Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Swelling pressures of compacted Ca-bentonite
Abstract One of the major functions of a bentonite buffer for a HLW repository is to provide the buffer with a self-sealing capacity through its ability to swell on contact with free water. Swelling pressure measurements were carried out to investigate the swelling behavior of Ca-bentonite. Experimental results showed that the swelling pressure increased with an increase in dry density, and its dependence on dry density increased at higher dry densities beyond 1.6Mg/m3. The effect of salinity on the swelling pressure for the Ca-bentonite was different from that for Na-bentonite. The swelling pressure of the Ca-bentonite was higher in a diluted concentration of NaCl solution (0.04M) compared with de-mineralized water, and it then decreased with an increase in the concentration of the NaCl solution beyond 0.04M. Such a swelling behavior of the Ca-bentonite was explained by the ion-exchange of Ca2+ for Na+ from the solution followed by hydration with water molecules and osmosis due to the differences in concentrations of the NaCl solutions.
Highlights ► Swelling pressures were measured to investigate the swelling behavior of Ca-bentonite. ► The effects of dry density and salinity on the swelling pressures were investigated. ► The swelling mechanism for the Ca-bentonite in NaCl solutions was different from that for Na-bentonite. ► The swelling mechanism was conceptualized and explained based upon experimental results. ► The obtained results suggest an engineering significance in the design of a HLW repository.
Swelling pressures of compacted Ca-bentonite
Abstract One of the major functions of a bentonite buffer for a HLW repository is to provide the buffer with a self-sealing capacity through its ability to swell on contact with free water. Swelling pressure measurements were carried out to investigate the swelling behavior of Ca-bentonite. Experimental results showed that the swelling pressure increased with an increase in dry density, and its dependence on dry density increased at higher dry densities beyond 1.6Mg/m3. The effect of salinity on the swelling pressure for the Ca-bentonite was different from that for Na-bentonite. The swelling pressure of the Ca-bentonite was higher in a diluted concentration of NaCl solution (0.04M) compared with de-mineralized water, and it then decreased with an increase in the concentration of the NaCl solution beyond 0.04M. Such a swelling behavior of the Ca-bentonite was explained by the ion-exchange of Ca2+ for Na+ from the solution followed by hydration with water molecules and osmosis due to the differences in concentrations of the NaCl solutions.
Highlights ► Swelling pressures were measured to investigate the swelling behavior of Ca-bentonite. ► The effects of dry density and salinity on the swelling pressures were investigated. ► The swelling mechanism for the Ca-bentonite in NaCl solutions was different from that for Na-bentonite. ► The swelling mechanism was conceptualized and explained based upon experimental results. ► The obtained results suggest an engineering significance in the design of a HLW repository.
Swelling pressures of compacted Ca-bentonite
Lee, Jae Owan (Autor:in) / Lim, Jin Gyu (Autor:in) / Kang, Il Mo (Autor:in) / Kwon, Sangki (Autor:in)
Engineering Geology ; 129-130 ; 20-26
06.01.2012
7 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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