) and wetting treatment (S3) on the original basalt fibers as in Example 1.

[0109] Comparative Example 3 This comparative example provides a method for processing basalt fibers, for comparison with the embodiments of the present invention. The difference from Example 1 is that this comparative example completely omits the surface sputtering coating treatment (S2) step, and only performs the same surface etching treatment (S1) and wetting treatment (S3) on the original basalt fibers as in Example 1.

[0110] Comparative Example 4 This comparative example provides a method for processing basalt fibers for comparison with the embodiments of the present invention. The difference from Example 1 is that a conventional sizing agent formulation is used instead of the sizing agent in Example 1. The sizing agent's composition by weight percentage is: 9% polyurethane emulsion, 6% polyvinyl acetate, 0.5% silane coupling agent KH550, 2% potassium citrate, 0.5% lithium nitrate, 0.4% plant polyene phenol polyoxyethylene ether, and the balance being deionized water. The total amount of sizing agent prepared is 1000g, and the specific preparation process is the same as step S3 of Example 1, and the impregnation treatment is carried out under the same conditions (immersion for 12 hours, curing at 120°C for 12 hours). Except for the sizing agent formulation, the remaining preparation steps (including S1 etching treatment, S2 sputtering coating treatment, and fiber doping, etc.) are consistent with Example 1.

[0111] Comparative Example 5 This comparative example provides a method for processing basalt fibers, for comparison with the embodiments of the present invention. The difference from Example 1 is that the silicon tetrafluoride gas etching in step S1 of Example 1 is replaced by hydrochloric acid solution etching, while the parameters and doping amounts of all other steps (S2 surface sputtering coating treatment, S3 wetting agent preparation, and S4 wetting treatment) are completely consistent with those of Example 1.

[0112] The specific steps are as follows: S1: Surface etching treatment (hydrochloric acid etching) 100g of commercially available basalt fiber (fiber diameter 13-15 μm) was placed in an acid-resistant reaction vessel. A 35% hydrochloric acid (HCl) solution was added, with a liquid-to-solid ratio (mL:g) controlled at 10:1. The mixture was stirred and etched in a constant-temperature water bath at 60℃ for 50 min. After treatment, the acid solution was discarded, and the etched fiber was rinsed repeatedly with deionized water five times until the washing solution was neutral (pH≈7) to thoroughly remove residual chloride ions and reaction products from the fiber surface. After rinsing, the fiber was dried at 80℃ for later use.

[0113] Performance testing To verify the comprehensive performance of the modified basalt fiber-reinforced asphalt concrete provided by this invention, the relevant properties of basalt fiber-reinforced asphalt concrete were tested in accordance with the "Basalt Fiber Asphalt Mixture for Road Use" (GB / T 45019-2024) and the "Test Procedures for Asphalt and Asphalt Mixtures for Highway Engineering" (JTG 3410-2025).

[0114] 1) Freeze-thaw splitting tensile strength ratio: This index is used to evaluate the resistance of asphalt mixtures to water damage after undergoing freeze-thaw cycles. Asphalt mixture specimens are subjected to freeze-thaw cycles and no freeze-thaw cycles, and their splitting tensile strength is measured. The ratio (%) between the two is calculated. The higher the ratio, the better the durability of the material in a freeze-thaw environment, and the less likely it is to be damaged by water intrusion and frost heave.

[0115] 2) Schellenberg Segregation Rate: This rate is used to evaluate the degree of asphalt separation during high-temperature storage or transportation of asphalt mixtures. The asphalt mixture is left to stand at a certain temperature for a period of time (e.g., 185±2℃, 60 min), and the percentage of separated asphalt mass is measured. A lower segregation rate indicates better adhesion between the asphalt and aggregates, reducing the likelihood of asphalt loss during construction and contributing to the maintenance of the mixture's uniformity and stability.

[0116] 3) Kentaburg Fragmentation Loss: This measure evaluates the degree of aggregate detachment from asphalt mixtures during construction or use due to external forces (such as compaction or traffic loads). It simulates mechanical forces during construction or use and determines the percentage of detached aggregate mass relative to the total mass. A lower fragmentation loss indicates stronger cohesion in the mixture, making it less prone to loosening and spalling, and resulting in better durability.

[0117] 4) Low-temperature bending test: Used to evaluate the crack resistance of asphalt mixtures under low-temperature conditions. A bending test is performed on beam specimens at low temperatures (e.g., -37℃ to -21℃), and the maximum strain value (µε, micro-strain) at failure is measured. The larger the failure strain value, the more flexible the material is at low temperatures, and the stronger its crack resistance.

[0118] 5) Rutting Test: Used to evaluate the resistance of asphalt mixtures to permanent deformation under high temperature (usually >30℃) and repeated loading. It simulates repeated wheel rolling on the road surface, measuring the change in rutting depth per unit time (or after a certain number of rolling cycles), commonly expressed as "moving stability," with units of "cycles / mm." Higher moving stability indicates better high-temperature stability and stronger resistance to rutting.

[0119] The asphalt concrete in Examples 1-5 and Comparative Examples 1-5 incorporating modified basalt fibers was systematically tested, and the test results are shown in Table 1.

[0120] Table 1

[0121] As can be seen from the performance test data in Table 1, the basalt fiber (Examples 1-5) prepared by the three-step composite modification process of "chemical etching-physical sputtering-organic impregnation" of the present invention significantly outperforms the comparative examples in all key road performance aspects of the asphalt concrete.

[0122] Examples 1, 2, and 3 employed a complete modification process, and their performance indicators were significantly superior to all comparative examples. Example 3 demonstrated the most outstanding performance, achieving a freeze-thaw splitting strength ratio of 95%, a Schellenberg leakage rate as low as 0.2%, a Kentenberg scattering loss of 10%, a low-temperature flexural failure strain of 5000µE, and a rutting test stability of up to 8000 cycles / mm. This fully demonstrates the effectiveness of constructing a composite structure of "rough etched layer - inorganic coating - organic functional film": the etched layer provides mechanical anchoring points, the TiO2 / ZrO2 coating provides chemical stability and bonding sites, and the organic film layer provides final protection and interfacial bridging. The synergistic effect of these three elements enhances the physical interlocking, chemical bonding, and durable protection capabilities of the fiber-asphalt interface, thereby significantly improving the key performance indicators of asphalt concrete (durability under freeze-thaw conditions, asphalt leakage rate during construction, low-temperature flexibility, and high-temperature stability). Although the process parameters or wetting agent formulations were partially adjusted in Examples 4 and 5, their performance was still significantly better than that of the comparative example, indicating that the three-step composite modification system has a certain degree of process tolerance and formulation flexibility.

[0123] Example 4 extended the etching time from 50 min to 100 min. Its freeze-thaw splitting strength ratio (92%) and rutting stability (7500 times / mm) were slightly higher than Example 1, but its Kentenberg scattering loss (11%) was slightly worse. This indicates that moderately extending the etching time can increase surface roughness, but excessive etching may affect the film quality of the wetting agent. Example 5 adjusted the ratio of film-forming agent to silane coupling agent in the wetting agent. All its properties were slightly lower than in Example 1, indicating that the proportions of each component of the wetting agent need to be maintained within a suitable range to ensure the flexibility, adhesion, and durability of the film.

[0124] Comparative Example 1, which only underwent impregnation treatment, showed the lowest performance across all categories, indicating that a single impregnation treatment cannot fundamentally improve the bonding strength and durability of the fiber-asphalt interface. Comparative Example 2, which omitted etching and only performed sputtering and impregnation, showed slightly better performance than Comparative Example 1, but still significantly lower than Example 1, indicating that the lack of surface roughening structure weakens the mechanical anchoring effect of the coating. Comparative Example 3, which omitted sputtering and only performed etching and impregnation, also showed low performance, indicating that the lack of a titanium dioxide / zirconia coating cannot effectively isolate alkaline erosion and provide chemical bonding sites. Comparative Example 4, using a conventional wetting agent, showed performance comparable to Comparative Example 3, indicating that basalt fibers with specific surface structures obtained through etching and sputtering are difficult to match with ordinary wetting agents and cannot achieve a synergistic reinforcing effect. Comparative Example 5, which replaced silicon tetrafluoride vapor phase etching with hydrochloric acid solution etching, showed performance comparable to Example 2, but still lower than Examples 1 and 3, indicating that hydrochloric acid etching can also improve surface roughness to some extent. Vapor phase etching (as in Examples 1 and 3) still exhibits advantages in overall performance, which may be related to the more uniform surface morphology formed by vapor phase etching and its smaller impact on the strength of the fiber body.

[0125] In summary, this invention, through a three-step composite modification of "chemical etching, physical sputtering, and organic impregnation," can significantly improve the key performance indicators of asphalt concrete (durability under freeze-thaw conditions, asphalt exudation rate during construction, low-temperature flexibility, and high-temperature stability), thereby achieving the effects of suppressing cracks and rutting and extending service life.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing modified basalt fiber, characterized in that, Includes the following steps: S1: Surface etching treatment: Basalt fiber is placed in a reactor and silicon tetrafluoride gas is introduced for etching treatment to obtain etched basalt fiber. S2: Surface sputtering coating treatment: Using the etched basalt fiber as a substrate and titanium dioxide or zirconium dioxide as a target, radio frequency magnetron sputtering treatment is performed, followed by annealing treatment to obtain basalt fiber with surface coating. S3: Immersion treatment: Immerse the surface-coated basalt fiber in an impregnating agent, remove it, and then dry and cure it to obtain modified basalt fiber.

2. The preparation method according to claim 1, characterized in that, In step S1, the etching temperature is 130℃~140℃, and the processing time is 40~60min; and / or, The flow rate of the silicon tetrafluoride gas is 100–150 mL / min; and / or, Step S1 is followed by rinsing the etched basalt fibers with deionized water 2 to 3 times.

3. The preparation method according to claim 1, characterized in that, In step S2, the power of the radio frequency magnetron sputtering is 150–200 W, and the sputtering time is 30–60 min; and / or, The annealing treatment is performed at a temperature of 500℃~600℃ for a time of 1~2 hours; and / or, After the radio frequency magnetron sputtering and annealing treatment, the thickness of the titanium dioxide or zirconium dioxide nanocoating formed on the surface of the etched basalt fiber is 200–300 nm, preferably 220–250 nm; and / or, In step S3, the immersion time for the soaking treatment is 12-15 hours; and / or, The drying and curing temperature is 100℃~150℃, and the time is 10~15h; and / or, The mass ratio of basalt fiber raw material to the impregnating agent is 1:(5-10).

4. The preparation method according to claim 1, characterized in that, In step S3, the wetting agent comprises the following components by weight percentage: 3%–6% film-forming agent 1, 2%–5% film-forming agent 2, 5%–8% polyvinyl acetate, 0.1%–1% surfactant, 0.2%–1.2% silane coupling agent, 1%–2% pH adjuster, 0.2%–0.4% antistatic agent, 0.2%–0.5% lubricant, and the balance being deionized water; preferably, the solid content of film-forming agent 1 is 40–50 wt%; the solid content of film-forming agent 2 is 25–35 wt%; and the mass concentration of pH adjuster is 25–30%.

5. The preparation method according to claim 4, characterized in that, The film-forming agent 1 is an epoxy resin emulsion; and / or, The film-forming agent 2 is an acrylic emulsion; and / or, The silane coupling agent is an aminosilane coupling agent or an epoxy-based silane coupling agent; preferably one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane; and / or The pH adjuster is an organic amine or ammonia; and / or, The antistatic agent is a polyquaternary ammonium salt or ammonium chloride; and / or, The surfactant is a mixture of fatty alcohol polyoxyethylene ether and sodium octadecyl sulfate or a polypropylene-polyethylene block copolymer; and / or, The lubricant is an organosilicon lubricant; Preferably, the polyquaternary ammonium salt is selected from dodecyl dimethyl benzyl ammonium chloride, octadecyl trimethyl ammonium chloride, or hexadecyl trimethyl ammonium bromide.

6. The preparation method according to claim 4 or 5, characterized in that, The preparation method of the wetting agent includes: first, adding the pH adjuster and silane coupling agent to a portion of deionized water and stirring evenly; then adding the film-forming agent 1, film-forming agent 2 and polyvinyl acetate, stirring for 15-20 minutes; then adding the antistatic agent, lubricant, surfactant and the remaining deionized water, continuing to stir for 15-20 minutes, and then ultrasonically vibrating for 20-30 minutes; wherein, the pH value of the wetting agent is 7-8.

7. A modified basalt fiber, characterized in that, It is prepared by any one of claims 1-6.

8. The modified basalt fiber according to claim 7, characterized in that, The modified basalt fiber surface has, from the inside out, a roughened etching layer formed by silicon tetrafluoride etching, a titanium dioxide or zirconium dioxide nano-coating deposited by radio frequency magnetron sputtering and annealed, and an organic composite film layer formed by curing the wetting agent.

9. The application of a modified basalt fiber as described in claim 7 or 8 in asphalt concrete.

10. The application according to claim 9, characterized in that, The modified basalt fiber is added to the asphalt concrete in a short-cut form, with a fiber length of 6 to 12 mm, and the dosage in the asphalt concrete is 0.2% to 0.5% of the total mass of the asphalt mixture.

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