<p>In recent decades, the rate of construction and demolition (C &amp; D) waste has risen due to urbanization, population growth, and large construction projects like roads, bridges, etc. Utilizing recycled coarse aggregate (RCA) as a sustainable material in concrete helps to preserve natural resources, and reduce landfill waste and construction costs. Making use of RCA has a negative impact on the mechanical properties of concrete. Because, RCA tends to absorb more water, and has lesser density and crushing index than the natural coarse aggregate (NCA) due to the presence of old adhered mortar. Hence, the performance of concrete is degraded. In addition, RCA has a larger Interfacial Transition Zone (ITZ) than conventional concrete which is the weaker zone of concrete. For better performance of recycled aggregate concrete (RAC) various techniques have been adopted for enhancing the quality of RCA. On the other hand, by strengthening old ITZ, between old mortar and NCA, and new ITZ, which is between RCA and new mortar, the mechanical and durability properties of RAC can be enhanced. The present study confers about the optimized parameters of various treatment methods adopted for RCA for efficacious process and their influence on the ITZ of RAC. From the discussions, it was formulated that the treatment methods make a significant impact on the ITZs, which results in a stronger RAC than an untreated RAC. </p> Graphical abstract <p></p>