THE EFFECT OF APPLYING RICE HUSK ASH ON THE WORKABILITY AND FLEXURAL STRENGTH OF REVIBRATED AND NON-REVIBRATED REINFORCED CONCRETE

Abstract

This study examines the influence of rice husk ash (RHA) on the workability and flexural strength of revibrated and non-revibrated concrete beams. Concrete production incorporated the replacement of Ordinary Portland Cement (OPC) with 0%, 5%, 10%, 15% and 20% of RHA. The design mix ratio of 1:2:4 and water-cement ratio of 0.5 was used in the process. Fifty test specimens reinforced with 12mm steel bars were cast. Thirty-five of the beams were revibrated after the initial mixing and placement, seven beams each at each percentage replacement of OPC with RHA. The remaining fifteen beams, three each per each replacement were not revibrated. The results of slump test indicates that the workability of fresh concrete is improved by increasing RHA content. Further, addition of RHA in reinforced concrete considerably increases the flexural strength for both revibrated and non-revibrated beams. Results show that the highest flexural strength is obtained at 5% replacement and at 20 minutes for revibration time-lag interval.