Tribological and rheological characterisation of asphalt binders at different temperatures

Asphalt binder works as a binding by creating a thin film around the aggregate in asphalt pavement. Binder lubricity reduces the friction between aggregate particles and provides a better wear protection. Better wear protection prevents the degradation of pavement materials that occurs because of the traffic loading. Therefore, both proper compaction and surface interaction between the aggregates and asphalt binder are essential for enhanced long-term performance of the pavement. To explain surface interaction and rheology, the variation in friction coefficient and viscosity of three asphalt binders were tested at three different temperatures (135 degrees C, 50 degrees C and 25 degrees C) that an asphalt pavement is likely to withstand during its service life. While all binders show similar trends and the viscosity and Stribeck curves are similar at 135 degrees C and 50 degrees C, at 25 degrees C asphalt binders behave more like solids at lower sliding speed resulting in a different trend. Results show that rheological tests only provide the flow behaviour, whereas tribological tests provide a better understanding of friction and surface interaction between the aggregates and asphalt binder.