Abstract:
Recent interest in environment-friendly materials has led to the use of agricultural by-products as raw material for the production of many construction materials. Because of this the material that used in this study was coffee husk and halls which are residues of coffee processing. Today; these materials are burnt on the field or dumped on land or in rivers. The main objective of this study was to investigate the optimal replacement of sand by Coffee Husk in the production of light weight and low-cost hollow concrete block. Depending on the type and amount, the lab-make the hollow concrete block had been fulfill the requirements of Ethiopian, American, Indian and European standards with respect to general use in dry conditions and partly in humid conditions of 7 th , 14 th , and 28 th days. Specifically this experimental study was conducted by preparing two types of HCB test samples. The test sample of HCB was produced by using mix proportion 1:6 of cement and sand. Out of the six parts of aggregate, the aggregate was replaced with 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100% amounts of coffee husk by volume. Based on the result, the HCB without coffee husk achieved 3.82Mpa mean compressive strength and the HCB with 30% coffee husk achieved 3.64Mpa mean compressive strength. The optimum replacement was obtained at 30% coffee husk. The production cost of all HCBs with coffee husk was found lower than the HCB without coffee husk. The weight comparison made, the HCBs with coffee husk were found lighter than HCB without coffee husk. The hollow concrete block with coffee husk in this study has achieved a better cost reduction in production cost, higher reduction in weight with 45.63% and a smaller reduction in compressive strength with 4.95% than hollow concrete blocks without coffee husk. The study further recommended to the micro and small HCB producers to increase the production of HCB with coffee husk, for the contractors and clients of Jimma Town to use this product instead of importing HCB.
