Eco-Friendly Concrete: A Dual Surface Modification Approach for Enhanced Mechanical Performance of Recycled Coarse Aggregates

This study aims to boost the mechanical performance of eco-friendly concrete by addressing challenges related to recycled coarse aggregates (RCA), particularly aged cement mortar adhering to aggregate surfaces. Employing a novel dual approach involving abrasion and cement slurry treatments, the research effectively removes old mortar from the RCA surface and introduces a new surface. This dual treatment minimizes strength loss and enhances the bond with the concrete matrix. Various percentages of surface-modified RCA (SMRCA) replace traditional coarse aggregates, with evaluations covering modulus of elasticity, workability, split tensile strength, flexural strength, compressive strength, porosity, and microstructural features. Results indicate that the dual modification approach significantly improves mechanical performance, particularly at a 50% SMRCA replacement rate, where compressive, flexural, and split tensile strength increase by 14.23%, 8.05%, and 4.96%, respectively. The SMRCA 75 mixture emerges as the most economically viable and aligns with eco-friendly concrete objectives.