Toward sustainable construction: A critical review of recycled aggregate concrete properties and future opportunities

The increasing demand for sustainable construction materials has positioned recycled aggregate concrete (RAC) as a viable alternative to conventional concrete (CC). RAC utilizes aggregates sourced from construction and demolition (C&D) waste, contributing to resource conservation, landfill reduction, and carbon footprint mitigation. However, the incorporation of recycled aggregates (RA) presents challenges related to variable quality, higher water absorption, and the presence of adhered mortar, all of which can adversely affect workability, strength, and durability. This review comprehensively examines the properties and performance of RAC, focusing on fresh-state characteristics, mechanical behavior, and long-term durability under aggressive environmental conditions. It also highlights key strategies for improving RAC quality, including pre-treatment of recycled aggregates, the use of supplementary cementitious materials (SCMs) such as fly ash (FA) and silica fume (SF), and fiber reinforcement to enhance mechanical and durability performance. Life Cycle Assessment (LCA) studies demonstrate that RAC significantly reduces embodied energy and greenhouse gas emissions, supporting the principles of the circular economy. Despite these environmental benefits, several barriers limit RAC’s widespread application, such as inconsistent standards, lack of awareness among stakeholders, and uncertainties in performance prediction. This paper identifies critical research gaps, particularly in the development of reliable mix design methods, long-term field performance evaluations, and innovative recycling technologies. The review concludes that, with targeted research and standardized quality control measures, RAC can become an integral part of sustainable construction practices worldwide, offering both environmental and economic advantages.