Evaluation of combined effects of real-fire and natural environment in a building granite

摘要

Different decay factors influence the minero-chemical characteristics and the physico- mechanical properties of building stones. Weathering and exposure to high temperatures (such as those achieved during a fire) can contribute to their deterioration. The aim of this work was to identify and describe changes induced by weathering and fire exposure of a granite applied in a traditional Galician country property. In this real-case it was possible to collect granite blocks from fire affected and non-affected areas. Surface properties (color and gloss) and petrographic, mineralogical, physical (open porosity and capillary water absorption) and ultrasonic (VP, VS, VP/VS, E, K, mu and sigma) parameters have been evaluated in both sets. The results shows that the granite used in this property has inherited alteration features (presence of kaolinite, chlorite and goethite associated to high values of porosity, capillary water uptake and moderate values of ultrasound velocities and elastic parameters). Identification of clay minerals and iron oxides in fire affected samples allowed to estimate that the temperature reached by this inherited altered granite was lower than 490 degrees C. Those intrinsic characteristics associated to a relatively low fire temperature justify the physical-mechanical modifications observed. (C) 2021 Elsevier Ltd. All rights reserved.