Road paving materials and their preparation methods

Abstract

This invention discloses a road pavement material and its preparation method. The key technical point aims to solve the problems of traditional pavement materials' self-healing particles having a single triggering mechanism and difficulty in repairing early-stage cracks. The pavement material includes composite mineral aggregates, intelligent responsive self-healing particles, and a multifunctional epoxy adhesive. The outer shell of the intelligent responsive self-healing particles is composed of a shape memory polymer and thermally expandable microspheres, with an internal polyelectrolyte complex responsive membrane. The repair solution contains multiple effective components. The composite mineral aggregates consist of basalt aggregates, carbon nanotubes, and a silicon nitride nano-coating. The preparation method covers the preparation of the composite mineral aggregates, intelligent responsive self-healing particles, and multifunctional epoxy adhesive, as well as the pavement material molding steps. This invention, through the unique shell design of the intelligent responsive self-healing particles, achieves multiple triggering mechanisms, enabling the release of the repair solution in the early stages of cracking, effectively improving the self-healing ability of the pavement material and extending its service life.

Description

Technical Field

[0001] This invention relates to the field of road paving technology, specifically to a road paving material and a method for preparing the road paving material. Background Technology

[0002] Road paving materials refer to materials used to pave road surfaces to provide passage for vehicles and pedestrians. Traditionally, asphalt concrete is the most commonly used paving material. However, after years of application, it has been found that asphalt, being a low molecular weight thermoplastic material, is greatly affected by external environmental factors such as temperature. It has poor temperature stability and water resistance, resulting in a short service life. Therefore, in order to improve the performance of paving materials, epoxy-modified asphalt and pure epoxy thermosetting materials have been developed to replace traditional asphalt, thereby improving the durability of paving materials.

[0003] Thermosetting materials do not possess the self-healing ability of asphalt-based materials to repair minor cracks at certain temperatures. As a result, these materials have poor crack resistance when used in road paving, affecting their service life. Therefore, existing methods involve adding self-healing particles to thermosetting paving materials. When the material cracks, these self-healing particles break, releasing a self-healing solution to fill the crack and repair it, preventing further damage.

[0004] Current self-healing granules typically use epoxy resin as the outer shell. They mainly rely on the mechanical cracking (elongation at break) of the outer shell to release the repair solution, which is a relatively simple triggering method. However, in actual applications, the situation of cracks is quite complex. In the early stages of actual road surface cracks, the stress concentration is low, which prevents the outer shell from cracking, thus preventing the release of the repair solution and making it impossible to repair the crack in the early stages. This leads to further expansion of the crack and affects the timeliness of repair. Summary of the Invention

[0005] This invention proposes a road paving material and a method for preparing the road paving material, which solves the problem that the self-healing particles in paving materials in related technologies have a relatively simple triggering mode, low stress concentration in the early stage of cracks, and are unable to repair cracks.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a road paving material comprising composite mineral aggregates, intelligent responsive self-healing particles, and a multifunctional epoxy adhesive; wherein the intelligent responsive self-healing particles are uniformly embedded on the upper surface of the paving layer formed by the composite mineral aggregates; the intelligent responsive self-healing particles comprise an outer shell and a repair solution encapsulated within the outer shell, and a responsive membrane covering the inner side of the outer shell is disposed between the outer shell and the repair solution; the outer shell is composed of a shape memory polymer and thermally expandable microspheres; the responsive membrane is made of a polyelectrolyte composite, comprising chitosan and sodium alginate.

[0007] The present invention is further configured such that the repair solution comprises methyltrimethoxysilane, nano-silica, graphene nanosheets, nano-copper oxide antibacterial agent, and polyethylene glycol.

[0008] The present invention is further configured such that the composite mineral aggregate includes basalt aggregate and carbon nanotubes dispersed within the basalt aggregate, and the surface of the basalt aggregate is coated with a silicon nitride nano-coating.

[0009] The present invention is further configured such that the multifunctional epoxy adhesive comprises a two-component epoxy resin, nano-titanium dioxide, and rubber elastomer particles.

[0010] The present invention is further configured such that the thermally expandable microspheres contain a low-boiling-point organic solvent with a particle size of 5-10 micrometers and a mass accounting for 10%-15% of the total mass of the shell.

[0011] The present invention is further configured such that the shape memory polymer is made of polycaprolactone.

[0012] A method for preparing road paving materials, comprising the following steps:

[0013] S1. Preparation of composite mineral aggregate: Basalt aggregate A with a particle size of 5-10 mm and basalt aggregate B with a particle size of 10-20 mm are selected and mixed to obtain basalt aggregate. Then, silicon nitride nano-coating is formed on the surface of the mixed basalt aggregate by vapor deposition technology. Finally, it is mixed with carbon nanotubes to obtain composite mineral aggregate.

[0014] S2. Preparation of intelligent response self-healing particles: The repair solution is injected into the space of the response membrane, and then the shell is wrapped around the outside of the response membrane through injection molding to obtain complete intelligent response self-healing particles.

[0015] S3. Preparation of multifunctional epoxy adhesive: Nano-titanium dioxide and rubber elastomer particles are added to a two-component epoxy resin in a certain proportion and stirred, and a curing agent is added during the process;

[0016] S4. Road paving material forming: First, lay composite mineral aggregate on the road surface, then evenly distribute intelligent responsive self-healing particles on the upper surface of the composite mineral aggregate, and compact them to embed the self-healing particles into the composite mineral aggregate; finally, spray multifunctional epoxy adhesive on the surface of the composite mineral aggregate with intelligent responsive self-healing particles.

[0017] The present invention further specifies that the specific preparation steps of step S2 are as follows:

[0018] A1. Shell preparation: Polycaprolactone particles and thermally expanded microspheres are added to a twin-screw extruder for melt mixing to obtain a composite material;

[0019] A2. Preparation of responsive membrane: Chitosan solution is slowly added dropwise to sodium alginate solution, and then stirred with a magnetic stirrer to obtain a mixed solution. The mixed solution is then poured into a mold and placed in an oven to dry to form a polyelectrolyte composite smart responsive membrane. Finally, it is cut into a suitable size to obtain the responsive membrane.

[0020] A3. Preparation of repair solution: Methyltrimethoxysilane, nano silica, graphene nanosheets, nano copper oxide antibacterial agent and polyethylene glycol are added to the reaction vessel in sequence. They are first mixed under low speed stirring, then ultrasonically dispersed, and finally stirred at high speed to obtain the repair solution.

[0021] A4. Assembly: First, inject the repair solution into the response membrane using a syringe. Then, seal the response membrane containing the repair solution. Next, place the response membrane containing the repair solution into an injection mold. Then, inject the well-mixed composite material from the twin-screw extruder into the mold, so that the composite material completely encapsulates the response membrane and the repair solution. Finally, cool and demold to obtain intelligent response self-healing particles.

[0022] The present invention is further configured such that, in step S3, the nano-titanium dioxide is first pretreated, and the pretreatment steps are as follows:

[0023] B1. Add nano-titanium dioxide powder to anhydrous ethanol to obtain a titanium dioxide suspension;

[0024] B2. The titanium dioxide suspension in B1 is dispersed by ultrasonic technology to obtain a uniformly mixed suspension;

[0025] B3. After centrifuging the uniformly mixed suspension in B2, remove the impurities in the supernatant and then precipitate to obtain high-purity titanium dioxide.

[0026] The present invention is further configured such that, in step S3, the rubber elastomer particles are pretreated, and the pretreatment steps are as follows:

[0027] C1. Small rubber elastomer particles are obtained by cryogenically pulverizing rubber elastomer particles at low temperature.

[0028] C2. Add toluene solution to small rubber elastomer particles, and then stir with a stirrer to obtain swollen rubber elastomer particles.

[0029] In summary, the beneficial effects of this invention are as follows:

[0030] Compared to existing technologies, this invention employs a shell design combining shape memory polymers and thermally expandable microspheres, enabling the particles to respond to changes in temperature or stress, thereby releasing the repair solution for repair in the early stages of crack formation. This multi-trigger mechanism ensures timely release of the repair solution even under low crack stress conditions, preventing further crack propagation and effectively improving the self-healing capability of pavement materials, thus extending their service life. Attached Figure Description

[0031] Figure 1 This is a perspective view of Embodiment 1.

[0032] Figure 2 This is a partial view of Embodiment 1.

[0033] Figure 3 These are the steps involved in the preparation of road paving materials.

[0034] Figure 4 This refers to the preparation steps of intelligent response self-healing particles.

[0035] Reference numerals: 1. Composite mineral aggregate; 2. Multifunctional epoxy adhesive; 3. Smart responsive self-healing particles. Detailed Implementation

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of the present invention. Example 1:

[0037] like Figure 1-2 As shown, this embodiment discloses a road paving material, including composite mineral aggregate 1, smart responsive self-healing particles 3, and multifunctional epoxy adhesive 2. The smart responsive self-healing particles 3 are uniformly embedded on the upper surface of the paving layer formed by the composite mineral aggregate 1, and the multifunctional epoxy adhesive 2 is sprayed on the upper surface of the paving layer formed by the composite mineral aggregate with the smart responsive self-healing particles embedded on its surface.

[0038] The composite mineral aggregate, with its compact packing structure, bears the main road load. Large-diameter basalt aggregate forms the skeleton, while small-diameter aggregate fills the voids. Combined with a silicon nitride nano-coating enhancing durability and carbon nanotubes improving mechanical properties, this layer effectively disperses vehicle loads, resists wear and environmental erosion, and ensures the basic load-bearing capacity and stability of the road surface. Meanwhile, the intelligent responsive self-healing particles distributed among the composite mineral aggregate act as the road's "repair guardians." When cracks appear in the road surface, whether due to vehicle vibration, stress concentration, or temperature changes, the outer shell of the self-healing particles ruptures, releasing a repair solution. The components of the repair solution fill and repair the cracks, preventing further expansion and maintaining the integrity of the road structure. Simultaneously, a surface layer composed of multifunctional epoxy adhesive is applied, with fine sand sprinkled on top before curing. The multifunctional epoxy adhesive further strengthens the overall integrity of the road surface, enhances protection of the underlying materials, and improves wear resistance. The fine sand increases the road's coefficient of friction, improving driving safety. During vehicle operation, the surface layer directly bears the friction and wear of the tires, while also resisting the influence of external environmental factors such as rain and ultraviolet rays.

[0039] The road paving material is laid out in a composite mineral aggregate layer and an epoxy adhesive layer from bottom to top through the paving process. The intelligent response self-healing particles are embedded in the upper surface of the aggregate paving layer. This partially embedded state provides a certain degree of physical protection for the particles.

[0040] When vehicle loads are applied to the road surface, the primary pressure is borne by the composite mineral aggregate layer. Because of its tightly packed structure, the aggregate layer effectively disperses stress. The self-healing particles embedded within are surrounded and supported by the aggregate particles, and do not directly bear the entire vehicle pressure. Only when cracks appear in the road surface, causing changes in localized stress, and these changes are transmitted to the self-healing particles, will their mechanism for releasing the repair solution be triggered.

[0041] Furthermore, the intelligent responsive self-healing particles include a shell and a repair solution encapsulated by the shell, with the shell and repair solution isolated by a responsive membrane; the shell is made of a shape memory polymer and thermally expandable microspheres; the responsive membrane is made of a polyelectrolyte complex, which includes chitosan and sodium alginate.

[0042] Specifically, the outer shell is composed of polycaprolactone and thermally expandable microspheres containing a low-boiling-point organic solvent. Polycaprolactone possesses unique shape memory properties, with a glass transition temperature between 40 and 50°C. Under normal road surface temperatures, it remains in a glassy state with relatively fixed molecular chain segments and a stable structure; it can recover its original shape under certain temperature or stress conditions, thereby triggering the outer shell to crack. The thermally expandable microspheres have a particle size of 5-10 μm and are added at 10%-15% of the outer shell material.

[0043] When tiny cracks appear in the road surface, the vibrations and stresses generated by vehicle traffic are transmitted to the self-healing particles. On one hand, even if the temperature rise at the crack is not significant, the continuous stress causes the polycaprolactone (PVC) molecular chains to gradually orient and deform. According to the viscoelastic theory of polymers, under stress, the conformation of the PVC molecular chains changes. When the stress reaches a certain level, the molecular chains begin to overcome internal resistance, sliding and rearranging, thus triggering shape recovery. On the other hand, the thermally expandable microspheres expand under slight stress or temperature increases. The thermally expandable microspheres contain low-boiling-point organic solvents. When subjected to external temperature increases or pressure changes, the organic solvents vaporize and expand, increasing the volume of the thermally expandable microspheres. In the local environment where the crack occurs, stress concentration and slight temperature changes can both trigger the expansion of the thermally expandable microspheres. The synergistic effect of the shape recovery of PVC and the expansion of the thermally expandable microspheres leads to the rupture of the outer shell, releasing some of the repair solution.

[0044] The polyelectrolyte complex of the responsive membrane is mainly formed by the electrostatic interaction of chitosan and sodium alginate. When moisture intrudes into the cracks, it typically contains various ions, such as calcium, magnesium, and hydrogen ions. These ions exchange with the ions in the polyelectrolyte complex membrane. Chitosan molecules contain a large number of amino groups, while sodium alginate molecules contain carboxyl groups. During the formation of the polyelectrolyte complex membrane, the amino and carboxyl groups are bound together by electrostatic interactions. When external ions enter the membrane, they exchange with the amino or carboxyl groups in the membrane, altering the membrane's charge distribution and chemical composition. According to the Donnan equilibrium principle, ion exchange causes a change in the ion concentration difference across the membrane, thus altering the membrane's osmotic pressure. To balance the osmotic pressure, the membrane absorbs moisture and swells. When the swelling reaches a certain level, the membrane structure is damaged, further releasing the remaining repair solution.

[0045] The dual-shell design, consisting of an outer shell and a responsive membrane, makes it highly sensitive to minute stress changes. Even in the early stages of stress accumulation, small stress fluctuations can induce microscopic adjustments in the shape memory polymer molecular chains, and the thermally expanding microspheres also respond to changes in the local environment. Once a subtle trend of change emerges, these components begin to work synergistically, gradually altering the stability of the outer shell structure. This causes the repair solution to tend to be released prematurely, thus initiating the repair process before the crack has significantly widened. This dual-response mechanism greatly increases the triggering conditions for the release of the repair solution, improving the success rate of repair under various complex crack conditions.

[0046] Furthermore, the design of the outer shell and the responsive membrane allows the outer shell to rupture first, rapidly releasing a portion of the repair solution in the early stages of crack formation to initially seal and fill the crack, preventing further expansion. As time progresses, if moisture enters the crack, the inner responsive membrane begins to function. Due to the presence of moisture, the methyltrimethoxysilane in the repair solution can more effectively hydrolyze and condense to form a network structure that fills the crack. Components such as nano-silica and graphene nanosheets can also more fully exert their effects in enhancing filling performance and improving the strength of the repaired area. This phased repair process allows the repair solution to more precisely adapt to the development stage of the crack, improving the stability and reliability of the repair effect, thus achieving progressive crack repair.

[0047] Furthermore, the repair solution encapsulated in the intelligent response self-healing particles includes methyltrimethoxysilane, graphene nanosheets, nano-copper oxide antibacterial agent, and polyethylene glycol. Among them, methyltrimethoxysilane is the main repair component, nano-silica has a high specific surface area and good dispersibility, graphene nanosheets have excellent mechanical properties, nano-copper oxide antibacterial agent has antibacterial activity, and polyethylene glycol can improve the fluidity of the repair solution.

[0048] When the repair solution is released, the methyltrimethoxysilane in the repair solution undergoes a rapid hydrolysis reaction in the presence of water to generate silanols. The silanols then undergo a condensation reaction to gradually form a three-dimensional siloxane network structure, which achieves a tight bond with the surrounding composite mineral aggregates to fill the cracks.

[0049] Nano-silica, with its high specific surface area and good dispersibility, fills the pores of the siloxane network, making the siloxane network denser and thus enhancing its filling performance. Furthermore, due to its high specific surface area, it can undergo more physical and chemical interactions with the active groups on the aggregate surface, allowing the repair area to better integrate with the aggregate into a whole, thereby improving the density of the repair area.

[0050] Graphene nanosheets, with their high strength and high modulus, significantly enhance the strength of the repaired area, enabling the repaired cracks to withstand vehicle loads.

[0051] Nano-copper oxide antibacterial agents inhibit the growth of microorganisms in cracks by disrupting microbial cell membranes or generating reactive oxygen species, thus preventing the degradation of pavement material performance caused by microbial growth.

[0052] Polyethylene glycol (PEG) improves the fluidity of the repair solution. During the hydrolysis and polycondensation process, PEG helps methyltrimethoxysilane reach all parts of the crack more quickly, forming a more complete siloxane network. Synergistically, PEG helps these nanomaterials disperse uniformly in the repair solution, working with nano-silica and graphene nanosheets. It acts as a dispersant, preventing the agglomeration of nano-silica and graphene nanosheets, allowing them to better exert their reinforcing effects. This, in turn, ensures that the repair solution can diffuse rapidly and uniformly within the crack, maximizing its repair function.

[0053] Furthermore, the composite mineral aggregate, as the base material for road paving, includes basalt aggregate and carbon nanotubes dispersed within the basalt aggregate, with the surface of the basalt aggregate coated with a silicon nitride nano-coating.

[0054] Specifically, basalt aggregate is used as the base aggregate, which is a mixture of aggregate A (5-10 mm in diameter) and aggregate B (10-20 mm in diameter) in a 1:1 mass ratio. The larger-diameter aggregate B is interspersed to form a stable skeleton, providing the main load-bearing support for the road surface. Meanwhile, the smaller-diameter aggregate A fills the gaps between the larger-diameter aggregates, further compacting the structure and reducing internal porosity. This allows the entire aggregate system to evenly and effectively distribute vehicle loads, avoiding localized stress concentration and thus effectively improving the road surface's load-bearing capacity, preventing deformation and subsidence due to excessive pressure.

[0055] Carbon nanotubes possess a unique one-dimensional tubular structure and excellent mechanical properties, with a tensile strength of 100-600 GPa, more than 100 times that of steel. They also exhibit good flexibility and a high aspect ratio, allowing them to intersect between aggregate particles. At the microscopic level, carbon nanotubes form physical and chemical adsorption interactions with the aggregate surface. When the aggregate is subjected to external forces, such as repeated vehicle loads on the road surface, the carbon nanotubes can absorb some of the stress due to their high strength. Through their tensile deformation, carbon nanotubes effectively absorb energy, preventing the formation and propagation of cracks. They can evenly distribute stress to the surrounding aggregate particles, avoiding stress concentration in weak areas of the aggregate, thereby significantly improving the adhesion between aggregates, enhancing the tensile strength and toughness of the material, and further improving the durability of the road surface.

[0056] Silicon nitride nano-coatings can be deposited on cleaned and dried basalt aggregates using chemical vapor deposition equipment, forming a hydrophobic layer on the surface of the basalt aggregates. This effectively prevents moisture from adhering to and penetrating the aggregate surface. Furthermore, its high hardness and chemical stability can enhance the aggregates' wear resistance and corrosion resistance, resisting frequent wear from vehicle tires and erosion from external chemicals, thus significantly extending the service life of the road surface.

[0057] Furthermore, a multifunctional epoxy adhesive is applied to the surface of the basalt aggregate after it has been laid. This adhesive can firmly bond the composite mineral aggregate together. It mainly consists of two-component epoxy resin, nano titanium dioxide, and rubber elastomer particles.

[0058] Two-component epoxy resin is the main component of multifunctional epoxy adhesives, and its molecular structure contains two or more epoxy groups. During the curing process, the epoxy resin and the curing agent react chemically, and the epoxy groups open to form a cross-linked network structure. The epoxy groups of the epoxy resin can react chemically with the active groups such as hydroxyl and amino groups on the surface of composite mineral aggregates and intelligent responsive self-healing particles to form chemical bonds. At the same time, during the curing process, the epoxy resin forms physical adsorption on the surface of aggregates and particles, further enhancing the adhesion through van der Waals forces. This dual effect of chemical bonding and physical adsorption enables the epoxy adhesive to firmly bond composite mineral aggregates, intelligent responsive self-healing particles, etc., together to form a whole structure, ensuring the integrity and stability of the pavement during use.

[0059] The nano-titanium dioxide mixed in possesses photocatalytic activity. Under ultraviolet light, the valence band electrons in its crystal structure absorb photon energy and transition to the conduction band, forming photogenerated electron-hole pairs. These photogenerated holes have strong oxidizing properties, capable of oxidizing water adsorbed on the surface of the nano-titanium dioxide to generate hydroxyl radicals, while the photogenerated electrons can reduce oxygen in the air to superoxide anion radicals. These active oxygen species have strong oxidizing capabilities, capable of oxidizing and decomposing organic matter on the road surface, such as oil stains, dust, and rubber particles from tire wear, into harmless substances like carbon dioxide and water. During road use, ultraviolet light from sunlight continuously irradiates the surface of the epoxy adhesive containing nano-titanium dioxide, continuously stimulating the photocatalytic reaction, thereby keeping the road surface clean and reducing driving safety hazards caused by road pollution. For example, oil stains reduce the friction between the road surface and tires, increasing the risk of vehicle skidding.

[0060] Styrene-butadiene rubber (SBR) elastomer particles are uniformly dispersed within epoxy resin, enhancing its toughness and impact resistance. At the microscopic level, when the epoxy adhesive is subjected to external impact, the rubber elastomer particles undergo significant elastic deformation, absorbing and dispersing the impact energy. An interfacial transition zone is formed between the rubber elastomer particles and the epoxy resin through physical and chemical interactions. Under external force, this transition zone effectively transfers stress, allowing the rubber elastomer particles and epoxy resin to work synergistically. For example, when the road surface is subjected to sudden braking or impact from a heavy vehicle, the rubber elastomer particles can disperse the concentrated impact force into the surrounding epoxy resin through their elastic deformation, preventing stress concentration and subsequent cracking of the epoxy adhesive. Simultaneously, the presence of the rubber elastomer particles also inhibits crack propagation. When cracks occur within the epoxy adhesive, the rubber elastomer particles act as a bridge at the crack tip, preventing further crack extension. This improves the adhesive's toughness and impact resistance, enhancing road surface durability.

[0061] Road surface repair process: When micro-cracks appear on the road surface, the vibrations and stresses generated by vehicle traffic are transmitted to the self-healing particles. On the one hand, even if the temperature rise at the crack is not significant, the continuous stress will cause the polycaprolactone (PVC) molecular chains to gradually orient and deform. According to the viscoelastic theory of polymers, under stress, the conformation of the PVC molecular chains changes. When the stress reaches a certain level, the molecular chains overcome internal resistance and slide and rearrange, triggering shape recovery. On the other hand, the thermally expanding microspheres will expand under slight stress or temperature increases. In the local environment where the crack occurs, stress concentration and slight temperature changes may trigger the vaporization and expansion of the organic solvent inside the thermally expanding microspheres, increasing their volume. The synergistic effect of the shape recovery of PVC and the expansion of the thermally expanding microspheres causes the outer shell to rupture, releasing some of the repair fluid in time, buying time for crack repair.

[0062] When moisture intrudes into the cracks, it typically contains various ions, such as calcium, magnesium, and hydrogen ions. These ions exchange with the ions in the polyelectrolyte composite membrane. According to the Donnan equilibrium principle, ion exchange alters the ion concentration difference across the membrane, causing a change in membrane osmotic pressure. To balance the osmotic pressure, the membrane absorbs moisture and swells. When the swelling reaches a certain extent, the membrane structure is disrupted, further releasing the remaining repair fluid to ensure the cracks are fully repaired. Example 2:

[0063] like Figure 3-4 As shown, a method for preparing road paving material, used to prepare the road paving material in Example 1, comprises the following steps:

[0064] S1. Preparation of composite mineral aggregate: Basalt aggregate A with a particle size of 5-10 mm and basalt aggregate B with a particle size of 10-20 mm are selected and mixed to obtain basalt aggregate. Then, silicon nitride nano-coating is formed on the surface of the mixed basalt aggregate by vapor deposition technology. Finally, it is mixed with carbon nanotubes to obtain composite mineral aggregate.

[0065] Specifically, in order to facilitate the adhesion of the nano-coating to the basalt aggregate, the selected and mixed basalt aggregate needs to be cleaned to remove dust and impurities from its surface. Then, it is placed in a drying oven and dried at a temperature of 105℃-110℃ to avoid moisture affecting the coating quality and the bonding effect between aggregates, while also preventing the coating from blistering, peeling off, and the uniformity of materials during aggregate mixing.

[0066] The preparation of silicon nitride nanocoating involves placing dried basalt aggregate in a reaction chamber, controlling the flow ratio of silane and ammonia gas to 1:3, setting the radio frequency power to 100-150W, and the deposition time to 30-45 minutes to form a silicon nitride nanocoating of 80-120nm.

[0067] Before being mixed with basalt aggregate, the carbon nanotubes need to be pretreated. The carbon nanotubes are added to a solution containing an appropriate amount of surfactant, such as a 0.5%-1% sodium dodecylbenzenesulfonate solution, and ultrasonically dispersed for 30-60 minutes. Then, they are mixed with the dried basalt aggregate in a high-speed mixer at 1000-1500 rpm for 20-30 minutes. This treatment reduces the surface tension of the solution with the surfactant, helping the carbon nanotubes disperse. Ultrasonic dispersion further breaks up the agglomeration of the carbon nanotubes. High-speed stirring ensures that the carbon nanotubes are uniformly attached to the surface of the aggregate and embedded in the aggregate pores, enhancing their bonding strength.

[0068] S2. Preparation of intelligent response self-healing particles: The repair solution is injected into the space of the response membrane, and then the shell is wrapped around the outside of the response membrane through injection molding to obtain complete intelligent response self-healing particles.

[0069] Specifically, the preparation steps for step S2 are as follows:

[0070] A1. Shell preparation: Polycaprolactone particles and thermally expanded microspheres are added to a twin-screw extruder for melt mixing to obtain a composite material;

[0071] A2. Preparation of responsive membrane: Chitosan solution is slowly added dropwise to sodium alginate solution, and then stirred with a magnetic stirrer to obtain a mixed solution. The mixed solution is then poured into a mold and placed in an oven to dry to form a polyelectrolyte composite smart responsive membrane. Finally, it is cut into a suitable size to obtain the responsive membrane.

[0072] A3. Preparation of repair solution: Methyltrimethoxysilane, nano silica, graphene nanosheets, nano copper oxide antibacterial agent and polyethylene glycol are added to the reaction vessel in sequence. They are first mixed under low speed stirring, then ultrasonically dispersed, and finally stirred at high speed to obtain the repair solution.

[0073] A4. Assembly: First, inject the repair solution into the response membrane using a syringe. Then, seal the response membrane containing the repair solution. Next, place the response membrane containing the repair solution into an injection mold. Then, inject the well-mixed composite material from the twin-screw extruder into the mold, so that the composite material completely encapsulates the response membrane and the repair solution. Finally, cool and demold to obtain intelligent response self-healing particles.

[0074] In the outer shell preparation process, polycaprolactone particles and thermally expanded microspheres are added to a twin-screw extruder at a ratio of 9:1. The temperature settings of the twin-screw extruder from the feeding section to the die head are 140-160℃, 160-180℃, 180-200℃, and 170-190℃, with a screw speed of 120-160 rpm. The outer layer of particles is formed by injection molding, with an injection pressure of 100-140 MPa, an injection temperature of 170-200℃, and a die temperature of 40-50℃. The twin-screw extruder ensures that the polycaprolactone and thermally expanded microspheres are fully melted and mixed to form a homogeneous composite system. Injection molding ensures a dense outer layer structure and precise dimensions.

[0075] The high proportion of polycaprolactone particles ensures that the shape memory effect of the particles can play a role in a wider range of temperature or stress, so that the particles can trigger the repair mechanism in time when cracks occur. The low proportion of thermal expansion microspheres ensures that the particles are not too sensitive to small stress changes, avoiding over-triggering caused by excessive temperature or stress.

[0076] In the preparation of the responsive membrane, the concentration of the chitosan solution is 1%-2%, and the concentration of sodium alginate is 1.5%-2.5%. After the chitosan solution is slowly added dropwise to the sodium alginate solution, a magnetic stirrer is used to stir the solution at a speed of 300-500 rpm until the pH value is adjusted to 5.5-6.5. The solution is then poured into a mold and dried in an oven at 40-50℃ for 24-36 hours to form a polyelectrolyte composite smart responsive membrane. By controlling the solution concentration, stirring speed, and pH value, the degree of crosslinking and ion exchange capacity of the membrane are ensured.

[0077] The repair solution is prepared with the following mass fractions of components: 64.2%-67.2% methyltrimethoxysilane, 25% nano-silica, 2% graphene nanosheets, 0.8% nano-copper oxide antibacterial agent, and 5%-8% polyethylene glycol. After mixing, the components are first stirred at a low speed of 300-500 rpm for 10-15 minutes to achieve initial mixing. Then, they are ultrasonically dispersed for 40-60 minutes to refine the particle size and ensure uniform dispersion. Finally, they are stirred at a high speed of 1200-1800 rpm for 20-30 minutes to enhance the mixing effect and form a stable self-repairing solution.

[0078] S3. Preparation of Multifunctional Epoxy Adhesive: Pretreated nano-titanium dioxide and pretreated rubber elastomer particles are added to a two-component epoxy resin in a specific ratio and stirred. Specifically, the raw materials are first initially mixed by stirring at a low speed of 300-500 rpm for 10-15 minutes, and then stirred at a high speed of 800-1200 rpm for 20-30 minutes to ensure uniform dispersion. During this process, a curing agent is added and stirred to allow the curing agent to react with the epoxy resin, causing the epoxy groups to open and form a cross-linked network structure.

[0079] Specifically, in step S3, nano-titanium dioxide first needs to undergo pretreatment, and the pretreatment steps are as follows:

[0080] B1. Add nano-titanium dioxide powder to anhydrous ethanol to obtain a titanium dioxide suspension with a mass fraction of 10%-15%;

[0081] B2. The titanium dioxide suspension in B1 is dispersed by ultrasonic technology to obtain a uniformly mixed suspension. Ultrasonic dispersion can break the agglomeration of nano-titanium dioxide and make it uniformly dispersed in anhydrous ethanol.

[0082] B3. After centrifuging the uniformly mixed suspension in B2, remove the impurities in the supernatant and then precipitate to obtain high-purity titanium dioxide. The centrifugation and precipitation steps can be repeated multiple times to improve the purity of titanium dioxide and ensure that it can better exert its photocatalytic effect in epoxy adhesives, decompose organic matter on the road surface, and keep the road surface clean.

[0083] In step S3, the rubber elastomer particles need to undergo pretreatment, and the pretreatment steps are as follows:

[0084] C1. Rubber elastomer particles are cryogenically pulverized at low temperatures to obtain small rubber elastomer particles; cryogenic pulverization reduces the particle size of rubber elastomer particles, making it easier to disperse uniformly in epoxy adhesives.

[0085] C2. Toluene solution is added to small rubber elastomer particles, and then the mixture is stirred to obtain swollen rubber elastomer particles. After re-swelling, the rubber elastomer particles can increase the contact area and interaction with epoxy resin, thereby improving the toughness and impact resistance of the adhesive.

[0086] S4. Road paving material forming: First, lay composite mineral aggregate on the road surface, then evenly distribute intelligent responsive self-healing particles on the upper surface of the composite mineral aggregate, and compact them to embed the self-healing particles into the composite mineral aggregate; finally, spray multifunctional epoxy adhesive on the surface of the composite mineral aggregate with intelligent responsive self-healing particles.

[0087] Experimental comparison data with existing materials:

[0088]

[0089] Based on the above comparative analysis and experimental data, the pavement material of this invention demonstrates superior performance compared to existing thermosetting materials with self-healing particles in terms of self-healing properties, repair effect, water resistance, durability, UV resistance, and impact resistance. In particular, the material exhibits significant performance improvements in dual-trigger mechanism, repair effect stability, water resistance, and UV resistance, effectively extending the service life of the pavement and reducing long-term maintenance costs.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the design concept of the present invention should be included within the protection scope of the present invention.

Claims

1. A road paving material, characterized in that, The invention comprises composite mineral aggregate (1), smart responsive self-healing particles (3), and multifunctional epoxy adhesive (2). The smart responsive self-healing particles (3) are uniformly embedded on the upper surface of the layer formed by the composite mineral aggregate (1). The smart responsive self-healing particles (3) include a shell and a repair solution enclosed by the shell. A responsive membrane covering the inner side of the shell is disposed between the shell and the repair solution. The shell is made of shape memory polymer and thermally expandable microspheres. The responsive membrane is made of polyelectrolyte composite, which includes chitosan and sodium alginate. The repair solution includes methyltrimethoxysilane, nano-silica, graphene nanosheets, nano-copper oxide antibacterial agent, and polyethylene glycol; The composite mineral aggregate (1) includes basalt aggregate and carbon nanotubes dispersed in the basalt aggregate, and the surface of the basalt aggregate is coated with a silicon nitride nano-coating. The multifunctional epoxy adhesive (2) comprises a two-component epoxy resin, nano-titanium dioxide, and rubber elastomer particles.

2. The road paving material according to claim 1, characterized in that, The thermally expandable microspheres contain a low-boiling-point organic solvent with a particle size of 5-10 micrometers and a mass accounting for 10%-15% of the total mass of the outer shell.

3. The road paving material according to claim 1, characterized in that, The shape memory polymer is made of polycaprolactone.

4. A method for preparing road paving material, used to prepare the road paving material according to any one of claims 1-3, characterized in that, The steps are as follows: S1. Preparation of composite mineral aggregate: Basalt aggregate A with a particle size of 5-10 mm and basalt aggregate B with a particle size of 10-20 mm are selected and mixed to obtain basalt aggregate. Then, silicon nitride nano-coating is formed on the surface of the mixed basalt aggregate by vapor deposition technology. Finally, it is mixed with carbon nanotubes to obtain composite mineral aggregate. S2. Preparation of intelligent response self-healing particles: The repair solution is injected into the space of the response membrane, and then the shell is wrapped around the outside of the response membrane through injection molding to obtain complete intelligent response self-healing particles. S3. Preparation of multifunctional epoxy adhesive: Nano-titanium dioxide and rubber elastomer particles are added to a two-component epoxy resin in a certain proportion and stirred, and a curing agent is added during the process; S4. Road paving material forming: First, lay composite mineral aggregate on the road surface, then evenly distribute intelligent responsive self-healing particles on the upper surface of the composite mineral aggregate, and compact them to embed the self-healing particles into the composite mineral aggregate; finally, spray multifunctional epoxy adhesive on the surface of the composite mineral aggregate with intelligent responsive self-healing particles.

5. The method for preparing road paving material according to claim 4, characterized in that, The specific preparation steps for step S2 are as follows: A1. Shell preparation: Polycaprolactone particles and thermally expanded microspheres are added to a twin-screw extruder for melt mixing to obtain a composite material; A2. Preparation of responsive membrane: Chitosan solution is slowly added dropwise to sodium alginate solution, and then stirred with a magnetic stirrer to obtain a mixed solution. The mixed solution is then poured into a mold and placed in an oven to dry to form a polyelectrolyte composite smart responsive membrane. Finally, it is cut into a suitable size to obtain the responsive membrane. A3. Preparation of repair solution: Methyltrimethoxysilane, nano silica, graphene nanosheets, nano copper oxide antibacterial agent and polyethylene glycol are added to the reaction vessel in sequence. They are first mixed under low speed stirring, then ultrasonically dispersed, and finally stirred at high speed to obtain the repair solution. A4. Assembly: First, inject the repair solution into the response membrane using a syringe. Then, seal the response membrane containing the repair solution. Next, place the response membrane containing the repair solution into an injection mold. Then, inject the well-mixed composite material from the twin-screw extruder into the mold, so that the composite material completely encapsulates the response membrane and the repair solution. Finally, cool and demold to obtain intelligent response self-healing particles.

6. The method for preparing road paving material according to claim 5, characterized in that, In step S3, the nano-titanium dioxide first needs to undergo pretreatment, and the pretreatment steps are as follows: B1. Add nano-titanium dioxide powder to anhydrous ethanol to obtain a titanium dioxide suspension; B2. The titanium dioxide suspension in B1 is dispersed by ultrasonic technology to obtain a uniformly mixed suspension; B3. After centrifuging the uniformly mixed suspension in B2, remove the impurities in the supernatant and then precipitate to obtain high-purity titanium dioxide.

7. The method for preparing road paving material according to claim 6, characterized in that, In step S3, the rubber elastomer particles need to undergo pretreatment, and the pretreatment steps are as follows: C1. Small rubber elastomer particles are obtained by cryogenically pulverizing rubber elastomer particles at low temperature. C2. Add toluene solution to small rubber elastomer particles, and then stir with a stirrer to obtain swollen rubber elastomer particles.

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