Accessories | Expansion and Control Joints
Control joints are typically used in concrete masonry to reduce the occurrence of shrinkage-related cracking. It is a continuous vertical joint filled with mortar, but with a bond breaker on one side so that tensile stress cannot develop across the joint. If control joints are not provided, a concrete masonry wall may crack as it shrinks over time.
Where control joints are provided in such a wall, they widen as the concrete masonry shrinks, preventing it from cracking. Control joints should be provided at regular intervals along the wall's length and near corners returns and changes in the wall's height, support or stiffness. Control joints will not relieve masonry expansion. Although concrete masonry expands during warm weather, it generally expands less than it shrinks. Control joints are often constructed to transfer lateral loads across the joint. Like control joints, expansion joints should be provided near corners in the masonry, near returns or changes in the planes of the masonry wall, at an y significant changes in the wall's height or stiffness, at changed in foundations and at regular intervals along the wall. It is also important to note that wire reinforcement should never cross the control joint.
Examples of Control Joints
Control Joint Specifications