再生路面用聚氨酯改性沥青改性机理与路用性能

To promote large-scale recycling of reclaimed asphalt pavement (RAP) and prolong the service life of asphalt pavements, a polyurethane prepolymer (PUP) system that includes a chain extender and other additives was used as the modifier to prepare a high-performance polyurethane-modified bitumen (PUMB). PUMB was then used to fabricate a recycled asphalt mixture containing 100% RAP, aiming to achieve the in-situ recycling of pavement using polymer bonding materials with superior mechanical properties and resilience. From the perspectives of molecular interactions, microscopic properties, and mechanical performance, the chemical modification mechanism of bitumen using the PUP system modifier was revealed, and the interactions between four fractions of bitumen and the modifier with different PUP content were studied in depth. The fundamental properties of PUMB and the performance of the recycled asphalt mixture were also evaluated. Results showed that PUP mainly crosslinked with the chain extender and few PUPs reacted with asphaltene components in bitumen in the chemical modification process, which jointly contributed to the level of crosslinking of PUP in PUMB of over 80%. When 55% PUP was added to the asphalt system, the optimal compatibility for the four fractions of bitumen with PUP was achieved, and the crosslinking structure system formed by modified bitumen was the most stable. In contrast to the virgin bitumen, the temperature-sensitivity of PUMB was significantly reduced, and the addition of the PUP system significantly improved the high-temperature deformation resistance, low-temperature crack resistance, and thermal-oxidative aging resistance of bitumen. The recycled asphalt pavement using PUMB as the binder has a potential use in regions with high traffic volumes, large seasonal temperature differences, or low temperatures. Compared with the conventional old asphalt pavement hot recycling technology, the recycled asphalt pavement with PUMB can lower the blending temperature, significantly promoting resource conservation and recycling. This study shows apparent advantages in enhancing quality and boosting efficiency during maintenance.