Multiscale optimization on polymer-based rejuvenators for the efficient recycling of aged high-viscosity modified asphalt: Molecular dynamics simulation and experimental analysis

Abstract

With the depletion of fossil fuels, the advancement of efficient pavement recycling technology has garnered widespread attention, which contributes to the promotion of sustainable economic and environmental development. The polymers in polymer-based composite rejuvenators (PBCRs) are the key to restoring the performance of aged high-viscosity modified asphalt (HVMA). To optimize the polymers in PBCRs, this study investigates the rejuvenation effect and interface diffusion mechanism of various PBCRs using molecular dynamics simulation and experimental analysis. First, four PBCRs with different polymer components were designed, and their impact on the performance of weather-aged HVMA were examined using the rheological test, low-temperature force ductility test, crack resistance test, and aging resistance test. Subsequently, the rejuvenation effects of four PBCRs were ranked using the comprehensive performance radar chart. Finally, molecular models and layer models of weather-aged HVMA and four PBCRs were constructed, and the diffusion fusion process and interaction mechanism were analyzed using the molecular dynamics simulation. The findings indicate that PBCRs can rebuild the polymer network structure, partially restore the rheology, elastic recovery, and low-temperature ductility of aged HVMA. Additionally, PBCRs significantly reduce the crack potential of aged HVMA and ensure satisfactory aging resistance. Molecular dynamics simulation shows that due to the differences in their molecular structures, the diffusion ability of PBCRs is ranked as follows: crumb rubber rejuvenator (CR + R) > SBR rejuvenator (SBR + R) > SBS rejuvenator (SBS + R) > HVM rejuvenator (HVM + R). In summary, SBS + R proves most effective in regulating asphalt components and rebuilding the polymer network structure, but its interfacial diffusion ability is inferior to CR + R and SBR + R. CR + R has the highest diffusion coefficient, but its rejuvenation effect is not ideal. HVM + R is slightly less effective at rejuvenation than SBS + R, but has the worst diffusion capacity. The rejuvenation effect and diffusion ability of SBR + R are both not ideal. This study has significant implications for optimizing the polymers in PBCRs and promoting the efficient rejuvenation and eco-friendly sustainable development of HVMA.