Effect of Locust Bean Pod Epicarp Ash (Lbpea) on the Compressive Strength of Revibrated Concrete

Abstract

The effect of locust bean pod epicarp ash (LBPEA) on the compressive strength of re-vibrated concrete is presented. The LBPEA used was obtained by controlled incineration of locust bean pod epicarp in an enclosed furnace. The result of the chemical analysis carried out on the LBPEA showed that it is a very good pozzolana with its SiO2, Al2O3, and Fe2O3 content percentage summation at 77.81%. Using a concrete mix ratio of 1:2:4 and a water-binder ratio of 0.6, a total of 147 cubes were cast and cured for 7, 14 and 28 days: 21 for control (0% LBPEA + 100% OPC); and 21 cubes for each other different percentages (5%, 10%, 15%, 20%, 25%, and 30%) replacements of OPC. Each category of cubes was initially vibrated and then re-vibrated at an interval of 10 minutes up till 1 hour. Compressive strength of the concrete cubes were determined at 7, 14 and 28 days curing age. The compressive strength increased gradually with curing age and a maximum compressive strength of 28.44 N/mm2 at 60 minutes revibration was obtained at 28 days for 5% of LBPEA. At 14 days curing, a maximum compressive strength of 24.76 N/mm2 at 60 minutes revibration was obtained for 0% of LBPEA. At 7 days curing, a maximum compressive strength of 25.29 N/mm2 at 60 minutes revibration was obtained for 0% of LBPEA. This suggests and is therefore recommended that a 5% replacement of OPC with LBPEA can be adopted for structural concrete production.