Shakedown of asphalt pavements considering temperature effect

Shakedown limit has been perceived as a useful guidance in pavement structure design against rutting. However, temperature, as one key factor influencing the shakedown limit of asphalt pavements, has barely been considered. In this paper, the shakedown phenomenon was first identified from wheel tracking tests for a pavement structure consisting of a dense bituminous macadam layer and a granular layer at 40°C. Based on a previously developed shakedown approach and the material elastic and plastic properties obtained through a series of tests, lower-bound shakedown limits of the layered system were determined and compared with the wheel tracking test results. Following that, an empirical relation between temperature and cohesion of asphalt mixture was suggested. A temperature-dependent shakedown approach was then proposed which can quickly obtain the shakedown limits of asphalt pavements over a range of temperatures. Results show that the shakedown limits decrease markedly with increasing temperature, accompanied by a shift of the failure mode from a granular layer failure to an asphaltic layer failure. One effective and economic way to enhance the pavement performance under high temperature is improving shear strength properties of asphalt mixtures. By using this method, pavement stability against rutting can be evaluated efficiently at any temperature.