Permanent Deformations of WMAs related to the Bituminous Binder Temperature Susceptibility

The purpose of this study is to evaluate the growth of permanent deformations in Warm Mix Asphalts related to their binder temperature susceptibility. Rutting builds up in the pavement under the repeated loading generated by the traffic along the wheels path. The distress develops in two different ways, the pre-consolidation rutting, deformation at variable volume, and the instability rutting, deformation at constant volume. These phenomena are directly related to the loading time, the shape of aggregates, the content of air voids, the type of binder and its temperature susceptibility. This study focuses on the binder contribution to rutting when subjected to high temperature variation. An accurate laboratory investigation was completed to assess how this material property influences the different propagation of permanent deformations. The EN 12697 - 22 Wheel Tracking test was performed at three different temperatures (40 - 50 - 60°C) on two gap graded asphalt mixtures. In order to evaluate how, at these temperatures, the properties of the bitumen act on the asphalt concrete tendency to exhibit permanent deformations, a series of DSR rheological tests were also conducted.