Abstract
Abstract Crack growth in asphalt concretes or bitumen is a major failure mode at low temperature conditions. However, the vast majority of fracture toughness studies for such materials have been mainly performed on asphalt mixtures and the crack growth analysis and fracture behavior of pure and neat bitumen has rarely been studied in the past. Therefore, in this paper low temperature crack growth behavior of bitumen (with penetration grade of 30/40) is investigated experimentally using a new and novel test configuration called inclined notched bend beam (INBB) specimen. In order to investigate the effect of environmental conditions on the cracking response of bitumen, the fracture toughness experiments were performed at two temperatures of −15 and −25 °C and two loading rates of 10 and 50 mm/min. It was shown that the tested 30/40 bitumen behaves as a brittle material for the whole testing conditions and mode I and II mixities ranging from pure mode I to pure mode II. Empirical fracture toughness envelopes were then extracted for the tested bitumen to understand typical fracture resistance values for any desired mode mixity. It was observed that the fracture toughness value decreases by moving from pure mode I to pure mode II demonstrating weaker strength of bitumen against shear type fracture in comparison with the tensile one. The reduction of mode II and mixed mode I/II fracture toughness values relative to the KIc was also predicted successfully by means of a well-known fracture condition.
Published Version
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