SEM-EDX study of bentonite alteration under the influence of cement alkaline solutions.
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2021Author:
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González-Santamaría, D.E., Justel A., Fernández, R., Ruiz, A.I., Stavropoulou, A., Rodriguez-Blanco, J.D., Cuevas, A., SEM-EDX study of bentonite alteration under the influence of cement alkaline solutions., Applied Clay Science, 212, 2021, 10622-Download Item:
Abstract:
Bentonite is a key barrier for the isolation of high-level radioactive waste within Deep Geological Repository. However, bentonite may be altered by contact with cementitious materials and their alkaline pore fluids. This study offers an extensive morphological and semi-quantitative characterization of the bentonite surface exposed to three types of alkaline pore fluids released by different cement-based materials. The bentonite surfaces were studied using a thorough scanning electron microscopy exploration and analysed using an energy-dispersive X-ray detector (SEM-EDX). In addition, statistical, element mappings, X-ray diffraction and infrared spectroscopy analyses were performed. The aim was to have a picture of the morphological and chemical alterations of bentonite at very early stages in accordance with the integrated approach necessary to address bentonite stability in the long-term. As a consequence of the reactivity, two types of morphologies stood out in the matrix of bentonite: platelets and coatings-like crusts characterized by their high Mg and Ca content. These alterations presented a different scope depending on the type of alkaline pore solution involved and suggested the precipitation of authigenic magnesium silicate hydrates (M-S-H) and/or trioctahedral clay minerals and Ca‑carbonates. The knowledge of the performance of bentonite subjected to these alkaline solutions can help in the evaluation of the most suitable cement-based materials to be used next to bentonite.
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Author: Rodriguez-Blanco, Juan
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Applied Clay Science;212;
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Bentonite, Alkaline perturbation, SEM-EDX, Cement, Engineered barrier systemSubject (TCD):
Nanoscience & Materials , Smart & Sustainable Planet , Nuclear Safety , cements , mineral-water interactionDOI:
10.1016/j.clay.2021.106223Metadata
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