Effect of water content on the mechanical behavior of thin clay films

In this work we measure the effect of water on the elastic and swelling properties of thin smectite clay films. The thin films exhibit a well organized structure with parallel clay particles and are about 40 μm thick. We measure the swelling potential of the films by analyzing Environmental Scanning Electron Microscopy pictures. We carry out tensile tests at various relative humidities to evaluate the impact of the water content on the elastic modulus of the films. In particular, the effect of the nature of the counter-ions is investigated. In parallel, we perform molecular dynamics simulations of clay layers with various water contents. At each water content, the thickness of the platelet and its elastic stiffness tensor are computed. We compare those numerical results at the scale of a clay layer with the experimental results at the scale of a clay film and discuss their relevance.