Large Amplitude Oscillatory Shear to Quantify Elastic and Viscous Nature of Aged and Unaged Bitumen at Different Temperatures

The temperature-sensitive characteristic of the bitumen plays a critical role in the performance of the bituminous binder. The accumulation of distress over a range of temperature depends on the proportion of elastic and viscous behavior of the binder. This paper attempts to separate the elastic and viscous behavior of binder at different temperatures and aging conditions using large amplitude oscillatory shear (LAOS) testing. A binder of VG30 grade as per Indian standard specification was used for this study. The material was sheared using constant strain amplitude for 10 min using a dynamic shear rheometer. Unaged, short-term aged, and long-term aged VG30 binder were subjected to 1% and 5% strain amplitude and the test was conducted at 5 Hz frequency. The test was conducted at the temperatures of 30°C, 45°C, and 60°C. The stress, strain, and strain rate waveform data were used to separate the elastic and viscous stress. The elastic and viscous stress was further used in studying the elastic/viscous behavior dominance at a specific temperature.