Exploring the Use of Waste Engine Oil as Rejuvenator for Hot Mix Recycling

Waste engine oil (WEO) has proven to be an effective rejuvenator. As WEO is a recycled material, the source is an important factor that can influence its applicability. The main question explored in this study is whether there is a difference between WEO from a single source and blended engine oils. The effect of source on performance of recycled mixes is evaluated in this study. Two rejuvenators—A (a blend of various unknown used engine oils) and B (WEO from a known single source)—and two aged binder contents (40% and 80%) are used. The dosage of the rejuvenator is evaluated using high-temperature performance grade. Fourier transform infrared analysis shows that rejuvenator A is an amine-based aliphatic hydrocarbon, whereas B is a plain aliphatic hydrocarbon. Abbreviations such as 40A, 80A, 40B and 80B are used, in which number represents percentage of aged binder and A and B represent rejuvenator type. Based on Hamburg test results, 40A and 80A demonstrate higher rut resistance than 40B and 80B. From the IDEAL-CT test, 40B shows a higher CT index value than 40A, but 80A performs better with regard to fatigue resistance than 80B. Rejuvenator A exhibits better moisture resistance than B. However, two-way analysis of variance reveals that only rut depth is influenced by the rejuvenator type (source). Even in rutting performance, it was observed that dosage is the key factor, rather than rejuvenator source. Based on the overall performance results, it is concluded that source does not significantly affect the role of WEO as a rejuvenator.