Role of Gypsum in the Strength Development of Fly Ashes with Lime

Sivapullaiah, Puvvadi V and Moghal, Arif Ali Baig (2011) Role of Gypsum in the Strength Development of Fly Ashes with Lime. In: Journal of Materials in Civil Engineering, 23 (2). pp. 197-206.

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Abstract

The strength of fly ash mixture often needs to be enhanced for its better utilization in geotechnical and environmental applications. Many fly ashes often improve their strength with lime but may not meet the requirements. Gypsum, which reduces the lime leachability, further improves the strength. An attempt is made in this paper to study the effect of gypsum on the strength development of two Class F fly ashes with different lime contents after curing them for different periods. The sustainability of improved strength has been examined after soaking the cured specimens in water and with different leachates containing heavy-metal ions. The strength of both the fly ashes investigated improved markedly up to a particular amount of the lime content, which can be taken as optimum lime content, and thereafter the improvement is gradual. The improvement in strength at higher lime contents continues for a longer period (even up to 180 days). Gypsum accelerates the gain in strength for lime-stabilized fly ashes, particularly in the initial curing periods at about optimum lime content. At high lime contents gypsum attributes very high strength after curing for long periods mainly due to the alteration of fly ash lime reaction compounds. Gypsum not only improves the reduction in the loss of strength due to soaking even at low curing periods but also improves the durability of stabilized fly ashes due to repeated cycles of wetting and drying.

Item Type:	Journal Article
Publication:	Journal of Materials in Civil Engineering
Publisher:	American Society of Civil Engineers
Additional Information:	Copyright of this article belongs to American Society of Civil Engineers.
Keywords:	Fly ash; Lime; Gypsum; Unconfined compressive strength; Durability
Department/Centre:	Division of Mechanical Sciences > Civil Engineering
Date Deposited:	22 Feb 2011 07:00
Last Modified:	22 Feb 2011 07:00
URI:	http://eprints.iisc.ac.in/id/eprint/35675

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