Relationship between glass transition temperature and low temperature properties of oil modified binders

• Tg temperature affects Tg temperature of binder significantly.
• Good linear relationship between Tg temperature and stiffness of asphalt.
• Tg temperature affects both rheological and fracture properties of asphalt.

Oils can be used as modifiers to improve low temperature performance of asphalt. However, the relationship between phase transition of oil modified asphalt and their low temperature properties still need more detailed research to reveal the effect of the transition on rheological properties. To investigate this, 9 different oils of bio-base and refined waste oils are used as modifiers in this study. During the study, Modulated Differential Scanning Calorimetry (MDSC) test is used to study the phase transition, and the Bending Beam Rheometer (BBR) test and Single Edge Notched Beam (SENB) test are used to evaluate the rheological and fracture properties of oil modified asphalts, respectively. It is found that the glass transition temperatures of oil modifiers are significantly different but are all much lower than the glass transition temperatures of asphalts. The results show that there is a good linear relationship between glass transition temperature and stiffness of asphalts, but no good correlation with the relaxation parameter (m) measured with the BBR. There is a much stronger correlation of the glass transition temperatures with the fracture properties of asphalts. Considering this strong relationship with the fracture properties, DSC test shows the potential possibility for quickly and accurately evaluating the low temperature fracture performance of asphalts. The combination of BBR and DCS can therefore be used to select the type and amount of oil modifier to meet a specific low temperature performance. The study was limited to one asphalt source and thus validation of the relationships for other asphalts is needed before generalizing the results.