In-pore tensile stress by drying-induced capillary bridges inside porous materials.

Majda Bouzid (1, 2) , Lionel Mercury (3) , Arnault Lassin (4) , Jean-Michel Matray (2) , Mohamed Azaroual (4)

1 IDES - Interactions et dynamique des environnements de surface
2 IRSN/DEI/SARG/LR2S - Laboratoire de Recherche sur le Stockage géologique des déchets et les transferts dans les Sols
3 ISTO - Institut des Sciences de la Terre d'Orléans
4 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)

We present here some evidences that capillary liquid bridges are able to deform micrometric cylindrical pores by tensile stress. Brine-soaked filter membranes are submitted to drying conditions leading to NaCl precipitation inside the 5-10 μm pores. A close examination demonstrated that two forms of NaCl crystallites are successively generated. First, primary cubic crystals grow, driven by the permanent evaporation. When this angular primary solid gets near the pore wall, while the evaporation makes the pore volume to be partly invaded by air, capillary liquid can bridge the nowsmall gap between the halite angles and the pore wall. In a second step, these small capillary bridges are frozen by a secondary precipitation event of concave-shaped NaCl. The proposed interpretation is that the liquid capillary bridges deform the host matrix of the membrane, and the situation is fossilized by the growth of solid capillary bridges. A quantitative interpretation is proposed and the consequences towards the natural media outlined.

Keywords: unsaturated zone; liquid water; tensile strength; poromechanics; soluble salts

Domains: Geophysics [physics.geo-ph]; Geophysics [physics.geo-ph]; Global Changes

Majda Bouzid, Lionel Mercury, Arnault Lassin, Jean-Michel Matray, Mohamed Azaroual. In-pore tensile stress by drying-induced capillary bridges inside porous materials.. Journal of Colloid and Interface Science, 2011, 355, pp.494-502. ⟨10.1016/j.jcis.2010.12.058⟩. ⟨insu-00551322⟩