Use of recycled aggregates in structural concrete

Abstract

Properties of the recycled aggregates and the suitability of the same in structural concrete were studied and compared them with natural aggregates. The results showed that the particle size distribution of recycled aggregates is compatible with those of natural aggregates. The recycled aggregates had abrasive and impact values of 48.7% and 27.10%, respectively while those of the natural aggregates were 29.5% and 11.45, respectively. Bulk density of recycled aggregates was 1065 kg/m3 with compared to 1296 kg/m3 of Natural aggregates and the water absorption was 2.82% with compared to 1.22 of Natural aggregates. The mix design proposed for concrete was grade 30. Properties of concrete made under three mixing scenarios of natural aggregate to recycle aggregate proportions such as 50% -50%, 25%-75%, and 0%-100% were compared with those of 100% natural aggregates. With increasing percentage of recycled aggregate content, compressive strength, flexural strength, tensile splitting strength and workability were significantly decreased. According to the results, grade 30 concrete properties could be achieved with mix proportions of 50% natural aggregate and 50% recycled aggregate, without significantly affecting the concrete properties, indicating a 50% saving of natural aggregates thus reducing environmental impacts and enhancing sustainability.