Sustainable Surface Courses Investigation of Plastic Waste as Modifier in Bitumous Concrete for Road Infrastructure

This study investigated the effectiveness of waste plastics, specifically Low-Density Polyethylene (LDPE) and High-Density Polyethylene (HDPE), as modifiers in bituminous concrete for flexible pavement applications. Rapid growth in plastic consumption and its non-biodegradable nature has intensified environmental concerns, motivating the reuse of plastic waste in road construction. In this work, shredded LDPE and HDPE were incorporated into bituminous mixes using dry, wet, and combined processes. Laboratory evaluations, including Marshall Stability, flow, indirect tensile strength, and compressive strength tests, were conducted to assess the performance of modified mixes. Results showed that plastic-modified bituminous concrete exhibited enhanced stability, durability, and resistance to rutting and cracking compared to conventional mixes. Optimum plastic content was identified as 8% for the dry process and 6% for the wet process. The study concludes that the addition of waste plastics improves mechanical properties, reduces bitumen consumption, and provides a sustainable and economical approach for flexible pavement construction.