Swelling ability and behaviour of bentonite-based materials for deep repository engineered barrier systems: Influence of physical, chemical and thermal factors
Compacted bentonite–sand (B/S) mixtures have been used as a barrier material in engineered barrier systems (EBSs) of deep geological repositories (DGR) to store nuclear wastes. This study investigates the individual and combined effects of different chemical compositions of deep groundwaters (chemic...
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| Format: | Article |
| Language: | English |
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Elsevier
2022-06-01
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| Series: | Journal of Rock Mechanics and Geotechnical Engineering |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S1674775522000543 |
| _version_ | 1828553404466593792 |
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| author | Mohammed Alzamel Mamadou Fall Sada Haruna |
| author_facet | Mohammed Alzamel Mamadou Fall Sada Haruna |
| author_sort | Mohammed Alzamel |
| collection | DOAJ |
| description | Compacted bentonite–sand (B/S) mixtures have been used as a barrier material in engineered barrier systems (EBSs) of deep geological repositories (DGR) to store nuclear wastes. This study investigates the individual and combined effects of different chemical compositions of deep groundwaters (chemical factor) at potential repository sites in Canada (the Trenton and Guelph regions in Ontario), heat generated in DGRs (thermal factor), dry densities and mass ratios of bentonite and sand mixtures (physical factors) on the swelling behavior and ability of bentonite-based materials. In this study, swelling tests are conducted on B/S mixtures with different B/S mix ratios (20/80 to 70/30), compacted at different dry densities (ρd = 1.6–2 g/cm3), saturated with different types of water (distilled water and simulated deep groundwater of Trenton and Guelph) and exposed to different temperatures (20 °C–80 °C). Moreover, scanning electron microscopy (SEM) analyses, mercury intrusion porosimetry (MIP) tests and X-ray diffractometry (XRD) analyses are carried out to evaluate the morphological, microstructural and mineralogical characteristics of the B/S mixtures. The test results indicate that the swelling potential of the B/S mixtures is significantly affected by these physical and chemical factors as well as the combined effects of the chemical and thermal factors. A significant decrease in the swelling capacity is observed when the B/S materials are exposed to the aforementioned groundwaters. A large decrease in the swelling capacity is observed for higher bentonite content in the mixtures. Moreover, higher temperatures intensify the chemically-induced reduction of the swelling capacity of the B/S barrier materials. This decrease in the swelling capacity is caused by the chemical and/or microstructural changes of the materials. The results from this research will help engineers to design and build EBSs for DGRs with similar groundwater and thermal conditions. |
| first_indexed | 2024-12-12T05:17:57Z |
| format | Article |
| id | doaj.art-0c34921217a34b2896d481de23ab5af4 |
| institution | Directory Open Access Journal |
| issn | 1674-7755 |
| language | English |
| last_indexed | 2024-12-12T05:17:57Z |
| publishDate | 2022-06-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Rock Mechanics and Geotechnical Engineering |
| spelling | doaj.art-0c34921217a34b2896d481de23ab5af42022-12-22T00:36:43ZengElsevierJournal of Rock Mechanics and Geotechnical Engineering1674-77552022-06-01143689702Swelling ability and behaviour of bentonite-based materials for deep repository engineered barrier systems: Influence of physical, chemical and thermal factorsMohammed Alzamel0Mamadou Fall1Sada Haruna2Department of Civil Engineering, University of Ottawa, Ottawa, Ontario, K1N 6N5, CanadaCorresponding author.; Department of Civil Engineering, University of Ottawa, Ottawa, Ontario, K1N 6N5, CanadaDepartment of Civil Engineering, University of Ottawa, Ottawa, Ontario, K1N 6N5, CanadaCompacted bentonite–sand (B/S) mixtures have been used as a barrier material in engineered barrier systems (EBSs) of deep geological repositories (DGR) to store nuclear wastes. This study investigates the individual and combined effects of different chemical compositions of deep groundwaters (chemical factor) at potential repository sites in Canada (the Trenton and Guelph regions in Ontario), heat generated in DGRs (thermal factor), dry densities and mass ratios of bentonite and sand mixtures (physical factors) on the swelling behavior and ability of bentonite-based materials. In this study, swelling tests are conducted on B/S mixtures with different B/S mix ratios (20/80 to 70/30), compacted at different dry densities (ρd = 1.6–2 g/cm3), saturated with different types of water (distilled water and simulated deep groundwater of Trenton and Guelph) and exposed to different temperatures (20 °C–80 °C). Moreover, scanning electron microscopy (SEM) analyses, mercury intrusion porosimetry (MIP) tests and X-ray diffractometry (XRD) analyses are carried out to evaluate the morphological, microstructural and mineralogical characteristics of the B/S mixtures. The test results indicate that the swelling potential of the B/S mixtures is significantly affected by these physical and chemical factors as well as the combined effects of the chemical and thermal factors. A significant decrease in the swelling capacity is observed when the B/S materials are exposed to the aforementioned groundwaters. A large decrease in the swelling capacity is observed for higher bentonite content in the mixtures. Moreover, higher temperatures intensify the chemically-induced reduction of the swelling capacity of the B/S barrier materials. This decrease in the swelling capacity is caused by the chemical and/or microstructural changes of the materials. The results from this research will help engineers to design and build EBSs for DGRs with similar groundwater and thermal conditions.http://www.sciencedirect.com/science/article/pii/S1674775522000543Deep geological repositoryEngineered barrierBentonite-sand materialsNuclear wasteSwelling capacitySwelling strain |
| spellingShingle | Mohammed Alzamel Mamadou Fall Sada Haruna Swelling ability and behaviour of bentonite-based materials for deep repository engineered barrier systems: Influence of physical, chemical and thermal factors Journal of Rock Mechanics and Geotechnical Engineering Deep geological repository Engineered barrier Bentonite-sand materials Nuclear waste Swelling capacity Swelling strain |
| title | Swelling ability and behaviour of bentonite-based materials for deep repository engineered barrier systems: Influence of physical, chemical and thermal factors |
| title_full | Swelling ability and behaviour of bentonite-based materials for deep repository engineered barrier systems: Influence of physical, chemical and thermal factors |
| title_fullStr | Swelling ability and behaviour of bentonite-based materials for deep repository engineered barrier systems: Influence of physical, chemical and thermal factors |
| title_full_unstemmed | Swelling ability and behaviour of bentonite-based materials for deep repository engineered barrier systems: Influence of physical, chemical and thermal factors |
| title_short | Swelling ability and behaviour of bentonite-based materials for deep repository engineered barrier systems: Influence of physical, chemical and thermal factors |
| title_sort | swelling ability and behaviour of bentonite based materials for deep repository engineered barrier systems influence of physical chemical and thermal factors |
| topic | Deep geological repository Engineered barrier Bentonite-sand materials Nuclear waste Swelling capacity Swelling strain |
| url | http://www.sciencedirect.com/science/article/pii/S1674775522000543 |
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