A thin-wearing-layer asphalt concrete and a method for producing the same

Abstract

This application relates to a thin-layer wear-resistant asphalt concrete and its preparation method, belonging to the field of asphalt concrete technology. It includes modified asphalt, coarse aggregate, fine aggregate, mineral powder, an interfacial active primer, and a dynamic toughening crosslinking agent. The interfacial active primer constructs a covalent anchoring layer and catalytic microdomains on the aggregate surface, guiding the dynamic toughening crosslinking agent to undergo a gradient crosslinking reaction in the asphalt mixture. This results in a high-modulus "hard shell" at the aggregate interface while maintaining a flexible "soft core" in the asphalt matrix. This structure eliminates the weak interfacial regions of traditional materials, optimizing stress transfer and improving load-bearing efficiency, thus significantly reducing the surface layer thickness. Simultaneously, the reversible exchange capacity of the dynamic covalent bonds in the crosslinking network under the action of the catalyst endows the material with microscopic self-adaptive functions, effectively inhibiting the initiation and propagation of microcracks, thereby simultaneously enhancing wear resistance while reducing the thickness.

Description

Technical Field

[0001] This application relates to the field of asphalt concrete technology, specifically to a thin-wearing-layer asphalt concrete and its preparation method. Background Technology

[0002] With the acceleration of urbanization and the continuous growth of traffic load, road engineering faces multiple challenges, including extending service life, reducing maintenance costs, and mitigating environmental burden. Against this backdrop, ultra-thin wearing course technology has become an important development direction for preventative pavement maintenance and surface optimization of new roads due to its ability to efficiently repair pavement defects, reduce material consumption, and minimize traffic disruption during construction. An ideal ultra-thin wearing course must possess excellent wear resistance, skid resistance, crack resistance, and durability while significantly reducing thickness, which places extremely high demands on the material design and preparation process of asphalt concrete.

[0003] Currently, existing technologies for reducing the thickness and improving the performance of asphalt concrete pavements mainly focus on the following aspects: First, using high-viscosity modified asphalt (such as high-content SBS modified asphalt or rubber asphalt) to enhance the bonding strength and toughness of the binder itself; second, optimizing aggregate gradation and designing a dense or discontinuous gradation structure to enhance the internal interlocking and stability of the mixture; and third, adding physical reinforcing fibers (such as polyester fibers or mineral fibers) or rigid particles (such as ceramic particles) to improve the crack resistance and wear resistance of the mixture. In addition, some studies have also explored using high-modulus asphalt concrete or special paving and compaction processes to ensure the load-bearing capacity of thin-layer structures. However, these methods primarily focus on improving the macroscopic structure of the asphalt matrix or mixture, failing to fundamentally address the strengthening of the weak link—the asphalt-aggregate interface. Insufficient interfacial bonding easily leads to aggregate spalling under the coupled effects of load and environment, resulting in early damage. This poses a severe challenge to the long-term durability and wear resistance of traditional thin-layer structures when subjected to heavy traffic or harsh environments.

[0004] Therefore, it is of great significance to develop an asphalt concrete with reduced surface layer thickness and excellent wear resistance. Summary of the Invention

[0005] This application provides a thin-layer asphalt concrete with wear resistance and its preparation method, which has the effect of reducing the surface layer thickness while maintaining excellent wear resistance.

[0006] Firstly, this application provides a thin-wearing-layer asphalt concrete solution using the following technical solution: A thin-wearing-layer asphalt concrete, characterized in that it is composed of the following components in parts by weight: 50-65 parts modified asphalt, 450-520 parts coarse aggregate, 320-380 parts fine aggregate, 70-90 parts mineral powder, 1.5-3.0 parts interface-active primer, and 7.5-16.5 parts dynamic toughening crosslinking agent. The dynamic toughening crosslinking agent can form a dynamic covalent network structure in the system. The β-hydroxy ester bond content in the network structure accounts for more than 60% of the total ester bonds. Under the catalysis of the component, a reversible transesterification reaction can occur at temperatures above 80°C.

[0007] By employing the above technical solution, the high proportion of β-hydroxy ester bonds provides a stable cross-linking strength and rigidity foundation for the network, ensuring the initial mechanical support required for the thin-layer structure. The dynamic reversibility of the network is key to achieving performance improvement. When the road surface temperature reaches or exceeds 80°C (e.g., under conditions of high summer temperatures or localized heating caused by traffic loads), the components can catalyze reversible exchange reactions of the ester bonds in the network. This dynamic recombination capability allows the material to dissipate energy through the breaking and reconstruction of internal chemical bonds when under stress, thereby effectively inhibiting the initiation and propagation of microcracks and enhancing the wear resistance and long-term durability of the thin wear layer.

[0008] Optionally, the method for preparing the interfacial active primer includes the following steps: S1. By weight, take 92-95 parts of anhydrous ethanol, 4-6 parts of KH-550 silane coupling agent, and 1-2 parts of nano zinc oxide. S2. Vacuum dry the nano zinc oxide at 110-120℃ for 2-3 hours; S3. At 25±5℃, add anhydrous ethanol to the stirred tank and stir at 200-300 rpm. Add KH-550 silane coupling agent and stir for 10-20 min. S4. Add the dried nano zinc oxide and ultrasonically disperse for 30-60 minutes; S5. After ultrasonic dispersion, continue mechanical stirring for 10-20 minutes to obtain a uniform suspension and obtain an interfacial active primer.

[0009] By employing the above technical solution, the vacuum drying of nano-zinc oxide in step S2 removes the physically adsorbed moisture on the surface of the nanoparticles, effectively inhibiting uncontrollable hard agglomeration due to high surface energy in subsequent organic solvents. This creates conditions for achieving nanoscale dispersion in the liquid phase. In step S3, KH-550 silane coupling agent is dissolved in anhydrous ethanol under low temperature and anhydrous conditions to ensure that the silane coupling agent maintains its chemical structure integrity and reactivity, avoiding pre-hydrolysis and deactivation or self-condensation of its ethoxy groups in the presence of water molecules, thereby ensuring effective chemical anchoring with the aggregate surface during application. The subsequent step S4 achieves uniform distribution of nano-zinc oxide in the liquid phase, which is crucial for maximizing the exposure of catalytic active sites.

[0010] The final product is a homogeneous suspension with a highly dispersed solid phase and well-preserved chemical activity of each component. This not only ensures the storage stability and redispersibility of the primer product itself during application, but more importantly, when applied to the surface of high-temperature aggregates, the solvent flash evaporation leaves behind an ultra-thin functional coating with uniformly distributed nanocatalysts and densely packed and intact silane coupling agent active sites. This lays a crucial material and structural foundation for the subsequent efficient, interface-catalyzed chemical crosslinking reaction with the dynamic toughening crosslinking agent in the asphalt phase.

[0011] Optionally, the method for preparing the dynamic toughening crosslinking agent includes the following steps: S1. By weight, take 30-40 parts of epoxidized soybean oil, 25-35 parts of E-51 epoxy resin, 20-30 parts of dimer acid, and 0.5-1.5 parts of zinc acetylacetonate. S2. Dehydrate the dimer acid under vacuum at 90-100℃ for 1-2 hours until the moisture content is less than 0.1%; S3. Add epoxidized soybean oil and E-51 epoxy resin to the reactor, and heat to 75-85℃ at 1.5-2.5℃ / min under nitrogen protection. S4. Increase the temperature to 110-130℃ at a rate of 1-2℃ / min, maintain the temperature for 90-120min, until the epoxy value drops to 60-70% of the initial value; S5. Cool down to 95-105℃, and add the dehydrated dimer acid dropwise at a rate of 0.5-1.5 parts / min. S6. After the addition is complete, raise the temperature to 110-130℃ and continue the reaction for 60 minutes until the acid value drops to 10-15 mg KOH / g. S7. Cool to 75-85℃, add zinc acetylacetone, stir for 30-40 minutes and then discharge to obtain a dynamic toughening crosslinking agent.

[0012] By employing the above technical solution, the dimer acid undergoes deep vacuum dehydration in step S2 to eliminate free water from the raw material. Water can not only interfere with stoichiometric equilibrium in the subsequent high-temperature esterification reaction, but also easily lead to unexpected hydrolysis side reactions of the epoxy groups, generating inactive diols, thereby directly affecting the formation efficiency of the target β-hydroxy ester bond and the purity of the final product.

[0013] The synthesis process (S3 to S6) employs stepwise temperature control and sequential feeding. First, the pre-mild reaction of the epoxy component (S4) forms a prepolymer with a certain molecular weight and uniform distribution of epoxy groups. This lays a controllable foundation for the subsequent chain extension reaction with dimer acid, effectively avoiding the risks of excessively rapid reaction, concentrated exothermic reaction, and localized gelation that may result from mixing all raw materials at once.

[0014] Subsequently, under strict control of the dropping rate, dehydrated dimer acid (S5) was introduced, and the isothermal reaction continued (S6) to ensure that the carboxyl and epoxy groups could react fully and slowly, maximizing the generation of β-hydroxy ester bonds necessary for building the dynamic network. At the same time, by precisely controlling the acid value to a low position, the main reaction was basically completed, and a chemically stable intermediate product was obtained.

[0015] Step S7 involves adding the catalyst zinc acetylacetone at a lower temperature. Physically isolating the catalyst introduction from the high-temperature synthesis stage effectively prevents the zinc catalyst from prematurely and excessively catalyzing the dynamic exchange reaction of the already formed ester bonds under the high-temperature environment of the synthesis reactor. This avoids uncontrolled molecular weight growth or pre-gelling of the product before it leaves the factory, ensuring the storage stability and workability of the crosslinking agent during storage and transportation. Its preset dynamic catalytic activity is locked until it is released and activated under the high-temperature conditions of asphalt concrete construction and use.

[0016] Optionally, the dynamic toughening crosslinking agent has a viscosity of 500-1000 mPa·s at 80°C, an epoxy value of 0.15-0.25 eq / 100g, and a gel time of 45-90 min at 170°C.

[0017] By adopting the above technical solution, the viscosity of 500-1000 mPa·s at 80℃ ensures that the component has good fluidity during preheating and metering, enabling smooth pumping and efficient initial mixing with high-temperature asphalt, and avoiding uneven dispersion or construction resistance caused by excessive viscosity.

[0018] The epoxy value of 0.15-0.25 eq / 100g quantitatively defines the reactivity of the component. This moderate epoxy group content is the material basis for building a chemical cross-linking network. It can provide sufficient reaction sites to cross-link with the functional groups on the surface of the interface-treated aggregate and other components to form a stable covalent network skeleton. It also avoids the increase in material brittleness due to excessive cross-linking points, thus enhancing strength while retaining the necessary toughness.

[0019] The gelation time of 45-90 minutes at 170℃ provides ample time for mixing, transporting, paving and compacting of asphalt mixtures containing this crosslinking agent, ensuring construction feasibility.

[0020] Optionally, the modified asphalt is SBS modified asphalt, and the SBS content is 3-5% of the asphalt mass.

[0021] By adopting the above technical solution, within this dosage range, SBS can be fully dispersed in asphalt and form a physical cross-linked network under suitable processes, thereby improving the high-temperature elastic recovery and low-temperature toughness of asphalt binders, while also enhancing their adhesion to aggregates. This modification directly translates into improved overall performance of asphalt concrete, which is beneficial for enhancing the wear resistance of thin wearing courses.

[0022] Optionally, the coarse aggregate is basalt or diabase with a particle size of 4.75-13.2 mm.

[0023] By adopting the above technical solution and selecting basalt or diabase, which are inherently high-strength and highly wear-resistant stones, the inherent ability of aggregate particles to resist crushing and abrasion is ensured. The upper limit of the coarse aggregate particle size is explicitly limited to 13.2 mm, which matches the typically thinned design depth of only 1.5-3.0 cm for thin abrasion layers. This allows for the formation of a tightly interlocked skeletal structure within a limited paving thickness, providing primary mechanical support and stability.

[0024] Meanwhile, this coarse aggregate skeleton also creates an ideal physical substrate for the chemical reinforcement system (i.e., the interfacial active primer and the dynamic toughening crosslinking agent) in the scheme. The aggregate surface can be more effectively modified at the interface, thereby promoting a stronger synergy between the chemically reinforced "interfacial strengthening layer" and the physically stable "mineral skeleton", jointly ensuring that the thinned pavement structure has excellent overall stiffness and wear resistance.

[0025] Optionally, the fine aggregate is manufactured limestone sand with a particle size of 0.075-4.75 mm.

[0026] By adopting the above technical solution, the good adhesion between limestone manufactured sand and asphalt helps to enhance the interfacial bonding force between asphalt mastic and aggregates, thereby improving the integrity and water damage resistance of the mixture. Secondly, the particle size range covering from filler to smaller stones can effectively fill the voids between coarse aggregate skeletons, forming a dense and stable skeleton-dense structure.

[0027] Meanwhile, the multi-faceted nature and rough surface texture of manufactured sand, formed during the production process, further enhance the interlocking and internal friction resistance between aggregate particles, which enables the mixture to maintain high structural stability and wear resistance even under thin-layer paving conditions.

[0028] Optionally, the mineral powder is a limestone mineral filler with a particle size ≤0.075mm.

[0029] By employing the above technical solutions, limestone mineral fillers, due to their surface chemical properties, typically exhibit good affinity with asphalt, which is beneficial for forming stable asphalt mortar. Their particle size range ensures that the filler has a sufficiently large specific surface area, allowing it to be fully coated by asphalt and uniformly dispersed during mixing, thus filling the gaps in the aggregate skeleton and increasing the material's density. In applications such as thin wearing courses, where structural homogeneity is extremely important, this ultrafine and well-defined mineral powder helps optimize the gradation of the mixture, forming a denser microstructure, thereby providing the surface layer with solid matrix strength, good compaction, and wear resistance.

[0030] Secondly, this application provides a method for preparing thin-wearing asphalt concrete, comprising the following steps: S1. Dry the coarse and fine aggregates at 100-110℃ for 3-4 hours until the moisture content is <0.3%, and dry the mineral powder at 90-100℃ for 2-3 hours until the moisture content is <0.5%. S2. Preheat the dried coarse and fine aggregates to 120±5℃; S3. Add the preheated aggregate to the mixing equipment, and spray the interface active primer with atomized spray under the stirring condition of 30-40 rpm. The spraying pressure is 0.3-0.5 MPa and the spraying time is 30-40 s. After spraying, continue to dry mix for 60-80 s. S4. Add modified asphalt at 165±5℃ and dynamic toughening crosslinking agent preheated at 80±5℃ to the mixing equipment, and add mineral powder at the same time. Mix at 40-50 rpm for 90-100 seconds at 170±5℃. S5. Seal and keep the mixture at 170-180℃ for 30-40 minutes. S6. Pave at 155-165℃, initial compaction temperature 140-150℃, secondary compaction temperature 130-140℃, and final compaction temperature 110-120℃. S7. Obtain a thin-wearing asphalt concrete layer after the road surface temperature drops below 50°C or at least 2 hours after paving.

[0031] By employing the above technical solution, under strict drying and preheating of the aggregate (S1) and mineral powder (S2), free moisture that affects adhesion is removed, allowing the aggregate to obtain a uniform and suitable temperature, creating a dry, hot, and highly active surface for subsequent interface modification. When the atomized interface-active primer is sprayed onto this surface (S3), its low-boiling-point solvent evaporates rapidly, forcing the effective components in the primer (such as coupling agents and catalysts) to adhere directly and tightly to the aggregate, thus laying the physical and chemical foundation for constructing a reinforced interface layer.

[0032] In the hot mixing stage (S4), the dynamic toughening crosslinking agent is preheated and added together with the high-temperature asphalt. This serves two purposes: first, it reduces the viscosity of the crosslinking agent, ensuring that it can be quickly and uniformly dispersed in the asphalt phase during the mixing process; second, it utilizes the mixing temperature to provide the necessary activation energy for the pre-set chemical reaction (ring-opening esterification of epoxy and carboxyl groups) in the crosslinking agent, thus initiating the crosslinking network construction process in the aggregate interface and the asphalt matrix.

[0033] The subsequent sealing and insulation step (S5) provides the necessary temperature and time conditions for the full development and curing of the dynamic covalent network (especially the high proportion of β-hydroxy ester bonds). This strengthens and stabilizes the bonding at the interface and the network structure of the bulk, thereby transforming the chemical potential initiated during mixing into the final physical properties of the concrete.

[0034] Finally, the temperature control procedures (S6, S7) from paving to opening follow the construction rules of hot-mix asphalt mixtures while taking into account the characteristics of the new material system. The stepped decreasing compaction temperature ensures the compactability of the mixture while effectively avoiding structural damage caused by excessive rolling; while the cooling and opening conditions ensure that the material can withstand traffic loads only after it has acquired sufficient initial structural strength, thus guaranteeing construction quality and early durability.

[0035] In summary, this application includes at least one of the following beneficial technical effects: 1. By constructing a covalent anchoring layer and catalytic microregions on the aggregate surface using an interfacial active primer, a gradient crosslinking reaction of the dynamic toughening crosslinking agent is guided within the asphalt mixture. This results in a high-modulus "hard shell" at the aggregate interface and a flexible "soft core" within the asphalt matrix. This structure eliminates the weak interfacial regions of traditional materials, optimizing stress transfer and improving load-bearing efficiency, thus significantly reducing the surface layer thickness. Simultaneously, the reversible exchange capacity of the dynamic covalent bonds (ester bonds) in the crosslinking network under the action of the catalyst endows the material with microscopic self-adaptive capabilities. Energy can be dissipated at stress concentration points through bond breakage and recombination, effectively inhibiting the initiation and propagation of microcracks, thereby simultaneously enhancing wear resistance while reducing the thickness of the surface layer. Detailed Implementation

[0036] Preparation Example 1 The preparation method of the surfactant primer includes the following steps: S1. Vacuum dry the nano zinc oxide at 120℃ for 2 hours until the moisture content is reduced to below 0.2%; S2. At 25°C, 94 parts of anhydrous ethanol were added to a stainless steel stirred tank. S3. Start the stirrer, set the speed to 250 rpm, and slowly add 5 parts of KH-550 silane coupling agent; S4. Continue stirring for 15 minutes until completely dissolved; S5. Add 1 part of dried nano zinc oxide; S6. Turn on the ultrasonic disperser, set the power to 500W and the frequency to 30kHz, and ultrasonically disperse for 45 minutes. S7. After ultrasonic dispersion, continue mechanical stirring (150 rpm) for 15 minutes; S8. Obtain a uniform milky white suspension, seal and store for later use.

[0037] Preparation Example 2 The difference between the surfactant primer and the preparation example 1 is that... S1. Vacuum dry the nano zinc oxide at 115℃ for 2.5 hours; S2. At 28°C, 92 parts of anhydrous ethanol were added to the stirred tank. S3. Stir at 300 rpm, add 6 parts of KH-550, and stir for 10 minutes; S5. Add 2 parts of dried nano zinc oxide; S6. Ultrasonic dispersion for 30 minutes (power 450W, frequency 28kHz). S7. Stir mechanically for 20 minutes.

[0038] Preparation Example 3 The difference between the surfactant primer and the preparation example 1 is that... S1. Vacuum dry the nano zinc oxide at 110℃ for 3 hours; S2. At 22°C, 95 parts of anhydrous ethanol were added to the stirred tank. S3. Stir at 200 rpm, add 4 parts of KH-550, and stir for 20 minutes; S5. Add 1 part of dried nano zinc oxide; S6. Ultrasonic dispersion for 60 minutes (power 550W, frequency 32kHz). S7. Mechanically stir for 10 minutes.

[0039] Preparation Example 4 The difference between the surface-active primer and the preparation example 1 is that the ultrasonic dispersion step is omitted and replaced with mechanical stirring (500 rpm) for 120 minutes.

[0040] Preparation Example 5 The difference between the interfacial active primer and the preparation example 1 is that undried nano zinc oxide is used instead of dried nano zinc oxide.

[0041] Preparation Example 6 The difference between the surface-active primer and the preparation example 1 is that KH-560 (γ-glycidoxypropyltrimethoxysilane) is used instead of KH-550.

[0042] Preparation Example 7 The preparation method of the dynamic toughening crosslinking agent includes the following steps: S1. The dimer acid was dehydrated under vacuum at 100°C for 1.5 hours until the moisture content was reduced to 0.08%. S2. Add 35 parts of ESO and 30 parts of E-51 epoxy resin to a four-necked reactor. S3. Introduce nitrogen for protection (0.5 L / min) and raise the temperature to 80 °C at a rate of 2 °C / min; S4. Increase the temperature to 120℃ at a rate of 1.5℃ / min, maintain the temperature for 100 minutes, and monitor the epoxy value until it drops to 65% of the initial value; S5. Cool down to 100℃ and add 25 parts of dehydrated dimer acid dropwise at a rate of 1 part / min. S6. After the addition is complete, raise the temperature to 120℃ and continue the reaction for 60 minutes. Monitor the acid value and wait for it to drop to 12 mg KOH / g. S7. Heat to 80℃, add 1 part of zinc acetylacetone, and stir for 35 minutes; S8. Discharge and seal for storage.

[0043] Preparation Example 8 The dynamic toughening crosslinking agent differs from that in Preparation Example 7 in that... S1, dimer acid was dehydrated under vacuum at 95°C for 2 hours; S3, ESO and E-51 are heated to 85°C; S4. Increase the temperature to 125℃ at 2℃ / min and react for 90 minutes (epoxy value drops to 70%). S5. Cool down to 105℃ and add dimer acid dropwise (0.8 parts / min). S6. Heat to 125℃ and react for 60 minutes (acid value 10mg KOH / g). S7. Cool down to 85℃, add catalyst and stir for 40 minutes.

[0044] Preparation Example 9 The dynamic toughening crosslinking agent differs from that in Preparation Example 7 in that... S1, dimer acid was dehydrated under vacuum at 105℃ for 1 hour; S3, ESO and E-51 are heated to 75°C; S4. Increase the temperature to 115℃ at a rate of 1℃ / min and react for 120 minutes (epoxy value drops to 60%). S5. Cool down to 95℃ and add dimer acid dropwise (1.2 parts / min). S6. Heat to 115℃ and react for 60 minutes (acid value 15mg KOH / g). S7. Cool down to 75°C, add catalyst and stir for 30 minutes.

[0045] Preparation Example 10 The dynamic toughening crosslinking agent differs from that in Preparation Example 7 in that all raw materials (35 parts ESO, 30 parts E-51, 25 parts dimer acid, and 1 part zinc acetylacetonate) are added to the reactor at once, reacted at 120°C for 180 minutes, and then cooled and discharged.

[0046] Preparation Example 11 The dynamic toughening crosslinking agent differs from that in Preparation Example 7 in that 1 part of dibutyltin dilaurate is used instead of zinc acetylacetonate.

[0047] Preparation Example 12 The dynamic toughening crosslinking agent differs from that in Preparation Example 7 in that no catalyst is added.

[0048] Example 1 A thin-wearing asphalt concrete is composed of the following components in parts by weight: 60 parts modified asphalt, 480 parts coarse aggregate, 360 parts fine aggregate, 80 parts mineral powder, 1.7 parts interface active primer, and 12 parts dynamic toughening crosslinking agent. Specifically, the interfacial active primer was obtained using Preparation Example 1; the dynamic toughening crosslinking agent was obtained using Preparation Example 7, with a viscosity of 500-1000 mPa·s at 80℃, an epoxy value of 0.15-0.25 eq / 100g, and a gel time of 45-90 min at 170℃; the modified asphalt was SBS modified asphalt, with an SBS content of 4% of the asphalt mass; the coarse aggregate was basalt or diabase with a particle size of 4.75-13.2 mm; the fine aggregate was limestone manufactured sand with a particle size of 0.075-4.75 mm; and the mineral powder was limestone mineral filler with a particle size ≤0.075 mm.

[0049] A thin-wearing-layer asphalt concrete, the preparation method includes the following steps: S1. Dry the coarse and fine aggregates at 105℃ for 3.5 hours until the moisture content is 0.22%, and dry the mineral powder at 100℃ for 2.5 hours until the moisture content is 0.35%. S2. Preheat the dried aggregate to 120℃; S3. Add the preheated aggregate to a small laboratory forced mixer and stir at 35 rpm. Spray the interface active primer with atomized spray (spray pressure 0.4 MPa, time 35 seconds) and continue to dry mix for 75 seconds. S4. Add modified asphalt at 165℃ and dynamic toughening crosslinking agent preheated at 85℃, and add mineral powder at the same time. S5. Mix at 170℃ and 45rpm for 95 seconds; S6. Place the mixture into a sealed container and keep it at 175℃ for 35 minutes; S7. Mold the specimen at 160℃.

[0050] Example 2 A thin-wearing asphalt concrete differs from Example 1 in that it is composed of the following components in parts by weight: 55 parts modified asphalt, 500 parts coarse aggregate, 350 parts fine aggregate, 85 parts mineral powder, 2 parts interface-active primer, and 8.5 parts dynamic toughening crosslinking agent.

[0051] Example 3 A thin-wearing asphalt concrete differs from Example 1 in that it is composed of the following components in parts by weight: 65 parts modified asphalt, 460 parts coarse aggregate, 370 parts fine aggregate, 75 parts mineral powder, 1.5 parts interface-active primer, and 16 parts dynamic toughening crosslinking agent.

[0052] Example 4 A thin-wearing asphalt concrete differs from Example 1 in that it uses an interfacial active primer obtained in Preparation Example 2 and a dynamic toughening crosslinking agent obtained in Preparation Example 8.

[0053] Example 5 A thin-wearing asphalt concrete differs from Example 1 in that it uses an interfacial active primer obtained in Preparation Example 3 and a dynamic toughening crosslinking agent obtained in Preparation Example 9.

[0054] Comparative Example 1 A thin-wearing asphalt concrete differs from Example 1 in that it specifically uses the preparation example 4 to obtain the interfacial active primer.

[0055] Comparative Example 2 A thin-wearing asphalt concrete differs from Example 1 in that it specifically uses the interfacial active primer obtained in Preparation Example 5.

[0056] Comparative Example 3 A thin-wearing asphalt concrete differs from Example 1 in that it specifically uses the interfacial active primer obtained in Preparation Example 6.

[0057] Comparative Example 4 A thin-wearing asphalt concrete differs from Example 1 in that it specifically uses the dynamic toughening crosslinking agent obtained in Preparation Example 10.

[0058] Comparative Example 5 A thin-wearing asphalt concrete differs from Example 1 in that it specifically uses the dynamic toughening crosslinking agent obtained in Preparation Example 11.

[0059] Comparative Example 6 A thin-wearing asphalt concrete differs from Example 1 in that it specifically uses the dynamic toughening crosslinking agent obtained in Preparation Example 12.

[0060] Comparative Example 7 A thin-wearing asphalt concrete differs from Example 1 in that it uses only the interfacial active primer obtained in Preparation Example 1 without adding a dynamic toughening crosslinking agent.

[0061] Comparative Example 8 A thin-wearing asphalt concrete differs from Example 1 in that it uses only the dynamic toughening crosslinking agent obtained in Preparation Example 7, without adding an interfacial active primer.

[0062] Detection example The shear strength, bond strength, permeability coefficient, and abrasion resistance (mass loss rate) of asphalt concrete were tested in accordance with JTG 3410-2025 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering". The repair strength recovery rate was tested by a three-point bending fatigue test on a beam. A small beam specimen (250×50×35mm) was fabricated and rotary compacted. Three-point bending was performed with a span of 200mm and a loading rate of 50mm / min, recording the failure strength σ0. A cyclic load of 0.7σ0 (10Hz) was applied until a 0.5mm wide crack appeared. The specimen was then placed in an oven at 80±1℃ for 24 hours. The failure strength σ1 was tested under the same conditions. The repair strength recovery rate (%) was calculated as σ1 / σ0 × 100%. The specific test results are shown in Tables 1 and 2.

[0063] Table 1

[0064] Table 2

[0065] The performance test data from Examples 1-5 and Comparative Examples 1-3 show that the preparation process of the interfacial active primer has a significant impact on the final road performance. Ultrasonic dispersion ensures uniform dispersion of nano-zinc oxide, forming a stable suspension, thereby creating a continuous and uniform catalytic interface layer on the aggregate surface. In Comparative Example 1 (without ultrasonic dispersion), the nano-zinc oxide severely agglomerates, resulting in uneven distribution of interfacial catalytic points, incomplete interfacial reactions, and a decline in various performance characteristics. In Comparative Example 2 (using undried nano-zinc oxide), moisture interferes with the hydrolysis-condensation process of the silane coupling agent, and the agglomeration of nanoparticles intensifies, leading to interfacial adhesion and catalytic failure. Although Comparative Example 3 (using KH-560) exhibits good dispersibility, the difference in functional groups (difference between epoxy and amino groups) reduces the reactivity with the epoxy groups in the dynamic toughening crosslinking agent, resulting in insufficient interfacial chemical bonding strength and limited performance improvement.

[0066] The performance test data from Examples 1-5 and Comparative Examples 4-6 show that the prepolymerization step of the dynamic toughening crosslinking agent is the key to controlling the molecular structure, ensuring the construction window, and final performance. Although Comparative Example 4 (skipping prepolymerization) has a low initial viscosity, making it easy to mix, its small molecular weight and excessive reactivity lead to over-crosslinking during mixing and transportation, resulting in difficult construction and brittle final material. Comparative Example 5 (using different catalysts) has insufficient transesterification catalytic activity, weak dynamic network recombination ability, and reduced repair performance. Comparative Example 6 (without catalyst) can hardly form an effective dynamic covalent network, and the material lacks repair ability.

[0067] The performance test data from Examples 1 and Comparative Examples 7-8 show that the technical effect of this invention can only be achieved by using the interfacial active primer and the dynamic toughening crosslinking agent in synergy. Comparative Example 7 formed a good anchoring layer on the aggregate surface, but lacked a reinforcing network penetrating the asphalt matrix, resulting in limited improvement in overall material performance, especially insufficient shear strength and repair capacity. Comparative Example 8 formed a dynamic network in the asphalt, but lacked strong chemical bonding with the aggregate, making the interface a weak link that was prone to peeling under shear and water damage. Only by using both in synergy can the integrated reinforcement effect of "strong interfacial anchoring + strong matrix toughening" be achieved.

[0068] The performance test data from Examples 1-5 show that, within the scope of the claims of this invention, adjusting the proportions of each component can yield better performance of asphalt concrete.

[0069] Please note that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The above embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A thin-wearing-coat asphalt concrete, characterized in that, It is composed of the following components in parts by weight: 50-65 parts modified asphalt, 450-520 parts coarse aggregate, 320-380 parts fine aggregate, 70-90 parts mineral powder, 1.5-3.0 parts interface active primer, and 7.5-16.5 parts dynamic toughening crosslinking agent. The dynamic toughening crosslinking agent can form a dynamic covalent network structure in the system. The β-hydroxy ester bond content in the network structure accounts for more than 60% of the total ester bonds. Under the catalysis of the component, a reversible transesterification reaction can occur at temperatures above 80°C.

2. The thin-wearing-coat asphalt concrete according to claim 1, characterized in that, The method for preparing the interface-active primer includes the following steps: S1. By weight, take 92-95 parts of anhydrous ethanol, 4-6 parts of KH-550 silane coupling agent, and 1-2 parts of nano zinc oxide. S2. Vacuum dry the nano zinc oxide at 110-120℃ for 2-3 hours; S3. At 25±5℃, add anhydrous ethanol to the stirred tank and stir at 200-300 rpm. Add KH-550 silane coupling agent and stir for 10-20 min. S4. Add the dried nano zinc oxide and ultrasonically disperse for 30-60 minutes; S5. After ultrasonic dispersion, continue mechanical stirring for 10-20 minutes to obtain a uniform suspension and obtain an interfacial active primer.

3. The thin-wearing-coat asphalt concrete according to claim 1, characterized in that, The method for preparing the dynamic toughening crosslinking agent includes the following steps: S1. By weight, take 30-40 parts of epoxidized soybean oil, 25-35 parts of E-51 epoxy resin, 20-30 parts of dimer acid, and 0.5-1.5 parts of zinc acetylacetonate. S2. Dehydrate the dimer acid under vacuum at 90-100℃ for 1-2 hours until the moisture content is less than 0.1%; S3. Add epoxidized soybean oil and E-51 epoxy resin to the reactor, and heat to 75-85℃ at 1.5-2.5℃ / min under nitrogen protection. S4. Increase the temperature to 110-130℃ at a rate of 1-2℃ / min, maintain the temperature for 90-120min, until the epoxy value drops to 60-70% of the initial value; S5. Cool down to 95-105℃, and add the dehydrated dimer acid dropwise at a rate of 0.5-1.5 parts / min. S6. After the addition is complete, raise the temperature to 110-130℃ and continue the reaction for 60 minutes until the acid value drops to 10-15 mg KOH / g. S7. Cool to 75-85℃, add zinc acetylacetone, stir for 30-40 minutes and then discharge to obtain a dynamic toughening crosslinking agent.

4. The thin-wearing-coat asphalt concrete according to claim 1, characterized in that, The dynamic toughening crosslinking agent has a viscosity of 500-1000 mPa·s at 80℃, an epoxy value of 0.15-0.25 eq / 100g, and a gel time of 45-90 min at 170℃.

5. The thin-wearing-coat asphalt concrete according to claim 1, characterized in that, The modified asphalt is SBS modified asphalt, and the SBS content is 3-5% of the asphalt mass.

6. The thin-wearing-coat asphalt concrete according to claim 1, characterized in that, The coarse aggregate is basalt or diabase with a particle size of 4.75-13.2 mm.

7. The thin-wearing-coat asphalt concrete according to claim 1, characterized in that, The fine aggregate is manufactured limestone sand with a particle size of 0.075-4.75 mm.

8. The thin-wearing-coat asphalt concrete according to claim 1, characterized in that, The mineral powder is a limestone mineral filler with a particle size ≤0.075mm.

9. The method for preparing thin-wearing asphalt concrete according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Dry the coarse and fine aggregates at 100-110℃ for 3-4 hours until the moisture content is <0.3%, and dry the mineral powder at 90-100℃ for 2-3 hours until the moisture content is <0.5%. S2. Preheat the dried coarse and fine aggregates to 120±5℃; S3. Add the preheated aggregate to the mixing equipment, and spray the interface active primer with atomized spray under the stirring condition of 30-40 rpm. The spraying pressure is 0.3-0.5 MPa and the spraying time is 30-40 s. After spraying, continue to dry mix for 60-80 s. S4. Add modified asphalt at 165±5℃ and dynamic toughening crosslinking agent preheated at 80±5℃ to the mixing equipment, and add mineral powder at the same time. Mix at 40-50 rpm for 90-100 seconds at 170±5℃. S5. Seal and keep the mixture at 170-180℃ for 30-40 minutes. S6. Pave at 155-165℃, initial compaction temperature 140-150℃, secondary compaction temperature 130-140℃, and final compaction temperature 110-120℃. S7. Obtain a thin-wearing asphalt concrete layer after the road surface temperature drops below 50°C or at least 2 hours after paving.

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