Review on Treatment Methods for Enhancing the Properties of Recycled Concrete Aggregate

The treatment techniques utilised to improve the qualities of recycled concrete aggregate (RCA) for its efficient use in cement mortar and concrete are critically examined in this review study. The use of RCA is often constrained by residual adhering mortar, which leads to increased porosity and water absorption and to reduced density, mechanical strength, and durability. The analysis consolidates results from published research on four primary therapeutic methods: sodium silicate treatment, rapid carbonation, cement-slurry impregnation, and polymer impregnation. These methods are evaluated based on their effects on water uptake, porosity, compressive strength, interfacial transition zone properties, and longevity. The analysed data suggest that the application of sodium silicate efficiently consolidates the bonded mortar and reduces water permeability, whereas carbonation facilitates calcium carbonate formation, enhances pore architecture, and strengthens aggregate–paste adhesion. Cement-slurry infusion improves the surface quality and mechanical properties of RCA, whereas polymer infusion significantly enhances impermeability and long-term resilience, although its elevated expense may limit widespread use. In summary, sodium silicate treatment and carbonation offer an advantageous balance of efficacy, feasibility, and ecological benefits. This analysis delineates the relative benefits and drawbacks of existing therapies and underscores the necessity for standardised treatment protocols, long-term efficacy evaluations, and assessments of environmental and economic impacts to facilitate the wider systemic implementation of treated RCA.