The increasing accumulation of plastic waste poses a significant environmental challenge, with millions of tons being discarded annually. At the same time, conventional asphalt binders used in road construction often exhibit inadequate performance under high temperatures, leading to rutting and deformation. To address both concerns, this study explores the potential of incorporating recycled plastic waste into asphalt binders as a sustainable solution for improving pavement durability. The objective of this research is to evaluate the mechanical properties, thermal stability, and overall performance of modified asphalt binders incorporated with recycled plastic waste. This study focuses on modifying asphalt binders using only two materials: 60/70 penetration-grade bitumen and recycled plastic bottle caps composed primarily of HDPE.The methodology involves laboratory experiments where asphalt binders are modified with different percentages of plastic waste (0%, 1%, 3%, 5%, 7% and 9%) and subjected to standard performance tests, including penetration, softening point, and ductility tests based on ASTM standards. The results indicate that increasing plastic content enhances the binder’s resistance to deformation, increases softening point temperatures, and reduces penetration values, signifying improved binder hardness and durability. However, a higher plastic percentage reduces ductility, necessitating optimization for practical applications.This study demonstrates that incorporating recycled plastic waste into asphalt binders can enhance binder performance while mitigating plastic pollution. The findings suggest that plastic-modified asphalt is a viable alternative for sustainable road construction, with economic and environmental benefits. Further research is recommended to evaluate the full mechanical performance of HDPE-modified asphalt mixtures particularly through Marshall stability testing as well as to assess their long-term field performance and environmental impacts.