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Physico-chemical interactions at the concrete-bitumen interface of nuclear waste repositories

Bertron, Alexandra and Ranaivomanana, Harifidy and Jacquemet, Nicolas and Erable, Benjamin and Sablayrolles, Caroline and Escadeillas, Gilles and Albrecht, Achim Physico-chemical interactions at the concrete-bitumen interface of nuclear waste repositories. (2013) EPJ Web of Conferences, 56 (10). 1-10. ISSN 2100-014X

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Official URL: http://dx.doi.org/10.1051/epjconf/20135601002


This study investigates the fate of nitrate and organic acids at the bitumenconcrete-steel interface within a repository storage cell for long-lived, intermediatelevel, radioactive wastes. The interface was simulated by a multiphase system in which cementitious matrices (CEM V paste specimens) were exposed to bitumen model leachates consisting of nitrates and acetic acid with and without oxalic acid, chemical compounds likely to be released by bitumen. Leaching experiments were conducted with daily renewal of the solutions in order to accelerate reactions. C-steel chips, simulating the presence of steel in the repository, were added in the systems for some experiments. The concentrations of anions (acetate, oxalate, nitrate, and nitrite) and cations (calcium, potassium, ammonium) and the pH were monitored over time. Mineralogical changes of the cementitious matrices were analysed by XRD. The results confirmed the stability of nitrates in the absence of steel, whereas, reduction of nitrates was observed in the presence of steel (production of NH4+). The action of acetic acid on the cementitious matrix was similar to that of ordinary leaching; no specific interaction was detected between acetate and cementitious cations. The reaction of oxalic acid with the cementitious phases led to the precipitation of calcium oxalate salts in the outer layer of the matrix. The concentration of oxalate was reduced by 65% inside the leaching medium.

Item Type:Article
HAL Id:hal-00875261
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Agence Nationale pour la Gestion des Déchets Radioactifs - ANDRA (FRANCE)
French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
French research institutions > Institut National de la Recherche Agronomique - INRA (FRANCE)
Université de Toulouse > Institut National des Sciences Appliquées de Toulouse - INSA (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
Laboratory name:
Deposited On:21 Oct 2013 11:32

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