Mechanism and Performance Characterization of Dry-Process Asphalt Mixtures Modified with LDPE/EVA/SBS Composite Particles

This study employed a dry-process method to prepare SBS/recycled LDPE/EVA composite-modified particles (CMP) for asphalt mixture modification. Conventional performance tests, including penetration tests, determined the optimal CMP dosage to be 8% by mass of asphalt. The rheological properties and microstructure of base asphalt, SBS-modified asphalt, and composite-modified asphalt were systematically compared, and the road performance of the corresponding mixtures was evaluated. The results demonstrated that the composite modifier forms a uniform elastic network within the asphalt, significantly enhancing both high- and low-temperature performance and fatigue life while also improving thermal stability and deformation resistance. The modification mechanism is predominantly based on physical blending, and the system exhibits good thermal stability. The outstanding performance of the mixture, including a 284.4% increase in dynamic stability and a 60.1% extension in fatigue life, is attributed to the formation of a "skeleton-asphalt-particle" multiphase structure. Comprehensive performance analysis indicated that optimal performance is achieved with an SBS/LDPE/EVA ratio of 1:1:1, highlighting the considerable practical engineering potential of this dry-process composite modification technology.