Prospects of Partial Substitution of Cement with Rice Husk Ash for Road Concrete Works

Abstract

Rice Husk Ash (RHA) has been found as a potential partial replacement for cement in concrete. This study attempts to make an evidence based evaluation of the sustainability and benefits of RHA utilisation as partial replacement of cement in road concrete works within Anambra State of Nigeria. The ashes of the rice husks collected from different locations were characterised. Direct interviews were conducted among the rice mill personnel and experts in the construction companies. The values of SiO2 + Fe2O3 + Al2O3 for the four analysed RHA samples ranged from 78.9% to 80.3% as revealed by the X-ray fluorescence analysis. This confirms that they are pozzolanic. The highest observed 28th day compressive strength of concrete was 41.8 N/mm2 for the concrete containing 10% RHA. Beyond the 10% replacement level, the compressive strength dropped below the control values. The result of the Analytical Hierarchy Process (AHP) analysis displayed the highest option preference of 40.3% for utilising RHA in road construction. These show that utilising RHA for road concrete works would be a sustainable option. 10% replacement of cement with RHA was recommended for optimum performance based on the compressive strengths of the tested RHA based concretes.