Comparison of MDT techniques for mechanical characterization of historical masonry

This paper presents the results of an experimental program evaluating the possibility of available Minor Destructive Testing (MDT) techniques for the mechanical characterization of historical masonry. In particular, the research focuses on mortar, the material component that is usually the most difficult one to be experimentally characterized in existing masonry structures. Masonry wallets were built in the laboratory using clay bricks and lime mortar, material combination corresponding to the vast majority of the historical construction. Different experimental tests were carried out: double punch test, pin penetration test and helix pullout test. The critical analysis and comparison of the experimental results show the potential of the investigated techniques and the possibilities for their improvement and further calibration. All the approaches considered are minimally invasive and induce negligible damage to the structure. For this reason, the results of the research could be useful for future studies on preventive conservation and maintenance of historical masonry structures.