ORIGINAL ARTICLE Sandstone alterations triggered by fire-related temperatures Z. Kompanı ´kova ´ • M. Gomez-Heras • J. Michn ˇova ´ • T. Durmekova ´ • J. Vlc ˇko Received: 26 November 2013 / Accepted: 17 February 2014 Ó Springer-Verlag Berlin Heidelberg 2014 Abstract The aim of the study was to identify and describe changes in two different sandstone types when undergoing different environmental and extreme tempera- ture regimes to assess the possibility of finding insolation weathering and how these sandstones would behave during and after a fire. The first step was the simulation in the laboratory of temperature regimes up to 60 °C which would correspond to extreme events that could be found in insolation cycles even in Central Europe and the second one was the temperature above 200 °C simulating in lab- oratory conditions the thermal regime of a potential fire situation at temperatures up to 200, 400, 600 and 800 °C. Heating the samples above 400 °C led to gradual changes in mineral composition, colour, surface roughness and physical properties reaching, eventually, total rock break- down through spalling and granular disaggregation. The different behaviour of sandstones exposed to high tem- peratures is mainly caused by their different mineral composition with various ratios of minerals that are more or less chemically stable at high temperatures as well as by the differences in the porosity. Keywords Stone decay  Environmental temperatures and fire-related decay  Mineral composition  Porosity  Optical surface roughness  Sandstone Introduction Physical properties and mineral changes of rocks associ- ated with crumbling, cracking and discolouration due to temperature variations caused by both environmental (insolation) and fire events have been observed since almost two centuries ago. First references on the influence of thermal stresses and thermal fatigue brought Bartlett (1832) in experiments where the thermal expansion and contraction for individual rocks used as building stones were determined. Two types of thermal weathering can be considered (Gomez-Heras et al. 2008a): first, ‘insolation weathering’ which corresponds to environmental cycles of heating and cooling and, second, ‘fire-related decay’. Both of them share mechanisms through which decay takes place, but are obviously different because of the moderate and cyclic nature of thermal changes in insolation weath- ering and the one-off extreme character of fire decay. The impact of ‘insolation weathering’ has been broadly contested, but it appears that even when its impact on its own is clearly overridden by other decay agents, fluctua- tions in surface temperature may facilitate thermally driven decay even in midlatitudes (Gomez-Heras et al. 2008a). Laboratory testing of repeated thermal changes in envi- ronmental regimes is intrinsically complicated without invoking to extreme temperature events, which somehow change the nature of the decay process (changing the focus from thermal fatigue to thermal shock). In nature, tem- perature fluctuates in accordance with different climatic cycles according to various geographic zones (Ramana and Z. Kompanı ´kova ´(&)  T. Durmekova ´  J. Vlc ˇko Department of Engineering Geology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynska ´ dolina, 842 15 Bratislava, Slovakia e-mail: zuzana.komp@gmail.com M. Gomez-Heras Instituto de Geociencias (CSIC-UCM), CEI Campus Moncloa (UPM, UCM, CSIC), ETS Arquitectura (UPM), 28040 Madrid, Spain J. Michn ˇova ´ Department of Geology of Mineral Deposits, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynska ´ dolina, 842 15 Bratislava, Slovakia 123 Environ Earth Sci DOI 10.1007/s12665-014-3164-2