SWBSS 2014, 3rd Interantional Conference on Salt Weathering of Buildings and Stone Sculputres pages:133-149
3rd International Conference on Salt Weathering of Buildings and Stone Sculptures -SWBSS location:Royal Institute for Cultural Heritage, Brussels, Belgium date:14-16 October 2014
Over the last few decades, brick masonry buildings in the UK, The Netherlands and Belgium have started suffering from a new type of salt efflorescence. This new efflorescence consists of sparingly soluble gypsum, and is therefore strongly persistent. Although gypsum efflorescence has already been known for several decades, there are still many open questions regarding the mechanisms behind this phenomenon. Numerical simulation of the transport and crystallization of gypsum in porous materials can contribute to a better understanding of the underlying processes, hence being helpful in the search for causes and solutions. However, due to the low solubility of gypsum and insensitivity to changes in temperature and relative humidity, calcium sulphate is generally not included in simulation software for salt transport and crystallization in porous materials. Therefore, this paper focuses on the numerical implementation of gypsum transport and crystallization in the Delphin simulation environment. As initial application, the simulation of wicking test is performed. The uptake test comprises an initially dry material sample in contact with gypsum solution at the bottom surface, while evaporation is allowed only at the top surface. The main objective is the study of the processes of transport and crystallization of gypsum in porous media, with relation to gypsum efflorescence on brick masonry.