Shear Strength of Concrete Masonry Joints

The experimental results of 46 shear tests of ungrouted and grouted concrete block masonry are reported. The shear specimens were tested under shear along the bed joints. The influence of mortar type, grout strength, bed-joint reinforcement, and the level of compressive stress normal to the bed joints were studied. The results indicate that the mortar joint's strength characteristics do not have a major effect on the resistance of masonry joints to shear-slip failure. The grout strength and the normal compressive stress are the most significant parameters influencing the joint capacity. The relative contribution of grouting towards increasing the joint shear strength decreases as the level of precompression increases. A strong correlation between the shear strength and the normal compressive stress is shown to exist for both ungrouted and grouted masonry under low levels of precompression.