Highly durable road paving material and method of making same

Abstract

This invention discloses a high-durability road pavement material and its preparation method. The material includes a skeleton structure, a binder phase, and an interface reinforcement layer, significantly improving durability through multi-layer synergistic effects. The skeleton structure consists of a continuous interlocking network of coarse and fine aggregates. The binder phase includes matrix asphalt, thermoplastic elastomer particles forming a spatial network cross-linked structure, and layered silicate mineral powders that are exfoliated and interspersed. The interface reinforcement layer is a coupling agent reaction product layer located between the aggregates and the binder, with one end chemically bonded to the aggregate surface and the other end physically entangled with the binder phase. The preparation method includes steps such as aggregate surface pretreatment, asphalt-modified slurry shear dispersion, and staged mixing. This invention effectively solves the problems of weak interfacial bonding, poor aging resistance, and easy fatigue cracking in traditional asphalt mixtures, achieving a significant improvement in the comprehensive performance and service life of road pavement materials.

Description

Technical Field

[0001] This invention relates to the field of road paving materials, specifically to a high-durability road paving material and its preparation method. Background Technology

[0002] In the field of road paving materials, modified asphalt mixtures are an important means to improve pavement performance and extend service life. Among existing technologies, Chinese patent CN202311223107.8 discloses a modified asphalt mixture, whose technical solution mainly focuses on the optimization of aggregate gradation and the limitation of macroscopic performance indicators, specifically including: ① Aggregate composition and gradation: Fine aggregate with a particle size of 0-2.36mm (mass fraction 21-25%), medium aggregate with a particle size of 4.75-9.5mm (fraction 37-40%), coarse aggregate with a particle size of 9.5-16.0mm (fraction 30-37%), and mineral powder with a mass fraction of 5%; it is specified that the aggregate material is basalt, the mineral powder material is limestone, and the modified asphalt is SBS modified asphalt.

[0003] ② Performance Indicator Constraints: This scheme ensures the quality of the mixture by limiting macroscopic performance indicators, including Marshall stability of not less than 13kN, high temperature dynamic stability of not less than 10,000 cycles / mm, low temperature bending tensile strain of not less than 2890με, freeze-thaw splitting strength ratio of not less than 84%, four-point bending fatigue life of not less than 1.17 million cycles, and residual stability ratio of not less than 88%.

[0004] However, this existing technology has the following limitations: its core technology remains at the level of macroscopic gradation control and macroscopic performance index specification, failing to address the fundamental durability problem from the perspective of material microstructure and interface strengthening. Specifically, this scheme does not involve the chemical bonding and physical entanglement reinforcement design of the aggregate-asphalt interface, and cannot effectively overcome problems such as weak adhesion and water damage sensitivity caused by the "weak boundary layer" at the interface; it also fails to construct a spatial network cross-linked structure and a layered interlaced distribution of anti-aging fillers in the asphalt binder phase, making it difficult to synergistically improve the cohesion, deformation resistance, and long-term anti-aging performance of the asphalt.

[0005] Therefore, although existing technologies have improved the macroscopic properties of asphalt mixtures to some extent by adjusting the gradation and setting performance indicators, they have failed to fundamentally solve the technical bottleneck of insufficient durability of road pavement materials caused by microstructural defects, weak interfacial bonding, and accelerated asphalt aging. Summary of the Invention

[0006] The present invention aims to solve the above-mentioned technical problems by providing a high-durability road paving material and its preparation method.

[0007] To solve the above-mentioned technical problems, the technical solution provided by the present invention is: a high-durability road paving material, comprising: A skeleton structure, the skeleton structure comprising a continuously distributed aggregate network; The binder phase fills the pores of the skeleton structure, and the binder phase includes matrix asphalt and modifier particles and anti-aging fillers dispersed in the matrix asphalt; An interface reinforcement layer is provided, which covers the surface of the aggregate particles in the aggregate network and is located between the aggregate particles and the binder phase.

[0008] Furthermore, the aggregate network includes coarse aggregate and fine aggregate, the coarse aggregate forming an interlocking structure, and the fine aggregate filling the gaps formed by the coarse aggregate; the apparent density of the coarse aggregate is greater than the apparent density of the fine aggregate.

[0009] Furthermore, the modifier particles are thermoplastic elastomer particles, which form a spatial network cross-linked structure in the binder phase.

[0010] Furthermore, the anti-aging filler includes layered silicate mineral powder, wherein the layered silicate mineral powder has a lamellae structure that is peeled off and interspersed in the binder phase.

[0011] Furthermore, the interface enhancement layer includes a coupling agent reaction product layer, one end of which is chemically bonded to the mineral active sites on the surface of the aggregate particles, and the other end is physically entangled and embedded in the binder phase.

[0012] Furthermore, the interlamellar spacing of the layered silicate mineral powder is 2.0 nm-4.5 nm, and the mass fraction of the layered silicate mineral powder in the binder phase is 3.0%-8.0%.

[0013] Furthermore, the mass fraction of the layered silicate mineral powder in the binder phase is 4.5%-6.5%.

[0014] Furthermore, in the microstructure of the high-durability road paving material, the volume of the binder phase accounts for 90%-98% of the total pore volume of the skeleton structure.

[0015] A method for preparing the aforementioned high-durability road paving material includes the following steps: S1: Provide aggregate particles, apply an interface treatment agent to the surface of the aggregate particles, and after drying and curing, form an interface reinforcement layer on the surface of the aggregate particles to obtain pretreated aggregate. S2: Heat the base asphalt to a molten state, add the modifier and anti-aging filler to the molten base asphalt in sequence, and perform shear dispersion to obtain a mixed slurry; S3: The pretreated aggregate and the mixed slurry are stirred and mixed so that the mixed slurry coats the surface of the pretreated aggregate and fills the pores of the skeleton structure formed by the accumulation of the pretreated aggregate, thereby obtaining the high-durability road paving material. In step S2, the process parameters for shear dispersion are: shear temperature of 170℃-185℃, shear rate of 3500r / min-5000r / min, and shear time of 45min-60min.

[0016] Furthermore, in step S3, the mixing process is divided into two stages: the first stage is dry mixing at a first rotation speed to form the skeleton structure of the pretreated aggregate; the second stage is wet mixing by adding the mixed slurry at a second rotation speed, wherein the first rotation speed is greater than the second rotation speed.

[0017] The advantages of this invention compared to the prior art are: 1. A continuous interlocking network is formed by using coarse and fine aggregate gradation. The design of coarse aggregate having a higher apparent density than fine aggregate enhances the stability of the skeleton. Fine aggregate fills the gaps and further optimizes the pore structure, which enables efficient filling of the binder phase while improving macroscopic mechanical properties and resistance to deformation.

[0018] 2. The thermoplastic elastomer particles dispersed in the matrix asphalt form a spatial network cross-linked structure, giving the binder excellent elastic and plastic recovery ability; the layered silicate mineral powders are interspersed after being peeled off, which not only enhances the cohesion of the binder, but also delays the aging migration of asphalt through the lamellae barrier, thereby achieving a synergistic improvement in high and low temperature performance and anti-aging performance.

[0019] 3. The coupling agent reaction product layer chemically bonds the active sites of the aggregate at one end and physically entangles and embeds the binder at the other end, eliminating the "weak boundary layer" at the aggregate-asphalt interface at the microscopic level, significantly improving the interfacial bonding strength, and reducing the risk of water damage and fatigue cracking.

[0020] 4. Staged mixing (dry mixing to form the skeleton first, then wet mixing to fill the binder) and optimization of shear dispersion parameters ensure uniform dispersion of the modifier and anti-aging filler, and precise matching of the volume fraction of the binder phase with the skeleton pores to maximize the synergistic effect of each component.

[0021] 5. Through multi-dimensional design of macro-gradation, micro-interface, and material phase, the material possesses excellent high-temperature rutting resistance, low-temperature crack resistance, water damage resistance, aging resistance, and fatigue resistance, fundamentally extending the service life of roads and reducing the total life-cycle maintenance cost. Detailed Implementation

[0022] To make the technical problems, technical solutions, and beneficial effects of this invention clearer, the following detailed description is provided with reference to embodiments and comparative examples. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0023] The material compositions of Examples 1-5 and Comparative Examples 1-3 are shown in Table 1, and the preparation methods are as follows: Example 1: 1. Raw material preparation: Coarse aggregate: Basalt crushed stone, apparent density 2.95 g / cm³, particle size 9.5-13.2 mm Fine aggregate: Manufactured limestone sand, apparent density 2.65 g / cm³, particle size 0.075-2.36 mm. Base asphalt: 70# road petroleum asphalt Modifier: SBS thermoplastic elastomer particles, particle size 0.5-1mm Anti-aging filler: Sodium-based montmorillonite, with a lamellar spacing of 3.2 nm. Interface treatment agent: silane coupling agent KH-550 2. Preparation steps: (1) Aggregate pretreatment: The coarse and fine aggregates were dried in an oven at 105℃ for 4 hours. The aggregates were added to a high-speed mixer, and 0.8% of the aggregate mass of silane coupling agent KH-550 (diluted to 10% concentration with ethanol) was sprayed in. The mixture was stirred at 80℃ for 15 minutes and then cured at 120℃ for 2 hours to obtain pretreated aggregates.

[0024] (2) Preparation of slurry mixture: The base asphalt was heated to 175℃ to melt, and 6% of SBS particles by weight of asphalt was added. The mixture was sheared at 180℃ and 4500 r / min for 50 min. Then, 5% of montmorillonite by weight of asphalt was added, and the mixture was sheared for another 10 min to obtain the slurry mixture.

[0025] (3) Two-stage mixing: Add the pretreated aggregate to the mixing pot and dry mix at 300 r / min for 15 s to form a skeleton structure. Then add the mixed slurry, reduce the speed to 150 r / min, wet mix for 45 s, and discharge temperature 160-165℃.

[0026] Examples 2-5: The method is basically the same as in Example 1, except that the relevant parameters are adjusted, as shown in Table 1.

[0027] Comparative Example 1: Aggregates with the same gradation are used, but no interface treatment is performed. Only 5% SBS is added to the asphalt, and no montmorillonite is added. Conventional mixing process is used, without distinguishing between dry and wet mixing stages.

[0028] Comparative Example 2: The aggregates are not treated at the interface, and 5% SBS and 5% montmorillonite are added to the asphalt. Conventional mixing processes are used.

[0029] Comparative Example 3: The aggregate undergoes interface treatment, and 5% SBS and 5% montmorillonite are added to the asphalt, but a uniform gradation is used (without distinguishing the density difference between coarse and fine aggregates), and a conventional mixing process is employed.

[0030]

[0031] Table 1. Composition (mass percentage) of the Examples and Comparative Examples

[0032] Note: The percentages in the table represent the percentage of the total mass of the material.

[0033] Performance testing: The test was conducted according to JTGE20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering", and the results are shown in Table 2.

[0034] Table 2 Performance Test Results

[0035] Results analysis: The overall performance of Examples 1-4 is significantly better than that of Comparative Examples 1-3, demonstrating the effectiveness of the triple synergistic enhancement mechanism.

[0036] Compared with Comparative Example 2 (all other conditions are the same), Example 1 showed a 35.7% increase in interfacial bond strength and an 8.6% increase in freeze-thaw splitting strength ratio, indicating that the interfacial reinforcement layer significantly improved water stability. Compared with Comparative Example 3, Example 1 showed a 95.3% increase in dynamic stability, proving that the interlocking skeleton formed by the density difference between coarse and fine aggregates can significantly improve high-temperature stability. A comparison of Examples 1 (5%), 3 (3.3%), and 4 (6.0%) showed that the 5% content resulted in the best overall performance; too low a content resulted in insufficient anti-aging effect, while too high a content affected workability. Example 5 had a high shear temperature (190℃), leading to partial degradation of SBS and a decrease in performance, proving that 175-185℃ is the optimal process window. The estimated service life of Example 1 reached 18-20 years, which is more than 100% higher than that of Comparative Example 1 (conventional material).

[0037] The present invention and its embodiments have been described above. This description is not restrictive. If a person skilled in the art is inspired by this description and designs a similar structure and embodiment without departing from the spirit of the present invention, such design should fall within the protection scope of the present invention.

Claims

1. A high-durability road paving material, characterized in that, include: A skeleton structure, the skeleton structure comprising a continuously distributed aggregate network; The binder phase fills the pores of the skeleton structure, and the binder phase includes matrix asphalt and modifier particles and anti-aging fillers dispersed in the matrix asphalt; An interface reinforcement layer is provided, which covers the surface of the aggregate particles in the aggregate network and is located between the aggregate particles and the binder phase.

2. The high-durability road paving material according to claim 1, characterized in that, The aggregate network includes coarse aggregate and fine aggregate, the coarse aggregate forming an interlocking structure, and the fine aggregate filling the gaps formed by the coarse aggregate; the apparent density of the coarse aggregate is greater than the apparent density of the fine aggregate.

3. The high-durability road paving material according to claim 1, characterized in that, The modifier particles are thermoplastic elastomer particles, which form a spatial network cross-linked structure in the binder phase.

4. The high-durability road paving material according to claim 1, characterized in that, The anti-aging filler comprises layered silicate mineral powder, wherein the layered silicate mineral powder has a lamellae structure that is peeled off and interspersed in the binder phase.

5. The high-durability road paving material according to claim 1, characterized in that, The interface enhancement layer includes a coupling agent reaction product layer, one end of which is chemically bonded to the mineral active sites on the surface of the aggregate particles, and the other end is physically entangled and embedded in the binder phase.

6. The high-durability road paving material according to claim 4, characterized in that, The interlamellar spacing of the layered silicate mineral powder is 2.0 nm-4.5 nm, and the mass fraction of the layered silicate mineral powder in the binder phase is 3.0%-8.0%.

7. The high-durability road paving material according to claim 6, characterized in that, The mass fraction of the layered silicate mineral powder in the binder phase is 4.5%-6.5%.

8. The high-durability road paving material according to any one of claims 1 to 7, characterized in that, In the microstructure of the high-durability road paving material, the volume of the binder phase accounts for 90%-98% of the total pore volume of the skeleton structure.

9. A method for preparing a high-durability road paving material as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1: Provide aggregate particles, apply an interface treatment agent to the surface of the aggregate particles, and after drying and curing, form an interface reinforcement layer on the surface of the aggregate particles to obtain pretreated aggregate. S2: Heat the base asphalt to a molten state, add the modifier and anti-aging filler to the molten base asphalt in sequence, and perform shear dispersion to obtain a mixed slurry; S3: The pretreated aggregate and the mixed slurry are stirred and mixed so that the mixed slurry coats the surface of the pretreated aggregate and fills the pores of the skeleton structure formed by the accumulation of the pretreated aggregate, thereby obtaining the high-durability road paving material. In step S2, the process parameters for shear dispersion are: shear temperature of 170℃-185℃, shear rate of 3500r / min-5000r / min, and shear time of 45min-60min.

10. The preparation method according to claim 9, characterized in that, In step S3, the mixing process is divided into two stages: the first stage is dry mixing at a first rotation speed, so that the pretreated aggregate forms the skeleton structure. In the second stage, the mixed slurry is added and wet-mixed at a second rotation speed, where the first rotation speed is greater than the second rotation speed.

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