Advanced Minor Destructive Testing for the Assessment of Existing Masonry

This thesis focuses on minor-destructive testing (MDT) techniques for the mechanical characterisation of historical mortars, as it is a fundamental task for the assessment of existing masonries. In the first part, a novel in-situ MDT technique is investigated, based on the field vane shear test for soils. The instrumentation consists in a four-winged pin (X-Drill) and a torque wrench. This research presents the results of an experimental campaign based on the comparison between standard tests and X-Drill measurements on different types of mortars. The interpretation of the test provides a possible correlation between the measured torque and the compressive strength of the material. In the second part, the thesis focuses on the extraction of samples to be tested in the laboratory. Brazilian tests can be carried out on cores including a diametral mortar joint with a defined inclination with respect to its original horizontal position. A new integrated methodology is developed for the comprehensive mechanical characterization of historical mortar based on different types of experimental tests results. This task is carried out by means of a large set of experiments performed ex-novo on lime mortar masonry walls built in the laboratory. The processing of the results from Brazilian tests on cores with inclined diametral joint is complemented with the application of the double punch tests on mortar joints that may be also extracted through core drilling. The proposed experimental methodology is then compared with the results obtained from standard tests performed on the same materials, such as compression tests, flexural tests and shear tests on triplets. Finally, the parameters obtained are used as input parameters for 2D and 3D numerical analyses based on the Continuum Damage Mechanics constitutive model. The comparison between the experimental results and the numerical analyses confirms the good prediction capacity of the proposed techniques.