ABSTRACT
The mechanical response of a bituminous material to the application of an external load is, in part, viscous. That is to say, an element of the deformation induced by the application of the load is time dependent and irrecoverable. Under repeated applications of load, the permanent deformation continues to accumulate. The consequence of this , in the case of bituminous paving mixtures subject to vehicular traffic, is that ruts develop in the wheelpaths. If severe, these ruts have a major effect on the serviceability of the pavement and maintenance is then required to restore the profile.
