Authigenic clay minerals from interface reactions of concrete-clay engineered barriers: A new perspective on MG-clays formation in alkaline environments
Entity
UAM. Departamento de Geología y GeoquímicaPublisher
MDPIDate
2018-08-21Citation
Minerals 8.9 (2018): 362ISSN
2075-163X (online)Funded by
This work has been in part financially supported by the Full-Scale Engineered Barrier Experiment Dismantling Project (FEBEX-DP) consortium (http://www.grimsel.com/gts-phase-vi/febex-dp/febex-dp-introduction) for dismantling and overcoring sampling. The research leading to these results has received funding from the European Union’s Horizon 2020 Research and Training Programme of the European Atomic Energy Community (EURATOM) (H2020-NFRP-2014/2015) under grant agreement No. 662147 (CEBAMA). Acknowledgments: To E. Rodríguez Cañas (KIKE), for his very good skills and aid in electron microscopy data adquisition in SIdI-UAM university service. his work has been in part financially supported by the Full-Scale Engineered Barrier Experiment Dismantling Project (FEBEX-DP) consortium (http://www.grimsel.com/gts-phase-vi/febex-dp/febex-dp-introduction) for dismantling and overcoring sampling. The research leading to these results has received funding from the European Union’s Horizon 2020 Research and Training Programme of the European Atomic Energy Community (EURATOM) (H2020-NFRP-2014/2015) under grant agreement No. 662147 (CEBAMA).Project
info:eu-repo/grantAgreement/EC/H2020/662147/EU//CebamaSubjects
Concrete-bentonite interaction; Deep geological repository; Engineered barrier system; Mg-clays; Nuclear waste; Geología; QuímicaRights
© 2018 by the authors. Licensee MDPI, Basel, Switzerland.Abstract
Artificial and singular geochemical environments are created around the engineered barrier systems (EBS) designed to isolate high level nuclear wastes in deep geological repositories. A concrete-bentonite interface takes place within the EBS and it builds a significant chemical gradient (pH), approximately from pH 8 (bentonite) to pH 12 (low alkali concrete), in a few millimetre thickness. This disequilibrium triggers dissolution and precipitation reactions and form a thin altered region. In this area, poorly ordered authigenic clay minerals, mainly hydrated magnesium silicates, are formed adjacent to hydrated calcium silicates and calcite precipitates adhered to the interface with concrete. This paper presents the development of this authigenic mineral layer comparing 6–18 months to 13 years interfaces. Scanning Electron Microscopy with Energy Dispersive X-ray spectroscopy (SEM-EDX) morphological and chemical characterization with the aid of ternary plots, X-ray diffraction (XRD) and infrared (IR) data show the young to old interface evolution from single brucite layers to stevensite-saponite silicates composition. Geochemical calculations indicate that this layer acts as a pH~11 buffer useful to minimize bentonite alteration and to favour the retention of amphoteric metal ions
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Google Scholar:Cuevas Rodríguez, Jaime Fernando
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Ruiz García, Ana Isabel
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Fernández Martín, Raúl
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González-Santamaría, Daniel
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Angulo, María
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Ortega, Almudena
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Torres, Elena
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Turrero, María Jesús
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