Correlation between Bitumen Polarity and Rheology

In this study, 26 bitumens covering a large variety in crude origin and processing conditions were evaluated, using rheological tests methods and the recently developed bitumen solubility model (BISOM) titrations. In BISOM, bitumen is characterised by its solubility in three different solvents, relating respectively to Van der Waals, polar and hydrogen bonding interactions. Since both BISOM and rheology produce a large number of data, and since it is not possible to change one parameter at a time, to investigate its influence, a statistical program SIMCA was used. In conclusion, it was found that stiffness versus temperature is, for unmodified bitumen, completely determined by the conventional test methods (penetration, R&B, viscosity) as was already stated by Heukelom. However, the shape of the phase angle with temperature or the elastic behaviour at a given stiffness shows a good relation with the parameters determining the hydrogen bonding potential and the polar interactions. The more hydroge...