Characterisation, mechanical and microstructural behaviour of an unsaturated silt

Abstract

This study investigates an unsaturated silt sampled from an embankment along the Bengawan Solo River in East Java, Indonesia. Load and soak oedometer tests were carried out on laboratory compacted samples and on undisturbed samples. For samples compacted dry of optimum at low dry densities, significant settlements were observed on wetting, with a maximum collapse potential of 14% evaluated. A qualitative investigation of the microstructure of the material was carried out using an Environmental Scanning Electron Microscope. Micrographs were taken of the material under the following conditions: (a) Compacted, (b) Compacted, Loaded, (c) Compacted, Loaded & Soaked, and (d) Undisturbed. The ESEM images suggest that the fabric of the Undisturbed sample and the Compacted, Loaded & Soaked sample are similar. These results appear to indicate that the undisturbed material sampled at the end of the wet season has already undergone the process of plastic collapse compression in-situ.