Brick masonry characterization and comparison with power-law equations for compressive strength

The design of a masonry representative of an existing one presents many open issues, particularly in the choice of its constituents, e.g., bricks and mortar, and the prediction of composite behavior. Mechanical properties of modern constituents are, in fact, significantly higher than those in existing structures, and their estimation, e.g., of compressive strength, is typically carried out using empirical power-law equations. However, these equations derive from tests on modern constituents and their assemblies, which limit their applicability to existing masonry. In this context, the paper presents a brick masonry characterization conducted at the University of Genoa. Among commercially available fired clay solid bricks, those with the lowest compressive strength (15 MPa) were selected. A low-strength (around 1 MPa) mortar was specifically produced for this study. The paper aims to critically discuss the experimental results and the challenges encountered in reproducing an existing brick masonry. Secondly, it contributes to consolidating the validity of eight power-law equations for predicting the compressive strength of masonry in the case of existing structures, by comparing empirical predictions with experimental results from this study and from 36 additional tests. Experimental strengths of brick and mortar were consistent with those reported in the technical data sheet. The mechanical properties of mortar were found to be highly sensitive to specimen preparation and curing conditions, while the brick aspect ratio was shown to influence the brick strength. The comparison between the experimental compressive strengths of masonry and empirical predictions for the complete dataset showed a relatively good accuracy for four of the eight equations considered.