Experimental evaluation of high RAP bituminous mixtures modified with recycled waste plastics

The increasing demand for sustainable road construction materials, driven by environmental concerns and resource scarcity, has accelerated efforts to incorporate recycled components into bituminous mixtures. In this context, reclaimed asphalt pavement (RAP) and recycled plastics have emerged as promising materials, which may be able to enhance both the environmental and mechanical performance of road pavements. While the individual effects of RAP and recycled plastics have been extensively studied, their combined influence still needs to be further explored. The present study investigated bituminous mixtures containing a recycled plastic compound (RPC) derived from waste plastics and 50 % RAP through a comprehensive laboratory testing program, which included determination of their stiffness properties, cracking resistance, and anti-rutting potential. The role of binder type was also examined by combining RPC with either a softer binder or a harder binder with a bio-based rejuvenator. For comparison, two additional mixtures were produced and tested: a control mixture produced with a neat bitumen without any modification and a mixture containing a SBS highly-modified binder. An extensive statistical analysis was performed on test data to evaluate the actual differences in mechanical characteristics among the mixtures. Overall, the experimental findings demonstrated that the combined use of RPC and high content of RAP represents a viable and promising solution for the production of sustainable asphalt mixtures. When employed together with a suitably selected neat binder and a rejuvenating agent, the modification with RPC may deliver performance levels comparable or even exceeding those of mixtures incorporating a SBS highly-modified binder.