Strength assessment of coconut shell as partial replacement for course aggregate in light weight concrete

This research work investigated the physical and chemical properties of coconut shell as an alternative material in light weight concrete, the effect of curing age on the compressive strength of coconut shell concrete and the effect of percentage replacement on compressive strength of coconut shell concrete. Coconut shell were obtained locally and were crushed to an average size of 20mm. Concrete was produced with mix ratio 1(cement):2(fine aggregate):4(coarse aggregate) with a constant water-cement ratio of 0.5, by replacing coarse aggregate volumetrically at 0%, 5%, 10%, 15% and 20% with crushed coconut shells and curing age at four (4) levels 7, 14, 21 and 28 days. The size of specimen used throughout was 100mm x 100mm x 100mm with at least three samples made for each percentage replacement of coarse aggregate. The characteristic properties of materials and coconut shell concrete such as particle size distribution, workability, bulk density, moisture content, specific gravity and compressive strength were reviewed in this study and investigated in the laboratory. The average compressive strength results at 7 days curing with 0%, 5%, 10%, 15%, and 20% are 12.96N/mm2, 10.16N/mm2, 7.71N/mm2, 8.25N/mm2 and 5.66 N/mm2 respectively. The average compressive strength results at 14 days curing with 0%, 5%, 10%, 15%, and 20% are 11.47N/mm2, 11.11N/mm2, 9.26N/mm2, 7.22N/mm2 and 6.85N/mm2respectively. The average compressive strength results at 28 days curing with 0%, 5%, 10%, 15%, and 20% are 14.86N/mm2, 11.91N/mm2, 9.72N/mm2, 8.65N/mm2 and 6.52N/mm2 respectively. The average compressive strength results at 28 days curing with 0%, 5%, 10%, 15%, and 20% are 18.51N/mm2, 14.64N/mm2, 11.10N/mm2, 9.22N/mm2 and 6.84N/mm2 respectively. The results showed that compressive strength, density and workability of the concretes decreases with increase in coconut shell replacement. Coconut shells can be used as partial replacement for the conventional stone aggregates in concrete production. Therefore, the use of coconut shell aggregate as a replacement in convectional concrete should be encourage in the locality where it is in abundance to enhance environmental cleanliness.