Evaluation of Mechanical Behavior of Treated Recycled Aggregate Concrete Modified with SCMs

The increasing demand for sustainable construction materials has emphasized the need to incorporate recycled aggregates and supplementary cementitious materials (SCMs) into structural concrete. This study examines the mechanical behavior of M30 grade concrete incorporating 100% treated recycled coarse aggregates (TRCA), with and without SCMs including fly ash (FA), silica fume (SF), and nano-silica (NS). A total of five mixes were prepared as per IS 10262:2019: a control mix with natural aggregates and four mixes using TRCA, three of which incorporated individual SCMs. Experimental evaluations included compressive strength at 7, 14, 28, and 90 days, split tensile strength at 28 and 90 days, and static modulus of elasticity at 28 days in accordance with IS 516:2013. Results indicated that concrete with TRCA alone showed slightly lower mechanical properties compared to the control mix. However, the inclusion of SCMs significantly enhanced performance. Notably, the mix containing 2% nano-silica achieved the highest values for compressive strength (52.4 MPa at 90 days), split tensile strength (4.6 MPa at 90 days), and elastic modulus (31,400 MPa), outperforming the control. The improvements are attributed to the pozzolanic activity and particle refinement effects of NS, which enhanced matrix densification and interfacial bonding. The findings demonstrate that the combined use of TRCA and nano-silica offers a sustainable and high-performance alternative to conventional concrete, aligning with circular economy principles and advancing the development of eco-efficient construction materials