Efficiency of Sustainable Rejuvenation of Bitumen Using Bio-based Rejuvenators and Waste Oils

This study primarily investigated the efficacy of sustainable rejuvenators in restoring the properties of aged bitumen as well as developing a method for optimising rejuvenator dosages. The rheological properties, determined via frequency sweep and linear amplitude sweep tests, were assessed using a virgin binder as a reference point. The findings revealed that all sustainable rejuvenators tested are viable, with a particular commercial product and tall oil (TO) exhibiting superior effectiveness. Conversely, waste cooking oil (WCO) and waste motor oil (WMO) presented sub-optimal results. The proposed rejuvenation index demonstrates its utility in evaluating rejuvenation efficacy and predicting the optimal dosages for any given rejuvenators. The fatigue resistance of the rejuvenated binders was satisfactory, and a reduction in strain sensitivity was observed. Furthermore, Fourier transform infrared spectroscopy (FTIR) analysis elucidated the rejuvenation mechanism, indicating that the rejuvenation process primarily involves physical softening rather than a chemical reversal of ageing. Rejuvenators mainly infuse saturates into aged bitumen, whereas ageing predominantly reduces the aromatics, thus making a complete restoration of the aged bitumen’s properties unachievable.