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Rudolf Holzer, Comenius University Bratislava (Slovakia)
Marek Laho, Comenius University Bratislava (Slovakia)
Martin Bednarik, Comenius University Bratislava (Slovakia)
Vladimir Greif, Comenius University Bratislava (Slovakia)
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The contribution deals with properties and decay of the dimension stone used on historic buildings and monuments, which was excavated in various geological complexes of Slovak Carpathians. The research was focused on representative building rocks used in the Bratislava region (Neogene Leitha limestone on St. Martin's Cathedral and Bratislava castle), in the Middle Slovakia region (volcanic agglomeratic tuffs on the St. Benedict Church in Hronsky Benadik, rhyolite of plague column of mining town Banska ?tiavnica), as well as in the Eastern Slovakia region (Flysch sandstones used on St. Jacob Church in Levoca and St. Aegidius Church in Bardejov).
The monuments are built from various types of very well workable weak detritic rocks, which are subject of decay, mainly weathering and call in some facade parts for the urgent restoration. The main aim of the research is concentrated on the determination of used lithological rock types, weathering manifestation and search for the sources of the authentic or similar replacement rock building substance.
Besides microscopic mineralogical and paleontological studies concentrated on the determination of the rock composition and induced exogenous changes, the laboratory assessment of physical and mechanical rock properties was realized. Presented basic physical and mechanical rock properties were determined on samples from confirmed excavation sites or adjacent quarries built up by similar rock material. The estimated porosity, water sorption, uniaxial compressive strength (dry scd, saturated scw and after freeze/thaw cycles samples scf), calculated softening (Cs=scw/scd) and freezing coefficients (Cf=scf/scd) and the loss of sample weight in the solution of Na2SO4, together with tests in Na2SO4 solution were regarded as suitable indicators of the stone durability.
Information obtained from field and laboratory dimension stone investigation was stored in the relational database, which contains a general information, data about the rock environment, physical properties of investigated rocks and rock utilization. Every row of data in the main database table (particularly for each locality) is connected with multiple rows of the database. Such database structure enables to connect the main table with any optional graphical object and to use the database in GIS environment. After the choice of any optional point, which represents the locality (site of dimension stone excavation) the database user obtains a complex information about the characteristics of investigated object, including the photodocumentation. Besides the actual excavation sites, all sites significant from the point of view replacement stone were elaborated. The database introduces an open system with the possibility of permanent data enhancement.
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