Strength Evaluation of Concrete with Recycled Coarse Aggregate Under Varying Mix Proportions.

Abstract

The global construction industry faces a critical sustainability challenge, marked by both the rapid depletion of natural aggregate (NA) resources and the severe environmental impact of accumulating construction and demolition ) waste in landfills. To address this dual pressure, this experimental research investigated the structural viability of replacing Natural Coarse Aggregate (NCA) with Recycled Coarse Aggregate (RCA) in concrete production. The study centered on two popular mix ratios, 1:1.5:3 and 1:1:2 (Cement: Fine Aggregate: Coarse Aggregate), testing four levels of RCA substitution: 0% (serving as the control), 25%, 50%, and 75%. Comprehensive preliminary testing was conducted to characterize the physical properties of all aggregates, including their Fineness Modulus, specific gravity and unit weight For compressive strength analysis, standard concrete cylinders were cast for all eight resulting mix variations, subjected to standard water curing, and monitored for strength development at 7, 14, 21, and 28-day. The results consistently demonstrated that an increase in RCA content leads to a progressive, non-linear decrease in compressive strength. From our result for using 25% recycled aggregate , strength gained 89%. For using 50% and 75% recycled used strength gained 81% and 71%