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Title: Characterization of Fe-smectites and their alteration potential in relation to engineered barriers for HLW repositories: The Nui Nua clay, Thanh Hoa Province, Vietnam
Authors: Lan Nguyen-Thanh
Thao Hoang-Minh
Kasbohm, Joern
Keywords: Fe-smectite;Fe-montmorillonite;Kinetic experiment;Alteration;HLW repository
Issue Date: 2014
Abstract: The stability of smectite-rich clay minerals is of interest because they could be candidates for engineeredbarriers for high-level radioactivewaste repositories. This research characterized the chemical and mineralogical proper-ties of the Nui Nua clay which forms from the weathering of the Nui Nua serpentinized ultramafic–maficmassif (ThanhHoa Province, Viet Nam) using several methods (including Fourier transform infrared spectrometry and transmission electron microscopy). The Nui Nua clay, taken from Co Dinh and My Cai valleys, is composed of Fe-smectites as the main phase with minor phases of normal smectite, quartz, talc, chlorite, kaolinite, amphibole, antigorite, feldspars and magnetite. The Fe-smectites were characterized as mixed-layer minerals (including Fe-montmorillonitic as anend-member) composed of illitic or dioctahedral vermiculitic layers and Fe-rich smec-titic layers. The proportion of the smectitic layer is approximately 80%; the interlayer sheet is dominated by Ca and Mg, while the octahedral sheet is dominated by Fe 3+ (not Al). The stability of the Nui Nua smectites was also investigated by a simulation in saturation of 1 M NaCl and deionized water under kinetic impaction. The average tetrahedral-Si content of the smectites increased or decreased depending on the“dynamic solution”or hydraulic regime. By chemical identification, the alteration of Fe-smectites is mainly increased by the smectitization process. This research suggests that the Nui Nua clay is a potential candidate for an engineered barrier because during the alteration process, neo-formation of a montmorillonitic layer occurs.
Description: APPLIED CLAY SCIENCE Volume: 101 Pages: 168-176 Published: NOV 2014
Appears in Collections:Bài báo của ĐHQGHN trong Web of Science

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