The rheological properties of asphalt are important in the characteristics of pavement used for long periods. The rheological properties of asphalt might be affected by repeat traffic loading or environmental factors such as ambient temperature, air, or UV radiation. This study investigated the effects of traffic and environmental factors on the aging of the asphalt and established an aging index based on the rheological properties of asphalt. Stiffness of asphalt was calculated with a nomograph and measured using a dynamic shear rheometer (DSR). The findings showed a very high correlation between stiffness calculated by nomograph and complex modulus measured by DSR regardless of the loading time and measurement temperature, as well as a very high correlation between complex modulus and loss modulus regardless of loading time, temperature, type of binder, field sample and accelerated aging sample. The relationship between damaged asphalt pavement and the rheological properties of asphalt is discussed.