Full Scale Tests on Grid Reinforced Flexible Pavements on the French Fatigue Carrousel

Grids are increasingly used. They have proved their efficiency, but there is presently no widely accepted design method to predict the long term life of grid reinforced pavements. This paper describes a full scale experiment carried out on the large pavement fatigue carrousel of IFSTTAR, to test simultaneously 3 pavement sections with different types of grids, in comparison with an unreinforced pavement structure. The tests are carried out on typical French low traffic pavement structures. Results up to approximately 800 000 loads are presented. The experiment is planed to continue to load the test sections up to at least 1 million loads. During the experiment, the behaviour of the pavement sections has been followed by deflection and rut depth measurements, and surface distress analysis (observation of cracks and other degradations). As observed on the circular APT for low traffic pavements with thin bituminous layers, crack development was following a transversal orientation. This experiment shows the necessity to better understand the grid behaviour by means of modelling, experiments and use of new measurement techniques as planned in the new Rilem TC-SIB and TC-MCD.