Influence of testing method on mode II fracture toughness (KIIc) of hot mix asphalt mixtures.

Till now, only very limited test results have been reported for mode II fracture toughness (KIIc) of asphalt mixtures. In the absence of any standard testing method for determining KIIc value for these materials, in this research, an experimental program is done to measure and investigate this parameter at low‐temperature using four different test specimens and configurations. The specimens have circular and semi‐circular shapes but with different crack types and loading setup namely: center cracked circular disc (CCCD), inclined cracked semi‐circular bend (ISCB), asymmetric semi‐circular bend (ASCB), and asymmetric edge notch disc bend (AENDB). The test results showed that KIIc depends significantly on the geometry and configuration of test sample such that its value determined from the AENDB sample is about twice the KIIc value of ISCB specimen. Among the investigated samples, the AENDB results can simulate more realistically the actual and field conditions of real cracked overlays subjected to traffic loading. KIIc results are also predicted successfully using two fracture criteria capable of considering the influence of geometry on mode II cracking. [ABSTRACT FROM AUTHOR]