A Comparative Study of the Effect of Moisture Susceptibility on Polyethylene Terephthalate-Modified Asphalt Mixes under Different Regulatory Procedures

Water damage is one of the main causes of road deterioration during its lifespan, leading to a decrease in the structural and functional qualities of the road surface. Moreover, the management and disposal of polyethylene terephthalate (PET) bottles at the end of their lifecycle are becoming increasingly complex challenges. Hence, this study investigates the feasibility of incorporating crushed PET bottles into the production of asphalt mixtures, considering different PET quantities (6%, 10%, 14%, 18%, and 22%) and two incorporation processes in the mixture design (dry process and modified dry process). PET-modified mixtures' volumetric properties, Marshall parameters, and moisture susceptibility characteristics were evaluated and compared with PET-free asphalt mixtures. The results indicated that PET content significantly influences the properties being assessed, and the modified dry process yields a higher resistance to moisture susceptibility. Finally, the obtained TSR (tensile strength ratio) results based on European standards are compared with those obtained using American standards, in an aim to comprehend and assess the testing methods, result reliability, and applicability.