Porosity investigation of compacted bentonite using XRD profile modeling
2012 (English)In: Journal of Contaminant Hydrology, ISSN 0169-7722, E-ISSN 1873-6009, Vol. 128, no 1-4, 19-32 p.Article in journal (Refereed) Published
Many countries intend to use compacted bentonite as a barrier in their deep geological repositories for nuclear waste. In order to describe and predict hydraulic conductivity or radionuclide transport through the bentonite barrier, fundamental understanding of the microstructure of compacted bentonite is needed. This study examined the interlayer swelling and overall microstructure of Wyoming Bentonite MX-80 and the corresponding homo-ionic Na+ and Ca2+ forms, using XRD with samples saturated under confined swelling conditions and free swelling conditions. For the samples saturated under confined conditions, the interparticle, or so-called free or external porosity was estimated by comparing the experimental interlayer distances obtained from one-dimensional XRD profile fitting against the maximum interlayer distances possible for the corresponding water content. The results showed that interlayer porosity dominated total porosity, irrespective of water content, and that the interparticle porosity was lower than previously reported in the literature. At compactions relevant for the saturated bentonite barrier (1.4-1.8 g/cm(3)), the interparticle porosity was estimated to <= 3%.
Place, publisher, year, edition, pages
2012. Vol. 128, no 1-4, 19-32 p.
Bentonite, Clay swelling, Microstructure, Porosity, Nuclear waste disposal, XRD
Earth and Related Environmental Sciences
IdentifiersURN: urn:nbn:se:kth:diva-91268DOI: 10.1016/j.jconhyd.2011.10.005ISI: 000300469600002ScopusID: 2-s2.0-81355138483OAI: oai:DiVA.org:kth-91268DiVA: diva2:509031
QC 201203122012-03-122012-03-122012-03-12Bibliographically approved