Rheological properties of polyphosphoric acid modified asphalt binder

The rheological properties of polyphosphoric acid (PPA) modified asphalt binder are investigated by the dynamic shear test. The composition change of modified asphalt is used to analyze the improvement mechanism of rheological characteristics. Test results indicate that the fractions of saturate and aromatic are decreased, while the fractions of resin and asphaltene are increased. The complex shear modulus of PPA modified asphalt binder decreases at lower temperatures, while the phase angle increases. At higher temperatures, the complex shear modulus of asphalt binder with PPA modifier increases while the phase angle decreases. The high temperature grade of PPA modified asphalt binder could be increased 1 similar to 2 levels when the content of PPA is up to 1.0 similar to 1.5%, which implied that the rutting resistance of PPA modified asphalt binder has improved significantly.