Leaching potential of metals and PAHs of asphalt rubber paving materials

Asphalt rubber (AR), a waste-based paving binder prepared with waste tyre rubber and asphalt binder, may contain hazardous components that pose environmental risks when applied to the road surface. This study aims to quantify this concern by characterizing the leaching process of AR using a multi-scale experimental method. The effects of various experimental variables on the leaching process were determined, and the leaching of metals and polycyclic aromatic hydrocarbons (PAHs) were characterized at three scales, i.e., binder, mortar, and mixture. The results suggested that AR presents no significant leaching concerns under most conditions, but the leaching of metals from AR might pose risks to the aquatic environments in the areas with acid rain. Furthermore, the leachability of metals increases with service time due to the aging of asphalt binder. The findings of this study can contribute to a better understanding of the environmental performance of AR and help conduct AR construction and maintenance in a more sustainable manner. © 2023 Elsevier Ltd.