Macroscopic effects of nano and microscopic phenomena in clayey soils and clay rocks

Based on long term investigations of the microstructure various geomaterials as different sensitive low plastic clays from Eastern Canada, unsaturated compacted silt Paris area, highly compressible deep marine clay gulf Guinea, MX80 bentonite and Callovo–Oxfordian claystone, considered possible barriers in geological radioactive waste disposal, two fundamentals distinct nano micro mechanisms governing their macroscopic volume changes have been identified. In structured dry soils, which an aggregate has evidenced, decrease under mechanical compression result collapse inter-aggregates pores ordered manner, larger to smaller, with no effect intra-aggregate porosity. The soil skeleton can hence be modelled elastic fragile porous matrix, affected by its pores. Things are due significant reactivity montmorillonite minerals water content that results initial matrix. adsorption layers molecules platelets respect suction or stress applied, evidenced time ago Soil science through X-ray diffraction techniques, appear able help better understanding phenomena like soils hydration bentonites. Interestingly, it also applies understand effects smectite behaviour claystone. These at microscopic scales provide a large variety natural clayey rocks.