Properties and Behaviour of Lime-Rice Husk Ash Cements

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Title: Properties and Behaviour of Lime-Rice Husk Ash Cements

Author(s): David J. Cook and P. Suwanvitaya

Publication: Special Publication

Volume: 79

Issue:

Appears on pages(s): 831-846

Keywords: calcium hydroxide; carbon; compressive strength; concrete durability; C-S-H; leaching; lime; microstructure; pozzolan cements; rice; shrinkage.

Date: 5/1/1983

Abstract:
The utilization of agricultural residues for building mater-ials is particularly attractive in developing countries where indigenous resources for building are hard pressed to cope with the demand. In this paper the use of rice husks, essentially a waste material in most countries, as a source for a pozzolanic material is described. The behaviour of lime - rice husk ash mixes in terms of strength, shrinkage, durability and microstructure are examined. It is shown that although maximum strengths are achieved with low lime mixes, lime leaching could seriously impair the durability and indeed the long term strength of these mixes. Accordingly, it is proposed that the optimum ratio of lime : rice husk ash should be about 1 : 1. Further, it is shown that within the limits of carbon contents likely to be encountered in the field, strength development is unaffected, though some retardation in initial and final set may occur. Finally, examination of the microstructure through x-ray diffraction analysis indicates that the hydrated matrix consists of calcium silicate hydrate of the CSH (II) type.