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Influence of Swelling Strain on Selected Engineering Properties of Bringelly Shale at Southwest Region of Sydney, Australia
Mapp Sc, MSc (Eng) Research Student, and David Airey Senior Lecturer, Department of Civil Engineering, University of Sydney, Australia | |
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ABSTRACT |
Bringelly shale (claystone, siltstone, laminite) from four different sites in the south west of Sydney metropolitan area was studied to investigate the relationship between selected engineering properties and swelling strain index. Swelling tests were performed on intact fresh samples with different geometry. In order to investigate the relationship between volumetric strains caused by swelling of the samples and their engineering properties, six index tests were undertaken and then correlated to volumetric strain index. The properties investigated included natural water content, Atterberg limits, dry density, bulk volume, porosity, and Slake durability index. X-ray diffraction analysis in conjunction with scanning analysis were performed on the same samples.
The results indicated that Slake durability index identified as low to medium has shown fairly strong correlation with volumetric increase. angle of lamination has a great influence in maintaining the intactness and yet the integrity of Bringelly shale. Impermeability, low porosity, high salt content, lamina structure, and clay mineralogy are the basic factors in promoting the swelling of Bringelly shale. X-ray diffraction analysis revealed the presence of kaolinite, smectite, mixed-layer clays and chlorite as dominant species in clay mineral composition of Bringelly shale. Scanning analysis indicated that shale fabric is most likely to be the prime cause for volumetric increase than mineral composition.
Keywords: Shale, swelling, X-ray diffraction, clay minerals
