Plastic roads: evaluating the role of waste PET in hot mix asphalt – a review

Plastic pollution has become a global environmental crisis, with millions of tons of polyethylene terephthalate (PET) waste accumulating in landfills and ecosystems. One promising solution is the integration of waste PET into hot-mix asphalt (HMA), offering the dual benefits of sustainable waste management and enhanced pavement performance. This review critically examines the mechanical, environmental, and economic impacts of PET-modified asphalt. Studies indicate that PET improves rutting resistance, durability, and flexibility, with optimal performance observed at moderate PET dosages (4– 6%). However, excessive PET content (> 6%) can lead to stiffening and premature cracking, while very high PET concentrations (> 20%) may reduce load-bearing capacity. Beyond mechanical benefits, the incorporation of PET significantly reduces carbon emissions and energy consumption, with Life Cycle Assessment (LCA) studies reporting a 47.4% reduction in Global Warming Potential (GWP). Economic analyses indicate that PET-modified asphalt can reduce bitumen consumption, resulting in potential cost savings; however, processing and collection costs remain significant barriers to the large-scale adoption of this technology. Despite promising laboratory results, long-term field trials remain limited, and concerns about phase separation, regulatory approval, and large-scale feasibility hinder widespread implementation. Future research should focus on long-term field evaluations, optimization of PET processing methods, and the development of standardized industry guidelines. Additionally, hybrid polymer modifications and multi-polymer blends should be explored to enhance performance and sustainability. With continued innovation and policy support, PET-modified asphalt presents a viable pathway toward greener and more durable road infrastructure.