Preparation method and application of nanometer silica fiber reinforced emulsified asphalt basalt composite material

Abstract

The application provides a preparation method and application of a nano-silica fiber reinforced emulsified asphalt basalt composite material, and belongs to the technical field of road engineering materials.The preparation method comprises the following steps: adding nano fibers and an interfacial chemical modifier into a first part of water, stirring, and then performing ultrasonic dispersion treatment to obtain a uniform nano fiber dispersion liquid; mixing emulsified asphalt and a dispersion stabilizer, stirring until the dispersion stabilizer is completely dissolved, then adding the nano fiber dispersion liquid, mixing, and then performing shearing stirring to obtain a nano fiber modified emulsified asphalt matrix; performing drying treatment on aggregate, wherein the aggregate comprises coarse aggregate and fine aggregate; dry mixing the dried coarse aggregate and fine aggregate; then synchronously adding the nano fiber modified emulsified asphalt matrix and a second part of water for wet mixing in a stirring state to prepare the composite material.The application is used for realizing uniform dispersion of the nano fibers in the asphalt system and synergistically improving the comprehensive road performance of the asphalt composite material.

Description

Technical Field

[0001] This invention belongs to the field of road engineering materials technology, specifically relating to a preparation method and application of a nano-silica fiber reinforced emulsified asphalt basalt composite material. Background Technology

[0002] As the primary paving material in modern road engineering, asphalt mixtures directly affect the service life, driving safety, and comfort of the road surface. Under the combined influence of multiple factors such as vehicle load, environmental temperature and humidity cycles, and water erosion, traditional asphalt pavements often face early-stage defects such as cracking, rutting, spalling, and water damage, severely impacting their service performance and durability.

[0003] To improve the overall performance of asphalt pavements, the industry has developed various modification technologies. Among them, fiber reinforcement technology involves adding fiber materials to asphalt to improve its mechanical properties and durability, thereby extending the service life of the pavement. Currently reported fiber materials include lignin fiber, polyester fiber, glass fiber, and basalt fiber.

[0004] In existing technologies, Chinese patent documents with publication numbers CN108797256A and CN103774518A employ centimeter-sized glass fibers or basalt fibers, using specialized equipment for a continuous "spraying-cutting-covering" operation at road construction sites to achieve rapid paving. However, this method has objective limitations. First, centimeter-sized fibers are difficult to ensure uniform dispersion in asphalt during high-speed spraying, easily leading to local enrichment or loss, resulting in uneven reinforcement. Second, the fibers and asphalt only physically coat each other at the moment of spraying, resulting in low interfacial bonding strength. Under moisture erosion and temperature stress, debonding easily occurs, which not only limits the improvement of interlayer bond strength but also directly weakens the material's water stability and fatigue resistance. Third, longer fibers are difficult to effectively bridge microcracks at low temperatures, limiting the improvement in low-temperature crack resistance. At the same time, the weak interfacial bonding at high temperatures also results in insufficient constraint on asphalt flow deformation, limiting the improvement in high-temperature stability.

[0005] For example, Chinese patent document CN118791259A describes a process where aggregates, base asphalt, SBS-modified emulsified asphalt, mineral powder, cement, wear-resistant filler, and mixed fibers are heated and mixed evenly to form an asphalt mixture. This mixture is then evenly sprayed and spread onto a cleaned road surface. While this technology uses millimeter-sized chopped mixed fibers, which are mixed evenly before application, improving the uniformity of fiber distribution, the interfacial bonding between the mixed fibers and asphalt still relies primarily on physical adsorption and mechanical interlocking, resulting in limited interfacial bond strength. Under long-term dynamic water pressure, freeze-thaw cycles, and fatigue loading, the fiber-asphalt interface is prone to debonding and slippage, leading to stress transfer failure, a significant reduction in reinforcement effect, and difficulty in fully utilizing the theoretical strength of the fibers.

[0006] Therefore, there is an urgent need to develop a new reinforcement technology that can synergistically improve the water stability, high temperature stability, low temperature crack resistance and fatigue resistance of asphalt pavement materials, so as to meet the requirements of long service life and high reliability of asphalt pavement materials. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a method for preparing nano-silica fiber reinforced emulsified asphalt basalt composite material, which addresses the shortcomings of the prior art, so as to achieve uniform dispersion of nanofibers in the asphalt system and synergistically improve the comprehensive road performance of the asphalt composite material.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: In a first aspect, a method for preparing a nano-silica fiber-reinforced emulsified asphalt basalt composite material is provided, comprising the following steps: S1: Add nanofibers and interfacial chemical modifiers to the first part of water, stir, and then disperse by ultrasonic treatment to obtain a uniform nanofiber dispersion. S2: Mix emulsified asphalt with a dispersant and stabilizer, stir until the dispersant and stabilizer is completely dissolved, then add the nanofiber dispersion obtained in step S1, mix and then shear and stir to obtain nanofiber modified emulsified asphalt matrix. S3: The aggregate is dried, including coarse aggregate and fine aggregate. The dried coarse aggregate and fine aggregate are dry-mixed, and then the nanofiber modified emulsified asphalt matrix obtained in step S2 and the second part of water are added simultaneously under stirring to wet-mix the composite material.

[0009] Optionally, the nanofibers are nano-silica fibers with a diameter of 80-250 nm and a length of 10-60 μm, and the amount of the nanofibers is 0.2%-0.4% of the mass of the aggregate.

[0010] Optionally, the interface chemical modifier is selected from at least one of silane coupling agents and titanate coupling agents, and the amount of the interface chemical modifier is 0.01-0.02% of the aggregate mass; Among them, the silane coupling agent is selected from at least one of silane coupling agent KH-550, silane coupling agent KH-660 and silane coupling agent KH-570, and the titanate coupling agent is selected from phthalate coupling agent NDZ-101.

[0011] Optionally, the aggregate is at least one of basalt aggregate, limestone aggregate, and granite aggregate; The mass ratio of coarse aggregate to fine aggregate is 6:4, the particle size of coarse aggregate is 5-10mm, and the particle size of fine aggregate is 0-5mm.

[0012] Optionally, the amount of emulsified asphalt used is 15-20% of the mass of the aggregate.

[0013] Optionally, the dispersing stabilizer is selected from at least one of polyvinyl alcohol, sodium carboxymethyl cellulose and polyacrylamide, and the amount of the dispersing stabilizer is 0.06-0.12% of the aggregate mass.

[0014] Optionally, in step S1, the stirring time is more than 1 minute, the ultrasonic dispersion power is 250-350W, the time is 8-10 minutes, and the temperature is 20±2℃.

[0015] Optionally, in step S2, the stirring speed is 700-900 r / min, the time is more than 5 min, and the temperature is 20±2℃; the shearing stirring speed is 4500-5000 r / min, the time is 10-15 min, and the water bath is heated to 30-35℃ during shearing stirring.

[0016] Optionally, in step S2, during the shearing and stirring process, the machine should be stopped and observed every 3-5 minutes.

[0017] Optionally, in step S3, the drying temperature is 100-110℃ and the time is 1-3h.

[0018] Optionally, in step S3, the dry mixing speed is 100-150 r / min, and the time is more than 5 min.

[0019] Optionally, in step S3, the wet mixing speed is 150-200 r / min, the time is 5-10 min, and the temperature is 25-30℃.

[0020] Optionally, the amount of water used in the first part is 1.5-3.0% of the mass of the aggregate, and the amount of water used in the second part is 6-10% of the mass of the aggregate.

[0021] Secondly, an asphalt composite material prepared by the above method is provided.

[0022] Thirdly, the application of the aforementioned asphalt composite materials in road engineering is provided, for example, for paving high-grade road surface layers, stress-absorbing layers, or bridge deck pavement layers.

[0023] In recent years, the rise of nanotechnology has provided new ideas for the modification of asphalt pavement materials. Theoretically, nanofibers, due to their small size and huge specific surface area, can be more uniformly dispersed in the matrix and can more effectively play a role in preventing cracks and toughening them during the microcrack initiation stage. However, applying nanofibers to asphalt, a complex and viscous non-aqueous system, faces significant technical challenges: First, the dispersion problem: the extremely high specific surface area of ​​nanofibers results in huge surface energy, making them prone to severe agglomeration. Conventional mechanical stirring is almost ineffective in deagglomerating and uniformly distributing them in asphalt. Second, the interface problem: the interface effect is more significant at the nanoscale. Without effective chemical bonding, the huge interface area may become a bottleneck in performance.

[0024] To address these challenges, existing technologies have not yet provided systematic and effective solutions. For example, existing technologies mostly focus on the combination of macroscopic fiber types (such as the hybrid fibers in CN108797256A) or their compounding with specific asphalt (such as the SBS-modified emulsified asphalt in CN118791259A), but do not address the technical difficulties of fiber dispersion and interface modification at the nanoscale. While another type of technology (such as CN110894153A) uses emulsified asphalt powder and glass fiber to modify cement-based materials, its technical approach is fundamentally different from solving the dispersion and interface problems of nanofibers in asphalt-based composite materials and cannot be directly adopted.

[0025] Therefore, how to overcome technical bottlenecks, achieve long-term stable and uniform dispersion of nanofibers in emulsified asphalt systems, and establish a strong and tough bond between fibers and asphalt through interfacial chemical design, thereby making a breakthrough in improving the mechanical properties and durability of asphalt composite materials at the microscopic level, has become a key technical problem that urgently needs to be solved in this field, and is also an important direction for developing the next generation of high-performance and long-life pavements.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: Based on the above technical solution, this invention provides a method for preparing nano-silica fiber reinforced emulsified asphalt basalt composite material, which realizes the uniform dispersion of nano-silica fiber in the asphalt system and synergistically improves the water stability, high temperature stability, low temperature crack resistance and fatigue resistance of the asphalt composite material.

[0027] First, this invention employs nanofibers, specifically nano-silica fibers. On one hand, by grafting active groups onto the surface of the nanofibers using an interfacial chemical modifier, the surface charge characteristics and hydrophilicity / hydrophobicity of the nanofibers are altered, reducing their tendency to aggregate. This also allows them to form strong chemical bonds with the polar components of the emulsified asphalt, effectively changing the weak interfacial state that relies on physical adsorption in traditional methods. This results in a dense "fiber-asphalt" adsorption layer, reducing the flow deformation of asphalt under high-temperature environments. This overcomes the technical challenges of water erosion and high-temperature softening at the fiber-asphalt interface, laying a chemical foundation for improving the water and high-temperature stability of asphalt composites. On the other hand, the strong interfacial bond between the nanofibers and the asphalt matrix prevents "fiber-asphalt" interface delamination under vehicle loads, thereby improving the shear resistance and overall structural stability of the composite material. This enhanced interfacial effect allows nanofibers to significantly outperform traditional fibers in inhibiting early road surface cracking and delaying fatigue damage, making them particularly suitable for high-grade highways with large temperature differences and heavy loads. Furthermore, this invention, combined with a high-speed shear dispersion process, enables the nanofibers to form a uniform three-dimensional network distribution within the emulsified asphalt. Based on this, the present invention not only uses interfacial chemical modifiers to modify the surface of nanofibers, but also rationally uses high-speed shearing machines for synergistic processing, so that the distribution of nanofibers is more uniform and reasonable, while ensuring that each fiber can play a reinforcing and crack-resistant role, avoiding weak areas in road surface strength caused by local agglomeration.

[0028] Secondly, this invention introduces a dispersing stabilizer, specifically selecting at least one of polyvinyl alcohol, sodium carboxymethyl cellulose, and polyacrylamide. This stabilizer prevents nanofiber particles from approaching and agglomerating again through steric hindrance or electrostatic stabilization. When mixed with emulsified asphalt in the subsequent process, it also prevents nanofibers from re-agglomerating at the oil-water interface or in the asphalt phase. This solves the problem of preventing re-agglomeration of nanofibers in complex multiphase systems and further ensures that nanofibers are uniformly distributed in the composite material, providing a structural basis for achieving low-temperature crack resistance and fatigue resistance.

[0029] Furthermore, this invention employs a multi-step approach involving the sequential addition of raw materials, ultrasonic dispersion, shearing and stirring, dry mixing, and wet mixing. Each step is interconnected and the order cannot be reversed. In particular, the preparation of a uniform nanofiber aqueous dispersion followed by its introduction into an emulsified asphalt system containing a dispersant stabilizer for high-speed shearing effectively ensures that the nanofibers do not agglomerate and form a strong interfacial bond with the emulsified asphalt. This is key to achieving a synergistic improvement in the water stability, high-temperature stability, low-temperature crack resistance, and fatigue resistance of asphalt composite materials.

[0030] Furthermore, in terms of environmental friendliness, emulsified asphalt, as a base material for cold-mix asphalt, does not require heating to 160-180℃ like hot-mix asphalt, thus saving energy during construction and reducing CO2 and NO emissions. xThe emission of harmful gases aligns with the green development trend of road engineering under the "dual carbon" policy. In terms of economics, the high activity of nanofibers allows for a much lower dosage than ordinary fibers. Although the unit price of nanofibers is slightly higher, the total material cost is still comparable to or even lower than traditional fiber-reinforced solutions. More importantly, nanofiber-reinforced emulsified asphalt mixtures can extend the service life of pavements and reduce the frequency and cost of later maintenance. From the perspective of total life cycle cost, the cost-effectiveness advantage is significant.

[0031] In summary, this invention achieves a synergistic improvement in the water stability, high-temperature stability, low-temperature crack resistance, and fatigue resistance of asphalt composite materials through the organic combination of aggregates, emulsified asphalt, nanofibers, interfacial chemical modifiers, dispersants, and multi-step sequential processes, demonstrating significant progress. Detailed Implementation

[0032] To better understand the present invention, the following embodiments further illustrate the content of the invention, but the scope of protection of the present invention is not limited to the following embodiments. Numerous specific details are set forth in the following description to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the present invention can be practiced without one or more of these details.

[0033] When a numerical range is disclosed in this invention, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Further, when the range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Moreover, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed in this invention should be understood to include any and all subranges to which they are incorporated.

[0034] To make the objectives and advantages of the present invention clearer, the technical solutions and effects of the present invention are further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and should not be used to limit the present invention. Unless otherwise specified, the following embodiments do not include components other than unavoidable impurities. Unless otherwise specified, the raw materials and instruments used in the embodiments are conventionally selected in the art. Experimental methods in the embodiments that do not specify specific conditions are implemented according to conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer.

[0035] In the following cases, the aggregate usage was 2304g, of which: coarse aggregate was 1404g and fine aggregate was 936g.

[0036] The coarse aggregate has a particle size of 5-10mm, and the fine aggregate has a particle size of 0-5mm, neither of which includes the lower limit value itself.

[0037] The nanofibers have a diameter of 80-250 nm and a length of 10-60 μm.

[0038] Example 1: A method for preparing a nano-silica fiber reinforced emulsified asphalt basalt composite material, comprising the following steps: S1: Add nanofibers and interfacial chemical modifiers to the first part of water, stir for 1 min, and then disperse by ultrasonication at a power of 300W for 10 min at a temperature of 25℃ to obtain a uniform nanofiber dispersion. S2: Mix emulsified asphalt with dispersant and stabilizer, stir at 800 r / min for 5 min at 25℃ until the dispersant and stabilizer is completely dissolved, then add the nanofiber dispersion obtained in step S1, mix and shear stir at 4500 r / min for 15 min. While shear stirring, heat to 32℃ in a water bath, stop the machine every 3 min to observe, and obtain a uniform nanofiber modified emulsified asphalt matrix. S3: The aggregate is dried at 105℃ for 2 hours. The aggregate includes coarse and fine aggregates. The dried coarse and fine aggregates are dry-mixed at 100 r / min for 5 minutes. Then, while stirring, the nanofiber modified emulsified asphalt matrix obtained in step S2 and the second part of water are added simultaneously for wet mixing at 150 r / min for 10 minutes and 27℃ to obtain the composite material.

[0039] In this embodiment, the nanofibers are nano-silica fibers, and the amount used is 0.2% of the aggregate mass. The interface chemical modifier is silane coupling agent KH-550, and the amount used is 0.013% of the aggregate mass; the aggregate is basalt aggregate; the amount of emulsified asphalt is 17.9% of the aggregate mass. The dispersing stabilizer is polyvinyl alcohol, and the amount used is 0.09% of the aggregate mass. The amount of water in the first part is 2.1% of the aggregate mass, and the amount of water in the second part is 7.9% of the aggregate mass.

[0040] Example 2: A method for preparing a nano-silica fiber reinforced emulsified asphalt basalt composite material, comprising the following steps: S1: Add nanofibers and interfacial chemical modifiers to the first part of water, stir for 1 min, and then disperse by ultrasonication at a power of 250W for 10 min and a temperature of 25℃ to obtain a uniform nanofiber dispersion. S2: Mix emulsified asphalt with dispersant and stabilizer, stir at 900 r / min for 5 min at 25℃ until the dispersant and stabilizer is completely dissolved, then add the nanofiber dispersion obtained in step S1, mix and shear stir at 4800 r / min for 12 min. While shear stirring, heat to 30℃ in a water bath, stop the machine every 3 min to observe, and obtain a uniform nanofiber modified emulsified asphalt matrix. S3: The aggregate is dried at 100℃ for 3 hours. The aggregate includes coarse and fine aggregates. The dried coarse and fine aggregates are dry-mixed at 100 r / min for 5 minutes. Then, while stirring, the nanofiber modified emulsified asphalt matrix obtained in step S2 and the second part of water are added simultaneously for wet mixing at 180 r / min for 8 minutes and at 25℃ to obtain the composite material.

[0041] In this embodiment, the nanofibers are nano-silica fibers, and the amount used is 0.3% of the aggregate mass. The interface chemical modifier is silane coupling agent KH-660, and the amount used is 0.017% of the aggregate mass; the aggregate is limestone aggregate; the amount of emulsified asphalt is 15% of the aggregate mass. The dispersing stabilizer is sodium carboxymethyl cellulose, and the amount used is 0.06% of the aggregate mass. The amount of water in the first part is 1.7% of the aggregate mass, and the amount of water in the second part is 9% of the aggregate mass.

[0042] Example 3: A method for preparing a nano-silica fiber reinforced emulsified asphalt basalt composite material, comprising the following steps: S1: Add nanofibers and interfacial chemical modifiers to the first part of water, stir for 1 min, and then disperse by ultrasonication at a power of 350W for 8 min at a temperature of 25℃ to obtain a uniform nanofiber dispersion. S2: Mix emulsified asphalt with dispersant and stabilizer, stir at 700 r / min for 5 min at 25℃ until the dispersant and stabilizer is completely dissolved, then add the nanofiber dispersion obtained in step S1, mix and shear stir at 5000 r / min for 10 min. While shear stirring, heat to 35℃ in a water bath, stop the machine every 5 min to observe, and obtain a uniform nanofiber modified emulsified asphalt matrix. S3: The aggregate is dried at 110℃ for 1 hour. The aggregate includes coarse and fine aggregates. The dried coarse and fine aggregates are dry-mixed at 150 r / min for 5 minutes. Then, while stirring, the nanofiber modified emulsified asphalt matrix obtained in step S2 and the second part of water are added simultaneously for wet mixing at 200 r / min for 5 minutes and 30℃ to obtain the composite material.

[0043] In this embodiment, the nanofibers are nano-silica fibers, and the dosage is 0.4% of the aggregate mass. The interface chemical modifier is silane coupling agent KH-570, and the dosage is 0.02% of the aggregate mass; the aggregate is granite aggregate; the emulsified asphalt dosage is 15% of the aggregate mass. The dispersing stabilizer is polyacrylamide, and the dosage is 0.12% of the aggregate mass. The first portion of water is 3.0% of the aggregate mass, and the second portion of water is 6% of the aggregate mass.

[0044] Example 4: A method for preparing a nano-silica fiber-reinforced emulsified asphalt basalt composite material, differing from Example 1 in that: the nanofibers are nano-silica fibers, and their dosage is 0.2% of the aggregate mass. The interface chemical modifier is phthalate coupling agent NDZ-101, and its dosage is 0.01% of the aggregate mass; the aggregate is a composition of basalt aggregate and limestone aggregate in a mass ratio of 1:1; the emulsified asphalt dosage is 16.5% of the aggregate mass. The dispersing stabilizer is polyvinyl alcohol, and its dosage is 0.08% of the aggregate mass. The water dosage in the first part is 1.5% of the aggregate mass, and the water dosage in the second part is 10% of the aggregate mass.

[0045] Example 5: A method for preparing a nano-silica fiber-reinforced emulsified asphalt basalt composite material, differing from Example 1 in that: the nanofibers are nano-silica fibers, and their dosage is 0.2% of the aggregate mass. The interface chemical modifier is silane coupling agent KH-570, and its dosage is 0.015% of the aggregate mass; the aggregate is limestone aggregate; and the emulsified asphalt dosage is 18.3% of the aggregate mass. The dispersing stabilizer is polyvinyl alcohol, and its dosage is 0.10% of the aggregate mass. The first portion of water is 2.3% of the aggregate mass, and the second portion of water is 8% of the aggregate mass.

[0046] Example 6: An asphalt composite material prepared by any of the methods in Examples 1-5 above.

[0047] Comparative Example 1: A method for preparing a nano-silica fiber reinforced emulsified asphalt basalt composite material, which differs from Example 1 in that: the interfacial chemical modifier in step S1 is omitted, and S1' is used instead of S1: the nanofibers are added to the first part of water, stirred for 1 min, and then ultrasonically dispersed. The ultrasonic power is 300W, the time is 10 min, and the temperature is 25℃ to obtain a nanofiber dispersion; the rest is the same as in Example 1.

[0048] Comparative Example 2: A method for preparing a nano-silica fiber reinforced emulsified asphalt basalt composite material, which differs from Example 1 in that: the dispersing stabilizer in step S2 is omitted, and S2' is used instead of S2: the nanofiber dispersion obtained in step S1 is added to the emulsified asphalt, and after mixing, shear stirring is performed at a speed of 4500 r / min for 15 min. While shearing and stirring, the mixture is heated to 32°C in a water bath. The machine is stopped and observed every 3 min to obtain the nanofiber modified emulsified asphalt matrix; the rest is the same as in Example 1.

[0049] Comparative Example 3: A method for preparing a nano-silica fiber reinforced emulsified asphalt basalt composite material, which differs from Example 1 in that: aggregate, emulsified asphalt, dispersant stabilizer, nanofiber, interfacial chemical modifier and water are mixed at 27°C and stirred evenly to obtain the composite material; the types and amounts of each raw material are the same as in Example 1.

[0050] Next, the content of the evaluation experiment will be explained.

[0051] The composite materials prepared in Examples 1-5 and Comparative Examples 1-3 were subjected to the following performance tests.

[0052] 1. Water stability: The test was conducted according to the method specified in JTG E20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" of the People's Republic of China's Transportation Industry Standard. Cylindrical specimens with a diameter of 101.6 mm × 63.5 mm were prepared using a Marshall compactor, with each side compacted 75 times, for a total of 6 specimens per group. The specimens were kept in a constant temperature water bath at 60±1℃ for 30-40 minutes, and the initial Marshall stability (MS1) was measured. Three specimens were then further immersed in water at 60±1℃ for 48 hours, and the post-immersion stability (MS2) was measured within 30 seconds after removal. The residual stability after immersion was calculated, where: Water immersion residual stability (%) = (MS2 / MS1) × 100%.

[0053] 2. High-Temperature Stability: The test was conducted according to the methods specified in JTG E20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" of the People's Republic of China's Transportation Industry Standard. Three 300mm×300mm×50mm slab specimens were prepared using a roller mill. The specimens were placed in a constant temperature chamber at 60±1℃ for 5 hours. A solid rubber wheel with a diameter of 200mm was used to roll the surface of the specimen back and forth at a pressure of 0.7MPa and a speed of 42 times / min, and the rutting depth was recorded at different times. The dynamic stability (DS) was calculated, where: Dynamic stability (times / mm) = (42 times / min × (t2-t1)) / (d2-d1) × C1 × C2, where C1 is the testing machine type coefficient and C2 is the specimen coefficient.

[0054] 3. Low-Temperature Crack Resistance: The test was conducted according to the methods specified in JTG E20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" of the People's Republic of China's Transportation Industry Standard. After roller rolling, the specimens were cut into 250mm×30mm×35mm prism specimens, with three specimens per group. The specimens were kept in a constant temperature chamber at -10±0.5℃ for 4 hours. A four-point bending device was used, with a support point spacing of 200mm and a loading rate of 50mm / min. The mid-span deflection and maximum load were recorded, and the bending failure strain (ε) was calculated. δ ),in: Bending failure strain = (6 × h × d) / L 2 Where h is the specimen height, d is the mid-span deflection at failure, and L is the distance between supports.

[0055] 4. Fatigue Strength: Tested according to the methods specified in JTG E20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" of the People's Republic of China's Transportation Industry Standard. After wheel rolling, the specimens were cut into 250mm×30mm×35mm prism specimens, three per group. The specimens were kept in a constant temperature chamber at 25±1℃ for at least 4 hours. A four-point bending device was used, with a sinusoidal load control mode, a stress ratio of 0.1, and a loading frequency of 10Hz. Load-strain curves were recorded until specimen failure. Performance was evaluated by fatigue life (the number of loading cycles to failure), typically using 10... 6 The stress ratio corresponding to each cycle is used as an indicator.

[0056] The performance test results are shown in Table 1.

[0057] Table 1 Test Results Table 1 shows that the composite materials prepared in Examples 1-5 of this invention are significantly superior to the comparative examples in terms of water stability, high-temperature stability, low-temperature crack resistance, and fatigue resistance. This demonstrates that the raw materials and preparation steps used in this invention form an organic whole, working together to achieve a comprehensive improvement in performance. The asphalt composite material of this invention can be applied to road engineering, such as for paving high-grade road surface layers, stress-absorbing layers, or bridge deck pavement layers.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a nano-silica fiber reinforced emulsified asphalt basalt composite material, characterized in that: Includes the following steps: S1: Add nanofibers and interfacial chemical modifiers to the first part of water, stir, and then disperse by ultrasonic treatment to obtain a uniform nanofiber dispersion. S2: Mix emulsified asphalt with a dispersant and stabilizer, stir until the dispersant and stabilizer is completely dissolved, then add the nanofiber dispersion obtained in step S1, mix and then shear and stir to obtain nanofiber modified emulsified asphalt matrix. S3: The aggregate is dried, including coarse aggregate and fine aggregate. The dried coarse aggregate and fine aggregate are dry-mixed, and then the nanofiber modified emulsified asphalt matrix obtained in step S2 and the second part of water are added simultaneously under stirring to wet-mix the composite material.

2. The preparation method of the nano-silica fiber reinforced emulsified asphalt basalt composite material as described in claim 1, characterized in that: The nanofibers are nano-silica fibers with a diameter of 80-250 nm and a length of 10-60 μm. The amount of nanofibers used is 0.2%-0.4% of the mass of the aggregate.

3. The preparation method of the nano-silica fiber reinforced emulsified asphalt basalt composite material as described in claim 2, characterized in that: The interface chemical modifier is selected from at least one of silane coupling agent and titanate coupling agent, and the amount of the interface chemical modifier is 0.01-0.02% of the aggregate mass; Among them, the silane coupling agent is selected from at least one of silane coupling agent KH-550, silane coupling agent KH-660 and silane coupling agent KH-570, and the titanate coupling agent is selected from phthalate coupling agent NDZ-101.

4. The preparation method of the nano-silica fiber reinforced emulsified asphalt basalt composite material as described in claim 3, characterized in that: The aggregate is at least one of basalt aggregate, limestone aggregate, and granite aggregate; The mass ratio of coarse aggregate to fine aggregate is 6:4, the particle size of coarse aggregate is 5-10mm, and the particle size of fine aggregate is 0-5mm.

5. The preparation method of the nano-silica fiber reinforced emulsified asphalt basalt composite material as described in claim 4, characterized in that: The amount of emulsified asphalt used is 15-20% of the aggregate mass; The dispersing stabilizer is selected from at least one of polyvinyl alcohol, sodium carboxymethyl cellulose and polyacrylamide, and the amount of the dispersing stabilizer is 0.06-0.12% of the aggregate mass.

6. The preparation method of the nano-silica fiber reinforced emulsified asphalt basalt composite material as described in claim 5, characterized in that: In step S1, the stirring time is more than 1 minute; The ultrasonic dispersion treatment uses a power of 250-350W, a time of 8-10 minutes, and a temperature of 20±2℃.

7. The preparation method of the nano-silica fiber reinforced emulsified asphalt basalt composite material as described in claim 6, characterized in that: In step S2, the stirring speed is 700-900 r / min, the time is more than 5 min, and the temperature is 20±2℃. The shearing and stirring speed is 4500-5000 r / min, and the time is 10-15 min. At the same time, the water bath is heated to 30-35℃. Preferably, during the shearing and mixing process, the machine should be stopped and observed every 3-5 minutes.

8. The preparation method of the nano-silica fiber reinforced emulsified asphalt basalt composite material as described in claim 7, characterized in that: In step S3, the drying temperature is 100-110℃ and the time is 1-3 hours. The dry mixing speed is 100-150 r / min, and the time is more than 5 minutes; The wet mixing speed is 150-200 r / min, the time is 5-10 min, and the temperature is 25-30℃; Preferably, the amount of water used in the first part is 1.5-3.0% of the mass of the aggregate, and the amount of water used in the second part is 6-10% of the mass of the aggregate.

9. An asphalt composite material, prepared by the method for preparing a nano-silica fiber reinforced emulsified asphalt basalt composite material according to any one of claims 1-8.

10. The application of the asphalt composite material as described in claim 9 in road engineering.

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