Infrared thermography for the investigation of physical–chemical properties and thermal durability of Tunisian limestone rocks

Abstract

Twenty-one limestone lithotypes from the extreme North of Tunisia (Bizerte region) were characterized in order to investigate their weathering resistance and the resulting damage from thermal shock cycles. An infrared thermography (IRT) monitoring was also conducted to assess the tendencies between the cooling rate index (CRI) and the physical (bulk density, porosity, capillarity and P wave velocity) or the chemical (calcium carbonate, silica and total organic carbon contents) characteristics of the carbonate rocks. Statistical clustering defined four classes in accordance with their different porosity values (1 % < n < 20 %). The obtained CRI within a 10-min of infrared thermography (IRT) survey allowed to forecast not only the total porosity of these rocks but also their major physical properties with a noticeable correlation trends before and even after thermal shock cycles.Similar findings proved the compatibility between the CRI10 and the chemical composition of the limestones due to the different thermal properties of the minerals. The lowest porous samples (n ≤ 5 %) with the highest calcium carbonate content (CaCO3 > 95%) seemed to be the most suitable ones for the infrared thermography (IRT) characterization by its best fitting trends with the CRI10. Thermal shock was very well remarked for all the clusters particularly based on the measures of CRI10 and capillarity, as they are mainly related to surface and subsurface features that are the most affected by the fast cooling process. This study highlighted the validity of the CRI10 as a reliable indirect parameter for the estimation, in laboratory, of low porous stones properties undergoing thermal weathering.