Multi-recyclability of asphalt mixtures modified with recycled plastic: towards a circular economy

Although asphalt pavements modified with recycled plastic have demonstrated enhanced performance, their recyclability remains under-explored, which is crucial under the scope of a circular economy. To address this, the present study investigates the multi-recyclability of asphalt mixtures, both with and without a recycled plastic modifier, at a recycling rate of 50% over two cycles using an open-loop and a closed-loop model. The research utilised an innovative recycled plastic modifier made from hard waste plastics, incorporated into the mixture via the dry method. To ensure control over consistency and variables while also considering the novelty of the recycled plastic modifier, the reclaimed asphalt pavements (RAPs) were prepared using a loose asphalt mixture ageing protocol. Additionally, a rejuvenator made of vegetal derivatives was used as the recycling agent, considering the high recycling rate over each cycle. The comprehensive evaluation of volumetric and mechanical performance revealed that asphalt mixtures containing the recycled plastic modifier performed comparably to unmodified mixtures over two recycling cycles. Furthermore, all the recycled mixtures exhibited superior performance in resistance to rutting, moisture susceptibility, and fatigue compared to the conventional asphalt mixture. Overall, it can be inferred that the asphalt mixture modified with recycled plastic is capable of being recycled over multiple life cycles without compromising its mechanical and performance characteristics