Why should edge courses of paving blocks sit on concrete bedding?

In pavement made up of paving blocks, the edge courses are normally designed to sit on concrete bedding and haunching. The reason of such provision is to prevent lateral movement of paving blocks when subjected to traffic loads. In essence, the edges formed by edge courses tie the body of the paving blocks as a single unit and they have to rely on concrete bedding and haunching to resist the sideway forces generated by moving traffic.

The concrete bed serves to keep the edge courses in position for surface level and it provides the dead loads in the retaining structure. On the other hand, concrete haunching also holds the edge courses in position from the point of view of lateral movement.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.