LUIGIA BINDA, CLAUDIA TIRABOSCHI and SILVIA ABBANEO
Politechnico di Milano, Italy
In the last decade or so the characterization of masonry materials by mechanical tests has been much discussed and tests proposed for masonry units, mortars and for masonry specimens. One of the most difficult parameters to measure is the bond strength between mortars and units, which is also one of the most important for calculation of the toad carrying capacity of the masonry. The authors were asked to characterize experimentally the materials used for the construction of a full scale model tested at the University of Pavia, in a scientific collaboration with a national research group (C.N.R.-G.N.D.T.). This was an opportunity to determine the fitness of codified and non-codified tests for measuring the most important mechanical parameters. Results from comparative experimental studies on bricks, mortars and on assemblages and small prisms of the same materials are given. Compressive and flexural tests, shear and tensile bond strength tests were carried out with the aims of: (i) measuring the most important parameters to be used for modelling the material behaviour, (ii) correlating specimen size and dimensions to the experimental results, (iii) comparing test methods proposed by international codes on testing masonry materials. Several problems were found, most of them concerning the difficulty of measuring the displacements on small specimens of weak materials such as the bricks and mortars used for the full scale model. Some of the problems have already been solved by the careful calibration of the measurement methods and equipment.