Towards critical low-temperature relaxation indicators for effective rejuvenation efficiency evaluation of rejuvenator-aged bitumen blends

Abstract

The relaxation behavior affected by aging and rejuvenation plays a crucial role in its low-temperature cracking potential of bitumen. However, there are limited studies on the relaxation performance of rejuvenated bitumen under different rejuvenation conditions. This paper aims to propose critical indicators to assess the rejuvenation efficiency of low-temperature relaxation performance of various rejuvenated binders. The effects of rejuvenator type/dosage and aging level on relaxation parameters are investigated. The τ50s, t25%, and A are recommended as critical indicators based on their high sensitivities to influence factors and rejuvenation percentage scope. Additionally, molecular dynamic simulation outputs on virgin/aged bitumen and rejuvenators explain the difference in rejuvenation effectiveness of different rejuvenators. The results show that bio-oil rejuvenator exhibits the highest efficiency on regenerating the relaxation performance. All relaxation parameters of aged bitumen can be regenerated by adding rejuvenators. MD simulations reveal that the molecular mobility and free volume ratio of rejuvenators mainly cause the difference in rejuvenation efficiency on the relaxation property between various rejuvenators. The diffusion capacity of rejuvenator shows a more dominant effect on rejuvenation efficiency than fractional free volume.