Effect of Factors Affecting Fracture Energy of Asphalt Concrete at Low Temperature

Low temperature cracking is considered one of the primary distress modes of asphalt pavements built in northern climates. The detrimental effects of low-temperature cracking of asphalt pavements have motivated new work in fracture testing of hot-mix asphalt (HMA). A comprehensive study was conducted to investigate the effect of various factors on the fracture resistance of asphalt mixtures at low temperatures. The Semi-Circular Bending (SCB) and Disc-Shaped Compact Tension Test (DCT) fracture tests were performed at three low temperatures to measure the fracture energy for 28 asphalt mixtures, which represent a combination of factors including binder type, binder modifier, aggregate type, asphalt content and air voids. In this study, the analysis from the experimental data indicates that fracture energy is strong v dependent upon temperature and significantly affected by type of aggregate and binder modifier. The results of the analysis show the significance of air voids in the SCB test, but no statistical difference was found for the DCT test data. The analysis also illustrates that richer mixtures, ones with more asphalt than the design optimum, are not necessarily more crack resistant.