EFFECT OF RECYLCED COARSE AGGREGATE ON PHYSICAL AND MECHANICAL PROPERTIES OF CONCRETE

Abstract

Experimental program has been conducted in this research to examine physical and mechanical properties of recycled coarse aggregate (RCA) made from crashing of standard concrete cubes. The studied properties include specific gravity, water absorption, bulk density and crushing index. These properties are compared to their counterparts obtained from natural coarse aggregate (NCA). The research also aims to study the effect of using the RCA on the mechanical properties of concrete. Different RCA ratios are used in constructing reinforced concrete columns to study their crack pattern, failure load, load- displacement relation, load-strain relation for longitudinal and transversal reinforcement, toughness and stiffness. The study includes four groups of specimens with 0%, 30%, 50% and 100% RCA replacement ratios. Six cubes, cylinders and small beams are constructed from each group to estimate the compressive, splitting and flexure strength at the age of 7 and 28 days. The research shows that RCA is a good alternative to NCA and the optimum RCA replacement ratio is 50%.