An Evaluation of Compressive Strength of Concrete made with Rice Husk Ash Obtained by Open Air Burning

Abstract

Pozzolanic materials have been demonstrated their effectiveness in producing high performance concrete. Artificial pozzolanas such as rice husk ash have gained acceptance as supplementary cementing materials in many parts of the world. This work evaluates the Compressive strength of rice husk ash (RHA) as a partial replacement for ordinary Portland cement (OPC) in concrete. A total of 90 cubes of 150mm dimensions were cast with cement replacement level by RHA ranging from 0 to 40%, while a control mix of 28-day target strength of 25N/mm2 was adopted. The cubes were cured in water and tested for compressive strength at 7, 14, 21 and 28 days. Stripping of the concrete cubes from the mould was carefully done after 24 hours of the concrete setting under air. The results with graph plotted show the trend of strength development of the samples. The results show that the density and compressive strength dropped decreased with increase in rice husk ash content. The 28-day, density and compressive strength dropped from 2485kg/m3 to 2122kg/m3 (i.e. 14.61% loss) and from 27.21N/mm2 to 19.00 (i.e. 30.17% loss) respectively for 0-40% variation of RHA content. The 10% RHA sample was found to show a show a promise of attaining similar strength as the control mix at a later curing age having progressed to about 90% (i.e 24.07N/mm2 – 89%) of the design Strength by the 28-day.