Effects of SARA fractions on low temperature properties of asphalt binders

Abstract

Effects of the chemical fraction on the low temperature rheological behaviours of asphalt binders were explored in this study. Four fractions, namely saturate, aromatic, resin and asphaltene (SARA), were obtained from eleven asphalt binders by a novel column chromatography separation method. In addition, the viscoelastic master curves for binders and their subsets were characterised by dynamic shear rheometer (DSR) at high frequencies (low temperatures). The results showed that the complex modulus and phase angle of asphalt binders were closely related to the changes of SARA fractions. Moreover, low temperature properties of asphalt binders characterised by the creep stiffness modulus and m-value were measured using bending beam rheometer (BBR) test. The increases of asphaltene in asphalt binder resulted in the decreases of creep stiffness modulus of asphalt as well as m-value. Further, the glass transition temperature (Tg) of resins, asphaltenes and asphalt binders were measured by differential scanning calorimetry (DSC) test. The results showed that the Tg values of asphalt binders were mainly determined by saturates and aromatics fractions. However, the Tg values of the asphalt binder would increase with the increase of asphaltene content. Finally, significant relationships between SARA fractions and low temperature parameters of asphalt binder specimens were found and conducted using linear regression analysis, indicating that the SARA fractions would perform significant effects on the low temperature properties of asphalt binders.