Rheological Characteristics of Polyphosphoric Acid-Modified Asphalt Mastic

In this study, a dynamic shear rheometer (DSR) and bending beam rheometer (BBR) were employed to characterize the rheological properties of asphalt modified with polyphosphoric acid (PPA) and containing different mineral fillers, forming a material referred to as asphalt mastic. Pulverized limestone filler (PLF), portland cement (PC), and hydrated lime (HL) were selected as mineral fillers. Filler-to-binder (F/A) ratios of 0.6, 0.9, 1.2, and 1.5 were chosen, which are defined as the weight ratio of filler and asphalt binder. The effects of F/A ratio and filler type on the complex shear modulus, phase angle, rutting parameter, fatigue parameter, m-value, and creep stiffness of various PPA-modified asphalt mastics were studied. Regression functions were built to express the relations between rutting parameter, fatigue parameter, creep stiffness, and F/A. The results indicated that the F/A significantly affected the stiffness of the modified asphalt mastic regardless of testing temperature, but had little effect on m-value at low temperatures. The modified asphalt mastics with different fillers showed different stiffness values but almost the same phase angle at the identical testing temperature