Investigation on rheological performance of sulphur modified bitumen (SMB) binders

In order to enhance the properties of base bitumen so as to improve the performance of bituminous mixture, it has been a common practice to modify the bitumen by adding some modifiers. Sulphur has been reported to be an effective extender for conventional bitumen. This study was attempted to develop a modified binder in the laboratory using VG-30 bitumen with sulphur (S) and study the effects of 'S' on the viscosity, rheological, penetration index and storage stability with effects of short and long term aging. The rheological study includes rutting, fatigue, master curve and Multiple Stress Creep Recovery (MSCR) test using Dynamic Shear Rheometer (DSR). It is observed that the modification of VG-30 with 2% of 'S' by weight at 140 °C temperature for about 60 min, resulted in homogeneous modified bitumen binder. The Superpave rutting parameter (G∗/Sinδ) and MSCR test results showed that, SMB-2S (VG-30 + 2% S) and SMB-3S (VG-30 + 3% S) binder exhibited better rut resistance performance, especially at high temperature. However, SMB-2S showed relatively lower value of Superpave fatigue factor and aging index value than SMB-3S, implying superior performance in fatigue and aging resistance behavior, respectively. Storage stability test results showed that modification with 2% S possessed better compatibility in bitumen matrix. Thus, it can be stated that the SMB-2S showed superior rheological and storage stability properties that can satisfy the requirements for resisting the rutting and fatigue cracking.