Role of Gypsum in the Strength Development of Fly Ashes with Lime
Publication: Journal of Materials in Civil Engineering
Volume 23, Issue 2
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.
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Acknowledgments
The writers are grateful to Dr. Baig M. Y. A., Retired Professor, SVUCE, for his assistance in revising the paper. The writers would like to thank the reviewers for their critical review and constructive comments.
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Information
Published In
Journal of Materials in Civil Engineering
Volume 23 • Issue 2 • February 2011
Pages: 197 - 206
Copyright
© 2011 ASCE.
History
Received: Dec 2, 2009
Accepted: Jul 18, 2010
Published online: Jul 29, 2010
Published in print: Feb 2011
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