Concrete – Pavement Joints 2
Contraction Joints have been previously described in Pavement Joints 1
The second most common form of Joint is the Expansion, or Isolation Joint.
Although concrete does shrink as it cures, in hot weather it will expand.
Unless an allowance is made for the expansion the concrete paving can push foundations. In long runs of concrete it can create a hump in the paving like the photo below.
The following sketch shows a typical Expansion Joint against a building.
Holes are drilled into the concrete and steel ‘dowel bars are grouted in, so they all face the same direction. In order to stop the concrete holding onto the dowel and stopping the expansion the dowel is fitted with a close fitting plastic sleeve both the joint and the end cap are also fitted with a compressible foam.
For more posts on on getting your paths and driveways correct see Concreting