Fracture Tests on Bitumen Films

This paper investigates the adhesive properties of bitumen films. Tensile tests on bitumen butt joints and double cantilever beam specimens, over a wide range of test conditions, are described. The test results are treated using fracture mechanics and strength of materials approaches. It is found that the failure strain of bitumen is generally independent of equivalent strain rate, in both the brittle and ductile regimes, whereas the “normalized toughness,” $G∕2h$ is rate independent in the brittle regime and rate dependent in the ductile regime ( $G=\text{strain}$ energy release rate, $2h=\text{film}$ thickness). The toughness of a typical paving bitumen is quantified, both for brittle fracture and ductile failure, and a mechanism map classifying the failure mechanisms as a function of temperature and strain rate is presented.