@article {217, title = {Effect of Water on Elastic and Creep Properties of Self-Standing Clay Films}, journal = {Langmuir}, volume = {32}, year = {2016}, month = {Feb-09-2016}, pages = {1370 - 1379}, abstract = {

We characterized experimentally the elastic and creep properties of thin self-standing clay films, and how their mechanical properties evolved with relative humidity and water content. The films were made of clay montmorillonite SWy-2, obtained by evaporation of a clay suspension. Three types of films were manufactured, which differed by their interlayer cation: sodium, calcium, or a mixture of sodium with calcium. The orientational order of the films was characterized by X-ray diffractometry. The films were mechanically solicited in tension, the resulting strains being measured by digital image correlation. We measured the Young\&$\#$39;s modulus and the creep over a variety of relative humidities, on a full cycle of adsorption-desorption for what concerns the Young\&$\#$39;s modulus. Increasing relative humidity made the films less stiff and made them creep more. Both the elastic and creep properties depended significantly on the interlayer cation. For the Young\&$\#$39;s modulus, this dependence must originate from a scale greater than the scale of the clay layer. Also, hysteresis disappeared when plotting the Young\&$\#$39;s modulus versus water content instead of relative humidity. Independent of interlayer cation and of relative humidity greater than 60\%, after a transient period, the creep of the films was always a logarithmic function of time. The experimental data gathered on these mesoscale systems can be of value for modelers who aim at predicting the mechanical behavior of clay-based materials (e.g., shales) at the engineering macroscopic scale from the one at the atomistic scale, for them to validate the first steps of their upscaling scheme. They provide also valuable reference data for bioinspired clay-based hybrid materials.

}, issn = {0743-7463}, doi = {10.1021/acs.langmuir.5b03431}, author = {Benoit Carrier and Matthieu Vandamme and Roland Jean-Marc Pellenq and Bornert, Michel and Ferrage, Eric and Hubert, Fabien and Henri Van Damme} } @article {46, title = {ESEM Study of the Humidity-Induced Swelling of Clay Film}, journal = {Langmuir}, volume = {29}, year = {2013}, month = {Oct-02-2013}, pages = {12823{\textendash}12833}, abstract = {
Abstract Image

We measured the humidity-induced swelling of thin self-standing films of montmorillonite clay by a combination of environmental scanning electron microscopy (ESEM) and digital image correlation (DIC). The films were about 40 \μm thick. They were prepared by depositing and evaporating a suspension of clay and peeling off the highly oriented deposits. The rationale for creating such original samples was to obtain mesoscopic samples that could be used to bridge experimentally the gap between the scale of the clay layer and the engineering scale of a macroscopic clay sample. Several montmorillonite samples were used: the reference clay Swy-2, the same clay homoionized with sodium or calcium ions, and a sodium-exchanged Cloisite. The edges of the clay films were observed by ESEM at various relative humidity values between 14\% and 95\%. The ESEM images were then analyzed by DIC to measure the swelling or the shrinkage of the films. We also measured the adsorption/desorption isotherms by weighing the film samples in a humidity-controlled environment. In order to analyze our results, we compared our swelling/shrinkage and adsorption/desorption data with previously published data on the interlayer spacing obtained by X-ray diffraction and with numerical estimates of the interlayer water obtained by molecular dynamics simulation. The swelling and the hysteresis of this swelling were found to be comparable for the overall macroscopic films and for the interlayer space. The same correspondence between film and interlayer space was observed for the amount of adsorbed water. This suggests that, in the range of relative humidities values explored, the films behave like freely swelling oriented stacks of clay layers, without any significant contribution from the mesoporosity. The relevance of this result for the behavior of clayey sedimentary rocks and the differences with the behavior of nonoriented samples (powders or compacted powders) are briefly discussed.

}, doi = {10.1021/la402781p}, author = {Benoit Carrier and Wang, Linlin and Matthieu Vandamme and Roland Jean-Marc Pellenq and Bornert, Michel and Tanguy, Alexandre and Henri Van Damme} }