Laboratory Simulation of Bitumen Aging and Rejuvenation to Mimic Multiple Cycles of Reuse

Abstract

A laboratory study on bitumen aging and rejuvenation was conducted to investigate the effect of the multiple cycles of reuse on bitumen properties. The bitumen studied was unmodified conventional paving grade 70/100 pen bitumen which was aged in the laboratory, then rejuvenated with 650/900 bitumen back to 70/100 grade. Four aging-rejuvenation cycles were conducted and properties were tested after each step. The aging procedure consisted of Rolling Thin Film Oven Test (RTFOT) followed by Pressure Aging Vessel (PAV) aging at 90 °C for 20 hours. Results suggest that bitumen hardens the most during the first cycle of aging with the following cycles asserting less influence. The physical bitumen properties could be restored close to the original state. However, the balance of elastic and viscous component was altered towards a more elastic behavior in each cycle. Therefore, it is debatable whether rejuvenation with soft bitumen restores the entire range of performance for the bitumen. The changes cannot be chemically reversed in described process, although the rejuvenator allows for the restoration of some physical properties.