EFFECT OF REVIBRATION ON THE FLEXURAL STRENGTH OF CONCRETE, USING LOCUST BEAN POD EPICARP ASH AS PARTIAL REPLACEMENT FOR CEMENT

Abstract

This study examines the flexural strength of reinforced and revibrated concrete beams using locust bean pod epicarp ash (LBPEA) as partial replacement for cement. The LBPEA used contained major oxides: Al2O3 (12.046%), SiO2 (49.054%) and Fe2O3 (8.925%). Fifty (50) reinforced concrete beams (150mm x 150mm x 600mm) were cast for each percentage (0%, 5%, 10%, 15% and 20%) cement replacements by LBPEA: thirty-five revibrated; fifteen non-revibrated; and were cured for 28 days. Revibration was carried out for 20 seconds at an interval of 10 minutes successions after initial vibration. Flexural strength test carried out using universal testing machine showed that the maximum flexural strength occurred at 30th minutes revibration time interval for both 0% and 5% replacements, 9.2N/mm2 for 0% and 9.0N/mm2 for 5%, while that of non-revibrated beams had 9.17N/mm2 and 8.33N/mm2 at 0% and 5% replacements respectively, thus projecting an improved strength of concrete beams produced at an optimal replacement of 5% LBPEA which is recommendable.