The interface joint between concrete and asphalt often opens, allowing water ingress. This water ingress can lead to a rapid breakup of the surface over this joint as traffic pounds this water repeatedly into the open crevices. 

Coupled with the damaging effects of freeze/thaw the concrete/blacktop interface joint soon becomes a maintenance issue. 

The reason that this joint is an issue is because of the differences in thermal expansion and contraction between concrete and asphalt. The different thermal movement profiles of the two surfaces result in a top joint which is unable to handle the movement and the result is a joint which degrades and opens further. 

The solution is to install a rebated Jointmaster repair which spans the joint. The Jointmaster material has excellent adhesion properties to both blacktop and concrete, so it remains bonded and watertight. In addition, the material’s flexible properties mean that the differences in thermal expansion can be accommodated without any subsequent failures. 

A typical repair dimension for this situation would be 200mm wide and 40mm deep.