Mixed plastic waste in the sustainable road: Thermal stability, mechanical properties, economic and environmental assessment

To counteract the environmental challenges arising from mixed plastic waste packaging, this work systematically investigated the benefits in performance, economy, and environment of food packaging plastic (FPP) used as road materials. Firstly, the characteristics of FPP were analyzed based on scanning electron microscope (SEM) and fourier transform infrared spectroscopy (FTIR). Thermal stability of FPP was determined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Then, the influence of FPP upon the workability of asphalt mixtures was evaluated by distribution, volume, density, void content, and compactive effort. Thereafter, the role of FPP in asphalt mixtures cracking and its microscopic mechanisms were evaluated based on the Superpave IDT, digital image correlation (DIC), and SEM. Finally, the economic and environmental benefits are analyzed based on the cost-benefit analysis (CBA) and life cycle assessment (LCA) models. The results show that FPP as a heterogeneous porous material maintains chemical stability at production temperatures, while the surface melts and bonds into larger particles. When the FPP content reaches 10% (by aggregate weight), the mixture is difficult to compact. As the FPP content increases, the tensile strength and elastic energy of asphalt mixtures gradually decrease, while the fracture energy and DCSE peaked at 5.5% and 7.0%, respectively. Low FPP content delays cracking, while high content accelerates cracking. FPP failure is controlled by crazing and fibrillation of PE and PP. Considering all factors, the optimal FPP content is 2% to 5%, which will bring 26.63 kEUR and 4.95 t CO 2 reduction in benefits per km of unit road pavement. These findings are expected to promote the utilization of mixed plastic in road construction, thereby fostering a green economic cycle and enhancing long-term sustainability.