DURABILITY ASSESSMENT OF CONCRETE MADE WITH RICE HUSK ASH AS ADMIXTURE
Publication Date : 01/02/2010
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This paper assesses the durability of concrete made with rice husk ash (RHA) as an admixture in concrete with addition of RHA of 0%, 5%, 10% and 15% respectively to concrete grades 20 and 30 respectively cured in normal environment (water) and aggressive environment (5%, 10% solution of sulphuric acid (H2SO4), hydrochloric acid (HCl), and nitric acid (HNO3)) respectively. RHA used was obtained by burning rice husk obtained from a local mill in Kano. The husk obtained was sun dried, screened and burned at a temperature of 400oC in an incinerator. The ash obtained was cooled and sieved through a 425μm sieve and added as an admixture during mixing. A concrete mix design in accordance with Department of Environment, United Kingdom (DOE U.K, 1975) method as reported by Teychem et al. (1975) was adopted to proportion the constituents of both grades of RHA Concrete. Concrete mixes of both grades of concrete were prepared and the properties of fresh and hardened concrete assessed. The compressive strength of cubes of samples of RHA concrete cured in water and in acidic solutions respectively were determined at 7, 28 and 56 days respectively in accordance with BS 1881 part 116 (1983). The water absorption of cubes of samples of RHA concrete cured in water for 28 days was also determined in accordance with BS 1881 part 122 (1983). The results showed an increase in compressive strength of samples of both concrete grades cured in water with addition of 5% and 10% RHA respectively but 5% addition of RHA had a better improvement in strength. Further increase in addition of RHA (15%) decreased the strength of RHA concrete. The compressive strength of RHA concrete cured in water increases with age. The compressive strength of RHA concrete cured in acidic solutions reduces with increase in addition of RHA and increase in concentration of acidic solution. Sulphuric acid solution was the most aggressive medium, then nitric acid and hydrochloric acid solutions respectively.
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