EVALUATION OF THE LOW TEMPERATURE FRACTURE RESISTANCE OF ASPHALT MIXTURES USING THE SEMI CIRCULAR BEND TEST (WITH DISCUSSION)

Low temperature cracking is the main distress in asphalt pavements built in the northern U.S. and Canada. Currently, there is no standard method to characterize the resistance to cracking of asphalt mixtures. This paper investigates the use of a Semi Circular Bend test as a candidate for a low-temperature cracking specification. A specimen preparation procedure, a test protocol, and methods to calculate the fracture toughness and the fracture energy are proposed. Three similar Superpave mixtures with different asphalt binders (PG 58-40, PG 58-34, and PG 58-28) used in the MnRoad pavement facility were tested at -30 degrees C and -40 degrees C and fracture properties were obtained. A split-plot analysis was performed on the experimental data to determine if these mixtures were statistically different. Based on the fracture energy, the finder type effect was significant. Preliminary results showed that advanced acoustic emission (AE) techniques could be used to study the low temperature cracking mechanism in asphalt mixtures.