Roald Hayen1
1)  Royal Institute for Cultural Heritage
Jubelpark 1, B-1000 Brussels, Belgium

Keywords: Hydrothermal modeling, frost damage, brick masonry.

Abstract. Mitigating frost, salt crystallization and biological growth related damage, often causing a continuous treat for the conservation of our cultural built heritage, requires an understanding of moisture migration. However, historic masonry is often a complex composite of various types of brick, natural stone, bedding and pointing mortar. In some cases additional finishing layers, such as a render, lime wash or paint layers, or even the influence of a hydrophobic treatment in the past will complicate further our interpretation of moisture migration throughout the masonry, while altogether it’s crucial to mitigate the observed damage and to select appropriate materials for repair. Therefore, hygro-thermal modeling, simulating moisture migration and possible stagnation of moisture within the masonry composite, can be a vital tool to assess and mitigate moisture-related damage. A heuristic approach to study moisture-related problems in historic masonry is presented and evaluated based on a case study of a late 19th century fortress of the city of Antwerp. The meter-thick massive masonry construction of the fortress suffers from severe material losses as half to one stone thick shells of the exterior surfaces detach. Following the proposed experimental and modeling approach the damage is assessed and a durable solution for repair is presented.