Subflorescence and plaster drying dynamics

Mamadou Diaga Seck (1) , Emmanuel Keita (2) , Pamela Françoise Faure (1) , Pierrick Cavalié (3) , Maxime van Landeghem (3) , Stéphane Rodts (1) , Philippe Coussot (1)

1 navier umr 8205 - Laboratoire Navier
2 IFSTTAR/MAST/FM2D - Formulation, Microstructure, Modélisation et Durabilité des Matériaux de Construction
3 SGR - Saint-Gobain Recherche

The dynamics of plaster drying and the impact of subflorescence on the process are described through Magnetic Resonance Imaging and X-Ray Microtomography measurements. It is shown that crystals deposit around the air-liquid interface the closest to the sample free surface, which induces a recession of this interface within the sample at a rate only depending on the current saturation (water to pore volume ratio). Thus the distribution of crystals deposited during evaporation essentially depends on the history of saturation. The drying dynamics then results from vapor diffusion through the less porous layers of crystal accumulation below the sample free surface. This in particular makes it possible to predict the dramatic decrease of the drying rate after successive imbibition-drying cycles.

Keywords: Plaster; drying; subflorescence; precipitation; dewetting

Domains: Mechanics of materials [physics.class-ph]

Mamadou Diaga Seck, Emmanuel Keita, Pamela Françoise Faure, Pierrick Cavalié, Maxime van Landeghem, et al.. Subflorescence and plaster drying dynamics. Chemical Engineering Science, 2016, 148, pp.203 - 211. ⟨10.1016/j.ces.2016.04.012⟩. ⟨hal-01784858⟩