Generalized Fractional Viscoelastic Modeling of Low Temperature Characteristics of Asphalt Binders Modified with Polyphosphoric Acid and Distillate Aromatic Extracts Oil

Abstract

In this paper, the combined effect of adding polyphosphoric acid (PPA) and distillate aromatic extracts (DAE) oil on rheological and mechanical characteristics of neat asphalt binder at high and low temperature is investigated. PPA was added to neat asphalt binder with three different contents of .5, 1, and 2% by weight of asphalt, and DAE was added to neat and PPA-modified asphalt binders to the extent of 1%. In total, one neat and seven modified asphalt samples were investigated in this research by implementing dynamic shear rheometer and bending beam rheometer for evaluating high and low temperature respectively. Using superpave protocol criteria, high and low service temperature of all specimens are determined. In addition, an extension of the simple fractional viscoelastic model is developed as a generalized fractional viscoelastic model to determine and describe low temperature parameters of all samples including damping ratio and dissipated energy ratio. Results show that using 1% of PPA in conjunction with 1% of DAE can balance high and low temperature appropriately to obtain a modified asphalt binder of PG7-28 from a neat asphalt binder of PG64-22. Also, implementing the generalized fractional viscoelastic model successfully resolved shortcomings of simple fractional element, especially for capturing variation of damping ratio and phase angle versus frequency.