Geotechnical characterization of limestones employed for the reconstruction of a UNESCO world heritage Baroque monument in southeastern Sicily (Italy)

A detailed laboratory characterization of limestones employed for the reconstruction of Saint Nicholas Cathedral, a UNESCO World Heritage monument in southeastern Sicily, is presented herein with the purpose of achieving a complete knowledge on the behavior of such rocks under stress, whose engineering geological aspect had not been investigated before for scientific purposes. Specimens were sampled at three sites, where this rock is quarried from two lithofacies of the same geological formation, and are similar to other limestone varieties quarried worldwide and employed as construction material. Although slight differences between the samples occur at a macroscopic scale, geotechnical tests highlighted relevant differences from the physical and mechanical points of view. In order to look for one or more factors responsible of such dissimilarities, a statistical analysis was carried out and interesting outcomeswere achieved with the help of a microscopic analysis of the specimens. Moreover, attention was paid on the modes of failure of tested specimens under compression, whose attitude was described and correlated to selected properties of the rock. Results have both a practical implication, because of the employment of this rock type as engineering material worldwide, and a scientific relevance, due to the peculiar behavior that such rock offered under stress.