Compressive Strength Evaluation of Bush Gravel Concrete Containing Rice Husk Ash and Bone Powder Ash

Abstract

In this study, rice husk ash (RHA) and Bone Powder ash (BPA) were separately used as partial replacements of Portland Limestone Cement (PLC) in concrete production. A concrete mix proportion of 1:2:4 with a water to cement ratio of 0.5 was adopted. The ashes were obtained through open air burning. Sieve analysis, specific gravity, bulk density, moisture content, AIV and ACV tests were carried out on the aggregates. Concrete mixes were prepared for 100% PLC as control while RHA and BPA were used to replace PLC at 5, 10, 15, 20 and 25%. For each mix point, 3 cube samples were cast for four different curing ages. A total of 144 concrete cubes of were cast. Workability of the fresh concrete samples were checked using slump test. Compressive strength test was carried out on the hardened concrete samples at 7, 14, 21 and 28 days. From the results obtained, the workability of the fresh concrete decreases with increasing RHA and BPA content. In all the samples, compressive strength continued to increase with increase in curing age while the strength continued to decrease with increasing RHA and BPA content. The control samples had the highest strength of 26.27N/mm2. Average compressive strengths of 21.89, 17.61, 11.32, 9.78 and 7.05 N/mm2 were recorded at 5, 10, 15, 20 and 25% replacement of PLC with RHA respectively. Average compressive strengths of 16.67, 14.03, 11.60, 10.56 and 8.77 N/mm2 were recorded at 5, 10, 15, 20 and 25% replacement of PLC with BPA respectively. It was concluded amongst others that: RHA can be used in producing normal strength concrete at an optimal replacement level of 5%, BPA cannot be used in producing normal strength concrete even at a replacement level of 5%, and at higher replacement levels of PLC with BPA (15, 20 and 25%), higher strengths are obtained when compared to the use of RHA at the same replacement levels.