Effect of Multiple Aging-Rejuvenating Cycles (MARC) on critical rheological and fatigue properties of asphalt binder

Abstract

A variety of recycling agents are widely applied today to restore and enhance the physical and rheological properties of reclaimed asphalt binders (RAB). Whereas the effectiveness of these recycling agents is significantly affected by their composition and the degree of aging of asphalt, it remains unclear if they are actually restoring the whole original binder properties, or only some of the critical properties. In addition, there remains important questions about repeated recycling and how much these agents can in fact continue to restore the critical performance-related properties of the repeatedly recycled binders. Therefore, multiple aging-rejuvenating cycles (MARC) test is specially designed and the changes of G*, phase angle, and fatigue properties of asphalt binders after repeated PAV aging and subsequent additions of selected recycling agents that vary significantly in composition are investigated. In this paper, the rheological properties of asphalt and the fatigue-LAS test are used to quantify the critical properties at different aging stages and recycling agents. Results show that while the recovery of G* is possible for all agents, it is more challenging to restore the phase angle by the recycling agents used. Furthermore, results demonstrate that the recycling agents have limited capacity for restoring fatigue life at high strain level after repeated aging. The findings raise concerns about the future of repeated recycling and highlight the need to evaluate more than the LVE properties, and to sort out the changes in phase angle from the G* in order to understand the effect of these recycling agents. Additionally, for recycling agents, the performance in each cycle will change in MARC. Compared with bio-oil, it is risky to directly utilize re-refined engine oil bottom (REOB) with aged asphalt because of its invalidation after MARC.