What is the main purpose of using concave joints in masonry?

The main purpose of using concave joints in masonry is to resist rain penetration. Concave joints are designed to create a curved groove that helps shed water away from the surface of the masonry. This curvature reduces the likelihood of water seeping into the mortar joints, which can lead to damage, such as freeze-thaw cycles in colder climates. The design effectively directs any incoming moisture away from the wall, creating a more weatherproof structure.

While aesthetics and structural strength are also important considerations in masonry, the primary function of concave joints centers around water management. This strategic design feature contributes significantly to the longevity and durability of masonry by minimizing the risk of water infiltration and subsequent damage from moisture.