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Interaction of Alkalis (CS+) With Calcium Silicates Hydrates

Published online by Cambridge University Press:  10 February 2011

P. Faucon ,
T. Charpentier ,
P. Henocq ,
J.C. Petit ,
J. Virlet  and
F. Adenot
P. Faucon
Affiliation:
Service de Chimie Moléculaire, CEA Saclay, 91191 Gifsur Yvette, France
T. Charpentier
Affiliation:
Service de Physique de l'Etat Condensé, CEA Saclay, 91191 Gifsur Yvette, France
P. Henocq
Affiliation:
Service de Chimie Moléculaire, CEA Saclay, 91191 Gifsur Yvette, France
J.C. Petit
Affiliation:
Service de Chimie Moléculaire, CEA Saclay, 91191 Gifsur Yvette, France
J. Virlet
Affiliation:
Service de Chimie Moléculaire, CEA Saclay, 91191 Gifsur Yvette, France
F. Adenot
Affiliation:
Service d'Entreposage et de Stockage des Déchets, CEA Saclay, 91191 Gif sur Yvette, France
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Abstract

C-S-H of different Ca/Si ratios were synthesized in suspension. Cesium chloride (0.5 M) was put in contact with these C-S-H in reactors for 30 days at 25 °C with solution/solid ratios of 50. The quantities of cesium fixed by the C-S-H was determined by microanalyses and the mechanisms of retention in relation with the C-S-H structure was investigated by 133Cs Nuclear Magnetic Resonance (NMR). The influence of the humidity yield in which the C-S-H were stored was also studied.

At 100% of humidity, some cesium ions are trapped in the pore network of the C-S-H. However, most cesium ions are incorporated in the hydrated interlayers of the C-S-H between the silica chains of the structure. They are mobile in this interlayer space. At high Ca/Si ratio, the charge of incorporated Cs+ ions in the structure should be compensated by the associated Cl- incorporation. At low Ca/Si, the presence of silanol groups in the C-S-H structure, which becomes closer to that of tobermorite (Ca/Si about 0.8), makes possible the exchange or substitution H'<->Cs'. The resulting retention of cesium in the C-S-H then becomes higher.

Keywords

Cement pasteCesiumC-S-HretentionNMRChloride
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 506: Symposium – Scientific Basis for Nuclear Waste Management XXI , 1997 , 551
Copyright
Copyright © Materials Research Society 1998

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References

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