Use of GPC Chromatograms to Characterize Aged Asphalt Cements

Selected physical properties of asphalt cement are significantly changed by artificial aging under thin film oven test conditions. The changes in physical properties are also reflected in the molecular size distribution as determined by high‐pressure gel permeation chromatography (GPC). Statistical analyses show that absolute and kinematic viscosity are related to large‐sized and some small‐sized molecules, while penetration is related only to medium‐sized molecules. Dividing GPC chromatograms into 10 slices shows better resolution than using three or six slices in regression analysis. The regression analysis shows significant correlations between the three physical properties and GPC chromatograms. These models establish relationships between various physical properties and the molecular size distribution of asphalt cements. Since these models are developed for three different asphalt cement sources, three different grades for each source, and three different aging conditions, they demonstrate the general applicability of using GPC analysis to characterize asphalt cements, predict their physical properties, and identify the aging of asphalt cements.