What is a plate dowel?
A plate dowel is a flat, plate-shaped steel dowel placed in the joint between two concrete floor bays. It transfers vertical load from one slab to the other so the edges cannot step relative to each other, while still letting the slabs themselves move.
The classic solution is a round, smooth, debonded dowel bar. That only permits movement along the axis of the bar. In large floor bays — industrial floors, distribution warehouses — the concrete shrinks in two directions at once. A round dowel then locks up in the direction parallel to the joint and causes exactly the cracking it was meant to prevent.
How the plate dowel solves it
The plate dowel is rectangular, square or diamond shaped (the well-known “diamond dowel”) and sits in a plastic sleeve or pocket cast into one side of the joint. Because the sleeve is wider than the dowel, the slab can move both perpendicular to and parallel to the joint. Load transfer perpendicular to the floor plane is retained.
An added benefit: a plate shape puts plenty of material right at the joint, where bearing and shear stresses peak, and little material further away where it is not needed. That makes it material efficient.
Points for installation
- Alignment. Plate dowels are more forgiving of misalignment than round bars, but the sleeve must still sit square to the joint and at mid-depth.
- Height. At the neutral axis — halfway through the slab thickness. Set too high or too low, the dowel will split the concrete.
- Centres. Follow from the calculation; they depend on slab thickness, wheel loads and expected joint opening. This is not a decision for the site.
- Fixed on one side only. The sleeve or sliding face must stay clean; concrete or debris in the sleeve will block the movement after all.
Plate dowels are used in contraction joints, construction joints and movement joints of ground-bearing slabs and concrete pavements. For structural connections in building walls and floors, heavier shear dowels or approved dowel systems are normally specified.
Related terms
- Dowel
- Shear dowel
- Movement joint
- Concrete shrinkage
- Concrete floor
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