Salt damage of porous materials

The pressure generated by crystal growth of salts (and ice) in confined spaces of porous materials such as stone, brick, and concrete is a major cause of damage in modern constructions, ancient monuments and other objects of art. Crystal growth is also considered as an important weathering mechanism of natural rocks in a variety of environments not only on earth but also on Mars.

Examples of salt damage

acetate salts in museum objects

Damage mechanism

Our research is concerned with the mechanism of salt damage including both theoretical considerations [1–3] and experimental work [4,5]. A thermodynamically consistent equation for the pressure exerted by crystals growing in porous materials can be derived using expressions for the chemical potentials of the loaded and the unloaded faces of a crystal that is confined in a porous material. A growing crystal can only exert stress if it is in contact with a pore solution that is supersaturated with respect to the unloaded faces of the crystal. The theoretical treatment can be extended to include size effects, i.e. influences of the crystal-liquid interfacial energy, and yields a general equation for the crystallization pressure [2].

Publications

1. Steiger M., J. Cryst. Growth 2005, 282, 455–469.
2. Steiger M., J. Cryst. Growth 2005, 282, 470–481.
3. Flatt R.J., Steiger M., Scherer G.W., Environ. Geol. 2007, 52, 187–203.
4. Steiger M., Linnow K., Juling H., Gülker G., El Jarad A., Brüggerhoff S., Kirchner D.,
   Cryst. Growth Des. 2008, 8, 336–343.
5. Steiger M., Asmussen J., Geochim. Cosmochim. Acta 2008, 72, 4291–4306.