Rheological and low temperature properties of asphalt composites containing rock asphalts

• Mechanical properties of composites with rock asphalts are evaluated and compared.
• A method that does not need extraction of binder from rock asphalt is pursued.
• Rock asphalt increases stiffness but decreases low temperature performance of composites.
• Rock asphalt decelerates the aging rate of composites.

This paper presents the findings from a study conducted to evaluate the potential impact of different types of rock asphalts on performance of asphalt composites. Fine aggregate matrix (FAM) mixtures were prepared by incorporating three different types of rock asphalts – Buton, QC and UM for this study. The methodology used in this study avoided the extraction of asphalt binder from rock asphalt and simplified the process of evaluating the potential impact of rock asphalts on mixture performance. Rheological properties were measured using frequency–temperature sweep tests with a dynamic shear rheometer and creep–relaxation tests with a bending beam rheometer. Tensile strengths of the composites at low temperatures were also measured by applying monotonically increasing deflection. The critical cracking temperatures were computed using a hypothetical cooling rate for the purposes of comparing material durability. Results from this study demonstrated that addition of rock asphalts increases material stiffness and slightly reduces relaxation potential of asphalt composites at low temperatures. A comparison of properties before and after long-term aging also revealed a slightly lower rate of aging for mixtures modified with rock asphalt as compared to the control mix.