Multiscale Study of the Effect of Polyacrylamide Rejuvenator on the Performance of Aged Asphalt

To address the poor low-temperature crack resistance of aged asphalt for recycling, this study investigates the use of a polyacrylamide rejuvenator (PAM) for its performance recovery. A multiscale approach was employed to evaluate the influence of PAM on the high- and low-temperature performance and long-term aging resistance of aged asphalt. The results indicate that PAM enhances molecular mobility and promotes diffusion and interaction within aged asphalt. By regulating the proportion of light and heavy components, PAM reduces the aging degree of the aged asphalt and enhances its low-temperature crack resistance. After the incorporation of PAM, the performance grade shifted from PG 76-10 to PG 70-22, indicating enhanced low-temperature performance while maintaining satisfactory high-temperature stability. Further, compared with virgin asphalt and styrene–butadiene–styrene (SBS)-modified asphalt, PAM-rejuvenated asphalt exhibited superior long-term aging resistance.