Rheological evaluation of bitumen modified using antistripping additives synthesised from waste polyethylene terephthalate (PET)

The use of amine-based additives is common practice to improve the stripping resistance and performance properties of bituminous mixtures. This study is concerned with the synthesis of additives derived from waste Polyethylene Terephthalate (PET), and investigation of its effect as an effective modifier for bitumen. Firstly, two amine functionalised additives namely bis(2-hydroxyethyl) terephthalamide (BHETA) and bis(2-aminoethyl) terephthalamide (BAET) were chemically synthesised using an aminolysis process from waste PET. The effects of BAET and BHETA on bitumen and bituminous mixture performance were then identified through conventional binder, Marshall Stability, Hot water stripping, Superpave performance, and Hamburg Wheel Tracking tests. The results indicated that BAET modified bitumen showed a significant improvement in moisture resistance as well as other properties such as enhanced Marshall stability, low and high temperature performance. On the other hand, BHETA modified bitumen did not show similar characteristics and exhibited only a marginal performance improvement as compared to the virgin bitumen. It was inferred from the proposed interaction mechanism that the terminal functional group of the additives has a substantial effect in determining the performance properties of such modified binders. Overall, this study has confirmed the possibility of using waste PET materials as an environmentally friendly modifier for bituminous mixtures.