Influence of Geometry of Cylindrical Samples in the Mechanical Characterization of Existing Brickwork

Abstract

The mechanical characterization of masonry is of paramount importance for the structural assessment of historical constructions against both vertical and horizontal actions. In particular, the compressive strength of masonry is normally regarded as a critical parameter for structural analysis. However, an accurate determination of the mechanical properties of masonry is a difficult task due to the complex and heterogeneous behavior of the material. The mechanical characterization of historical masonry is also hindered by the need to limit damage caused by inspection in culturally valuable buildings. Recent researches and standards point to the possibility of estimating the compressive strength of existing brickwork by testing cylindrical samples of at least 150 mm diameter extracted from the brickwork walls. This work investigates the possibility of carrying out similar tests on smaller diameter cylinders. Using smaller cylinders may allow the extraction of a larger amount of samples and also permit the reduction of the extent of damage caused to the building. This study presents a comparison between compression tests performed on 150 mm and 90 mm diameter cylindrical samples to evaluate the strength and stiffness of masonry consisting of lime mortar and clay bricks. The tests were carried out in the laboratory on samples extracted from masonry walls by using a dry core-drilling procedure and then regularized with high strength mortar caps. The experimental results show the relationship between the different geometries of core samples regarding strength values, failure modes and crack patterns. The study contributes to the application of experimental tests on cylindrical samples as a minor destructive technique to estimate the mechanical parameters of historical brickwork under compression.