Enhancing concrete sustainability: a critical review of the performance of recycled concrete aggregates (RCAs) in structural concrete

In the context of sustainable construction, recycled concrete aggregates (RCAs), including both fine and coarse fractions derived from construction and demolition waste (CDW), are gaining traction due to their potential to mitigate environmental impacts by reducing reliance on natural aggregates and minimizing waste. This paper provides a comprehensive review of the effects of RCAs on the mechanical and durability properties of concrete, including compressive and tensile strengths, modulus of elasticity, and resistance to environmental degradation. The review highlights that the presence of adhered mortar and higher porosity in RCAs generally leads to reduced mechanical performance and durability. However, pretreatment methods—mechanical, chemical, and thermal—along with optimized mix designs and the use of supplementary cementitious materials (SCMs) have shown to significantly improve the concrete properties of RCAs. Additionally, recent studies on carbon dioxide (CO2) capture through the accelerated carbonation of RCAs offer promising environmental benefits. Life cycle assessment (LCA) analyses reveal reductions in energy use, CO2 emissions, and material costs when RCAs are properly processed and locally sourced. Despite challenges related to RCA quality variability, the review identifies pathways for the effective use of RCAs in structural applications.