Effect of substitution of cement with rice husk ash on compressive strength of concrete using plastic fibres and super plasticizer

Abstract

India is a major rice producing country and the husk generated during millings is mostly used as fuel in the boilers for processing paddy, producing energy through direct combustion and/or by gasification. About 20 million tonnes of Rice Husk Ash (RHA) is produced annually and is a great environ mental threat, causing damage to the land and the surrounding area in which it is dumped. In the conversion of rice husks to ash, the combustion process removes the organic matter and leaves silica rich residue. The fiber inclusions increase the strength of the cement-stabilized specimens as well as that of the ash-soil specimens and change their brittle behavior to ductile behavior. In this paper, the effect of different contents of Rice Husk Ash (RHA) added to concrete containing super plasticizer and with and without plastic fibers on its compressive strength has been studied. Samples with 3%, 5%, 7%, 10%, 12% and 15% content of RHA replacing the cement have been tested. The results have been compared with those for the control sample and viability of adding RHA to concrete has been studied. It was observed that up to 10% of cement can be replaced with RHA mixed with plastic fibres with nearly equivalent compressive strength. Further replacement of cement up to 15% will result in concrete of fair compressive strength.