The accelerating accumulation of plastic waste has emerged as one of the most complex and persistent environmental challenges of the twenty-first century, intersecting material production systems, waste governance, ecological degradation, and infrastructure development. Among the various valorization pathways proposed to mitigate plastic pollution, the incorporation of recycled plastic into asphalt mixtures for road construction has gained substantial academic, industrial, and policy attention. This research article develops an extensive, theoretically grounded, and critically analytical examination of recycled plastic–modified asphalt systems as a sustainable infrastructure strategy. Drawing strictly on the provided body of literature, the study situates plastic-modified asphalt within broader debates on plastic waste management, circular economy transitions, pavement engineering, and environmental risk mitigation. The analysis integrates materials science perspectives on polymer–bitumen interactions, mechanical performance implications for asphalt mixtures, and durability considerations under varying climatic and loading conditions. Simultaneously, it interrogates environmental dimensions, including life cycle impacts, microplastic generation risks, and the limits of waste-based solutions in addressing systemic overproduction of plastics.

Methodologically, this article adopts an integrative qualitative synthesis approach, critically examining experimental findings, review-based evidence, and conceptual frameworks across environmental science and pavement engineering scholarship. The results section interprets convergent and divergent findings on mechanical performance, moisture resistance, aging behavior, and interfacial adhesion mechanisms in plastic-modified asphalt mixtures, emphasizing how polymer type, processing method, and dosage fundamentally shape outcomes. The discussion extends beyond performance metrics to explore governance constraints, technological lock-in risks, and ethical considerations surrounding the framing of infrastructure as a sink for plastic waste. Particular emphasis is placed on reconciling optimistic engineering narratives with critical environmental scholarship that questions whether downstream recycling solutions can meaningfully offset unchecked plastic production.

The article concludes that recycled plastic–modified asphalt represents neither a panacea nor a marginal intervention but rather a context-dependent technological pathway whose sustainability outcomes hinge on rigorous material selection, regulatory oversight, and integration within broader plastic reduction strategies. By synthesizing dispersed strands of literature into a unified analytical framework, this study contributes a comprehensive academic foundation for future research, policy deliberation, and engineering practice related to sustainable road construction and plastic waste valorization.