Paper by TRILLET from ISCR 10th 2006 Brussels Belgium
The composite pavement concept can be described as an association of bituminous layers or modular elements with cement concrete. The desired objective is the association of two or more layers of a different nature in such a way that the specific advantages of both types can be profited from thus making it possible to obtain durable, comfortable and attractive roads. The standard motorway cross-section used in Belgium between 1970 and 1981, made up of 20 cm of lean concrete, 6 cm of bituminous mix, and 20 cm of continuously reinforced concrete, was in fact a composite pavement avant la lettre. In 1981, major changes were made to the standard cross-section. Without going into details, we may in particular mention the suppression of the layer of bituminous mix. The role played by this sandwich filling was in fact widely underestimated. All these changes were to give rise to failures near the outer edge of the slow lane, and which were given the name punch outs. These started to appear towards the end of the eighties on various sections of motorway, in particular on the E411 (Brussels Arlon) and the E25 (Liège Neufchâteau). The increase in the incidence of punch outs gave rise to such concern that it was decided to proceed to a major restoration programme spread over a period of 3 years. The chosen solution was to transform the sections concerned into composite pavement by providing either an inlay or an overlay. The article reviews the history of this dossier and discusses all the technical aspects from design to construction and delivery.