Investigating aging properties of bitumen modified with polyethylene-terephthalate waste plastic

This paper examines the merits of using recycled polyethylene terephthalate (PET) in bitumen to improve short and long-term aging of bituminous composites used in roadway constructions. A concern with PET is its low compatibility with bitumen leading to its segregation; here, we functionalized PET with waste cooking oil to enhance its compatibility with bitumen. We then studied the efficacy of functionalized PET to delay aging in bituminous composites. To do so, PET particles treated with waste vegetable oil and non-treated PET particles were separately blended into bitumen using a high-shear mixer and aged in the laboratory using a rolling thin film oven (RTFO) and a pressure aging vessel (PAV). The rheological and chemical changes that occurred with aging were captured by a dynamic shear rheometer (DSR) and a Fourier transform infrared (FTIR) spectroscopy. The results showed that binders containing PET had high resistance to aging as measured by their low change in activation energy and healing index after exposure to extended aging. Functionalized PET referred to as “Oil-treated PET” here, has proven efficiency in reducing aging effects, as indicated by lower values of the aging indexes. Oil-treated PET-modified binders lost 15.6% of their healing capacity after long-term aging whereas neat binders lost almost 66%. The outcome of this study exploits the synergy between two waste streams including waste vegetable oil and waste plastics to produce a sustainable modifier for roadway construction to extend their service life while promoting resource conservation and recycling.