Published Paper Details:

This study investigates the effect of partial replacement of natural coarse aggregate with recycled coarse aggregate (RCA) on the compressive strength and workability of concrete. With the increasing demand for sustainable construction materials, the utilization of construction and demolition waste has become a critical strategy for reducing the environmental footprint of the construction industry. In this experimental research, RCA was used to replace natural aggregate at three levels: 10%, 20%, and 30%, by weight. Additionally, silica fume was incorporated at a fixed dosage of 10% by weight of cement to enhance the pozzolanic activity and improve overall concrete performance. Concrete mixes were prepared using a fixed mix ratio of 1:2:4 (cement: sand: aggregate) with a constant water-cement ratio. For each replacement level, mixes were prepared with and without silica fume, resulting in eight different mix combinations. Standard 150 mm concrete cubes were cast, cured for 28 days, and tested as per IS 516:1959 for compressive strength. Slump tests were also conducted to assess the workability of the mixes. Results showed that compressive strength decreased with increasing RCA content in the absence of silica fume. However, mixes containing silica fume showed a significant improvement in strength, recovering up to 90% of the control mix's compressive performance. Workability slightly declined with RCA content but improved with silica fume addition. The study concludes that up to 30% RCA replacement, especially when combined with silica fume, can be effectively used in structural concrete, promoting sustainable practices without significantly compromising strength or workability