Performance of HDPE Waste and Lignin-Modified Asphalt for Sustainable Road Pavement

Asphalt is the main binding material in flexible pavements, which is viscoelastic, flexible, and recyclable, thus supporting sustainable road construction. However, conventional asphalt has limitations in withstanding heavy traffic loads and temperature variations, making it susceptible to rutting and durability problems. Utilizing High-Density Polyethylene (HDPE) plastic waste and lignin as asphalt modifiers is a promising alternative because HDPE can enhance stiffness and deformation resistance. In contrast, lignin can improve binder compatibility and mixture stability. This research aims to determine the Optimum Asphalt Content (OAC) for 60/70 penetration asphalt modified with 4%, 5%, and 6% HDPE and 3% lignin. Evaluation was conducted using the Marshall test and the Marshall immersion test. The research results showed that the OAC values were 5.65% for penetration 60/70 asphalt, 5.63% for 4H3L, 5.73% for 5H3L, and 5.60% for 6H3L. The highest Marshall stability was obtained in the 6H3L mixture at 2316 kg, while the 24-hour immersion stability remained high at 2099 kg. All mixtures also achieved Residual Strength Index values above 90%, indicating adequate resistance to moisture damage. The study contributes experimental evidence that HDPE waste and lignin can improve mixture stability while maintaining adequate moisture resistance