Stiffness Properties and Moisture-Induced Damage Resistance of High-RAP Asphalt Mixtures Modified with Recycled Waste Plastics

This study investigated the stiffness and moisture-induced damage resistance of asphalt mixtures containing 50% RAP and different dosages of a recycled plastic compound (RPC) added through the hybrid method. For comparison purposes, an unmodified mixture and a wet-modified mixture including a highly SBS-modified binder were also analyzed and assumed as references. Furthermore, the effect of a bio-based rejuvenating agent was examined. Stiffness properties were determined by means of indirect tensile stiffness modulus tests at different temperatures; moisture damage resistance was assessed following a procedure developed at the Czech Technical University in Prague. Findings demonstrated that the higher the RPC dosage, the more enhanced the stiffness of the mixtures. The incorporation of the rejuvenator counteracted this stiffening effect at higher temperatures, especially for mixtures with higher RPC content. The combined presence of RAP and high RPC content reduced moisture resistance, while the use of the rejuvenating agent proved beneficial. Overall, the outcomes highlighted the potential of such a RPC in high-RAP mixes, provided that plastic dosage and rejuvenator are adequately balanced.