When evaluating asphalt mixtures for low temperature performance, currentstandards are based heavily on asphalt binder properties. This approach does not take into account interaction between the binder and aggregate, both chemically and physically. This interaction has been shown to have significant influence to the cracking resistance of asphalt mixtures. This paper investigates three laboratory tests that evaluate cracking resistance of asphalt mixtures at low temperatures. The first test is the traditional tensile strength test, the Indirect Tensile Test (IDT). The two other tests are fracture tests: Semi-Circular Bending (SCB) and Disk-Shaped Compact Tension [DC(T)]. Field cores were obtained from ten pavement sections in Minnesota and Illinois for testing in the lab. Results from the three laboratory tests were compared and correlated with field performance data.Results showed that the tensile strength from the IDT did not vary significantly for the ten mixtures. The SCB and DC(T) correlated relatively well to each other depending on the test temperature. The SCB showed the best correlation and highest Spearman's rank correlation coefficient when comparing to the observed quantity of cracking in the field. It was concluded that the laboratory fracture tests, either SCB or DC(T), are better suited for qualitative cracking performance predictions at low temperatures compared to the IDT. For quantitative predictions, it is recommended to apply advanced analytical and/or numerical models that take into account material properties, environmental conditions, and loading conditions. It is also recommended that additional studies comparing laboratory fracture parameters with the field performance should be conducted.
Abstract