Polyurethane-precursor/Styrene-Butadiene-Styrene Composite Modified Asphalt and Its Modification Mechanism

To effectively solve the problems of large amount of modifier, poor thermal storage stability, and thermodynamic instability faced by the current production of polymer modified asphalt, the polyurethane-precursor-based reactive modifier (PRM) and styrene-butadiene-styrene (SBS) were employed to prepare the PRM/SBS composite modified asphalt in this study. Taking base asphalt, PRM modified asphalt and SBS modified asphalt as references, the performance and modification mechanism of PRM/SBS composite modified asphalt were studied by macro-micro methods. Results show that the composite modification process presents both physical and chemical characteristics. PRM can not only produce obvious chemical cross-linking with asphalt molecules, but also act as a compatibilizer between asphalt and SBS to promote the formation of a more stable network structure in PRM/SBS composite modified asphalt. Based on the above mechanism, the addition of PRM significantly improves the thermal storage stability of SBS modified asphalt. PRM/SBS composite modified asphalt has higher resistance to high-temperature permanent deformation than SBS modified asphalt with the same modifier content, and it presents a good low-temperature performance.