A construction joint with interlocking elements or keys that prevent lateral movement while allowing for expansion and contraction, commonly used in concrete and masonry construction for structural continuity.

A keyed joint is a construction joint with interlocking elements or keys that prevent lateral movement while allowing for expansion and contraction, commonly used in concrete and masonry construction for structural continuity. These joints feature projecting elements (keys) on one side that fit into corresponding recesses on the adjacent side, creating mechanical interlocking that maintains alignment and transfers loads while accommodating movement. Keyed joints are essential for maintaining structural integrity in segmented construction while allowing for thermal and moisture-related dimensional changes.

The primary purposes include preventing lateral displacement between adjacent elements, maintaining structural alignment and continuity, transferring loads across construction joints, accommodating thermal expansion and contraction, controlling crack formation and location, providing mechanical interlock for stability, and ensuring long-term structural performance.

Types and configurations encompass concrete keyed joints, masonry keyed joints, precast keyed joints, and specialty joint designs for different applications.

Fun Fact: The concept of keyed joints dates back to ancient Roman construction, where they used interlocking stone blocks in aqueducts and bridges! Modern keyed joints in concrete can accommodate movements of several inches while maintaining structural integrity. Some of the largest keyed joints are found in dam construction, where they can be several feet deep. Interestingly, the “key” doesn’t always have to be rectangular – trapezoidal and dovetail shapes are often used for better mechanical interlock!

• Butt Joint
• Cold Joint
• Construction Joint