Properties of Waste Polyethylene Terephthalate (PET) Modified Asphalt Mixes: Dependence on PET Size, PET Content, and Mixing Process

Management and disposal of waste polyethylene terephthalate (PET) bottles is an ever-growing challenge. The present study investigated the effect of incorporation of shredded waste PET bottles on properties of asphalt mixes in terms of: (i) process of PET addition, (ii) PET content, and (iii) PET size. Experimental design included three variables: two processes (dry process, and modified dry process), three PET contents (2.5%, 5.0%, and 7.5% by weight of binder), and two PET sizes (2.36–1.18 mm, and 0.30–0.15 mm). Volumetric properties, Marshall parameters, and moisture susceptibility characteristics of PET modified mixes were evaluated and compared with control mix (without PET). Analysis of variance (ANOVA) was performed to evaluate main and interaction effects of the variables. Results indicated that all the three variables had significant influence on the measured properties. Further, mixes prepared using modified dry process outperformed other mixes and showed highest resistance towards moisture induced damage.