COMPRESSIVE STRENGTH OF CONCRETE MADE WITH COAL WASHERY REJECTS AS COARSE AGGREGATE

The demand of natural aggregates is rapidly becoming high day by day in the construction industry. Various attempts are being made to find substitutes for natural aggregates. In India, about 70% of electricity is produced by combustion of good quality coal. In the process of coal washing, large quantities of impure coal are being rejected and causing disposal problems. These rejected impure coals are called as Coal Washery Rejects (CWR). To maintain the environmental sustainability, an attempt has been made in the present study to use new material CWR as partial replacement of coarse aggregate in concrete. This investigation studied the compressive strength of concrete containing CWR at different replacement levels (0% - 50%). The compressive strength values were compared to M 25 grade of conventional concrete (CC). From the results, it is observed that the increase in CWR replacement level decreased the compressive strength. This decrease was marginal at 20% and 30% replacement levels, but beyond 30%, the decrease was very much significant. Hence, it is revealed that 30% CWR replacement can be considered as optimum level in the construction industry.