Viscoelastic-based approach to evaluate low temperature performance of asphalt binders

Through the strategic highway research program (SHRP) project, time-temperature superposition (TTS) was used to reduce the loading time of bending beam rheometer (BBR) test. Based on TTS, stiffness of the asphalt binder after a two-hour loading time is similar to that after 60 s at 10 °C above. This study attempted to evaluate the TTS validity using finite element (FE) method by developing master curves in a broad range of low temperatures. The results indicated that TTS was neither valid for modified asphalt binders nor for neat binder. Also, in addition to the loading time dependency of m-value, limiting values of stiffness and m-value find no rheological acceptance. As a remedy, thermally induced stress (TIS) due to cooling of asphalt binder was obtained from finite element method and employed to meet rheological needs. TIS indicates similar consequences with existing field data and previous studies related to gradation of different modified asphalt binders with almost similar content of modifiers.