Patrycja Baryla

Despite the increasing understanding of bentonite behaviour, there is still missing evidence on how different hydro-mechanical loadings, including sequences of hydration and compression, affect the fabric and the volume change behaviour of the material. It is generally assumed that the interplay between the behaviour of clay assemblages and the overall fabric of the material is the reason of having final states that are dependent on the stress path followed. Here the results of an experimental campaign aiming to study these factors are reported and discussed. Free swelling and swelling pressure tests were performed, both followed by compression to a relatively high stress. The experimental program involved various samples that were dismantled at intermediate states in order to perform microstructural observations by means of mercury intrusion porosimetry and electronic scanning microscopy. It was observed that while the void ratio at a given stress level depends on the stress path, ...

Compacted bentonite is considered to be used for deep geological nuclear waste disposal due to its isolation properties such as low permeability, solute retention and swelling pressure. To ensure that these properties will remain favourable throughout the long-term performance, understanding its physical behaviour in front of environmental variables is paramountThe study of expansive soils in geotechnics and geomechanics has been historically motivated because of the damage related to foundations during wetting and drying cycles. In recent decades, research has also been driven by the foreseen use of these materials, in particular bentonite, as buffers in nuclear waste disposal concepts. In this context the main behaviour to be predicted is the swelling pressure development, which will condition the microbial activity and the sealing. The characterisation of material was done determining: the evolution of macroscopic parameters (such as axial strains, void ratio and, in case of isoc...