Freeze-thaw resistance of limestone roofing tiles assessed through impulse vibration monitoring and finite element modeling in relation to their microstructure

摘要

Stone slate used for roofing is often considered as a key element of architectural heritage, especially in the French "Massif Central" region, where it contributes to the Mediterranean agropastoral cultural land-scape of the "Causses and Cevennes" perimeter registered on the UNESCO World Heritage List. This material is subjected in service to severe and cycled climatic conditions (freeze-thaw) that may lead from mechanical damage to failure and thus compromise its use. In this paper, a damage assessment strategy of limestone roofing tiles samples during freeze-thaw cycles, based on the monitoring of their impulse vibration response, is proposed. Variations of the modal parameters such as resonant frequencies, damping ratios and mode shapes are analyzed through a 3D finite element model of each sample. This allows quantifying the loss of dynamic stiffness due to the ongoing damage and drawing comparisons between the studied materials in relation to their microstructural and mesostructural damages. Thus presence of pre-existing diagenetic features, such as stylolites (Ds in Nicholson classification), inside limestone tile-stone with unimodal micropore, or with presence of high porosity volume, constitute weaknesses of the stone that can lead to damage. (C) 2019 Elsevier Ltd. All rights reserved.