France Fifteen Years Review on the Behaviour of Composites Pavements Concrete on Asphalt Mix

On the initiative of concrete road professionals on the one hand – the French cement industry represented by its trade association CIMBETON and concrete pavement construction companies represented by the trade association SPECBEA – and the French road administration represented by SÉTRA on the other hand, a new concrete pavement structure was developed in France around 1995. This new structure is composed of Continuously Reinforced Concrete Pavement (CRCP) placed, not conventionally on a lean concrete subbase, but on a subbase made of asphalt material, more precisely on improved asphalt bound material. The purpose is to take advantage of the bonding, even temporary, of the two layers to have the subbase play a true part in the design of the pavement. The objective is to achieve a structure with long lasting of life at a lower cost, by reducing thicknesses. Based on this concept, two experimental projects were carried out on the national road network. The first project was accomplished in 1998, a 3 km pavement on the RN141, near Angoulême in Charente (south-west of France). The second project, a 2x3 km pavement, was carried out in 2001 on the RN4, between Nancy and Strasbourg in Moselle (north-east of France) where the climate is more rigourous and more continental. In order to accelerate reports on structural behaviour, “fuse” reference sections were built, specifically with 10 cm of CRCP on 8 cm of class 3 asphalt-bound material. To this day, these test sections, which have been carrying very heavy traffic (approx. 2000 heavy goods vehicles/day and per direction) for 15 years, have exceeded the theoretical service life for which they were calculated. The last series of tests were carried out during the summer of 2013. The present article provides a review of these tests, showing promising results that exceed designers’ expectations for this structure and validate the design hypotheses considered.