Investigation of the thermo-hydro-mechanical behavior of Czech bentonite used as a model material for planning of high level nuclear waste disposal

The work involved in the thesis is mainly focused on the Czech bentonite which is originally from Cerny vrch deposit (north western region of the Czech Republic). The compacted bentonites are prepared from the industry provided bentonite powder with an initial water content around 10%. Dry densities from 1.27 to 2 g/cm3 were used for laboratory testing, specifically 1.27, 1.60 and 1.90 g/cm3 were used for water retention measurements, microstructures and fractal pore analysis. Dry densities of 1.25 to 1.95 g/cm3 were used for mechanical tests such as one dimensional swelling strain and oedometer load-unload tests. The vapor equilibrium method was used to impose the suction on samples ranging from 3.29 MPa to 286.7 MPa. Mercury intrusion porosimetry (MIP) and environmental scanning electron microscope (ESEM) were utilized for the microstructure analysis. The water retention measurements were performed at 20, 40, 60 and 80 řC respectively, results show that the increasing of temperature can decrease the water retention capacity. The influence of compaction and suction on microstructure was compared and studied. MIP tests were performed on the samples which were equilibrated at suction of 3.29, 38 and 286.7 MPa on wetting path of both low and high dry densities. The samples equilibrated at suction of..