Induced Joint

Summary

Induced Joint - In a concrete floor slab, an induced joint is created to control the location of the formation of shrinkage cracks.

Technical Information

An induced joint is created by weakening lines of the concrete slab to ensure cracking occurs in a controlled manner. This prevents random cracking happening throughout the rest of the slab. The design of these joints is important to ensure the panels are spaced appropriately so further cracks won’t then form in the middle of the panel.

Most induced joints act as restrained joints and have a continuous span of fabric reinforcement across the joint. If designed to be a free-movement joint, dowels are cast perpendicular to where the intended crack will be induced, however, this is rarely seen in an industrial floor.

Most load transfer across an induced joint is provided by aggregate interlock and the reinforcement which crosses the joint. If the induced joint becomes a dominant joint, it may open wide enough so that the aggregate no longer interlocks and load transfer is only provided by the reinforcement.