The use and vulnerability of medieval masonries in Balaton region, Hungary

The geology of the region strongly influences the construction materials of Medieval structures and, consequently, the available raw materials. The current study focuses on the use and vulnerability of various lithotypes and renders in a Medieval Ruined Chuch in West Central Hungary, close to Lake Balaton. The church was constructed in the 13^th century and was rebuilt in several periods using various lithotypes and renders. The identification of primary lithologies followed the generation of point clouds by Terrestrial Laser Scanner and the drawing of walls. More than ten various stone types were found, including Jurassic cherty limestone, cemented Triassic limestone (Muschelkalk), basalt tuff, basalt, red Permian sandstone, grey Tertiary sandstone, highly porous Miocene limestone, and travertine. The properties of stones and condition assessment were made by using non-destructive on-site strength tests such Schmidt hammer and Duroskop. Micro-drilling technique was also applied to assess the strength parameters of renders: medieval lime-based mortars, 20^th-century portland cement based mortars. Small samples were also taken for laboratory analyses. Our studies suggest that the application of portland cement bearing renders in the 20^th century caused significant damage to the structure, accelerating weathering processes. Medieval lime mortars are relatively durable and show smaller-scale alterations. The use of various lithotypes leads to differential weathering of the structure. The long-term preservation of this building depends on the use of appropriate renders and the refurbishment of wall sections that are structurally unstable.