Microwave and radio wave supported drying as new options in flood mitigation of imbued decorated historic masonry

Abstract

Abstract For mitigation of the impact on flood-damaged cultural heritage buildings and sites, solely conservation-compatible and noninvasive strategies can be applied. All procedures have to take into account not only the specific situation after flooding but also the material properties and the characteristics of the artwork related to the building. After a heavy flooding event damaging the monastery Marienthal in Germany demonstration studies were proceeded to evaluate heritage-adequate treatment strategies for the drying of a decorated chapel. To respect and preserve the original gypsum stucco interior drying in certain temperature limits had to be respected. Particularly, direct volumetric heating methods were employed working with electromagnetic waves in the frequency ranges of either microwaves or radio waves. The studies comprised heating tests on site and experiments on a heritage-representative masonry specimen. It could be shown that the removal of water could be significantly enhanced by both techniques. Radio wave heating was demonstrated to allow a more homogeneous and better controlled treatment in comparison to microwave application, which is especially relevant in case of sensitive materials such as gypsum. With respecting that limits the techniques can be applied in combination with efficient removal of moisture from the ambient air by ventilation in order to reduce the drying time thus limiting subsequent damage of the heritage building.