Experimental and theoretical framework for illustrating the dependency of fracture toughness with tensile, bending, and compression loading in asphaltic samples

Opening mode fracture behavior of asphalt mixture is studied experimentally and theoretically using three full disk-shaped specimens, namely, edge-notched disk bend (ENDB), disk-shaped compact tension (DCT), and center-cracked Brazilian disk (CCBD). While the ENDB sample is subjected to pure bending, the BD and DCT specimens are loaded by diametral compression and pin loading tension, respectively. The experimental results showed the noticeable role of loading type on the cracking resistance of asphaltic mixtures such that the specimen loaded in diametral compression showed significantly smaller fracture toughness than the DCT specimen (that is loaded under tension). The K-Ic results determined from the ENDB also lie between the K-Ic of DCT and CCBD testing methods. The discrepancies observed between the experimental results of the three specimen types were related to different signs and magnitudes of T-stress in these test samples. Accordingly, by taking into account the effect of such stress term via employing modified maximum normal strain theory, the mode I test data were predicted theoretically. Finally, the test data obtained from the CCBD and DCT samples were estimated in terms of the K-Ic of the ENDB specimen (as the reference sample).

Automated summary

The opening mode fracture behavior of asphalt mixture was investigated experimentally and theoretically using three different types of disk-shaped specimens. The results showed that the loading type significantly affected the cracking resistance, with specimens loaded in diametral compression exhibiting lower fracture toughness than those loaded under tension. By considering the effect of stress term and employing modified maximum normal strain theory, the mode I test data were theoretically predicted.