TITLE:
Effect of Partial Replacement of Ordinary Portland Cement (OPC) with Ghanaian Rice Husk Ash (RHA) on the Compressive Strength of Concrete
AUTHORS:
Derrick Nii-Laryea Botchway, Russell Owusu Afrifa, Charles Yeboah Henaku
KEYWORDS:
Rice Husk Ash, Agricultural Waste, Mineral Admixture, Pozzolanic Activity, Compressive Strength
JOURNAL NAME:
Open Journal of Civil Engineering,
Vol.10 No.4,
December
14,
2020
ABSTRACT: The
cost of cement has made concrete production expensive such that the housing
deficit in developing countries is on the rise despite all the efforts by
governments and other stakeholders to produce affordable housing units for the
populace. Ashes of agricultural products such as rice husk, known as mineral
admixtures may have pozzolanic characteristics which would be more beneficial
to the housing industry in terms of strength gain and economy than being
pollutants to the environment. Rice Husk Ash (RHA), because of its finely
divided form and very high silica content and amorphousness, proved to be
useful for strength gain of Rice Husk Ash Concrete (RHAC). Rice husk ash was
manufactured by uncontrolled burning, ground, sieved and replaced with cement at
0%, 5%, 10%, 15%, 20% and 25% in mass for the mixes C20, C25, C30 and C35 where
their compressive strengths were verified at 3, 7, 14, 21, 28, 56, 90 and 180
days. The X-ray diffraction pattern list indicated amorphous as well as
diffused peak of about 8000 counts of SiO2 representing crystalline
structures identified as cristobalite. A physical examination of the RHA showed
very fine appearance, grey color and specific gravity of 2.06. The chemical
analysis also revealed the existence of oxide content to be 55.8% representing
0.78% of Fe2O3, 54% of SiO2 and 1.06% of Al2O3 representing 20.23% lower than the minimum value of 70% required for pozzolans.
Generally, the compressive strength values decreased as the RHA content in the
mixes increased but when compared to the control concrete the optimum
replacement percentage of Ordinary Portland Cement (OPC) with RHA at 5% showed
an increase above the control concrete for C20 mix. The increase in the RHA in
the mixes resulted in the high demand for water in all the mixes.