A Review on Recycled Concrete Aggregate for Sustainable Engineering: Performance Limitations, Enhancement Strategies, and Practical Applications

Recycled concrete aggregate (RCA) is gaining increasing attention as a potential replacement for natural aggregates due to the growing demand for environmentally responsible construction materials. Within the context of circular economy principles and climate-responsive infrastructure, this paper synthesizes recent developments in RCA performance optimization, environmental benefits, and policy integration. Performance limitations are primarily associated with the presence of adhered mortar and weak interfacial transition zones, which contribute to increased water absorption and reduced mechanical strength. However, these limitations can be mitigated through combined approaches involving chemical treatments, bio-based surface modification, mechanical refinement, and optimized mix designs incorporating supplementary cementitious materials. Emerging techniques such as carbonation curing and bio-deposition further enhance RCA by improving material performance while enabling carbon storage within cementitious systems. The review also highlights the importance of aligning RCA deployment with public procurement strategies, localized standards, and optimized logistics, particularly in emerging economies such as the Philippines. Priorities for future work include field-scale validation under tropical conditions, artificial intelligence-driven mix optimization, and context-sensitive life cycle assessment. Overall, RCA represents a scalable pathway toward more resource-efficient and low-carbon construction systems, supporting United Nations Sustainable Development Goals (SDGs) 9, 11, and 13