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Microstructure, Mass Transport and Densification of Slag Cement Pastes

Published online by Cambridge University Press:  21 February 2011

Q. L. Feng
Affiliation:
Department of Chemistry, University of Aberdeen, Old Aberdeen, Scotland, AB9 2UE
F. P. Glasser
Affiliation:
Department of Chemistry, University of Aberdeen, Old Aberdeen, Scotland, AB9 2UE
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Abstract

The kinetics and mechanism of the hydration reactions in slag cements were explored in blends containing either 40 or 50 wt% ground granulated blast furnace slag, made to a water:solid ratio of either 0.50 or 0.60 and aged 7d to 885d at 20°C. The microstructure of the slag rapidly differentiates into zonal structures. Analytical electron microscopy has been used to analyze the composition and indirectly determine the mineralogy of the zones. It is shown that considerable chemical matter is transported out of the slag grains, resulting in porosification of the former slag grains and densification of the cement hydrate matrix. This is supported by mass balance calculations. The driving force for these migrations is accounted for by the existence of a chemical potential gradient of water; hydrophyllic species such as Ca, Si, etc. migrate into regions of high chemical potential for water. The densification of the phase matrix is probably responsible for the low permeabilities of matured slag-cement blends.

Type
Research Article
Copyright
Copyright © Materials Research Society 1990

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References

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