Thermal and cold flow properties of bio-derived rejuvenators and their impact on the properties of rejuvenated asphalt binders

Rejuvenators are widely used to improve the properties of asphalt binders particularly low temperature and fatigue cracking behavior. Rejuvenators vary significantly in terms of their physical properties and chemical composition. The nature of the interaction between the rejuvenators and the base asphalt binders is very complex and an extensive study into the chemical and thermal properties of the rejuvenators and how they impact the rheological properties of rejuvenated binders is of paramount importance. In this research, a neat PG58-28 binder is rejuvenated with three different materials produced from soybean oil at a dosage of 6% by total weight of binder. The rheological properties of the control and rejuvenated binders are assessed using performance grades showing a drop in both the critical low and high temperature grades with rejuvenation. The oxidative stability of the rejuvenators as well as the rejuvenated binders is studied using thermogravimetric analysis (TGA). The crystallization and melting points of the rejuvenators are observed using differential scanning calorimetry (DSC). DSC is also used to examine the glass transition temperatures of the control and rejuvenated binders. The TGA results showed one of the rejuvenators to be susceptible to oxidation which agreed with the rolling thin film oven (RTFO) mass loss results. The glass transition temperature of the rejuvenated binders decreased denoting improved low temperature cracking properties in line with the performance grade results.