Mechanical Properties of Permeable Flexible Pavement Modified with Plastic Waste

Recent advancements have shown that incorporating plastic waste into asphalt mixtures enhances pavement durability and rutting resistance, promoting sustainable road construction. However, research has largely focused on impermeable pavements, with limited attention to permeable asphalt applications. This study addresses this gap by evaluating the mechanical properties of permeable asphalt modified with high-density polyethylene (HDPE) and polyethylene terephthalate (PET) waste. Aggregates were assessed for strength using Los Angeles Abrasion, Aggregate Crushing Value, and Aggregate Impact Value tests. Bitumen was modified with shredded PET and HDPE (1.18–3 mm) at 3%, 6%, 9%, and 12% by weight. Modified bitumen was tested for penetration, softening point, specific gravity, and flash point. Penetration values decreased from 68 mm (unmodified) to 55 mm (9% PET) and 28 mm (12% HDPE), while softening point increased to 62°C, indicating enhanced thermal stability. Flash point improved from 250°C to 322°C; specific gravity remained stable. A permeable asphalt mix was designed following ASTM D7064, identifying 4.3% as the optimum bitumen content. Laboratory evaluation showed improved Marshall Stability, peaking at 13.2 kN (3% HDPE) and 8.7 kN (9% PET). Flow ranged within 2–6 mm, air voids increased slightly. Abrasion loss and drain down reduced, indicating improved durability and binder retention. ITS yielded a tensile strength ratio of 84%, reflecting good moisture resistance. These results demonstrate that incorporating HDPE and PET plastic waste in permeable asphalt can enhance pavement performance while contributing to stormwater management, flood mitigation, sustainable plastic reuse and eco-friendly infrastructure in urban areas of developing countries.