Effect of Guinea Corn Husk Ash as Partial Replacement for Cement in Concrete

Abstract

This paper reports an investigation on Guinea Corn Husk Ash (GCHA) as partial replacement of Ordinary Portland Cement (OPC) in concrete. The percent replacement levels by weight were 5%, 10%, 15%, 20% and 25% in 1:2:4 concrete mix with 0.65 water - cement ratio. The chemical constituents of the GCHA were SiO2 (78.19%), Al2O3 (1.36%), Fe2O3 (0.84%), CaO (3.34%), MgO (3.76%), K2O (7.67%), P2 O5 (2.95%) and Na2O, TiO2, SrO, Cl, MnO, S03 in trace quantities. Since SiO2, Al2O3, and Fe2O3 have a combined constituent percent in excess of 70% (i.e. 80.39%), GCHA meets the requirement of a pozzolana in accordance the relevant standards. The GCHA concrete gave compressive strength in the range of 9.5 N/mm 2 for 25% ash and 26.3 N/mm 2 for 5% ash at 28 days curing period. The 5% value was higher than that of plain concrete which was 25.5N/mm 2 . The trend shows that 10% GCHA should not be exceeded for a competitive value for compressive strength. The density of GCHA-cement concrete slightly reduced with increase of GCHA, for example it reduced by 2.27% for 25% ash at 28days curing. However it slightly increased at 5% replacement level again. Further work on the Water Absorption Capacity, permeability and durability parameters of GCHA- cement concrete is recommended.