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Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Elevated temperature effects on swelling pressure of compacted bentonite
AbstractUnderstanding the effects of temperature on the hydro‐mechanical behavior of compacted bentonite is important for performance assessments of bentonite‐based buffer, backfill, and sealing systems in deep geological disposal of high‐level radioactive wastes. Motivated by such applications, most past experimental studies were focused on highly compacted and high‐quality bentonite. Such degrees of dry densities may not be economically or technically feasible for other emerging applications, including as an alternative material to cement in plugging and abandonment of wells. A bespoke high‐pressure high‐temperature constant rate of strain (CRS) apparatus was developed for the work reported here to conduct a series of tests for evaluating the hydro‐mechanical response of compacted bentonite to elevated temperatures. Experiments were performed with bentonite specimens with high impurity contents at a range of dry densities (1.1, 1.4, and 1.7 Mg/m3) and temperatures between 20 and 80°C. The results show that temperature increase leads to the decrease of swelling pressure for all studied densities. Larger reductions of swelling pressure were observed with increasing dry densities, suggesting the possibility of a larger exchange of pore water in the microstructure system of the clay. The transfer of water from micropores to macropores at elevated temperatures is shown to be a key controlling process at high‐density compacted bentonite by which temperature affects the swelling pressure and hydraulic conductivity.
Highlights Laboratory results of swelling pressure of bentonite as an alternative plug material are presented. Swelling pressure of low clay content bentonite is reported for ranges of temperature and dry densities. Increasing temperature was found to reduce the swelling pressure at any dry density. Accelerated hydration at high temperatures is linked to microstructure evolution and swelling pressure drop.
Elevated temperature effects on swelling pressure of compacted bentonite
AbstractUnderstanding the effects of temperature on the hydro‐mechanical behavior of compacted bentonite is important for performance assessments of bentonite‐based buffer, backfill, and sealing systems in deep geological disposal of high‐level radioactive wastes. Motivated by such applications, most past experimental studies were focused on highly compacted and high‐quality bentonite. Such degrees of dry densities may not be economically or technically feasible for other emerging applications, including as an alternative material to cement in plugging and abandonment of wells. A bespoke high‐pressure high‐temperature constant rate of strain (CRS) apparatus was developed for the work reported here to conduct a series of tests for evaluating the hydro‐mechanical response of compacted bentonite to elevated temperatures. Experiments were performed with bentonite specimens with high impurity contents at a range of dry densities (1.1, 1.4, and 1.7 Mg/m3) and temperatures between 20 and 80°C. The results show that temperature increase leads to the decrease of swelling pressure for all studied densities. Larger reductions of swelling pressure were observed with increasing dry densities, suggesting the possibility of a larger exchange of pore water in the microstructure system of the clay. The transfer of water from micropores to macropores at elevated temperatures is shown to be a key controlling process at high‐density compacted bentonite by which temperature affects the swelling pressure and hydraulic conductivity.
Highlights Laboratory results of swelling pressure of bentonite as an alternative plug material are presented. Swelling pressure of low clay content bentonite is reported for ranges of temperature and dry densities. Increasing temperature was found to reduce the swelling pressure at any dry density. Accelerated hydration at high temperatures is linked to microstructure evolution and swelling pressure drop.
Elevated temperature effects on swelling pressure of compacted bentonite
Deep Underground Science and Engineering
He, Linhua (Autor:in) / Sedighi, Majid (Autor:in) / Mosleh, Mojgan Hadi (Autor:in) / Jivkov, Andrey (Autor:in) / Liu, Jiangfeng (Autor:in)
23.01.2025
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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