Enhancing sustainable concrete performance: dual treatment of recycled coarse aggregates for improved strength and durability
Harish Panghal, Sandeep Chaudhary, Awadhesh Kumar
Abstract
This study seeks to enhance sustainable concrete by improving the performance of recycled coarse aggregates (RCA), with a particular focus on overcoming the challenges posed by aged cement mortar on the aggregate surfaces. A novel dual treatment method, combining chemical and abrasion techniques, is employed to improve the strength and durability of surface-modified recycled coarse aggregates (SMRCA). The process begins with hydrochloric acid treatment to weaken the mortar adhesion, followed by abrasion to remove the weakened mortar. This approach minimizes strength loss and strengthens the bond between the aggregate and the concrete matrix. Comprehensive analyses, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) spectroscopy, alongside tests for compressive strength, drying shrinkage, electrical resistivity, and chloride ion penetration, reveal significant improvements. Notably, a 32.64% increase in strength is observed at a 25% replacement (SMRCA 25), demonstrating the effectiveness of the treatments. While a slight reduction of 8.31% is observed at 100% replacement (SMRCA 100), substantial strength gains of 1.68% and 20.40% are achieved at 75% and 50% replacement levels, respectively. Furthermore, SMRCA concrete exhibits reduced drying shrinkage (17–21%), increased electrical resistivity (34–42%), and enhanced resistance to chloride ion penetration (28–31%) at 100% replacement, indicating improved durability compared to conventional RCA.