Asphalt binder comprises four main fractions—asphaltenes (A), saturates (S), aromatics (A), and resins (R)—referred to as “SARA”. Asphaltenes plays an important role in determining the linear viscoelastic behavior of asphalt binders. In this research, asphaltenes are added as a distinct modifier to improve the performance properties of asphalt binder. The modified binders are aged using a rolling thin film oven. A dynamic shear rheometer is then used to measure the rheological properties of the binders at high temperatures. Changes in the chemical composition of the modified binders are also studied through the determination of SARA fractions, using precipitation and gravity-driven chromatography methods. The rheological results show that asphaltenes improve the stiffness and elasticity of asphalt binder. It is also shown that the addition of asphaltenes raises the high Performance grade (PG) temperature of the asphalt binder, with every 6% of asphaltenes added resulting in a one-interval increase in high PG temperature grade. SARA analysis shows that the increase in polar fraction content due to the addition of asphaltenes causes the stiffness, elasticity, and viscosity of asphalt binders to increase. The results indicate that asphaltenes are an effective yet inexpensive additive to improve asphalt binder properties at high temperatures.

In this study, high, intermediate, and low-temperature properties of two crude oil asphalts and three different oil sand bitumens from Alberta’s oil sands distilled at distillation temperatures of 400 °C, 430 °C, and 460 °C were evaluated. High and intermediate temperature properties, of the asphalt binders at different distillation temperatures were studied using a dynamic shear rheometer (DSR) through performance grading (PG) test. Low-temperature properties and performance grading were evaluated using a bending beam rheometer (BBR). The DSR high-temperature analysis indicated that oil sand bitumens distilled at high temperatures have significantly higher stiffness and are able to satisfy the Superpave PG binder performance specifications, particularly with respect to rutting resistance. BBR low-temperature resistance shows that, irrespective of the asphalt source, oil sand bitumens distilled at lower temperatures are more resistant to cracking at low temperatures. The overall results indicate that oil sand bitumens are thus suitable to be used for both asphalt pavements requiring low and high-temperature resistance.