Plate dowels are now available in a range of sizes and shapes. Different shapes are available for both the steel dowel plates, and the plastic sheaths which encase the dowels. The sheaths allow for the movement of the concrete relative to the dowel plates.
Much of the concrete movement will be perpendicular to the line of the joint as the joint opens. However, some relative movement between the bays of concrete on each side of the joint will also occur along the line of the joint. It is vital that the dowels allow for this relative movement. If the dowels do not allow for this movement, then unnecessary stresses will develop in the slab, and these may contribute to cracking.
With the range of floor construction techniques available, the selection of the dowels must suit the design of the floor, and adequately allow for slab movement, while still retaining adequate load capacity.