Investigation of the Performance Properties of Asphalt Binder and Asphalt Mixture Modified by Polyphosphoric Acid

Changing the rheological and mechanical behavior of pure bitumen is one of the most important reasons of usage of bitumen modifiers. Polyphosphoric acid is newer additive compared to other additives used in the road construction industry. This additive is used to improve the performance behavior of bitumen and improve bitumen rheological properties such as rutting. In this article, the effect of polyphosphoric acid on performance behavior of bitumen and asphalt mixtures with similar mechanical and chemical properties, but with different chemical compositions, is discussed. Various experiments have been conducted in the field of bitumen and asphalt mixture modification with polyphosphoric acid polymer. The results showed that the addition of PPA can improve the high temperature performance and reduce the temperature sensitivity of the modified bitumen, but it has a slight effect on the low temperature performance. According to the results, bitumens modified with polyphosphoric acid have better fatigue resistance compared to bitumens modified with SBS. Modifying bitumen with PPA leads to an increase in softness, a decrease in permeability, and a decrease in temperature sensitivity. The combination of PPA/SBR has the best rutting resistance in the asphalt mixture due to the highest strength and the smallest rut depth.