Exploring the reduction of laboratory testing for the cohesive zone model for asphalt concrete

Abstract

The cohesive zone model is a popular tool used to predict cracking in asphalt concrete. However, two of the three inputs required for the cohesive zone model, tensile stress and fracture energy, come from destructive laboratory tests. If the peak load from a fracture test (which supplies fracture energy) could be substituted for the tensile strength, the amount of laboratory testing could be halved. This research compared the peak loads from the single-edge notch beam, semi-circular bend and disk-shaped compact tension fracture tests as well as the tensile strength from the standard indirect tension (IDT) test. Even accounting for specimen geometry, the data did not indicate consistent correlation of the three fracture tests with the IDT test across various testing temperatures, loading rates or sample type (laboratory vs field samples). Therefore, no fracture test provided a sufficiently robust correlation to recommend replacing the tensile strength with the peak load of the fracture test for the cohesive zone model.