Variation in shear properties of masonry

Simultaneously with building masonry walls for lintel-tests, mortar prisms and shear-triplets were made. About four hundred mortar prisms were tested according to EN 1052-11 to validate the mechanical properties of the industrially made masonry mortar used. A series of tests was performed in which the mortar properties were varied by adding sand to study its effect on shear strength. Shear triplets were made using bricks but also using pieces of concrete lintel. More than two hundred triplets were tested in shear according to EN 1052-3. The features of the shear test set-up used, are discussed. The goal of the shear tests was to establish the strength variation due to a deliberate variation of mortar properties and mortar-unit interface. Shear strength increased and mortar compressive strength decreased when more sand was added. Suggestions for improvement of the test set-up are given.