Comprehensive study on the performance of SBS and crumb rubber composite modified asphalt based on the rubber pretreatment technology

The SBS/crumb rubber composite modified asphalt (SBS/CRCMA) demonstrates excellent high-temperature and fatigue resistance, but poor storage stability and workability. To address these deficiencies, this study attempts a novel process to pretreat CR with furfural extraction oil (FEO), and meticulously evaluates the impact of this CR pretreatment on the high-temperature, mid-temperature, low-temperature performances, compatibility, and microstructure of SBS/CRCMA, employing a suite of analytical techniques: penetration test, softening point test, ductility test, Brookfield viscosity test, dynamic shear rheological (DSR) tests, cigar tube tests, fluorescence microscopy (FM), Fourier Transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The results indicate a marked enhancement in the compatibility and storage stability of the SBS/CRCMA with CR pretreatment, bringing it in line with requisite standards. However, this treatment mildly impairs the high-temperature deformation resistance and elastic recovery capability. SBS/CRCMA with one hour pretreatment emerges as the ideal, striking a harmonious balance between high-temperature stability, fatigue resistance, and resistance to low-temperature cracking. Detailed micro-morphological and chemical analysis reveal that the CR pretreatment leads to the formation of stratified layers within the CR, featuring numerous pores that facilitate interaction with the asphalt. During the SBS/CRCMA preparation process, CR and asphalt interacts physically, with CR experiencing swelling but only limited chemical degradation. Overall, this comprehensive exploration of the rheological, chemical, and morphological changes of SBS/CRCMA under varying CR pretreatment durations provides valuable insights for the advancement and application of this economically and environmentally viable material in pavement engineering.