Colloquium Prof. Michael Steiger
When: Tuesday 19 November 2013
Where: Ceres, 0.31, TU/e campus
The pressure generated by crystal growth of salts in confined spaces of porous building materials such as stone, brick and concrete is generally recognized as a major cause of damage in ancient monuments and modern buildings. Crystal growth is also considered as an important weathering mechanism of natural rocks in a variety of environments. Crystallization is the result of phase changes that are induced by variation of ambient temperature and relative humidity. Unfavorable climatic conditions may result in repeated cycles of crystallization–deliquescence, hydration–dehydration and freezing–thawing, respectively. Under such conditions, building materials and natural rocks are subject to rapid decay.
First, I will discuss the underlying damage mechanism and the theory of crystallization pressure. Next, I will briefly review the composition of salt mixtures typically found in building materials and will discuss the relevant phase equilibria and the environmental conditions leading to phase changes and crystal growth. Finally, I will present a multi-component electrolyte solution model to predict the crystallization pathways in salt mixtures. Such models are a useful tool to predict appropriate environmental conditions to avoid salt damage in building materials, i.e., conditions that reduce the frequency of phase changes inducing crystal growth.