Research Progress and Prospect of Polyphosphoric Acid Modified Asphalt Technology

In order to clarify the current status of polyphosphoric acid (PPA)-modified asphalt technology, to solve its road problems, and to promote its further popularization and application, the research progress of PPA-modified asphalt technology in scientific research and engineering is summarized. Firstly, the chemical modification mechanism of PPA on asphalt is revealed from the components, chemical reaction and microstructure; the engineering application and service situation of PPA-modified asphalt pavements at home and abroad are evaluated; finally, the future research direction of PPA-modified asphalt is envisioned. The PPA-modified asphalt with dosage of 0.5%,1.0%,1.5%,2.0% was studied, and the presence of PPA was almost indistinguishable from that in the fluorescence micrographs of modified asphalt, and the compatibility between PPA and asphalt was excellent. Atomic force microscopy has a higher resolution relative to fluorescence electron microscopy as well as scanning electron microscopy.The results show that PPA can react chemically with asphalt components to increase the asphaltene content, and the incorporation of PPA helps to improve the high temperature performance, aging resistance, and fatigue characteristics of asphalt. At present, there is no supporting application guide for PPA-modified asphalt technology, and the lack of long-term observation of PPA-modified asphalt test sections restricts the popularization and application of PPA-modified asphalt technology in China.