Preparation and Performance Evaluation of Organic Diatomite-Based High-Viscosity Modified Asphalt as Permeable Asphalt Pavement

High-viscosity modified asphalt (HVMA) permeable pavement is an essential component of sponge city, placing high demands on the viscosity and durability of asphalt binder. The preparation of diatomite-based high-viscosity modified asphalt binder (D-HVMA) demonstrates dual values in performance improvement and cost reduction of pavement. In this study, HVMAs were prepared by combining crumb rubber, styrene–butadiene–styrene, and terpene resin. To elucidate the effect of silane coupling agent (SCA)-treated organic diatomite on the performance of HVMA, diatomite treated with different contents of SCA were added to the HVMA to prepare the organic diatomite-based high-viscosity modified asphalt binder (OD-HVMA). The optimal content of each modifier in OD-HVMA was determined by the orthogonal experimental design and gray correlation analyses. The performance-related properties of OD-HVMA were characterized by physical and rheological tests. The modification mechanism was revealed using Fourier transform infrared spectroscopy and scanning electron microscopy. The results show that the OD-HVMA presents improved viscosity, high-temperature performance, low-temperature performance, and fatigue resistance compared with the D-HVMA. Because the SCA treatment promotes the lipophilicity of diatomite, the organic diatomite can be uniformly distributed in asphalt binder and adsorb the lightweight components of asphalt binder, so OD-HVMA exhibits good storage stability. Considering the significantly improved performance and good cost efficiency, OD-HVMA is expected to enhance the durability of permeable pavements and shows excellent potential for constructing sponge cities.