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 KIc results determined from the ENDB also lie between the KIc 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 KIc of the ENDB specimen (as the reference sample). Highlights Significant effect of loading type (tensile, compression, and bending) on mode I fracture toughness of disk‐shaped asphaltic mixture. Variations of determined KIc values with the sign and magnitude of T‐stress in the tested disk‐shaped samples. Utilization of maximum normal strain model for predicting the mode I fracture toughness ratios. ENDB specimens can provide a more accurate KIc value compared to the CCBD and DCT samples.