Evaluation of Semicircular Bend Geometric Properties for Asphalt Concrete Testing

Abstract

A semicircular bend [SC(B)] test is widely used to evaluate the low-temperature performance of asphalt concrete. However, it is not clear what the proper thickness of a specimen should be, nor the proper notch configuration. This research is targeted to investigate the influence of thickness and notch configurations on stress intensity factors and the fracture energy of asphalt concrete specimens using AASHTO TP 105. Three levels of specimen thickness and three types of notch configuration were set as two variables. Besides, the representative volume element and plane strain status of the SC(B) were discussed. The test results showed the following: (1) the specimen thickness and test temperature did not statistically impact the stress intensity factor; (2) the specimen thickness was significantly impacting on fracture energy; (3) when interacted with the specimen thickness, the notch configuration and test temperature were statistically significant to the fracture energy; and (4) the SC(B) test in this study exhibited the lowest variance in the test results at the condition of −12°C, a semicircular notch, and a 50-mm specimen thickness. In conclusion, the specimen thickness was recommended to be 50 mm for the nominal maximum aggregate size (NMAS) 12.5-mm specimen.