Gel Formation at the Front of Expanding Calcium Bentonites
| Autor: | Patrik Sellin, Jon F. Harrington, Katherine A. Daniels, Ian Mounteney, Antoni E. Milodowski, Simon J. Kemp |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
gel
Materials science lcsh:QE351-399.2 010504 meteorology & atmospheric sciences XRD Sodium calcium bentonite chemistry.chemical_element 010502 geochemistry & geophysics 01 natural sciences Matrix (geology) swelling medicine Substrate (aquarium) 0105 earth and related environmental sciences lcsh:Mineralogy EDXA Radioactive waste Geology surface area radioactive waste disposal Geotechnical Engineering and Engineering Geology ESEM chemistry Chemical engineering Bentonite Swelling medicine.symptom Clay minerals Groundwater water uptake |
| Zdroj: | Minerals, Vol 11, Iss 215, p 215 (2021) Minerals Volume 11 Issue 2 |
| Popis: | The removal of potentially harmful radioactive waste from the anthroposphere will require disposal in geological repositories, the designs of which often favour the inclusion of a clay backfill or engineered barrier around the waste. Bentonite is often proposed as this engineered barrier and understanding its long-term performance and behaviour is vital in establishing the safety case for its usage. There are many different compositions of bentonite that exist and much research has focussed on the properties and behaviour of both sodium (Na) and calcium (Ca) bentonites. This study focusses on the results of a swelling test on Bulgarian Ca bentonite that showed an unusual gel formation at the expanding front, unobserved in previous tests of this type using the sodium bentonite MX80. The Bulgarian Ca bentonite was able to swell to completely fill an internal void space over the duration of the test, with a thin gel layer present on one end of the sample. The properties of the gel, along with the rest of the bulk sample, have been investigated using ESEM, EXDA and XRD analyses and the formation mechanism has been attributed to the migration of nanoparticulate smectite through a more silica-rich matrix of the bentonite substrate. The migration of smectite clay out of the bulk of the sample has important implications for bentonite erosion where this engineered barrier interacts with flowing groundwater in repository host rocks. |
| Databáze: | OpenAIRE |
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