This thesis presents the conclusions and recommendations of an intensive seven month investigation into joint failures in the concrete pavements of Ontario. It was discovered that a large proportion of the failures resulted from longitudional compressive stresses within the pavement caused by restrained thermal expansion. The stresses can cause spalls, blow-ups and damage to bridges. The recommended repair of these failures is the installation of relief gaps in the pavement to allow for this thermal expansion. The major factors causing the stress conditions are; infiltration of the joints and random transverse cracks and the existence of moisture surrounding the concrete pavement.