The purpose of this paper is to look at some aspects of the effect of asphalt chemical composition on the properties and behavior of some fresh asphalt binders, as well as of plant-aged and field-aged samples, and the manner in which long-term aging may be affected by changes in material composition. The asphaltic binders involved are of the straight-run and propane-precipitated asphalt blend types, all of the 60/70 penetration grade. At this stage, data accumulated reflect construction conditions and the beginning of the service life of the test sections. No pavement distress has been reported so far that would warrant linkage to the type and characteristics of the asphalt binder used. However, definite relationships were found among the chemical composition of the asphalt and its physicorheological changes during short-and long-term aging. These relationships were also significant enough to distinguish among the behavior of straight-run asphalts and PPA asphalt blends. As more data become available with time, it is hoped that a more definite relationship can be established among the physicochemical properties of the asphalt and their effect on material behavior and longer-term pavement performance.