Rheology of Virgin Asphalt Binder Combined with High Percentages of RAP Binder Rejuvenated with Waste Vegetable Oil
Connor R. Dugan, Christopher R. Sumter, Shivani Rani, Syed Ashik Ali, Edgar A. O’Rear, Musharraf Zaman
Abstract
Waste cooking oils (WCOs) show promise as a rejuvenator for reclaimed asphalt pavement (RAP) binders. Their use helps to make RAP a renewable resource and to address environmental concerns related to WCO disposal. While studies suggest that 100% RAP for pavement is feasible, RAP will likely be combined with a virgin binder and aggregate incrementally in the field. In this study, the rheological properties of the virgin binder blended with a simulated RAP binder and 10% waste vegetable oil (WVO) as a rejuvenator were examined. Viscosities below that of a PG 64-22 virgin binder were observed with WVO in blends of 40 or 60% RAP and the virgin binder. The virgin-60% RAP/WVO binder blend retained a Superpave grade of the virgin binder and was found to satisfy requirements for both rutting parameter and fatigue resistance. Results indicated that WVO significantly reduced the effects of long-term ageing, making the blend containing RAP durable. The effect of RAP content on WVO/virgin binder blends was most pronounced on the rutting parameter. A "molecular lubrication" model is suggested as a mechanism for the viscosity reduction with WVO.