Shear behaviour of bed joints in ashlar stone masonry walls reinforced with polymer mortar

The shear behaviour of bed joints in ashlar stone masonry (ASM) walls was investigated by conducting tests on nine groups of ordinary mortar joints and four groups of joints reinforced with polymer mortar. The experimental variables included the normal compressive stress and the mortar strength. The test results showed that the failure process of the joint specimens could be characterised by three distinct stages: the elastic stage, the crack development stage and the slip stage. The slip stage was identified as the primary stage for energy dissipation. The shear strength of the bed joints was found to increase non-linearly with the increment of normal compressive stress. The incorporation of polymer mortar was observed to enhance the shear strength of the ASM bed joints under vertical load by 14.7–23.4%. Based on the experimental data and analysis, formulas were developed to predict the shear strength of ASM bed joints with either ordinary mortar or reinforced with polymer mortar. Good agreement between the predictions and the experimental results was achieved.