Torsional Shear Testing of Mortar

Abstract

This paper presents a complex multidisciplinary approach to characterize the torsional shear on thin-walled cocciopesto lime mortar tubes. The approach employs (i) an in-house developed biaxial electro-mechanical loading frame designed for torsional loading, (ii) an optical measurement setup based on the digital image correlation technique to monitor and record the deformation during loading and (iii) a numerical model using finite element simulation to assess localization of shear failure. Prior to torsional loading, the mortar specimen needs to be firmly secured into the loading frame without exposing it to unwanted tensile or bending loading and possible crushing at fixture points. During the torsional loading, the mortar tube must be able to freely move axially. An optical measurement setup based on the digital image correlation technique allowed to quantify deformation measurements during torsional testing and provided the strain field on the observed surface. The mode of torsional failure was finally assessed from finite element simulations and compared to experimental measurements.