Displacement and strain fields at a stone/mortar interface by digital image processing

This work is part of a study of historical masonry behavior. It deals with the homogenization of periodic and heterogeneous structures like masonry, which is composed of stones linked by joints of mortar. Combined compressive-shearing tests were performed in order to study the mortar interface behavior. Deformation properties were measured, locally, by an optical extensometer. Like the speckle method, this principle uses digital image correlation processing. Compared to the volume of the joint. the size of aggregates induces heterogeneities. An experimental protocol is proposed to determine homogenous deformation according to joint width and localized deformation according to joint height. This approach accurately characterizes the interface at a microscale level and enhances high compaction strain at the interface.