Comparison Between Investigation Techniques for the Evaluation of the Compressive Properties of Brick Masonry Structures

Existing masonry buildings, representing a large portion of the building stock in the Mediterranean area, are usually characterized by the presence of different constituent materials. The modifications experienced over time could have modified the static configuration of the structures and could trigger local damages and crises. Therefore, it is of fundamental importance to assess the safety of these constructions and to determine if retrofitting interventions are needed. In this framework, one of the crucial aspects is the mechanical characterization of masonry. Concerning brick masonries, several testing methodologies exist for the determination of the compressive strength, the elastic modulus and the Poisson’s ratio. In particular, slightly-destructive tests, such as double flatjack tests and compressive tests on masonry cores, can be performed in place of destructive tests due to their limited invasiveness. However, they could be less representative of the overall behavior of masonry structural elements. The objective of the research is to evaluate the reliability of slightly-destructive tests in evaluating the compressive properties of masonry. An experimental campaign is presented, in which masonry specimens were built to reproduce a poor-quality brick masonry typology. Standard compression tests on wallets and double flatjack tests, both monotonic and cyclic, were performed. Moreover, masonry cores were extracted from the masonry specimens and tested in compression. Compressive strength, elastic modulus and Poisson’s ratio were evaluated from each testing methodology. The results obtained from the double flatjack tests and the tests on cores, in terms of strength and deformability properties, were compared with the results of the standard compression tests, taken as reference. Correlations between the results of the slightly-destructive tests and the standard compression tests were established, obtaining a good agreement and confirming that the experimental techniques can be reliably adopted for the evaluation of the compressive properties of brick masonry.