Effect of coarse aggregate replacement with working mold from ceramic industry in lightweight aggregate concrete

This research investigated the possibility of deteriorated working mold (DWM) as a coarse aggregate for lightweight aggregate concrete (LWAC), which divided to two parts; Effect of coarse aggregate (CA) replacement with DWM and the ratio between coarse aggregate and cement (A/C) on properties of LWAC. The ratio of ordinary Portland cement (oPC): sand: CA are 1: 2.21: 3.03 and replaced CA with DWM at the levels of 0, 25 and 50 wt.%. The range of A/C ratio as 1:1, 2:1, 3:1 and 4:1 by weight and replaced CA with DWM at the level of 50% by weight. All concretes were tested for compressive strength, unit weight and water absorption at the age of 7, 14 and 28 days. The results showed that increasing the levels of DWM reduced density and compressive strength. The compressive strength and density of concrete with 25 and 50 wt.% of DWM decreased to 33, 11 % and 65, 23 % compared with normal concrete respectively. The lightweight aggregate concrete with DWM at the level of 50 wt.% in the A/C ratio of 4: 1 gave the compressive strength at 28 days and density of 19.4 MPa and 1744 kg/m3. This satisfies the strength and density requirement for structural lightweight concrete of the ASTM C330 and ACI 213R-04 except water absorption which was 13.22 wt.% higher than the other ratios. Experimental results indicate that it is possible to produce environmentally-friendly lightweight concrete with DWM as coarse aggregate from the ceramic industry.