Utilizing of Waste Vegetable Cooking Oil in bitumen: Zero tolerance aging approach

Aging is simply the oxidation of bitumen and as a result of aging significant changes are observed in physical, rheological and chemical properties of bitumen binders. However, aging can also be prevented by using some anti-aging agents in bitumen. The main question addressed in this paper is assessment the effect of using Waste Vegetable Cooking Oil (WVCO) as an anti-aging agent in base bitumen. The response of WVCO modified bitumen against both short (SHT) and long-term (LOT) aging and high and low temperature behavior of base and aged samples are evaluated with physical and rheological tests including penetration, softening point, viscosity, dynamic shear rheometer and bending beam rheometer. To determine the optimum WVCO rate to prevent SHT and LOT aging, a novel approach is specified based on Aging index (AI), which is calculated for each aging case and test method, individually. Zero value of AI is defined as Zero Tolerance Aging (ZTA) and the rate of WVCO corresponding to that value is determined as Zero-Tolerance Aging Dosage (ZTAD) for SHT and LOT aged bitumen. The results showed that different ZTAD values are obtained for each aging cases and evaluation methods. When considering the evaluation methods, higher ZTAD values are observed in physical tests than the rheological ones. Moreover, higher amount of WVCO is required to prevent long term aging in physical assessment, while aging term effect is not apparent in rheological tests. (C) 2019 Elsevier Ltd. All rights reserved.