| Abstract: |
In the past few decades, making concrete utilizing recycled aggregates (RA) has become an attractive method to deal with environmental degradation, natural resource depletion, and the increasing amount of construction and demolition (C&D) waste. This meta-analytical review combines results of a wider range of experimental and field studies to evaluate the overall impact of recycled aggregate replacement ratios on concrete strength indicators including compressive strength, tensile strength, flexural strength, and modulus of elasticity. A systematic review of peer-reviewed literature from January 2020 to January2024 was performed. Studies eligible for inclusion examine the use of recycled coarse aggregates (RCA) and recycled fine aggregates (RFA) as substitution of natural aggregates (NA) in mixtures partially or fully. The review highlights certain consistent trends: compressive strength tends to decrease with a higher replacement level, especially at replacement levels over 30–50%, while water-cement ratio and interfacial transition zone (ITZ) quality become important variables. Numerous research reveal that pre-treatment processes including carbonation, acid washing and polymer impregnation can significantly reduce strength loss. A meta-analysis also indicates that the variability in sources, test protocols, and additions of supplementary cementitious material (SCM) are responsible for heterogeneity of the outcomes. This paper critically examines the lack of uniformity in the methods are employed in studies of this nature and proposes structured guidelines for future studies. The results confirm the feasibility of using RCA as a partial replacement (up to 30%) of natural aggregates with a negligible influence on the mechanical performance of structural elements which, together with its environmental characteristics, leads to closing the loop in construction and supporting the circular economy. |
