Effect of wet-and-dry ageing in seawater on the swelling properties and hydraulic conductivity of two amended bentonites
Mazzieri, F.; Di Emidio, G.; Pasqualini, E. (2017). Effect of wet-and-dry ageing in seawater on the swelling properties and hydraulic conductivity of two amended bentonites. Applied Clay Science 142: 40-51. https://dx.doi.org/10.1016/j.clay.2016.10.031
In: Applied Clay Science. Elsevier: Amsterdam. ISSN 0169-1317; e-ISSN 1872-9053, more
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| Keyword |
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Bentonite; Amendment; Polymers; Swelling; Hydraulic conductivity;Ageing; Desiccation |
| Authors | | Top |
- Mazzieri, F.
- Di Emidio, G., more
- Pasqualini, E.
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| Abstract |
Amended bentonites have been proposed with the primary purpose of improving their chemical compatibility relative to conventional bentonite. As these materials are relatively new, their durability and long-term performance need to be evaluated. Wet-dry conditions may occur in many applications where bentonite liners are in use. In this study, two amended materials, the MultiSwellable bentonite and a DPH (Dense Prehydrated) GCL were subjected to simulated wet-dry ageing. Distilled water (DW) and natural seawater (NSW) were used as permeant liquids. After five wet-dry cycles, the hydraulic conductivity of both materials increased by two to three orders of magnitude. Unhealed desiccation cracks were identified as responsible for the increase in permeability. Conversely, wet-dry ageing in DW did not impact significantly the permeability of the DPH GCL. For both materials, post-test swell index and XRD diffraction indicated a loss of the chemical amendment, likely solubilised and/or eluted during the wet phases. The results point out that further investigation is necessary to fully address the permanence of swelling and permeability performances of these amended clays after long-term field service. Adequate measures are recommended to prevent or limit desiccation damage for use in applications where aggressive inorganic permeant liquids (e.g., NSW) are present. |
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