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Phase Development and Pore Solution Chemistry in Ageing Blast Furnace Slag-Portland Cement Blends

Published online by Cambridge University Press:  26 February 2011

D. E. Macphee
Affiliation:
Department of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen AB9 2UE, U.K.
M. Atkins
Affiliation:
Department of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen AB9 2UE, U.K.
P. P. Glassar
Affiliation:
Department of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen AB9 2UE, U.K.
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Abstract

Blast furnace slag (BPS) cement blends have certain advantages for the encapsulation of low and intermediate radioactive wastes. However, their hydration reactions are more complex than for Portland cement because Portland cements fully react within several years whereas slag hydration takes considerably longer. Empirical testing of blends matured for short periods, up to several years, are not therefore adequate to characterise the chemical immobilisation potential of such systems. A modelling approach is required to predict long—term properties.

This paper is concerned with defining the internal environment within slag-cement matrices. The important parameters for definition are pH, Eh, solubilities and speciation in the aqueous phase, and solid phase equilibria. Compatibility studies in the CaO-CaSO4-Al2O-SiO2-MgO-H2O system are described and compared with the results of X-ray diffraction on pastes aged up to 2 years. In addition, pore water compositions for slag-rich cements are given, and the potential for predicting their redox level(Eh) by extending the present model is discussed.

Type
Research Article
Copyright
Copyright © Materials Research Society 1989

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References

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