Study on preparation and pavement performance of polyurethane modified asphalt based on in-situ synthesis method

In this study, based on the molecular structural analysis of traditional asphalt binder and polymer modifiers, hydroxyl-terminated polybutadiene (HTPB), which possesses a similar structure to asphalt binder and has a low polarity, were selected as soft segments for use as a polyurethane (PU) modifier. The PU was prepared in the asphalt binder based on an in-situ synthesis methodology, providing a new type of PU modified asphalt binder. The microstructure and molecular structure of the PU modified asphalt binder were analyzed by fluorescence microscopy and infrared spectroscopy. The high and low temperature performance, mechanical properties and water stability of PU modified asphalt binder were studied. Microstructure analysis shows that the PU can be formed in the asphalt binder, and has better compatibility compared with SBS. PU can gradually form a spatial network structure in the asphalt binder when its content exceeds 4 wt%. As the PU content increases, the modified asphalt binder exhibits better high-temperature deformation resistance and low-temperature cracking resistance. In particular, after the PU content exceeds 4 wt%, the low-temperature performance of the modified asphalt binder is better than that of 5 wt% SBS modified asphalt binder. In addition, following an increase in PU content, the adhesion and water stability of the modified asphalt binder and aggregate are significantly improved. This study will help provide guidance for the research and development of PU modified asphalt binder.