Nanomaterial Composite Compatibilized Rubber-Plastic Elastomer-Asphalt Interface Mechanism and Performance Evaluation

Conventional rubber-plastic modified asphalt often suffers from poor compatibility and thermal storage stability, which limits its engineering application. To address this issue, this study proposes a prefabricated nano-reinforced rubber-plastic thermoplastic elastomer (TPE) modification strategy. The specific objective was to comparatively investigate how different waste plastic matrices (HDPE, LDPE, and PP) and two representative nano-oxides (ZnO and TiO₂) affect the interfacial evolution, storage stability, rutting resistance, fatigue durability, and low-temperature cracking resistance of modified asphalt. The prefabricated nano-reinforced TPE modifier was incorporated into the base asphalt, and its storage stability, interface evolution and multi-scale rheological properties were evaluated. The results show that all modified binders exhibited good thermal storage stability, with softening point differences below 2.5 °C. The enhancement mechanism was mainly governed by physical blending, swelling adsorption, and interfacial synergistic interactions rather than the formation of new chemical functional groups. A clear synergistic matching relationship between plastic type and nanoparticle type was identified. LDPE-based systems showed better phase compatibility and fatigue/low-temperature performance, whereas HDPE-based systems were more favorable with respect to improvement of high-temperature rutting resistance. In addition, ZnO contributed more significantly to storage stability, rutting resistance, and fatigue resistance, while TiO₂ was more beneficial for low-temperature crack resistance. These findings provide new insight into the interfacial design of nano-reinforced rubber-plastic modified asphalt and offer guidance for performance-oriented and sustainable pavement materials.