Evaluating the low-temperature creep properties of polyphosphoric acid-polymer composite-modified asphalt.

The objective of this study was to explore the effect of polyphosphoric acid (PPA) on the low-temperature creep properties of styrene–butadiene-styrene (SBS) and crumb rubber (CR)-modified asphalt binder. PPA-SBS and PPA-CR composite-modified asphalt with different PPA contents were prepared by a high-speed shear method. The low-temperature properties of composite-modified asphalt were studied by bending beam rheometer (BBR) test, and the test results were fitted by the Burgers model to assess the creep property of the asphalt. From the test results, it is demonstrated that the low-temperature properties of polymer-modified asphalt were weakened after PPA was added. At low temperatures, the stiffness modulus (S) of PPA-CR composite-modified asphalt was half that of PPA-SBS, and the creep rate (m) was more than 9.4% higher. The results of relaxation time ($\lambda$ λ), dissipated energy ratio (DER), and the derivative of creep compliance (J'(t)) showed that the creep property of PPA-CR composite-modified asphalt is better than that of PPA-SBS and SBS-modified asphalt at low temperatures. Moreover, the antiaging ability of polymer-modified asphalt was also ameliorated by incorporating PPA, regardless of SBS or CR. [ABSTRACT FROM AUTHOR]