Research of Low-Temperature Performance of Polyphosphoric Acid-Modified Asphalt

Polyphosphoric acid (PPA) modifier, which can effectively improve the rheological properties of asphalt, is widely used in pavement engineering. In order to accurately evaluate the low-temperature performance of PPA-modified asphalt, in this study, PPA-modified asphalt and PPA/SBR-modified asphalt were prepared. The modification mechanism was explored by scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR). Bending Beam Rheology (BBR) test was carried out, and four indexes, including K index, viscous flow (eta(1)), low-temperature integrated flexibility (Jc), and relaxation time (lambda), were obtained by combining the Burgers model. The optimal low-temperature performance evaluation index of modified asphalt was determined by the analytic hierarchy process (AHP). The test results show that PPA addition to asphalt will produce chemical reactions, which can effectively improve the compatibility between SBR and neat asphalt. In the multi-index evaluation based on K, eta(1), Jc, and lambda, the same optimum content of PPA was obtained. AHP analysis further demonstrates that Jc is the optimal evaluation index for laboratory research on the low-temperature performance of PPA-modified asphalt, and lambda index is the ideal evaluation index for the low-temperature performance of asphalt in engineering applications.

Automated summary

In this study, the modification mechanism of polyphosphoric acid (PPA) modified asphalt was explored using scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR). The Bending Beam Rheology (BBR) test was conducted, and four indexes including K index, viscous flow (eta(1)), low-temperature integrated flexibility (Jc), and relaxation time (lambda) were obtained. The optimal low-temperature performance evaluation index of the modified asphalt was determined using the analytic hierarchy process (AHP). The results showed that PPA addition to asphalt improved the compatibility between SBR and neat asphalt by chemical reactions. Based on the multi-index evaluation, Jc was found to be the optimal evaluation index for laboratory research, while lambda was ideal for engineering applications.