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Available Alkalis in Fly Ash

Published online by Cambridge University Press:  25 February 2011

Chau Lee ,
Scott Schlorholtz  and
Turgut Demirel
Chau Lee
Affiliation:
Department of Civil Engineering, Iowa State University, Ames, Iowa 50010
Scott Schlorholtz
Affiliation:
Department of Civil Engineering, Iowa State University, Ames, Iowa 50010
Turgut Demirel
Affiliation:
Department of Civil Engineering, Iowa State University, Ames, Iowa 50010
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Abstract

The available alkalis of six Iowa fly ashes, four Class C and two Class F, have been studied as outlined by the procedures listed in ASTM C 311. The purposes of the study were to: (1) assess the significance of the test when it is used to analyze different fly ashes; (2) to investigate the possibility of decreasing the time required to complete the test (it currently requires 28 days for curing). When cured for 28 days at 38 C, the available alkalis were found to be about 60% and 30% of the total equivalent alkalis (equivalent alkalis = %Na20 + 0.658 × %K20) for Class C and Class F fly ashes, respectively. However, more than 85% and more than 40% of the total equivalent alkalis for the Class C and Class F fly ashes, respectively, were mobilized after 5 to 6 months of curing at 38 C. It was concluded that the available alkali test described in ASTM C 311 tends to underestimate the amount of equivalent alkalis present in Class C fly ash-calcium hydroxide mixtures after long periods of time.

Type
Articles
Information
MRS Online Proceedings Library (OPL) , Volume 65: Symposium T – Fly Ash and Coal Conversion By-Products II , 1985 , 125
Copyright
Copyright © Materials Research Society 1986

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