Digital image analysis contribution to the evaluation of the mechanical decay of granitic stones affected by fires

Abstract

The study of the decay promoted in building stones by fire is important in the context of the conservation and restoration of historic buildings. As opposed to granular stones, which are more sensitive to chemical changes, tough stones present a noticeable mechanical decay after being affected by fires. The direct observation of decay features at a micro-scale could be the key for understanding the decay processes at greater scales, especially in the cases where extensive sampling is not recommendable or even possible. Microscopic techniques allow quantifying fracture system and establishing differences among different types of fractures. Results obtained so far have demonstrated image analysis and processing techniques as a useful tool to help establishing, in a qualitative and quantitative way, the fracture system variations resulting from mechanical stresses induced by fire.