###### Abstract  
The integration of waste plastics into pavement materials offers a dual benefit of enhancing road performance and mitigating the environmental burden of plastic waste. This review critically examines the opportunities and challenges associated with incorporating waste plastics in pavement construction, with an emphasis on their impact on the mechanical properties, durability, and life cycle performance of pavements. Special attention is given to the environmental implications, particularly the potential generation and release of micro- and nano-plastics during the pavement life cycle. This paper further evaluates current monitoring and analytical methodologies for detecting plastic emissions from road surfaces and explores emerging approaches for minimizing environmental risks. By providing a comprehensive synthesis of existing knowledge, this review seeks to support sustainable practices and inform policy development within the frameworks of circular economy and environmental stewardship. waste plastics; asphalt pavement; pavement durability; microplastics; environmental impact; circular economy; sustainable pavement materials 222-223-2301  
(PET), high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC), and bituminous binders and mixtures [5,8,9]. These thermoplastics, which constitute the majority of post-consumer plastic waste, demonstrate advantageous thermal and mechanical properties. Among them, LDPE, HDPE, and PP are widely considered ideal for pavement modification due to their compatible melting points and favourable interaction with bitumen [10,11]. However, PET requires significantly higher processing temperatures, and PVC presents environmental concerns due to the release of toxic gases when heated, which limits their applicability [10,11]. Thermosetting polymers, which do not re-melt upon heating, are typically considered less suitable for such purposes. The concept of incorporating plastics into pavements is not new; initial investigations go back to the 1990s. The increase in plastic waste production is anticipated to exceed 1 billion tonnes per year by 2050 [1], encouraging research in this field. Current findings indicate that waste plastics might improve the mechanical and durability characteristics of pavements, decrease dependency on virgin materials, and contribute to climate change mitigation through lowering the embodied carbon of road works [12, 13, 14]. The current practice includes three principal strategies for incorporating plastics into pavements: the wet method, the dry method, and hybrid or mixed methods [5,8]. In the wet method, polymers are mixed with the hot bitumen binder, enhancing its viscosity, elasticity, and resistance to rutting and fatigue [15,16]. In contrast, the dry method involves incorporating shredded or pelletized plastics into the heated aggregates [9]. The dry method has attracted considerable interest because of its simplicity and capacity for incorporating greater plastic materials [17,18]. Hybrid methods are designed to combine the advantages of both approaches, although their commercial applicability remains limited. The selection of process significantly affects performance results, environmental hazards, and practical executions. Wet-processed binders often demonstrate enhanced rheological properties; nonetheless, they provide difficulties with storage stability and phase separation [19]. Dry-processed mixes, although easier to integrate into existing asphalt plants, may lead to a less uniform distribution of plastics and greater microplastic (MP) release over their service life [14,20]. Numerous investigations have consistently indicated enhancements in mechanical performance. Plastic-modified binders demonstrate elevated softening points, reduced penetration values, improved rutting resistance, and enhanced elastic recovery, representing their ability to resist deformation under load [10,19,21].