Evaluation of UV aging behaviors of polyphosphoric acid (PPA) modified asphalt and its asphalt mixture

Abstract

Effects of Polyphosphoric Acid (PPA) on the ultraviolet (UV) aging properties of asphalt and asphalt mixture were studied. The morphologies of these binders were characterized by Fourier Transform Infrared Spectroscopy (FTIR) spectra and Thermo- Gravimetric (TG) analysis. Then, the effects of PPA on asphalt and its mixture before and after UV aging were investigated in terms of the physical properties and pavement performances. Results showed that the mechanisms of PPA-modified asphalt were physical and chemical reactions; both UV aging and PPA additive could prompt the polycondensation of light components in asphalt. Compared to control samples, the introduction of PPA enhances the asphalt properties and intensifies the asphalt mixture performance. Furthermore, the asphalt performance aging variations (penetration aging index, softening point increment, ductility aging index, and G*/sinδ aging index) decreased significantly due to the introduction of PPA. It was shown that the effects of UV aging on the behaviors of asphalt and asphalt mixture were constrained with the addition of PPA by inhibiting the increase of carbonyl in the oxidation process.