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Ubachukwu, O. A.
Department of Civil Engineering, Michael Okpara University of Agriculture, Umudike, P.M. B. 7267, Abia State, Nigeria
Kalu, G. J.
Department of Civil Engineering, Michael Okpara University of Agriculture, Umudike, P.M. B. 7267, Abia State, Nigeria
Idiok, U. T.
Department of Civil Engineering, Topfaith University, Mkpatak, Akwa Ibom State, Nigeria
ABSTRACT
The geometrical growth rate of human population has resulted in increased demand for infrastructures. This has resulted in reduced supply of sand. This paper is aimed at investigating the mechanical properties of concrete made with 15% partial replacement of sand with crushed oyster shells (COS) as it relates to varying water-cement ratio. A total number of 144 cubes of 150mm x 150mm x 150mm grade 25 concrete were produced comprising standard concrete cubes of 72 and those of sand-crushed oyster shells concrete of 72 cubes. The concrete cubes were cast with varying water-cement ratio of 0.35, 0.4, 0.45, 0.5, 0.55 and 0.6. The cubes were cured for 3, 7, 14 and 28 days. They were crushed with the Universal Testing Machine. The experimental results showed that there was an increase in workability of concrete made with 15% sand-crushed oyster shells at different water-cement ratio. The slump of sand-crushed oyster shell concrete was 67mm at 0.6 w/c ratio, while that of standard concrete is 62mm. This shows a slump difference of 5mm. Also, the maximum compressive strength obtained decreased from 32.53N/mm2 for a 0% COS replacement to 31.29N/mm2 for a 15% replacement at a w/c ratio of 0.35 in 28 days, the minimum compressive strength reduced from 13.99N/mm2 for 0% replacement to 13.24N/mm2 for 15% replacement at 0.6 w/c ratio in 3 days. In addition, the density of the concrete cubes made with 15% COS and 85% sand generally decreased slightly relative to the ones made with 0% COS. The density at 0% COS and 100% sand was 2611 kg/m3 at 0.5 w/c ratio, while that of 15% COS and 85% sand was 2590 kg/m3 at 0.5 water-cement ratio. This experiment will not only reduce the dependency of concrete on sand, but will also address and mitigate the environmental and health consequences of indiscriminate disposal of waste oyster shell in regions where they are available.
Keywords: crushed oyster shell, concrete, sand, aggregate, partial replacement
https://doi.org/10.33922/j.ujet_v10i1_2
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Published
Tuesday, April 23, 2024
Issue
Vol. 10 No. 1, June 2024
Article Section
GENERAL
The contents of the articles are the sole opinion of the author(s) and not of UJET.
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