Enhancing Concrete Performance with Treated Recycled Aggregates: A Comparative Study of Coating, Chemical, and Abrasion Treatments

This research focuses on optimizing the use of recycled coarse aggregates (RCA) in concrete by evaluating three advanced surface treatments: coating, chemical, and abrasion treatments. The study explores coating RCA with cement paste, using hydrochloric acid to weaken attached materials, and applying an abrasion machine to remove mortar. The main goal is to enhance the bond between recycled aggregates and the cement matrix, leading to substantial improvements in concrete properties. Chemical treatment emerged as the most effective, yielding a 32.40% increase in compressive strength at 7 days and a 22.47% increase at 28 days compared to untreated RCA. Flexural strength improved by 15.07% at 7 days and 10.71% at 28 days with chemical treatment. Abrasion treatment enhanced abrasion resistance but resulted in a 16.75% reduction in compressive strength at 7 days and a 14.28% reduction at 28 days at higher replacement levels. Cement slurry treatment showed a 28.30% increase in compressive strength at 7 days and a 19.70% increase at 28 days, and a 13.15% increase in splitting tensile strength at 25% replacement. X-ray Diffraction and Scanning Electron Microscopy analyses indicated that surface treatments improved the microstructure of RCA, leading to better concrete quality and strength. These results demonstrate the potential of surface-modified RCA for sustainable construction, offering a viable method for up to 50% replacement of conventional aggregates while minimizing environmental impact.