Role of hydro-mechanical coupling in the damage process of limestones used in historical buildings

Fabien Cherblanc (1, 2) , Jérémie Berthonneau (3) , Philippe Bromblet (4)

1 LMGC - Laboratoire de Mécanique et Génie Civil
2 BIOTIC - Biomécanique des Interactions et de l'Organisation des Tissus et des Cellules
3 CEE - Department of Civil and Environmental Engineering [Cambridge]
4 CICRP - Centre Interdisciplinaire de Conservation et Restauration du Patrimoine

Historical monuments of the Provence region display different sensitivities to spalling decay. Even if some phenomenological scenario have been proposed, the physical processes that govern this kind of damage have not been clearly identified and quantified. The more reliable hypothesis involves the hydro-mechanical behaviour of such limestones triggered by naturally occurring expandable clay minerals (smectite). In order to sense the internal factors involved, a characterization campaign has been carried out. Clay mineral quantification was performed based on a recent methodology coupling transmission electron microscopy, X-ray spectrometry, X-ray diffraction. The relevant mechanical properties were characterised with a particular attention paid on their dependencies on the water content. Then, permeability, capillary pressure, vapour diffusion, sorption isotherm, and hydric dilation of these stones were measured. This set of experimental characteristics was introduced in a numerical model of a block inside a masonry structure to simulate water transport and mechanical behaviour. Simple climatic scenarios have been imposed to simulate alternating wetting and drying boundary conditions. Numerical simulations showed that the mechanical stresses generated by hydric dilation or shrinking are not large enough to lead to a direct damage. Nevertheless, in a case study, numerical simulations highlighted some tendencies in agreement with observations.

Mots clés: limestone; spalling decay; clay minerals; hydro-mechanical behaviour; numerical simulation

Domaines: Mécanique des matériaux [physics.class-ph]; Construction durable; Réhabilitation

Fabien Cherblanc, Jérémie Berthonneau, Philippe Bromblet. Role of hydro-mechanical coupling in the damage process of limestones used in historical buildings. 13th International Congress on the Deterioration and Conservation of Stone , Sep 2016, Glasgow, United Kingdom. ⟨hal-01364003⟩