This paper evaluates the efficacy of a hybrid treatment for waste-plastic granules using a bio-oil and carbon coating to make the plastic granules compatible with asphalt binder, to promote environmental sustainability and enhance pavement performance. The bio-oil used in this study was derived from waste vegetable oil, and the coating with carbon was performed using graphene nanoparticles. To evaluate the extent of surface treatment of plastic granules, the formation of surface functional groups was tracked using Fourier transform infrared spectroscopy and Raman spectroscopy, and their surface energy before and after treatment was measured using inverse gas chromatography. In addition, the thermomechanical properties and phase separation of asphalt binders containing treated-plastic granules were studied. The study results showed that the total surface energy of plastic was increased by 49% after treatment-promoting interactions between plastics and binder. This in turn led to an 86% reduction in
the separation of plastics and binder. The viscosity of binder containing plastics increased significantly; however, the binder with treated plastic had 56% lower viscosity than the binder with non-treated plastic. Binder with treated plastic had increased resistance to fatigue cracking, as evidenced by a significant reduction in G*Sin(d) compared to the binder with non-treated plastic. Low-temperature properties were also improved for binder with treated plastic compared to binder with non-treated plastic. Finally, the moisture-induced shear-thinning index showed that the presence of treated plastic granules in binder made the binder less susceptible to moisture.