A comprehensive review and evaluation of recycled aggregates as a sustainable construction material

Abstract The construction sectButleror generates 30%–40% of global solid waste, predominantly concrete debris, prompting interest in Recycled Aggregates (RA) as a sustainable alternative to natural aggregates. Recycled Aggregate Concrete (RAC) commonly exhibits 10%–20% lower compressive strength, higher water absorption, and increased carbonation due to porous adhered mortar and dual Interfacial Transition Zones (ITZ). Performance improvements are achievable using Supplementary Cementitious Materials (SCMs) like silica fume and fly ash, advanced mixing techniques such as the Two-Stage Mixing Approach (TSMA), and hybrid fibers, which enhance strength, durability, and shrinkage control. Structurally, RAC beams and slabs show comparable flexural properties to conventional concrete but with increased deflection and slightly reduced seismic resistance. Despite progress, key research gaps remain, including variability in RA quality, absence of standardized mix design protocols, and notably, limited long-term field data. This review uniquely integrates bibliometric analysis with comprehensive synthesis, providing critical insights into RAC mechanical, durability, and structural behaviour while emphasizing avenues for future research and practical adoption in sustainable construction.