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Title: On the physico-chemical evolution of low-pH and CEM I cement pastes interacting with Callovo-Oxfordian pore water under its in situ CO{sub 2} partial pressure

Within the framework of geological repositories for radioactive waste, structural concretes must be adapted to the underground chemical conditions. CEM I cement-based materials are characterised by high pH that may produce an alkaline plume in the near-field of the repository. In order to avoid this problem, low-pH cements have been designed. This study compares the physico-chemical behaviour of a low-pH material with a CEM I cement paste, both being subjected to leaching by an aqueous solution. An original experimental setup was designed to reproduce the underground conditions using a specific CO{sub 2} regulation device. Under these conditions, the low-pH material was strongly degraded, which results in coarser porosity, whereas thickness degradation of the CEM I cement paste is limited by the precipitation of a magnesium-calcite crust over the surface, which reduces the exchange of soluble species. This paper also presents a new approach for microstructure characterisation based on high-resolution X-ray microtomography.
Authors:
 [1] ;  [2] ;  [2] ;  [1] ;  [3] ;  [4] ;  [5] ; ;  [6] ;  [1] ;  [7]
  1. CEA, DEN, DPC, SCCME, Laboratoire d'Etude du Comportement des Bétons et des Argiles, F-91191 Gif-sur-Yvette (France)
  2. (France)
  3. CEA, DEN, DTCD, SPDE, Laboratoire d'Etude de l'Enrobage des Déchets, F-30207 Bagnols-sur-Cèze (France)
  4. CEA, IRAMIS, SIS2M, Laboratoire de Structure et Dynamique par Résonnance Magnétique, F-91191 Gif-sur-Yvette (France)
  5. Andra Scientific Division, 1-7 Rue Jean Monnet, Parc de la Croix Blanche, 92298 Chatenay Malabry Cedex (France)
  6. Department of Physics, University of Jyväskylä, P.O. Box 35, FIN-40351 Jyväskylä (Finland)
  7. Université de Poitiers, Laboratoire HYDRASA, UMR CNRS, 6269 Poitiers (France)
Publication Date:
OSTI Identifier:
22323133
Resource Type:
Journal Article
Resource Relation:
Journal Name: Cement and Concrete Research; Journal Volume: 58; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; AQUEOUS SOLUTIONS; CALCITE; CARBON DIOXIDE; CARBONATES; CEMENTS; CONCRETES; HARDNESS; MAGNESIUM; MICROSTRUCTURE; PARTIAL PRESSURE; POROSITY; RADIOACTIVE WASTES; WEAR RESISTANCE; X RADIATION