The mechanisms of plaster drying

Mamadou Diaga Seck (1, 2) , M van Landeghem (3) , P Faure (1) , Stéphane Rodts (1) , R Combes (4) , P Cavalie (5) , E Keita (1) , Philippe Coussot (2, 1)

1 navier umr 8205 - Laboratoire Navier
2 Rhéophysique
3 PPMD - Laboratoire de Physico-Chimie des Polymères et des Milieux Dispersés
4 E3S - Supélec Sciences des Systèmes
5 LPA - Laboratoire Pierre Aigrain

We show that the drying rate of plaster pastes is significantly lower than that expected for a pure liquid evaporating from a simple homogeneous porous medium. This effect is enhanced by the air flow velocity and the initial solid/water ratio. Further tests under various conditions and with the help of additional techniques (MRI, ESEM, Microtomography) for measuring the drying rate and local characteristics (water content, porosity) prove that this effect is due to the crystallization of gypsum ions below the sample free surface, which creates a dry region and decreases the drying rate by increasing the length of the path the vapor has to follow before reaching the free surface.

Domaines: Sciences de l'ingénieur [physics]; Sciences de l'ingénieur [physics]; Mécanique [physics.med-ph]; Physique [physics]; Matière Condensée [cond-mat]; Electrons fortement corrélés [cond-mat.str-el]; Physique [physics]; Physique [physics]; Physique Atomique [physics.atom-ph]

Mamadou Diaga Seck, M van Landeghem, P Faure, Stéphane Rodts, R Combes, et al.. The mechanisms of plaster drying. Journal of Materials Science, 2015, 50 (6), pp.2491-2501. ⟨10.1007/s10853-014-8807-x⟩. ⟨hal-01172479⟩