Dynamic mechanical properties of composite polyphosphate modified bitumen mixture.

In order to investigate the dynamic mechanical properties of polyphosphoric acid (PPA) and SBS co-modified asphalt mixtures, uniaxial compression dynamic modulus tests were conducted. The influences of temperature and frequency on the dynamic modulus and phase angle were analyzed. Additionally, dynamic modulus and phase angle master curves were constructed based on the modified Havriliak-Negami (HN) model. A comparative analysis was also performed with SBS-modified asphalt mixtures. The results indicate that both types of asphalt mixtures exhibit similar trends in dynamic modulus and phase angle variations with changes in temperature and frequency. The HN model accurately fits the master curves of dynamic modulus and phase angle for both asphalt mixtures. In comparison to SBS-modified asphalt mixtures, the phase angle of PPA+SBS co-modified asphalt mixtures decreases at -10, 20, and 50 °C, while the dynamic modulus decreases at -10 °C, changes minorly at 20 °C, and increases at 50 °C. Over a wide frequency range, PPA+SBS co-modified asphalt mixtures exhibit increased dynamic modulus and decreased phase angle at high temperatures and low frequencies, while they show decreased dynamic modulus and relatively stable phase angle at low temperatures and high frequencies. These findings suggest that PPA+SBS comodification endows asphalt mixtures superior dynamic mechanical properties. [ABSTRACT FROM AUTHOR]