AN EXPERIMENTAL INVESTIGATION ON STEEL FIBER REINFORCED CONCRETE MADE BY PARTIAL REPLACEMENT OF COARSE AGGREGATE WITH CONCRETE DEMOLITION WASTE

Demolition of old structures to make way for new and modern ones are common features inmetropolitan areas due to rapid urbanization. However, very little demolished concrete is recycled or reused. The strict environmental laws and lack of dumping sites in urban areas, on one hand, are makingthe disposal of demolition wastes problematic while, on the other hand, the quarrying of raw materials is becoming dif icult. The present work presents the results of experimental investigations carried out toevaluate the effect of partial replacement of cement, fine aggregate and coarse aggregate by dif erent partsof demolished wastes on strength and workability of concrete made. For the study, design mix concrete ofgrade M-30 was prepared using IS 10262-2009. Thereafter, the replacement of dif erent constituents ofconcrete, one at a time was carried out by replacing these with the dif erent sieved fractions of crusheddemolition waste. The compressive strength at 7, 14 and 28 days and workability in terms of slump valuewere measured. The compressive strength of these mixes was measured on 150mm cubes. Test resultsshow that the behavior of recycled waste concrete The compressive strength of recycled concrete with 0%, 20% 25% and 30% coarse aggregate replacement by demolition waste coarse aggregate at 7,14 and28 days is comparable to that of referral concrete. The compressive strength of recycled concrete madeusing 5% of demolition waste coarse aggregate is almostsimilar to referral concrete. Further, the resultsindicate that still higher replacement of the constituent materials is possible without much compromisingthe 28 days strength and workability