COMPOSITIONAL OPTIMIZATION FOR A SUPERIOR ASPHALT BINDER

The aging characteristics of naphthene aromatic (NA) and polar aromati c (PA) fractions of an aromatics material were investigated by studyin g the viscosity and other related properties of aged NA, PA and combin ed NA and PA fractions of five SHRP core asphalts (AAA-I, AAD-1, AAF-1 , AAG-1 and AAM-1). These materials and six supercritical fractions of AAF-1 were aged in air at temperatures of 95 degrees C and 100 degree s C. The aged fractions were characterized in terms of viscosity tempe rature susceptibility (VTS), the tendency to harden due to oxidative a ging CHS), and the asphaltene formation as a result of carbonyl conten t growth (AFS) as well as the viscosity-asphaltene relationship. Low f requency limiting viscosity, carbonyl content, and asphaltene content were measured to obtain these parameters. NA fractions have smaller HS than PA. NA fractions have a bit larger log viscosity increase than t he PA for the same amount of asphaltene addition, but they have smalle r AFS. Furthermore, NA fractions are much less temperature susceptible in viscosity than Pk Aromatics have properties between their NA and P A fractions. An asphalt binder with superior aging characteristics may be produced by oxidizing a certain supercritical fraction to a desire d viscosity level.