Feasibility of ultrasonic measurements for characterizing rheological properties of asphalt binders

Ultrasonic measurement (UM) may provide an inexpensive alternative to sophisticated tests currently used to characterize rheological properties of asphalt binders. This research investigates the feasibility of application of high frequency immersion UM to characterize performance grade (PG) asphalt binders. Nine different PG asphalt binders were selected for this investigation. Short term aged, long term aged and un-aged samples were prepared for ultrasonic measurements. For each binder, velocity (V) and integrated response (IR) of the ultrasonic wave were measured at five temperatures. Mechanical test to obtain rheological properties were also performed on the same asphalt binder grades. Variation of ultrasonic measured parameters with temperature was studied. Correlations between the ultrasonic measurements and rheological properties were explored. Results indicated that ultrasonic velocity of the asphalt binders decreases with increase in their temperature. Modified asphalt binders showed lower velocity compared to un-modified ones.