A kind of MOF modified mineral fiber additive and its preparation method and application

Abstract

The present application relates to the technical field of road engineering materials, in particular to a MOF modified mineral fiber additive and its preparation method and application. The additive comprises a mineral fiber substrate which is sequentially subjected to acid washing treatment and surface functionalization modification, and a MOF which is loaded on the surface of the mineral fiber substrate by in-situ growth. The preparation method comprises the following steps: ultrasonic cleaning and acid washing pretreatment of the mineral fiber, surface modification by a silane coupling agent, and in-situ growth of a MOF functional layer on the surface of the fiber. The fiber utilizes the regular channels and adjustable surface chemistry of the MOF to realize selective adsorption and inhibition of VOCs in the asphalt construction stage and pollutants in the vehicle exhaust in the road service process; at the same time, the surface polar groups and the rough and porous layer of the MOF synergistically improve the adhesion and dispersion stability of the fiber and the asphalt interface, build a uniform three-dimensional reinforcing network, and improve the Marshall stability, water stability and dynamic stability of the asphalt mixture, and improve the anti-rutting, anti-cracking and anti-fatigue performance.

Description

Technical Field

[0001] This invention relates to the field of road engineering materials technology, specifically to a MOF-modified mineral fiber additive, its preparation method, and its application. Background Technology

[0002] Asphalt and its modified asphalt are widely used in road surface and base courses due to their excellent adhesion and workability. With increasing traffic load and service life requirements, on the one hand, pavement structures need better resistance to rutting, cracking, and fatigue; on the other hand, asphalt releases volatile organic compounds (VOCs) and odorous gases during high-temperature processes such as mixing, transportation, and paving, raising concerns about their impact on the construction environment and human health. Therefore, how to improve road performance while maintaining environmental friendliness has become a comprehensive problem that needs to be addressed in asphalt material modification.

[0003] In existing technologies, mineral fibers such as basalt fiber and diabase fiber have been widely used in asphalt or asphalt mixtures as crack-resistant and toughening materials. They improve the crack resistance and fatigue resistance of the structure by forming fiber bridging and bonding effects. However, these mineral fibers are mostly directly incorporated in a physical manner. The fiber surface is mainly composed of inert metal oxides or silicon-oxygen skeletons. The interface polarity is fixed and there is a lack of controllable functional groups. The compatibility with the hydrocarbon-based asphalt matrix in terms of wettability and adhesion is limited. Problems such as fiber agglomeration, uneven dispersion, and insufficient interfacial adhesion are prone to occur. The three-dimensional toughening network is difficult to form fully, and its crack-resistant and toughening effect is not effectively exerted. Nor is any VOCs-related function endowed to the fiber.

[0004] Some existing patents modify the interface of asphalt or fibers by adding compatibilizers, resins, or coupling agents, primarily aiming to improve mechanical properties and bonding effects. However, these patents still treat mineral fibers as a single mechanical reinforcing phase, neglecting the control of construction odors and VOC emissions. Regarding odor control, existing technologies using plant extracts, odor masking agents, or inorganic adsorbents have significant drawbacks: the former can only mask odors but cannot eliminate VOCs, while the latter easily aggregates in the asphalt system, forming stress concentration points and severely impairing the material's low-temperature performance and stability with the asphalt. More importantly, these odor-neutralizing or adsorbing components are independent of the mineral fiber reinforcement system, requiring separate dosage and process design, resulting in complex formulations. Structural reinforcement and VOC control are handled by different additives, and an integrated technical solution simultaneously achieving "crack resistance and toughening + odor-neutralizing adsorption" on the same mineral fiber carrier has not yet been formed.

[0005] Furthermore, with the development of porous functional materials, metal-organic frameworks (MOFs), as a new type of material with large specific surface area and tunable pore structure, have been used as functional adsorption phases in fields such as gas adsorption and air purification. Related patents mostly revolve around filter media or fixed-bed adsorption structures. In existing publicly available technologies, MOFs are typically used as independent powders or coatings, primarily focusing on their adsorption performance itself. They do not address the structural and interface design characteristics of high-temperature, high-viscosity, and high-shear systems like asphalt, nor do they organically combine MOFs with mineral fibers such as basalt fibers and diabase fibers through surface chemistry, enabling the mineral fibers to simultaneously provide crack resistance and toughening while also possessing stable porous adsorption capabilities.

[0006] Therefore, there is an urgent need to develop a new type of functional additive for asphalt mixtures that can improve the stability of the system structure, enhance the overall road performance, and reduce odor emissions in order to meet the needs of high-quality and green applications. Summary of the Invention

[0007] In view of this, the present invention provides a MOF-modified mineral fiber additive, its preparation method, and its application. By introducing polar active groups such as -NH2 and -COOH onto the surface of mineral fibers and constructing a MOF porous functional layer with regular channels and tunable chemical sites in situ on the fiber surface, the fibers simultaneously acquire the ability to adsorb pollutants such as VOCs during construction and service, and significantly improve their interfacial bonding and dispersibility with asphalt, thereby constructing a stable three-dimensional reinforcing network in asphalt mixtures. The present invention achieves a synergistic effect of odor reduction and emission reduction with improved rutting resistance, crack resistance, and fatigue resistance, and is applicable to various asphalt systems, with the advantages of strong process compatibility and dual improvement in environmental and mechanical properties.

[0008] The technical solution of this invention is implemented as follows:

[0009] In a first aspect, the present invention provides a MOF-modified mineral fiber additive, comprising a mineral fiber matrix that has been sequentially acid-washed and surface-functionalized, and a MOF loaded on the surface of the mineral fiber matrix by in-situ growth.

[0010] Preferably, the MOF is composed of a metal salt and an organic ligand; the metal salt includes one or more of chromium salt, zinc salt, copper salt or zirconium salt; the mineral fiber includes one or more of basalt fiber, diabase fiber, glass fiber or rock wool fiber.

[0011] More preferably, the mineral fiber is a short-cut fiber with a diameter of 5~25μm and a length of 3~20 mm.

[0012] More preferably, the organic ligand includes one or more of 2-methylimidazole, terephthalic acid, or trimesic acid.

[0013] Preferably, the MOF loading is 9.7% to 31.8% based on the mass of the mineral fiber matrix.

[0014] In a second aspect, the present invention provides a method for preparing MOF-modified mineral fiber additives as described in the first aspect, comprising the following steps:

[0015] S1. Pre-treatment of mineral fibers by acid washing;

[0016] S2. Surface modification of pickled mineral fibers using surface functionalizing agents;

[0017] S3. Place the surface-modified mineral fibers in a reaction solution containing metal salts, organic ligands and mineralizing agents to carry out in-situ reaction.

[0018] Preferably, in step S1, the acid washing pretreatment is carried out in an acid solution with a pH value of 3 to 4; the acid solution includes one or more of hydrochloric acid, acetic acid, and citric acid.

[0019] Specifically, when the pH of the acid solution is too high, the acid washing effect is insufficient, making it difficult to effectively remove inorganic impurities and inert oxides from the fiber surface. Consequently, the number of hydroxyl groups and active sites on the fiber surface available for subsequent silane coupling and in-situ MOF growth is limited, which is not conducive to the uniform loading of MOF. When the pH of the acid solution is too low, the acidity is too strong, which can easily cause excessive etching on the fiber surface, and even cause fiber structural defects or a decrease in mechanical properties. At the same time, it may lead to uneven distribution of surface active sites, affecting the stable binding of MOF on the fiber surface.

[0020] More preferably, in step S1, the temperature of the pickling pretreatment is 25~60℃, and the pickling time is 2~24h.

[0021] Preferably, in step S2, the surface functionalizing agent includes one or more of γ-aminopropyltriethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, carboxyethyltrimethoxysilane, or carboxypropyltrimethoxysilane.

[0022] More preferably, in step S2, the surface functionalizing agent is dissolved in water or ethanol to obtain a surface functionalizing agent solution with a mass fraction of 0.5% to 5%; the modification method includes impregnation, the impregnation temperature is 20 to 60°C, and the impregnation time is 0.5 to 2 hours.

[0023] Preferably, in step S3, the molar ratio of the metal cation, organic ligand, and mineralizing agent in the metal salt is 1:(1-4):(0.24-4.8); the mineralizing agent includes one or more of hydrofluoric acid or acetic acid.

[0024] Specifically, when the amount of organic ligands is too low or the content of mineralizers is insufficient, the nucleation rate of MOFs is slow, the crystal growth is insufficient, and MOFs with low crystallinity or underdeveloped pore structure are easily formed, resulting in a low specific surface area. When the amount of organic ligands or mineralizers is too high, MOF crystals are prone to overgrowth or agglomeration, and the pore structure may collapse or become blocked, which is also not conducive to further improving the specific surface area.

[0025] More preferably, in step S3, the reaction temperature is 25~300℃ and the reaction time is 1~48h; specifically, when preparing zinc-based MOF, the mineralizing agent is acetic acid, and the reaction is carried out at 25~120℃ for 1~24h; when preparing chromium-based MOF, the mineralizing agent is hydrofluoric acid, and the reaction is carried out at 150~300℃ for 8~48h.

[0026] Specifically, the temperature and time control in step S3 is to match the heterogeneous nucleation and in-situ growth requirements of MOFs with different metal systems on the fiber surface.

[0027] For zinc-based MOF systems, under the condition of using acetic acid as a mineralizer, in a relatively mild reaction environment of 25~120℃ and 1~24h, zinc ions and organic ligands can preferentially coordinate and nucleate on the fiber surface, inhibiting the rapid generation of free crystals in the solution, thereby promoting the uniform in-situ growth of MOFs on the fiber surface.

[0028] For chromium-based MOF systems, due to the slow coordination kinetics of chromium ions and the high requirements for crystal structure stability, when hydrofluoric acid is used as a mineralizing agent, the metal-ligand coordination process needs to be effectively activated at 150–300 °C for 8–48 h to allow MOFs to gradually nucleate, grow, and form a stable porous structure on the fiber surface. If the reaction temperature is too low or the reaction time is insufficient, MOFs will have difficulty forming continuous and stable crystal nuclei on the fiber surface, easily leading to low loading or insufficient bonding force. If the reaction temperature is too high or the reaction time is too long, MOF crystals are prone to rapid growth or aggregation in the solution, which is not conducive to their directional in-situ growth on the fiber surface.

[0029] Preferably, before step S1, a cleaning step of the mineral fiber is included, specifically including: placing the mineral fiber in an organic solvent for ultrasonic cleaning, followed by drying; the organic solvent includes one or more of acetone and ethanol; the ultrasonic cleaning time is 10~60 min, the cleaning temperature is 20~40℃; the drying temperature is 100~120℃, and the drying time is 0.5~3 h.

[0030] Thirdly, the present invention provides an application of the MOF-modified mineral fiber additive as described in the first aspect in asphalt mixtures.

[0031] Fourthly, the present invention provides a MOF-modified mineral fiber asphalt concrete, which comprises the MOF-modified mineral fiber additive as described in the first aspect; the dosage of the additive is 0.2% to 0.6% of the total mass of the asphalt mixture.

[0032] Fifthly, the present invention provides a method for preparing MOF-modified mineral fiber asphalt concrete as described in the fourth aspect, comprising the following steps:

[0033] A1. Heat the asphalt, and heat the coarse aggregate, fine aggregate and MOF modified mineral fiber additive separately;

[0034] A2. After mixing the coarse aggregate and fine aggregate evenly, add asphalt and mix. Finally, add MOF modified mineral fiber additive and mix until uniform, thus obtaining the asphalt concrete.

[0035] Preferably, in step A1, the asphalt is heated to 160~190℃, and the coarse aggregate, fine aggregate and MOF modified mineral fiber additive are heated to 175~195℃ respectively.

[0036] Compared with the prior art, the advantages of the present invention are as follows:

[0037] (1) The MOF on the surface of the modified fiber described in this invention has a regular pore structure and controllable surface chemical properties. Its pore windows and surface functional groups can specifically adsorb typical VOCs molecules released during asphalt construction. During the road service stage, this structure is also suitable for capturing small molecule polar pollutants (such as oxygen-containing volatiles) and some aromatics in vehicle exhaust, thereby achieving environmental benefits throughout the entire life cycle from construction to service.

[0038] (2) In this invention, the amorphous phase on the fiber surface is moderately etched by acid washing, which increases the surface roughness and exposes more metal hydroxyl sites. Subsequently, the silane coupling agent is used to form strong covalent bonds with these hydroxyl groups through hydrolysis-condensation reaction, thereby constructing an organic interface layer containing amino or carboxyl groups on the fiber surface. This interface not only strongly anchors the MOF precursor through coordination, promoting its heterogeneous nucleation and growth, but also serves as a flexible transition layer to alleviate the internal stress that may be caused by the difference in thermal expansion coefficients between MOF and fiber matrix, thereby improving the stability of the functional layer in the hot-mix asphalt process.

[0039] (3) In this invention, MOF is grown in situ on mineral fibers at the micron scale. The three-dimensional network formed by the fibers in the asphalt mixture is used as a physical support, so that the functional sites of MOF can be spatially separated and immobilized, effectively avoiding aggregation and loss, and ensuring functional durability.

[0040] (4) The polar functional groups (-NH2, -COOH) introduced by the surface modification of the mineral fibers described in this invention significantly improve the wettability and interfacial adhesion of the hydrophobic asphalt to the fibers. The stronger interfacial bonding enables the fibers to more effectively transfer and disperse stress, thereby fully exerting their bridging and crack-preventing effects, and jointly enhancing the structural integrity and durability of the mixture. Therefore, while achieving environmental benefits, it also synergistically improves the mechanical properties of the material, such as high-temperature rutting resistance, low-temperature crack resistance, and fatigue resistance.

[0041] (5) The ultrasonic cleaning, pickling, silanization and solvothermal reaction involved in the preparation method of the present invention are all mature and controllable unit operations in the field of materials. The process flow is clear and there are no special requirements for equipment. The raw materials used (such as mineral fibers, silane coupling agents, metal salts, etc.) are all common industrial products with controllable costs. The overall process route is highly compatible with the existing asphalt mixing process and has a solid foundation for large-scale production and engineering promotion. Detailed Implementation

[0042] The MOF-modified mineral fiber additive prepared by the technical solution of this invention has comprehensive effects such as interface enhancement, stable nucleation, selective adsorption of odorous VOCs, and improved dispersibility. When applied to asphalt mixtures, it can significantly suppress VOCs emissions during the construction stage, improve the odor environment, and simultaneously enhance the rutting resistance, water damage resistance, and overall structural stability of asphalt mixtures.

[0043] The core mechanism of this invention is as follows: The acid leaching step moderately etches the metal oxide phases on the surface of mineral fibers such as basalt and diabase. On the one hand, this removes surface inert impurities and powders, exposing more surface metal hydroxyl active sites. On the other hand, it generates a certain micro-rough structure and allows for the dissolution of a small amount of metal ions, providing necessary coordination centers for the heterogeneous nucleation of MOFs. Subsequently, the fibers are immersed in a solution of aminosilane coupling agent and / or carboxylsilane coupling agent. Both aminosilane and carboxylsilane first undergo hydrolysis to generate -Si-OH, which then undergoes a dehydration condensation reaction with the metal hydroxyl groups on the fiber surface to form stable Si-OM covalent bonds, thereby constructing a strong organosilicon molecular layer on the fiber surface.

[0044] Furthermore, the outermost layer of this organosilicon molecular layer exposes polar functional groups such as amino or carboxyl groups. These functional groups can form initial adsorption sites with metal ions or organic ligands through coordination, hydrogen bonding, and electrostatic interactions, significantly reducing the heterogeneous nucleation energy barrier. This allows MOFs to preferentially nucleate on the fiber surface and gradually grow in situ into a continuous porous functional layer, rather than nucleating spontaneously in solution and then depositing as powder. The spatial three-dimensional structure and stable anchoring sites provided by the silane layer also effectively inhibit MOF aggregation, resulting in a uniform, dense, and robust growth morphology.

[0045] Ultimately, the active metal hydroxyl sites formed by acid washing covalently bond with the silane coupling agent, giving the fiber surface stable polar functional groups. These groups can coordinate and adsorb with metal ions and organic ligands in the MOF precursor, guiding the MOF to preferentially nucleate on the fiber surface and maintain uniform growth, thus firmly adhering to the fiber surface and maintaining the integrity of its porous structure. The presence of MOF endows the fiber with significant gas adsorption capacity, while the silane-modified fiber has enhanced adhesion to the asphalt interface, making the fiber more uniformly dispersed and structurally more stable in the mixture. This simultaneously improves the odor environment during construction and enhances the mechanical and durability properties of the asphalt mixture.

[0046] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0047] In this document, the terms “containing,” “comprising,” or “including” are open-ended expressions, meaning they include the contents specified in this invention but do not exclude other aspects.

[0048] In this document, the terms “optional,” “optionally,” or “optional” generally refer to an event or condition that may, but may not, occur, and the description includes both cases in which the event or condition occurs and cases in which the event or condition does not occur.

[0049] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0050] In the following embodiments, basalt is used as the aggregate; wherein the coarse aggregate has a particle size of 2.36~16mm and the fine aggregate has a particle size of <2.36mm.

[0051] In the following embodiments, the asphalt used includes SBS modified asphalt, rubber modified asphalt, and base asphalt; the SBS modified asphalt has a penetration of 52 mm, a softening point of 67°C, and a ductility greater than 20 cm; the rubber modified asphalt has a penetration of 48 mm, a softening point of 74°C, and a ductility greater than 10 cm; and the base asphalt has a penetration of 71 mm, a softening point of 49°C, and a ductility greater than 100 cm.

[0052] In the following examples, the selected mineral fibers are short-cut basalt fibers with a diameter of 16 μm and a length of 6 mm.

[0053] Unless otherwise specified, all materials and equipment used in this invention are commercially available products in the field; γ-aminopropyltriethoxysilane (chemically pure) and carboxyethyltrimethoxysilane (chemically pure) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; chromium nitrate nonahydrate (Cr(NO3)3·9H2O, chemically pure) and zinc nitrate hexahydrate (Zn(NO3)2·6H2O, chemically pure) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; hydrofluoric acid (40 wt.%, chemically pure) and acetic acid (chemically pure) were purchased from Sinopharm Chemical Reagent Co., Ltd.; terephthalic acid (chemically pure) was purchased from Sigma-Aldrich Shanghai Trading Co., Ltd.; and 2-methylimidazole (chemically pure) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0054] Example 1

[0055] This embodiment provides a MOF-modified mineral fiber additive, its preparation method, and its application, including the following steps:

[0056] (1) Take 100g of short-cut basalt fiber as the mineral fiber matrix, add 1L of a 1:1 mixture of acetone and ethanol, ultrasonically clean at 25℃ for 30min, filter out the fiber after cleaning, and dry at 110℃ for 1h to obtain pretreated basalt fiber.

[0057] (2) Add the pretreated basalt fiber obtained in step (1) into a hydrochloric acid solution with pH=3, control the liquid-solid ratio to be 10:1, soak at 40℃ for 6 hours for acid washing treatment, wash with deionized water after acid washing until the pH of the washing solution is close to neutral, filter and dry at 100℃ for 1 hour to obtain surface pretreated basalt fiber.

[0058] (3) Add the surface-pretreated basalt fiber obtained in step (2) to a γ-aminopropyltriethoxysilane ethanol solution with a mass fraction of 2 wt.%, control the liquid-solid ratio to be 15:1, and immerse it at 40°C for 2 h to allow the silane to undergo hydrolysis and condensation reaction on the fiber surface and introduce -NH2 functional groups; after immersion, take out the fiber, rinse it with a small amount of ethanol, and then dry it at 100°C for 1 h to obtain surface-activated basalt fiber;

[0059] (4) Weigh 35g of the surface-activated basalt fiber prepared in step (3), prepare deionized water as the reaction solvent at a solid-liquid ratio of 1:10, add it to 350g of deionized water, dissolve 28g of Cr(NO3)3·9H2O and 17.4g of terephthalic acid in the water, then add the surface-activated basalt fiber, add 3.75mL of hydrofluoric acid, and carry out a hydrothermal reaction at 220℃ for 8h. At this time, Cr 3+ The molar ratio of terephthalic acid to hydrofluoric acid was 1:1.5:1.2, which enabled MIL-101(Cr) to grow in situ on the fiber surface. After the reaction was completed, the fibers were cooled, separated, and then washed and purified successively with deionized water, N,N-dimethylformamide (DMF), and ethanol to obtain the washed fibers.

[0060] (5) The washed fibers obtained in step (4) are dried at 100°C for 12 hours and then crushed and loosened to obtain basalt fiber additives with MIL-101(Cr) type MOF surface loading.

[0061] Thermogravimetric analysis (TG) results showed a significant mass loss step around 450℃, corresponding to the decomposition of the MIL-101(Cr) skeleton. Calculations based on the percentage mass decrease at this weight loss step indicate that the loading of MIL-101(Cr) on the basalt fiber matrix in Example 1 was approximately 22.4 wt.%; this demonstrates that the in-situ hydrothermal synthesis process successfully grew and loaded a corresponding proportion of MOF material on the fiber surface.

[0062] Furthermore, the basalt fiber additive with surface loading of MIL-101(Cr) prepared in this embodiment was added to different types of asphalt systems at 0.4 wt.% of the asphalt concrete. Specifically, a rubber asphalt system with a rubber powder content of 20%, an SBS modified asphalt system, and a base asphalt system were selected. All three asphalt systems were prepared according to the SMA-13 ​​aggregate gradation in the "Technical Specification for Construction of Highway Asphalt Pavement" (JTGF40-2004), and the median gradation value was taken as the design mix proportion. The specific operation is as follows:

[0063] 1) Heat the asphalt to 175℃, and heat the coarse aggregate, fine aggregate and MOF modified mineral fiber additive to 185℃ respectively;

[0064] 2) After mixing the coarse aggregate and fine aggregate evenly, add asphalt and mix for 60 seconds. Then add the chromium-based MOF modified basalt fiber prepared in this example and continue mixing for 40 seconds to prepare three kinds of MOF modified mineral fiber asphalt mixtures. They are respectively named Sample 1-1 (chromium-based MOF modified basalt fiber / rubber asphalt mixture), Sample 1-2 (chromium-based MOF modified basalt fiber / SBS modified asphalt mixture), and Sample 1-3 (chromium-based MOF modified basalt fiber / matrix asphalt mixture).

[0065] The performance test results of the MOF-modified mineral fiber asphalt concrete obtained in Example 1 are shown in Table 1. The VOCs concentration test method was as follows: 200 g of the obtained asphalt was heated to the construction temperature and maintained at this temperature for 30 minutes to allow the fumes in the asphalt to completely evaporate. To improve the uniformity of the heating process, the asphalt was stirred at a rate of 1000 rpm throughout the process. Subsequently, the gas emitted from the asphalt was collected by an air pump at a pumping speed of 0.5 L / min for 30 seconds and pumped into a carbon adsorption tube for subsequent thermal desorption / purge collection gas chromatography-mass spectrometry (GC-MS, Agilent 7890B-5977B). Large particulate pollutants were filtered out to prevent clogging of the adsorption tube.

[0066] For the test methods of Marshall stability, freeze-thaw splitting strength ratio, residual stability and dynamic stability, please refer to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG 3410-2025).

[0067] Table 1 Performance test results of MOF-modified mineral fiber asphalt concrete obtained in Example 1

[0068]

[0069] Example 2

[0070] This embodiment provides a MOF-modified mineral fiber additive, its preparation method, and its application, including the following steps:

[0071] (1) Take 100g of short-cut basalt fiber as the mineral fiber matrix, add 1L of a 1:1 mixture of acetone and ethanol, ultrasonically clean at 20℃ for 10min, filter out the fiber after cleaning, and dry at 100℃ for 0.5h to obtain pretreated basalt fiber.

[0072] (2) Add the pretreated basalt fiber obtained in step (1) into an acetic acid solution with pH=4, control the liquid-solid ratio to be 10:1, soak at 60℃ for 2h for acid washing treatment, wash with deionized water after acid washing until the pH of the washing solution is close to neutral, filter and dry at 100℃ for 1h to obtain surface pretreated basalt fiber.

[0073] (3) The surface-pretreated basalt fibers obtained in step (2) are added to a γ-aminopropyltriethoxysilane ethanol solution with a mass fraction of 0.5 wt.% and the liquid-solid ratio is controlled at 15:1. The solution is immersed at 20°C for 2 hours to allow the silane to undergo hydrolysis and condensation reaction on the fiber surface and introduce -NH2 functional groups. After the immersion is completed, the fiber is taken out, rinsed with a small amount of ethanol, and then dried at 80°C for 2 hours to obtain surface-activated basalt fibers.

[0074] (4) Weigh 30g of the surface-activated basalt fiber prepared in step (3), and use deionized water as the reaction solvent at a solid-liquid ratio of 1:10. Add the solution to 300g of deionized water. Dissolve 10.0g of Cr(NO3)3·9H2O and 16.6g of terephthalic acid in water, then add the surface-activated basalt fiber. After adding 5.35mL of hydrofluoric acid, carry out a hydrothermal reaction at 220℃ for 8h. At this time, Cr 3+ The molar ratio of terephthalic acid to hydrofluoric acid was 1:4:4.8, which enabled MIL-101(Cr) to grow in situ on the fiber surface. After the reaction was completed, the fibers were cooled, separated, and then washed and purified successively with deionized water, DMF and ethanol to obtain the washed fibers.

[0075] (5) The washed fibers obtained in step (4) are dried at 100°C for 12 hours and then crushed and loosened to obtain basalt fiber additives with MIL-101(Cr) type MOF surface loading.

[0076] Based on the thermogravimetric analysis (TG) results, the percentage decrease in mass of the weight loss step indicates that the loading of MIL-101(Cr) on the basalt fiber matrix in Example 2 is approximately 9.7 wt.%, indicating that a low proportion of MOF material was grown and loaded in situ on the fiber surface.

[0077] Furthermore, the basalt fiber additive with surface loading of MIL-101(Cr) prepared in this embodiment was added to different types of asphalt systems at 0.6 wt.% of the asphalt concrete. Specifically, a rubber asphalt system with a rubber powder content of 20%, an SBS modified asphalt system, and a base asphalt system were selected. All three asphalt systems were prepared according to the SMA-13 ​​aggregate gradation in the "Technical Specification for Construction of Highway Asphalt Pavement" (JTGF40-2004), and the median gradation value was taken as the design mix proportion. The specific operation is as follows:

[0078] 1) Heat the asphalt to 160℃, and heat the coarse aggregate, fine aggregate and MOF modified mineral fiber additive to 175℃ respectively;

[0079] 2) After mixing the coarse aggregate and fine aggregate evenly, add asphalt and mix for 60 seconds. Then add the chromium-based MOF modified basalt fiber prepared in this example and continue mixing for 40 seconds to prepare three kinds of MOF modified mineral fiber asphalt mixtures. They are respectively named Sample 2-1 (chromium-based MOF low-concentration modified basalt fiber / rubber asphalt mixture), Sample 2-2 (chromium-based MOF low-concentration modified basalt fiber / SBS modified asphalt mixture), and Sample 2-3 (chromium-based MOF low-concentration modified basalt fiber / matrix asphalt mixture).

[0080] The performance test results of the chromium-based MOF low-concentration modified mineral fiber asphalt concrete obtained in Example 2 are shown in Table 2.

[0081] Table 2 Performance test of chromium-based MOF low-concentration modified mineral fiber asphalt concrete obtained in Example 2

[0082]

[0083] Example 3

[0084] This embodiment provides a MOF-modified mineral fiber additive, its preparation method, and its application, including the following steps:

[0085] (1) Take 100g of short-cut basalt fiber as the mineral fiber matrix, add 1L of a 1:1 mixture of acetone and ethanol, and ultrasonically clean it at 40℃ for 60min. After cleaning, filter out the fiber and dry it at 120℃ for 3h to obtain pretreated basalt fiber.

[0086] (2) Add the pretreated basalt fiber obtained in step (1) into a hydrochloric acid solution with pH=3, control the liquid-solid ratio to be 10:1, soak at 25℃ for 24h for acid washing treatment, wash with deionized water until the pH of the washing solution is close to neutral after acid washing, filter and dry at 120℃ for 3h to obtain surface pretreated basalt fiber.

[0087] (3) The surface-pretreated basalt fibers obtained in step (2) are added to a γ-aminopropyltriethoxysilane ethanol solution with a mass fraction of 5 wt.%, and the liquid-solid ratio is controlled at 15:1. The solution is immersed at 60°C for 0.5 h to allow the silane to undergo hydrolysis and condensation reaction on the fiber surface and introduce -NH2 functional groups. After the immersion is completed, the fiber is taken out, rinsed with a small amount of ethanol, and then dried at 110°C for 1 h to obtain surface-activated basalt fibers.

[0088] (4) Weigh 40g of the surface-activated basalt fiber prepared in step (3), and add it to 400g of deionized water as the reaction solvent at a solid-liquid ratio of 1:10. Dissolve 40g of Cr(NO3)3·9H2O and 17.2g of terephthalic acid in water, then add the surface-activated basalt fiber, add 1.08mL of hydrofluoric acid, and carry out a hydrothermal reaction at 220℃ for 8h. At this time, Cr 3+ The molar ratio of terephthalic acid to hydrofluoric acid was 1:1:0.24, which enabled MIL-101(Cr) to grow in situ on the fiber surface. After the reaction was completed, the fibers were cooled, separated, and then washed and purified with deionized water, DMF and ethanol in sequence to obtain the washed fibers.

[0089] (5) The washed fibers obtained in step (4) are dried at 100 °C for 12 h, and after being crushed and loosened, basalt fiber additives with surface-loaded MIL-101(Cr) type MOF are obtained.

[0090] Based on the thermogravimetric analysis (TG) results, the percentage decrease in mass of the weight loss step indicates that the loading of MIL-101(Cr) on the basalt fiber matrix in Example 3 was approximately 31.8 wt.%, indicating that a high proportion of MOF material was grown and loaded in situ on the fiber surface.

[0091] Furthermore, the basalt fiber additive with surface loading of MIL-101(Cr) prepared in this embodiment was added to different types of asphalt systems at 0.2 wt.% of the asphalt concrete. Specifically, a rubber asphalt system with a rubber powder content of 20%, an SBS modified asphalt system, and a base asphalt system were selected. All three asphalt systems were prepared according to the SMA-13 ​​aggregate gradation in the "Technical Specification for Construction of Highway Asphalt Pavement" (JTGF40-2004), and the median gradation value was taken as the design mix proportion. The specific operation is as follows:

[0092] 1) Heat the asphalt to 190℃, and heat the coarse aggregate, fine aggregate and MOF modified mineral fiber additive to 195℃ respectively;

[0093] 2) After mixing the coarse aggregate and fine aggregate evenly, add asphalt and mix for 60 seconds. Then add the chromium-based MOF modified basalt fiber prepared in this example and continue mixing for 40 seconds to prepare three kinds of MOF modified mineral fiber asphalt mixtures. They are respectively named Sample 3-1 (chromium-based MOF high-concentration modified basalt fiber / rubber asphalt mixture), Sample 3-2 (chromium-based MOF high-concentration modified basalt fiber / SBS modified asphalt mixture), and Sample 3-3 (chromium-based MOF high-concentration modified basalt fiber / matrix asphalt mixture).

[0094] The performance test results of the chromium-based MOF high-concentration modified mineral fiber asphalt concrete obtained in Example 3 are shown in Table 3.

[0095] Table 3 Performance test of chromium-based MOF high-concentration modified mineral fiber asphalt concrete obtained in Example 3

[0096]

[0097] Example 4

[0098] The difference between this embodiment and Embodiment 1 is that:

[0099] In step (3), γ-aminopropyltriethoxysilane is replaced with carboxyethyltrimethoxysilane;

[0100] Step (4): Weigh 35g of the surface-activated basalt fiber prepared in step (3), and prepare a water / methanol mixed solvent with a solid-liquid ratio of 1:10 as the reaction medium, wherein the volume ratio of water to methanol is 1:1. Add the mixed solvent to 350g of the mixed solvent. Dissolve 10.4g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and 11.5g of 2-methylimidazole in the water / methanol mixed solvent respectively. Then mix the two solutions and add them to the surface-activated basalt fiber. Under stirring conditions, add 2g of acetic acid as a mineralizing agent to make the Zn in the reaction system... 2+ The molar ratio of 2-methylimidazole to acetic acid was 1:4:1. The reaction system was then transferred to a 1L stainless steel high-pressure reactor lined with polytetrafluoroethylene and subjected to a hydrothermal reaction at 120℃ for 4 hours. This allowed ZIF-8 to undergo heterogeneous nucleation and in-situ growth on the surface of basalt fibers, forming a uniformly distributed zinc-based MOF functional layer. After the reaction was completed, the mixture was naturally cooled to room temperature, separated, and then washed and purified sequentially with deionized water, DMF, and anhydrous ethanol. Finally, it was dried at 80℃ to obtain the ZIF-8 modified basalt fiber additive.

[0101] The remaining steps are the same as in Example 1; three MOF-modified mineral fiber additives were prepared respectively; they are referred to as Sample 4-1 (zinc-based MOF-modified basalt fiber / rubber asphalt mixture), Sample 4-2 (zinc-based MOF-modified basalt fiber / SBS modified asphalt mixture), and Sample 4-3 (zinc-based MOF-modified basalt fiber / matrix asphalt mixture).

[0102] The performance test results of the zinc-based MOF modified mineral fiber asphalt concrete obtained in Example 4 are shown in Table 4.

[0103] Table 4 Performance test results of zinc-based MOF-modified mineral fiber asphalt concrete obtained in Example 4

[0104]

[0105] Comparative Example 1

[0106] The difference between this comparative example and Example 1 is that this comparative example uses pretreated basalt fibers that have not been acid-washed, activated with silane, and loaded with MOF. That is, steps (2), (3), and (4) are omitted, and the pretreated basalt fibers are directly used to prepare asphalt mixtures according to the same fiber content and asphalt mixing process as in Example 1.

[0107] Three types of ordinary basalt fiber asphalt mixtures were prepared and designated as Comparative Sample 1-1 (basalt fiber / rubber asphalt mixture), Comparative Sample 1-2 (basalt fiber / SBS modified asphalt mixture), and Comparative Sample 1-3 (basalt fiber / matrix asphalt mixture).

[0108] Comparative Example 2

[0109] The difference between this comparative example and Example 1 is that commercial MIL-101 was directly added to the asphalt mixture as a neutralizing agent, without mineral fibers; the dosage was 0.4% of the asphalt mixture mass.

[0110] Three types of MOF / asphalt mixtures were prepared and designated as Comparative Sample 2-1 (MOF / rubber asphalt mixture), Comparative Sample 2-2 (MOF / SBS modified asphalt mixture), and Comparative Sample 2-3 (MOF / base asphalt mixture).

[0111] Comparative Example 3

[0112] The difference between this comparative example and Example 1 is that this comparative example uses the pre-treated basalt fiber in step (1) to directly physically mix MOF, that is, (2), (3) and (4) are cancelled; commercial MIL-101 and the pre-treated basalt fiber in step (1) are directly mixed evenly at a mass ratio of 2:8 to obtain a physically blended MOF / basalt fiber mixture, and then the mixture is added to asphalt concrete at the same total fiber content as in Example 1;

[0113] Three types of physically blended MOF / basalt fiber asphalt mixtures were prepared and designated as Comparative Sample 3-1 (MOF / basalt fiber / rubber asphalt mixture), Comparative Sample 3-2 (MOF / basalt fiber / SBS modified asphalt mixture), and Comparative Sample 3-3 (MOF / basalt fiber / matrix asphalt mixture).

[0114] Comparative Example 4

[0115] The difference between this comparative example and Example 1 is that this comparative example uses surface-activated basalt fiber physically mixed with MOF that has been acid-washed and activated with silane in step (3). That is, commercial MIL-101 and the surface-activated basalt fiber obtained in step (3) are directly mixed evenly at a mass ratio of 2:8 without MOF in-situ growth reaction, to obtain a physically blended MOF / modified basalt fiber mixture. The mixture is then added to asphalt concrete at the same total fiber content as in Example 1.

[0116] Three types of physically blended MOF / modified basalt fiber asphalt mixtures were prepared and designated as Comparative Sample 4-1 (MOF / modified basalt fiber / rubber asphalt mixture), Comparative Sample 4-2 (MOF / modified basalt fiber / SBS modified asphalt mixture), and Comparative Sample 4-3 (MOF / modified basalt fiber / matrix asphalt mixture).

[0117] Comparative Example 5

[0118] The difference between this comparative example and Example 1 is that this comparative example uses pretreated basalt fibers that have not been acid-washed, have not been activated with silane, and have only grown MOF in situ. That is, steps (2) and (3) are omitted, and the pretreated basalt fibers are directly grown in situ with MIL-101(Cr) according to the method described in step (4); ordinary MOF / basalt fiber additive is obtained; and asphalt mixture is prepared according to the same fiber content and asphalt mixing process as in Example 1.

[0119] Based on the thermogravimetric analysis (TG) results, the percentage decrease in mass at the weight loss steps indicates that the loading of MIL-101(Cr) on the basalt fiber matrix in Comparative Example 5 is approximately 5.4 wt.%.

[0120] Three types of ordinary MOF / basalt fiber asphalt mixtures were prepared and designated as Comparative Sample 5-1 (ordinary MOF / basalt fiber / rubber asphalt mixture), Comparative Sample 5-2 (ordinary MOF / basalt fiber / SBS modified asphalt mixture), and Comparative Sample 5-3 (ordinary MOF / basalt fiber / matrix asphalt mixture).

[0121] Comparative Example 6

[0122] The difference between this comparative example and Example 1 is that conventional lignin fiber is used instead of the MOF modified mineral fiber of the present invention in this comparative example. The lignin fiber content, asphalt type and mixing process are the same as in Example 1. This is used to compare the differences between the fiber of the present invention and traditional organic fiber in terms of odor removal performance and road performance.

[0123] Three types of lignin fiber asphalt mixtures were prepared and designated as Comparative Sample 6-1 (lignin fiber / rubber asphalt mixture), Comparative Sample 6-2 (lignin fiber / SBS modified asphalt mixture), and Comparative Sample 6-3 (lignin fiber / matrix asphalt mixture).

[0124] Comparative Example 7

[0125] The difference between this comparative example and Example 1 is that only the pH of the hydrochloric acid solution in step (2) is 2; the rest is the same as in Example 1; MOF-modified basalt fiber additive is obtained.

[0126] The resulting asphalt mixtures were designated as Comparative Sample 7-1 (MOF-modified basalt fiber / rubber asphalt mixture), Comparative Sample 7-2 (MOF-modified basalt fiber / SBS-modified asphalt mixture), and Comparative Sample 7-3 (MOF-modified basalt fiber / matrix asphalt mixture).

[0127] Comparative Example 8

[0128] The difference between this comparative example and Example 1 is that only the mass fraction of γ-aminopropyltriethoxysilane in step (3) is increased to 8%; the rest are the same as in Example 1; MOF modified basalt fiber additive is obtained.

[0129] The resulting asphalt mixtures were designated as Comparative Sample 8-1 (MOF-modified basalt fiber / rubber asphalt mixture), Comparative Sample 8-2 (MOF-modified basalt fiber / SBS-modified asphalt mixture), and Comparative Sample 8-3 (MOF-modified basalt fiber / matrix asphalt mixture).

[0130] Comparative Example 9

[0131] The difference between this comparative example and Example 3 is that the loading of MOF on the mineral fiber is further increased; its step (4) is as follows: 40g of the surface-activated basalt fiber prepared in step (3) is weighed, and deionized water is prepared as the reaction solvent at a solid-liquid ratio of 1:10 and added to 400g of deionized water; 56g of Cr(NO3)3·9H2O and 24.1g of terephthalic acid are dissolved in water, and then the surface-activated basalt fiber is added. After adding 1.5mL of hydrofluoric acid, a hydrothermal reaction is carried out at 220℃ for 8h. At this time, Cr 3+ The molar ratio of terephthalic acid to hydrofluoric acid was 1:1:0.24, which enabled MIL-101(Cr) to grow in situ on the fiber surface. After the reaction was completed, the fibers were cooled, separated, and then washed and purified with deionized water, DMF and ethanol in sequence to obtain the washed fibers.

[0132] The remaining steps are exactly the same as in Example 3; MOF-modified basalt fiber additives are obtained.

[0133] Based on the thermogravimetric analysis (TG) results, the percentage decrease in mass at the weight loss step indicates that the loading of MIL-101(Cr) on the basalt fiber matrix in Comparative Example 9 is approximately 40.5 wt.%. Asphalt mixtures prepared in the same manner as in Example 3 are designated as Comparative Sample 9-1 (MOF ultra-high concentration modified basalt fiber / rubber asphalt mixture), Comparative Sample 9-2 (MOF ultra-high concentration modified basalt fiber / SBS modified asphalt mixture), and Comparative Sample 9-3 (MOF ultra-high concentration modified basalt fiber / matrix asphalt mixture).

[0134] First, the specific surface area of ​​the MOF-modified mineral fiber additives prepared in Examples 1-4, the commercial MIL-101 in Comparative Example 2, the MOF / basalt fiber mixture in Comparative Example 3, the MOF / modified basalt fiber mixture in Comparative Example 4, the ordinary MOF / basalt fiber additive in Comparative Example 5, and the MOF-modified mineral fiber additives (over-etched, over-silane modified, and high loading) in Comparative Examples 7-9 were tested respectively, and the results are shown in Table 5.

[0135] Table 5. Specific surface area of ​​additives in Examples 1-4 and Comparative Examples 1-9

[0136]

[0137] Meanwhile, the present invention will conduct performance tests on the asphalt concrete obtained in proportions 1 to 9, and the results are shown in Table 6.

[0138] Table 6. Performance test results of asphalt concrete in Comparative Examples 1-9

[0139]

[0140] The test results of Examples 1-3 show that the MOF-modified mineral fiber asphalt mixture of the present invention can significantly reduce VOCs concentration while simultaneously improving key road performance characteristics such as Marshall stability, freeze-thaw splitting strength ratio, residual stability, and dynamic stability. Example 1 represents the optimal mix ratio, with a significant reduction in VOCs concentration in all three asphalt systems, and the rubber asphalt system showing a reduction of up to 84.77%. Simultaneously, its dynamic stability is significantly higher than that of the comparative mixtures, indicating that the present invention has a synergistic amplification effect in terms of "odor reduction and emission reduction" and "structural enhancement."

[0141] Examples 2 and 3 also showed superior overall performance compared to the comparative examples, further verifying that within the ratio range defined by the present invention, MOF-modified mineral fibers can stably exert the dual effects of adsorption and emission reduction as well as mechanical enhancement.

[0142] Example 4 demonstrates that zinc-based MOF (ZIF-8) modification of mineral fibers can also play a significant role in asphalt systems. Although the specific surface area of ​​zinc-based MOF is generally lower than that of chromium-based MOF, the MOF functional layer structure formed on the fiber surface is complete and stable. In asphalt mixtures, it can still significantly improve mechanical properties such as Marshall stability, freeze-thaw splitting strength ratio, residual stability, and dynamic stability, with a reinforcing effect comparable to high specific surface area MOF systems. This result indicates that the technical effect of the present invention does not solely rely on the limiting specific surface area of ​​the MOF, but rather originates from the stable interface structure constructed by the in-situ growth of the MOF on the surface of the mineral fibers. By forming a strong bond with the fiber matrix, zinc-based MOF can effectively improve the dispersion stability and load-bearing efficiency of fibers in asphalt, thereby expanding the applicability of MOF types while ensuring mechanical reinforcement effects. This proves that the present invention has good versatility and engineering adaptability for MOF systems with different metal centers.

[0143] As shown in Comparative Example 1, the VOCs concentration of asphalt mixture using only untreated basalt fiber is not reduced significantly, the improvement in mechanical properties is limited, and the Marshall stability and dynamic stability are significantly lower than those in Example 1, indicating that it is difficult to achieve both odor reduction and reinforcement by simply physically incorporating mineral fibers.

[0144] As shown in Comparative Example 2, although adding MIL-101(Cr) powder directly to asphalt can reduce the VOCs concentration by about 70%, the strength and high-temperature stability of the mixture are significantly deteriorated due to the easy agglomeration and unstable dispersion of MOF in the asphalt. The overall road performance is lower than that of the embodiment of the present invention, indicating that "MOF alone" without a reasonable interface structure is insufficient to meet engineering requirements.

[0145] Comparative Example 3 shows that while physically mixing MIL-101(Cr) with basalt fiber can increase the specific surface area and reduce VOCs to some extent, the MOF is prone to detachment or secondary agglomeration during mixing and service due to the lack of in-situ growth and chemical bonding on the fiber surface. Consequently, its dynamic stability and freeze-thaw splitting strength ratio are still lower than those of Example 1. Furthermore, although the BET specific surface area of ​​the composite fiber in Comparative Example 3 is higher than that of the low-ratio Example 2, it is still lower than that of the optimal ratio Example 1, further demonstrating that the in-situ constructed continuous MOF functional layer is more conducive to the porous adsorption and reinforcement effects.

[0146] Comparative Example 4 shows that after acid washing and silane activation treatment of basalt fibers, physical blending with MIL-101(Cr) can improve the interfacial wettability and initial dispersion state between MOF and fibers to some extent. Compared with Comparative Example 3, which did not undergo surface activation, the MOF detachment and agglomeration phenomena are alleviated. Therefore, the dynamic stability and freeze-thaw splitting strength ratio of the resulting composite fiber in the asphalt system are slightly better than those of Comparative Example 3. However, since Comparative Example 4 also did not involve in-situ growth of MOF on the fiber surface, the relationship between MOF and fiber still mainly relies on physical adsorption, lacking a continuous and stable chemical bonding interface. Under high-temperature mixing and long-term service conditions, local detachment or migration is still inevitable, making it difficult to form a uniform and robust functional layer structure. Therefore, the mechanical properties and VOCs suppression effect of the asphalt mixture in Comparative Example 4 are still significantly lower than those in Example 1. Furthermore, the BET specific surface area of ​​the composite fiber obtained in Comparative Example 4 is basically the same as that in Comparative Example 3, indicating that simply relying on surface activation followed by physical mixing cannot significantly improve the effective exposed specific surface area of ​​MOF or its stable utilization efficiency; and its mechanical properties only show limited improvement, further illustrating that only by constructing a continuous, dense and stable MOF functional layer on the surface of mineral fibers through in-situ growth can the synergistic improvement of high specific surface area utilization and structural reinforcement performance be achieved simultaneously.

[0147] Comparative Example 5 shows that, due to the lack of hydroxyl groups and functional groups introduced through acid washing and silane activation on the fiber surface, MOFs mainly adhere to the fiber surface through weak physical adsorption, resulting in low interfacial bonding strength. During subsequent washing and use, some MOF particles are prone to peeling off, leading to a significantly lower BET specific surface area compared to the in-situ grown and interfacially stable MOF-modified fiber obtained in Example 1. When this MOF-modified basalt fiber was added to the asphalt system at the same dosage as in Example 1, the mechanical properties of the asphalt mixture, such as Marshall stability, freeze-thaw splitting strength ratio, and dynamic stability, were only slightly higher than those of the pure basalt fiber mixture without MOF addition, but significantly lower than those of the asphalt mixture prepared in Example 1. These results indicate that simply growing MOFs in situ without surface activation of the mineral fibers makes it difficult to obtain a stable and efficient MOF-loaded structure. The acid washing and silane activation steps play a crucial role in achieving a strong bond between MOFs and the fiber surface and maximizing their functionality. Secondly, by comparing Comparative Example 5 with Example 2, which had a lower loading, the influence of MOF loading on the performance of the composite material was further clarified, indicating that if too little MOF covers the fiber surface, its unique porous structure and active sites cannot fully act on the asphalt system.

[0148] As can be seen from Comparative Example 6, when conventional lignin fibers are used, the VOCs concentration is hardly reduced, and the Marshall stability, dynamic stability and other indicators are generally lower than those of the MOF modified mineral fibers of this invention, indicating that organic fibers are difficult to have both high temperature stability and odor adsorption capacity.

[0149] As shown in Comparative Example 7, lowering the pH of the pickling solution leads to excessive corrosion of the basalt fiber surface, destroying part of the silicon-oxygen skeleton and metal oxide structure, causing microcracks and even localized strength reduction on the fiber surface. This excessive pickling not only weakens the reinforcing effect of the fiber itself, but also leads to uneven nucleation and decreased adhesion during subsequent MOF in-situ growth, resulting in a lower BET specific surface area and interfacial stability of the obtained composite fiber compared to Example 1.

[0150] In Comparative Example 8, the excessive amount of silane coupling agent resulted in an overly thick organosilane coating layer on the fiber surface. This layer shielded the original inorganic active sites of the mineral fibers, inhibited the effective anchoring of metal ions to the fiber surface, and easily triggered silane self-condensation and local agglomeration, leading to a decrease in MOF nucleation density, pore blockage, and reduced specific surface area utilization. Under high-temperature asphalt mixing conditions, the thermal stability of this organic layer was insufficient, further weakening the synergistic reinforcement effect between fiber / MOF / asphalt.

[0151] The performance index of Comparative Example 9 was the lowest among all samples, indicating that more MOF is not necessarily better. Excessive MOF load may lead to pore blockage and structural densification due to excessive MOF layer thickness. In some cases, some MOF may even undergo pyrolysis or release volatile components under high-temperature mixing, thereby weakening the odor-neutralizing function. In addition, excessive MOF growth damages the fiber-asphalt interface structure: on the one hand, the excessively thick MOF layer is not firmly bonded to the fiber matrix and is prone to falling off during mixing and service, forming defect points; on the other hand, excessive MOF coverage hinders the direct bonding between the fiber and the asphalt, resulting in a decrease in stress transfer efficiency and damage to the overall mechanical properties.

[0152] In summary, through a systematic comparison of Examples 1-4 and Comparative Examples 1-9, it can be seen that the present invention, through acid washing and activation, silane coupling, and in-situ growth of MOFs on mineral fibers, constructs a composite structure on the fiber surface that combines porous adsorption and interface enhancement functions. This can significantly reduce VOC emissions and odor intensity during asphalt construction, while simultaneously improving the high-temperature stability, water damage resistance, and fatigue resistance of asphalt mixtures. The overall technical effect is significantly better than that of existing ordinary mineral fibers, lignin fibers, single MOF powders, and simple physical mixing schemes.

[0153] The embodiments described above are some, but not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preparing a MOF-modified mineral fiber additive, characterized in that, Includes the following steps: S1. Pre-treatment of mineral fibers by acid washing; S2. Surface modification of pickled mineral fibers using surface functionalizing agents; S3. Place the surface-modified mineral fibers in a reaction solution containing metal salts, organic ligands and mineralizing agents to carry out in-situ reaction; In step S1, the acid washing pretreatment is carried out in an acid solution with a pH of 3 to 4; the acid solution includes one or more of hydrochloric acid, acetic acid, and citric acid. In step S2, the surface functionalizing agent includes one or more of γ-aminopropyltriethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, carboxyethyltrimethoxysilane, or carboxypropyltrimethoxysilane; the surface functionalizing agent is dissolved in water or ethanol to obtain a surface functionalizing agent solution with a mass fraction of 0.5% to 5%. Based on the mass of the mineral fiber matrix, the loading of the MOF is 9.7% to 31.8%.

2. The preparation method according to claim 1, characterized in that, In step S3, the molar ratio of the metal cation, organic ligand and mineralizing agent in the metal salt is 1:(1-4):(0.24-4.8); the mineralizing agent includes one or more of hydrofluoric acid or acetic acid.

3. A MOF-modified mineral fiber additive obtained by the preparation method according to any one of claims 1 to 2, characterized in that, It includes a mineral fiber matrix that has been sequentially acid-washed and surface-functionalized, and an MOF loaded on the surface of the mineral fiber matrix by in-situ growth.

4. The MOF-modified mineral fiber additive according to claim 3, characterized in that, The MOF is composed of a metal salt and an organic ligand; the metal salt includes one or more of chromium salt, zinc salt, copper salt or zirconium salt; the mineral fiber includes one or more of basalt fiber, diabase fiber, glass fiber or rock wool fiber.

5. The application of the MOF-modified mineral fiber additive as described in any one of claims 3 to 4 in asphalt mixtures.

6. A MOF-modified mineral fiber asphalt concrete, characterized in that, It comprises MOF-modified mineral fiber additive as described in any one of claims 3 to 4; the amount of the additive is 0.2% to 0.6% of the total mass of the asphalt mixture.

7. A method for preparing MOF-modified mineral fiber asphalt concrete as described in claim 6, characterized in that, Includes the following steps: A1. Heat the asphalt, and heat the coarse aggregate, fine aggregate and MOF modified mineral fiber additive separately; A2. After mixing the coarse aggregate and fine aggregate evenly, add asphalt and mix. Finally, add MOF modified mineral fiber additive and mix until uniform, thus obtaining the asphalt concrete.

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