Effect of Thermal Cycling on the Creep-Recovery Behaviour of Road Bitumen

AbstractPavement performance and the viscoelastic behaviour of bitumen, transmitted to the asphalt wearing course, depend mainly on the qualities behind the binder and its thermal history on the site. The current climate changes generate exceptional variations in temperature. Changes in the climatic environment, such as sudden changes in temperature, the surface layers exhibit a severe cyclical freeze/thaw in winter or in cold region. During the summer or in hot region the phenomenon of heating/cooling causes hardening of the binder and therefore the pavement. The regional thermal factor and his instability, in the same day, have a significant role in the evolution of viscoelastic properties of the binder on site and remain the main causes of pavement deteriorations. Two types of thermal cycles were simulated in the laboratory on samples of asphalt of the same origin, followed by a creep-recovery characterization using the DSR. An analogue model of three elements has been proposed to simulate the rheological behaviour of binders. We recorded significant differences in rheological response, such as the evolution of viscoelastic properties and deformability, according to the type of thermal cycle and the applied number. These differences are found between the original sample and all samples that have undergone thermal cycling on the one hand, and between the two types of heat treatment of the other. The behaviour of the asphalt binder, after certain number of thermal cycle (operating period) depends on the nature and characteristics of climate in the region and the exposure time of the binder to thermal cycles. The geo-climatic factor and its changes have become essential parameters in the prediction of pavement behaviour on site and estimation of their life