Fatigue characteristics of sulphur modified asphalt mixtures

Abstract

The use of solid sulphur pellets has been shown to successfully extend and modify bitumen in an asphalt mixture with the subsequently modified asphalt mixture showing improved performance properties in terms of enhanced stiffness and increased resistance to permanent deformation. However, with the increase in stiffness comes the possible reduction in the fatigue and fracture properties of the sulphur modified asphalt mixture. Due to these concerns, the fatigue properties of sulphur modified asphalt mixtures have been investigated using both diametral, indirect tensile fatigue tests (ITFT) and two-point bending fatigue tests (2PB) under both controlled stress (load) and controlled strain (deformation) conditions. The fatigue tests have been undertaken at a temperature of 10°C and have used a range of fatigue failure definitions to quantify the laboratory fatigue cycles to failure. The fatigue results of the sulphur modified asphalt mixtures have been compared with a standard dense bitumen macadam (DBM) control mixture made using the same gradation and the same 40/60 penetration grade base binder. The fatigue comparisons were performed using the traditional strain criterion as well as a stress criterion. It can be seen from the results, that despite the significant stiffness gain, the fatigue properties of the sulphur modified asphalt mixtures compare well with the fatigue properties of the control mixtures. However, results were found to depend also on the testing configuration. © RILEM 2012.