Stabilization of Organic Soils with Fly Ash
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 137, Issue 9
Abstract
The effectiveness of fly ash use in the stabilization of organic soils and the factors that are likely to affect the degree of stabilization were studied. Unconfined compression and resilient modulus tests were conducted on organic soil–fly ash mixtures and untreated soil specimens. The unconfined compressive strength of organic soils can be increased using fly ash, but the amount of increase depends on the type of soil and characteristics of the fly ash. Resilient moduli of the slightly organic and organic soils can also be significantly improved. The increases in strength and stiffness are attributed primarily to cementing caused by pozzolanic reactions, although the reduction in water content resulting from the addition of dry fly ash solid also contributes to strength gain. The pozzolonic effect appears to diminish as the water content decreases. The significant characteristics of fly ash that affect the increase in unconfined compressive strength and resilient modulus include CaO content and ratio [or ratio]. Soil organic content is a detrimental characteristic for stabilization. Increase in organic content of soil indicates that strength of the soil–fly ash mixture decreases exponentially. For most of the soil–fly ash mixtures tested, unconfined compressive strength and resilient modulus increased when fly ash percentage was increased.
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Acknowledgments
Financial support for this study was provided by the National Science Foundation (NSF)NSF and the U.S. Federal Highway Administration Recycled Materials Resource Center (RMRC). Fly ashes used in the study were provided by Alliant Energy, Xcel Energy, We Energy, Great River Energy, and LaFarge North America. The findings and opinions in this report are solely those of the authors. Endorsement by NSFNSF, RMRC, or the fly ash suppliers is not implied and should not be assumed.
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Information & Authors
Information
Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 137 • Issue 9 • September 2011
Pages: 819 - 833
Copyright
© 2011 American Society of Civil Engineers.
History
Received: Sep 17, 2010
Accepted: Jan 6, 2011
Published online: Jan 8, 2011
Published in print: Sep 1, 2011
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