A review on waste plastic in flexible pavement: types, dosage, mixing, performance and challenges

The global challenge of plastic production and consumption calls for comprehensive strategies and solutions. In the construction sector, one promising approach to recycling involves utilizing discarded plastics for applications related to asphalt pavement. While this method offers potential opportunities for value-added recycling, addressing various challenges is crucial for its effective implementation. In this regard, this review article provides an overview of pertinent aspects associated with incorporating waste plastics into asphalt. To determine the most suitable type, optimal quantity, as well as size and shape of waste plastics, it is essential to consider key engineering performance factors such as asphalt viscosity, rutting, moisture susceptibility, cracking, and fatigue resistance. Failure to accurately determine the appropriate plastic dosage could lead to adverse effects on asphalt behavior. The incorporation of plastic waste into asphalt can be achieved through either wet or dry methods. Generally, incorporating plastic waste has shown improvements in performance parameters such as stiffness, resistance to rutting, and fatigue resistance. However, certain types of waste plastics have resulted in conflicting performance outcomes. Further research is necessary to understand the impact of different plastics on asphalt behavior and the potential economic and environmental implications of this approach. Moreover, investigating strategies to enhance compatibility between asphalt and plastic for improved storage stability is an area that warrants further exploration.