Author: Koichiro Fujimoto, Kiminori Sato
Clay minerals, as e.g. montmorillonite, abundantly exist in the slip zones such as earthquake faults and landslides. Water contents are an important factor for controlling slip behavior, since montmorillonite contains a considerable amount of water molecules compared with other clay minerals. Here, a series of mechanochemical milling experiments were conducted for montmorillonite at the water contents ranging from 0% to 800%. Decomposition occurs at the water contents below 25% and above 600%, which are well correlated with the consistency limits of montmorillonite reported so far, i.e. shrinkage/plastic and liquid limits, respectively. Montmorillonite is found to be effectively decomposed into amorphous materials at the water contents below the shrinkage/plastic limit. In the region of water content between shrinkage/plastic and liquid limits, decomposition cannot be achieved solely by the mechanochemical treatment. At the water contents higher than the liquid limit, decomposition is again started. The present work demonstrates that the degree of decomposition can be of usefulness for speculating how the water molecules behave in the slip zones in nature.
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