Microstructure and hydro-mechanical behaviour of compacted granular bentonite

In recent years, granular bentonite GB has become a reference material since it facilitates the backfilling operation due to high-density compacted granules with extended grain size distribution(maximum sizes around 10 mm). This investigation explores the initial microstructure of MX80-type GB and t...

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Bibliographic Details
Published in:E3S web of conferences 2023-01, Vol.382, p.14010
Main Authors: Zeng, Hao, Gonzalez-Blanco, Laura, Romero, Enrique, Fraccica, Alessandro
Format: Article
Language:English
Subjects:
Bentonite
Compacting
Compressibility
Computed tomography
Dry density
Drying
Grain size distribution
Matric suction
Mechanical properties
Mercury
Microstructure
Pore size
Pores
Porosity
Size distribution
Suction
Swelling pressure
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Summary:In recent years, granular bentonite GB has become a reference material since it facilitates the backfilling operation due to high-density compacted granules with extended grain size distribution(maximum sizes around 10 mm). This investigation explores the initial microstructure of MX80-type GB and the hydro-mechanical HM response observed at the phenomenological scale. Samples were statically compacted at a fixed dry density (1.55 Mg/m3 ), encompassing dry and wet sides of the optimum. Themicrostructural study was performed using a combination of X-ray micro-computed tomography and mercury intrusion porosimetry. The results indicate that the pore size density function of compacted GB can be simplified as a double-porosity network with micropores (intra-granular/aggregate pores) and macropores(inter-granular/aggregate pores). Compacting at the dry side increases macropores, making the sample more compressible on loading under as-compacted states despite the higher matric suction. The time evolution of the swelling pressure displays a double-peak pattern attributed to the particular microstructure of the samples. Moreover, the initial microstructure does not significantly influence the water retention properties without a marked hysteresis in the high-suction range under confined wetting/drying cycles. This work’s outcomes highlight the microstructure’s significance in the HM behaviour of compacted GB and provide further insight into the geotechnical properties of this material.
ISSN:2267-1242
2555-0403
2267-1242
DOI:10.1051/e3sconf/202338214010