The utilization of waste plastics in asphalt pavements: A review

Plastics are commonly used in all aspect in daily life. Lacking suitable approaches for waste treatment, a huge generation of waste plastics will cause the main global environmental issues. The most common types of waste plastics in the US municipal solid waste (MSW) stream include high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), Ethyl Vinyl Acetate (EVA), and polyvinyl chloride (PVC). Hot mix asphalt (HMA) is considered the ideal place to reuse waste plastics in high-value applications because of its high usage in highway construction. This paper comprehensively reviewed various types of waste plastics in asphalt pavement via wet and dry processes. In general, the incorporation of waste plastics into asphalt mixtures presented improvements in rutting resistance, fatigue resistance, and moisture resistance. However, compatibility and low-temperature performance problems remained during the application of plastic modified asphalt. Different approaches are adopted to improve the above limitations, including polymer additives, chemical additives, and nanomaterials. Additional studies should be focused on the aging effect, pavement performance monitoring, the stabilization among polymers, and the economic and environmental concerns of using plastics in asphalt pavements.