ABSTRACT
All pavement design procedures rely on subgrade soil tests, and the design determined as a consequence of the testing is only valid if (a) the foundation and pavement conditions assumed on the basis of these measurements are similar to those that actually pertain after construction and (b) they remain substantially unchanged during the design life of the road. Thus, for example, if the subgrade moisture content becomes much higher than that used in the design following, say, continuous rainfall over a poorly-drained road section, the result may well be a softening of the subgrade — which, in turn, will be reflected in pavement distress, e.g. surface cracking and the development of rutting and pot holes in the outer parts of the pavement and, especially, in the wheelpaths of heavy commercial vehicles.
