Investigation on compressive strength of masonry blocks manufactured using crushed coconut shells

Abstract

Coconut shells are produced in significant quantities in Sri Lanka as coconut tree has a large amount of usage in the country. Although coconut shell has different usages, considerably large amount of them remain in the environment as waste. Coconut shells dumped improperly to the environment provide breeding places for disease vectors such as rats and mosquitoes. Utilization of coconut shell as building material will be an important step to improve sustainability. In this study, an attempt was made to utilize Crushed Coconut Shell (CCS) in the manufacturing of masonry blocks as for the replacement of coarse aggregate (i.e., chips). Solid masonry blocks having the sizes of 360 mm ×100 mm ×170 mm were casted with the mix proportion of 1:5 Cement: Sand. Coconut shells were crushed, sieved and added to the mixture in different proportions to determine its optimum percentage of utilization. The blocks were experimented for 7, 14 and 28 day compressive strength. Compressive strength of crushed coconut shell based sand cement blocks with 20%, 25%, 30% (volume basis) of CCS have been examined, so as to investigate whether crushed coconut shell can be used as fully replacement of coarse aggregates and its optimum percentage. The structural performances of crushed coconut shell based sand cement blocks were compared with the same percentage of coarse aggregate sand cement blocks (i.e., control blocks). Water absorption capacity was investigated for this CCS based masonry blocks and was compared with conventional cement sand block with coarse aggregate.The optimum percentage of utilization of CCS was identified by considering maximum compressive strength that was obtained using laboratory experiments. It was found that the maximum compressive strength of CCS based cement sand block is achieved at 25% replacement level. The water absorption capacity was below the 12%, which is the requirement of maximum percentage of water absorption in masonry blocks.