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Electrokinetic Phenomena and Surface Characteristics of Fly Ash Particles

Published online by Cambridge University Press:  25 February 2011

R. I. A. Malek
Affiliation:
Materials Research Laboratory, The Pennsylvania State University University Park, PA 16802
D. M. Roy
Affiliation:
Materials Research Laboratory, The Pennsylvania State University University Park, PA 16802
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Abstract

The zeta-potentials of two fly ashes were studied (high-calcium and low-calcium). It was found that they possess a point of charge reversal at pH = 10.5 to 12. The point of zero charge (low-calcium fly ash) was found to be at pH = 5. Furthermore, it shifted to more acidic values after the fly ash is aged in several calcium-containing solutions. The surficial changes that could happen when mixing fly ashes with cement and concrete were further evaluated by aging fly ashes in different solutions: Ca(OH)2, CaSO4·2H2O, NaOH and water solutions. Information from analyses for different ionic species in the solutions and characterization of the solid residues (XRD and SEM) was used in tentative explanations for the different behavior of the two types of fly ash in cementitious mixtures and concrete.

Type
Research Article
Copyright
Copyright © Materials Research Society 1985

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