Several coupled flow formulations to model the osmotic processes in clays have been proposed in the literature. These theories were mostly used to model aspects such as osmotically induced consolidation, salt water intrusion and investigations on clay barriers for ensuring the long term safety of a disposal system. However, few studies have been concerned with osmotically induced expansion of fine grained materials. This paper presents theoretical and experimental work aiming at studying the effect of osmotic phenomena on the swelling of porous material containing salt crystals. Preliminary experimental work shows that swelling induced by dissolution of salt crystals in clays may be significant. A mixture of kaolin and NaCl crystals shows swelling when in contact with pure water. A formulation is proposed for the analysis of deformation induced by dissolution of salts in porous media in contact with fresh water. Numerical modelling of the experimental data provides a first insight of the problem.

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