INTERRELATIONSHIP BETWEEN PERFORMANCE-RELATED PROPERTIES OF ASPHALT CEMENT AND THEIR CORRELATION WITH MOLECULAR SIZE DISTRIBUTION

Abstract

Rheological parameters, Corbett analysis, colloidal instability, and molecular size distribution (MSD) were applied to investigate relationships between several physicochemical parameters. Emphasis is on the correlation between MSD and viscosity at 60 deg C, viscosity at 135 deg C, viscosity ratio at 60 deg C (after and before thin film oven test), penetration at 25 deg C, viscosity-temperature susceptibility (VTS), penetration-viscosity number (PVN) at 60 deg C and 135 deg C, colloidal instability (I sub c), and asphaltene content. The MSD was obtained using a semipreparative column and a gravimetric finish. The 20 virgin asphalts studied cover a wide viscosity range and were supplied over 7 years by 14 refineries. Virgin asphalts were laboratory-aged; field cores for seven were extracted. For virgin asphalts, viscosity at 60 deg C correlates strongly with each of viscosity at 135 deg C and penetration at 25 deg C. The MSD showed a strong correlation with viscosity at 135 deg C, PVN at 135 deg C, VTS, I sub c, and asphaltene content, and a weak correlation with viscosity ratio. The direction (sign) of association demonstrates that a high PVN and a low VTS (i.e., low temperature susceptibility), a low viscosity ratio (i.e., high resistance to aging), a low I sub c, and a low asphaltene content are all favored by high large molecular size (LMS), low medium molecular size (MMS), and low small molecular size percentages. Asphalts with high LMS/MMS ratios demonstrated common parameters.