Side drainage and sub-soil drainage layer operation and performance

A very favourable result emerges from the assessment of the soundness of structural arrangements adopted and developed over the past ten years (3rd International Conference at Purdue, April (985). After briefly reviewing this positive achievement resulting from closely concerted action of road managers, practical engineers and researchers, the authors more particularly deal with this theme in connection with concrete pavements constructed with thick slabs. The first pavement construction projects of this kind (1977/1978) can now be viewed in their proper perspective. More recent projects embody innovative features (geotextile draining layer), which are compared with other designs. The various observations of the mechanical functioning behaviour of the pavements are also reported. These show how improvement of the drainage at the interface of the concrete and its supporting course can affect the future maintenance of the condition and proprer functioning of sub-bases and subgrades. Besides, the effects of frost cannot be envisaged without linking them to the presence of water or to the moisture condition of the materials. It should be possible to link the non-erodability characteristics of materials tg their non-susceptibility to the effects of frost.