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[MIS04-05] The cooling Rate Index as a non-destructive tool for the forecasting of variable limestone rocks properties
Keywords:Limestone, Infrared thermography, Cooling rate index (CRI), Diffusivity, Physical properties, Chemical composition
The use of non destructive techniques becomes a requirement in the evaluation of built cultural heritage. The accuracy on stone characterisation and the assessemnet of their decay is thus a priority in this field. Thermal diffusivity is a parameter related to material’s density and consequently to porosity, as indicator of the decay or the weathering potential of a stone. Infrared thermography allows to determine, by means of non-contact measurements, the apparent diffusivity of rock and this, in our study case, by resorting to the determination of their cooling rate index (CRI).
In this work, the suitability of infrared thermography was tested on twenty Tunisian limestones that presented variable characteristics including a porosity varying from 1 to 20 ‰. After heating the samples homogeneously at 70 ℃, a monitoring of the cooling of the samples during 20 minutes was achieved in order to calculate the CRI and to establish a relationship with their porosity values.
The correlation diagrams between the CRI and the major physical properties of the limestones showed the suitability of this nondestructive tool for the forecasting of the bulk density, the porosity, the capillarity and the P wave velocity where the best fitting trends were recorded for the lowest porous samples with an R2 ≧ 0.90.
Similar findings showed the compatibility between the CRI and the chemical composition of the carbonate rocks due to the different thermal properties of the existing minerals.
In this work, the suitability of infrared thermography was tested on twenty Tunisian limestones that presented variable characteristics including a porosity varying from 1 to 20 ‰. After heating the samples homogeneously at 70 ℃, a monitoring of the cooling of the samples during 20 minutes was achieved in order to calculate the CRI and to establish a relationship with their porosity values.
The correlation diagrams between the CRI and the major physical properties of the limestones showed the suitability of this nondestructive tool for the forecasting of the bulk density, the porosity, the capillarity and the P wave velocity where the best fitting trends were recorded for the lowest porous samples with an R2 ≧ 0.90.
Similar findings showed the compatibility between the CRI and the chemical composition of the carbonate rocks due to the different thermal properties of the existing minerals.