Five asphalts were used in a laboratory testing program to establish a relationship between mixture properties and the binder properties. These five asphalts were used to make Florida Types S-1 asphalt concrete mixes, and Marshall specimens were fabricated from these mixes. The compacted specimens were subjected to different exposure conditions to study the effects of heat, ultraviolet light, air and natural sunlight to the hardening of asphalts. The exposure conditions used include (1) a convection oven at 140 F, (2) a forced-draft oven at 140 F (3) an ultraviolet oven at 140 F, and (4) natural weather on the roof. All the aged Marshall specimens were evaluated by the resilient modulus and indirect tensile tests at 41 and 77 F. Asphalt residues were recovered from the asphalt mixtures, and tests were performed on the recovered asphalt residues and the original asphalts to evaluate the effects of age hardening. Also, core samples and recovered asphalt residues from two paving projects at various ages were evaluated for consistency and infrared spectral characteristics. Analyses of variance and regression analyses were performed on the results to determine the significance of test parameters and to establish relationships. The effects of different artificial aging processes were compared. Relationships between laboratory aging and field aging were established. Infrared spectroscopic techniques were used effectively to identify the aging effects of asphalt binders. The Schweyer rheometer test can be used to directly measure the cracking potential of asphalt mixture at low temperature.