Permanent deformation behaviour of pavements with lightly cementitious layers

The permanent deformation characteristics of pavements with lightly cementitious base and subbase layers were studied under accelerated testing. The testing was done with the Heavy Vehicle Simulator (HVS) of the Transvaal Provincial Administration (TPA) on two pavements north of Pretoria. These pavements included a relatively deep and a relatively shallow pavement structure and it was found that those pavements could carry more traffic than was originally anticipated. The rate of permanent deformation on both types of pavements was linear, but changed to similar behaviour as that of granular materials after extensive trafficking. The dominant failure modes of the deeper pavement was compression (crushing) failure in the upper 50 mm to 75 mm of the cementitious bass layer, whilst that of the shallower pavement was typical fatigue failure followed by similar compression failure to that of the deeper pavement. Relative damage was also investigated and relatively low values for the relative damage exponent were obtained.