A review on sustainable use of recycled construction and demolition waste aggregates in pavement base and subbase layers

In recent times, the continuous growth of construction and demolition (C&D) activities have resulted in increases in the utilization of natural resources as well as global C&D waste production. A major part of C&D waste produced is dumped in landfills worldwide although some countries have adopted good recycling and reuse facilities to generated C&D waste. Based on an extensive critical review of published literature on the topic including global C&D waste recycling statistics and composition of generated wastes, this paper identifies key physical, mechanical, and geotechnical characteristics of recycled C&D waste aggregates specific to use as pavement base or subbase materials. Recycled aggregates typically have sufficient CBR, abrasion resistance, compressive strength and resilient modulus in accordance with various road standard specifications, which enable their applications for pavement base and subbase layer construction. Recycled aggregates typically have higher water absorption and lower specific gravity values than virgin aggregates. Furthermore, this study evaluates the feasibility and effectiveness of recycled aggregates in pavement base and subbase layers based on the detailed laboratory investigations. Additionally, case studies involving large-volume utilization of recycled aggregates for field-scale pavement construction are presented facilitating the broader adoption of recycled materials in sustainable construction of road pavements. These studies document crucial insights into its real field performance in terms of strength, durability and longevity. Finally, authors have discussed the potential challenges, research gaps and future insights on the use of recycled aggregates in pavement construction. The use of recycled aggregates in pavement construction still has some barriers and challenges such as availability in bulk quantity especially at the field scale and absence of road standards for application, which require further research and practical developments to promote the sustainable use of these materials in the future.