Influence of material properties and reinforcement on the compressive and shear strengths of concrete masonry: An experimental study

Abstract

The shear strength of reinforced masonry (RM) walls is influenced by the properties of blocks, mortar, grout, and reinforcement. Despite extensive research on the impact of these elements on masonry compressive strength, there is, to the knowledge of the authors, a notable gap in studies examining their effects on shear strength. This study experimentally investigates the influence of mortar and grout strengths, as well as vertical and horizontal reinforcement, on the compressive and shear stress-strain responses of concrete masonry prisms and assemblages. A total of 40 masonry prisms and 34 masonry assemblages were tested under concentric axial compression and diagonal tension loads, respectively. The behavior of prisms and assemblages was analyzed in terms of compressive and shear strengths, strain at peak stress, modulus of elasticity and rigidity, ultimate ductility index, and modulus of toughness. Additionally, the experimental results were compared with available equations in the literature and North American standards (i.e., CSA S304–14&24 and TMS 402/602–22) for predicting the compressive and shear masonry strengths. The findings reveal that increasing the mortar or grout strengths significantly enhance masonry shear strength but has a less pronounced effect on compressive strength. The presence of vertical or horizontal reinforcement alone or in combination contributes positively to masonry shear strength. For compression prisms, both superposition of masonry shell and grout core strengths and most existing literature equations tend to overestimate masonry compressive strength. The available literature equations for predicting masonry shear strength showed good agreement with the experimental results of this study. CSA S304–14&24 equations overestimate masonry compressive strength but underestimate shear strength, whereas TMS 402/602–22 underestimates both. This study highlights the need for better prediction methods for both compressive and shear strengths of concrete masonry in North American design standards.