Study on the performance and mechanism of physicochemically modified asphalt based on spatial crosslinking by the crumb rubber and polyurethane precursor

ABSTRACT Crumb rubber (CR)-modified asphalt shows positive effects on engineering performance and environmental conservation. However, its limited compatibility with asphalt due to unstable interactions poses challenges for its application. The incorporation of polyurethane precursor-based reactive modifier (PRM) facilitates the establishment of a three-dimensional crosslinked network structure within the asphalt, thereby enhancing pavement performance and compatibility. In this study, a novel compound-modified asphalt (CPMA) was prepared with CR and PRM. The performance of CPMA was assessed using the Dynamic Shear Rheometer (DSR), Blend Beam Rheology (BBR) and storage stability tests. Microstructure and modification mechanism were revealed by Atomic Force Microscopy (AFM) and Fluorescence Microscopy (FM) analyses. The results show that CPMA produced using an optimized process has better high-temperature performance and fatigue life than CR-modified asphalt (CRMA) and PRM-modified asphalt (PMA). Polar molecules, such as asphaltenes and resins, are crosslinked by the PRM to form a three-dimensional network, which enhances the thermal storage stability of CPMA. Furthermore, the flexibility and resilience of CR mitigated the low-temperature hardening of PMA. Physicochemical compound modifications provide significant advantages in terms of performance enhancement and system stability and demonstrate the potential of CR and PRM to complement and enhance their respective applications.