Trr No. 1323 Materials And Construction, pp. 1-9
Rheological parameters, Corbertt analysis, colloidal instability, and molecular size distribution (MSD) were applied to invesigate relationships between several physicochemical parameters. Emphasis is on the correlation between MSD and viscosity ratio at 60 C, viscosity at 135 C, viscosity at 60 C (after and before thin film oven test), penetration at 25 C, viscosity-temperature number (PVN) at 60 C and 135 C, colloidal instability (I ), 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 135 C, PVN at 135 C, VTS, I , 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 , and a low asphaltene content are all favored by high large molecular size (LMS0, low medium molecular size (MMS), and low small molecular size percentages. Asphalts with high LMS/MMs ratios demonstrated common parameters.