Recent Applications of MRI for the Study of Transfers in Porous Media – Internal Quantification of the Dynamics of Drying, Colloid Transport, Dispersion, Phase Transfers, Complex Fluid Flows

Orateur : Philippe COUSSOT (Laboratoire Navier (ENPC, IFSTTAR, CNRS), Université Paris-Est)

Liquid, ion or particle transport, or transfers between phases, inside civil engineering materials, play a critical role in their properties or their durability. Magnetic Resonance Imaging (MRI) allows to « visualize » the liquid phase within these non-transparent materials, but by using specific sequences it can also provide information on the liquid state, its motion, or even its interactions with the environment. More precisely, recent developments in that field, in particular in our lab, thus make it possible to measure the velocity field, the statistical distribution of velocities, the distribution of liquid states in time (e.g. bound or free water), the concentration distribution of suspended elements, etc. These information provides a straightforward quantification of various phenomena and sometimes leads to question usual assumptions based on macroscopic observations. I will present a few examples : homogeneous desaturation in drying nanoporous systems, subflorescence dramatically slowing down plaster drying, direct internal measurements showing lower dispersion than assumed so far, direct observation of colloid transport and adsorption in model soils, liquid transfers inside a composite concrete, peculiar characteristics of wood imbibition, breakage of the non-Newtonian characteristics of yield stress fluids flowing through a porous medium.

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