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Pore and hygric properties of porous limestones: a case study from Bratislava, Slovakia

Abstract Most historic stone monuments in Bratislava (Slovakia) are built with various types of porous, light and weakly cemented sedimentary rocks. These Neogene sandstones and limestones, also known as Leitha limestones, were quarried in the Vienna Basin. The various sedimentary environments are reflected in the heterogeneity of lithotypes and their cementation. The distinctly different pore structure of these rocks is reflected in their very variable physical properties and consequently in the distinct durability. Petrographic and petrophysical properties were determined on main ashlar types of the two most important historical monuments of Bratislava, the Castle and St Martin's Cathedral. Fresh samples of Leitha limestones were also obtained from the existing or abandoned quarries. The study includes a detailed petrographic examination of major rocks types and an assessment of their mineralogical composition by X-ray diffraction and microscopy. Hygric properties and porosity influence the weathering stability and the chances to apply conservation treatment. Parameters such as pore volume, pore size distribution by mercury porosimetry, specific surface of pores by nitrogen adsorption (BET) analysis as well as water sorption, capillary water uptake and drying behaviour were measured and compared for the six studied lithotypes.