title: Effect of Water on Elastic and Creep Properties of Self-Standing Clay Films.
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's modulus and the creep over a variety of relative humidities, on a full cycle of adsorption-desorption for what concerns the Young'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's modulus, this dependence must originate from a scale greater than the scale of the clay layer. Also, hysteresis disappeared when plotting the Young'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.
authors.affiliation: Laboratoire Navier (UMR 8205), Université Paris-Est, CNRS, ENPC, IFSTTAR , Marne-la-Vallée F-77455, France.
authors.forename: Benoit
authors.initials: B
authors.lastname: Carrier
authors.affiliation: Laboratoire Navier (UMR 8205), Université Paris-Est, CNRS, ENPC, IFSTTAR , Marne-la-Vallée F-77455, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Vandamme
authors.affiliation: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.|Centre Interdisciplinaire des Nanosciences de Marseille, CNRS (UPR 7251) , Campus de Luminy, Marseille 13288 Cedex 09, France.|<MSE>2, UMI 3466, CNRS-MIT , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
authors.forename: Roland J-M
authors.initials: RJ
authors.lastname: Pellenq
authors.affiliation: Laboratoire Navier (UMR 8205), Université Paris-Est, CNRS, ENPC, IFSTTAR , Marne-la-Vallée F-77455, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Bornert
authors.affiliation: Université de Poitiers/CNRS , UMR 7285 IC2MP, Poitiers 86022, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Ferrage
authors.affiliation: Université de Poitiers/CNRS , UMR 7285 IC2MP, Poitiers 86022, France.
authors.forename: Fabien
authors.initials: F
authors.lastname: Hubert
authors.affiliation: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.|Centre Interdisciplinaire des Nanosciences de Marseille, CNRS (UPR 7251) , Campus de Luminy, Marseille 13288 Cedex 09, France.|<MSE>2, UMI 3466, CNRS-MIT , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
authors.forename: Henri
authors.initials: H
authors.lastname: Van Damme