Performance enhancement of recycled coarse aggregates with dual treatment in concrete

This study addresses the growing demand for concrete and dwindling natural resources by presenting a dual-treatment method to enhance recycled coarse aggregates (RCA) for sustainable concrete. RCA was treated with 0.8 M hydrochloric acid for 24 h followed by mechanical abrasion in a Los Angeles abrasion machine. This process significantly reduced adhered mortar, improving the physical and mechanical properties of treated RCA (TRCA). TRCA was incorporated into M35 concrete mixes, replacing natural coarse aggregates at varying proportions (25%–100%). Results showed a 54.63% increase in 7-day compressive strength and a 39.88% improvement at 28 days for 25% TRCA (TRCA 25) compared to untreated RCA. Flexural strength improved by 39.93% at 7 days and 20.56% at 28 days. Durability tests revealed a 199.52% higher electrical resistivity and a 33.70% improvement in chloride penetration resistance for TRCA 25 at 28 days. Even at 100% replacement, TRCA showed a 21.10% reduction in chloride penetration compared to untreated RCA. This innovative treatment advances recycled aggregate concrete, offering a sustainable solution with superior performance, supporting high-quality construction while conserving resources.