Evaluation of the aggressiveness of different multi-axle loads using accelerated pavement tests

Abstract

This paper presents results of a full scale accelerated test performed on the IFSTTAR pavement fatigue carrousel, to study the effect of various multiple axle combinations on bituminous pavements. The tested combinations correspond to the permissible maximum loads in France for the following axle systems: tridem axle (255 kN), tandem axle with dual wheels (210 kN), tandem axle with single wheels (170 kN) and single axle with dual wheels (130 kN). Recently, however, the French road carriers’ federation was authorized to change the vehicle load from 400 kN to 440 kN. The consequences of this increase are also discussed. The test was performed on two thick bituminous pavement sections consisting of a 16-cm granular subbase and a 26-cm thick bituminous layer. Both pavements were instrumented with strain gages, vertical displacement and temperature sensors. The objective of this research is to compare the strain signals and the maximum strain levels obtained for different axle combinations and temperature conditions and then, to compare the results with classical pavement design calculations to assess the relative aggressiveness of the different axle systems. The fatigue life of the two pavements, however, was not studied because, owing to their thickness, too many load cycles would have been required to complete a full fatigue test.