Integrating 10R principles in pavement engineering: Circular economy pathway for reclaimed asphalt pavement

The production of substantial volumes of reclaimed asphalt pavement (RAP) worldwide poses a key challenge to pavement industry, mandating establishment of innovative strategies to keep resources in use and waste out of the environment, aligning with circular economy (CE) goals. Despite conducting extensive literature review on recycling technologies, environmental benefits, and mechanical properties of extremely RAP-containing asphalt mixtures, the green circularity of RAP materials has been only briefly addressed in existing studies. In this context, the present study conducts a thorough review, drawing upon relevant studies published from 2010 to 2025, to bridge circularity of these waste materials with the R-hierarchy, particularly 10 R principles, to develop potential strategies for reducing, reusing, refurbishing, remanufacturing, repurposing, upcycling, and downcycling RAP, thereby evolving a more sustainable pavement industry and promoting greener roadway construction. Additionally, a framework is proposed to more effectively manage the analysis of material flow within flexible pavements, while also facilitating the process of storing RAP based on 10 R principles of CE. Overall, this study contributes to fostering a greener, more sustainable road pavement industry through tailored showcases of CE applications for RAP materials aligning with a set of 10 R strategies. Overcoming characterized challenges and leveraging potential enablers can elevate the practical implementation of CE principles in RAP, leading to more energy-efficient solutions and optimized resource utilization across the pavement sector. • Showcases of implementing CE on reclaimed asphalt pavement (RAP) materials are provided. • CE strategies established on RAP are aligned with the 10 R principles. • A general framework for adopting CE on RAP across the lifecycle of flexible pavement is proposed. • Potential techniques to enhance the reuse and recycling of RAP in flexible pavements are presented. • Future outlooks are recommended to address identified barriers and leverage potential enablers.