Study on the Rheological Properties and Mechanism of Polyphosphoric Acid Modified Asphalt LIU Hongying, ZHANG Zhenxing, CHANG Rui, HAO Peiwen

Abstract:

Through dynamic shear rheological (DSR), repeated creep and recovery teat(RCRT) and bending beam rheological(BBR) test, the rheological behavior of polyphosphoric acid (PPA)modified asphalt, polymer modified asphalt and polymer mixed PPA modified asphalt at different temperature were comprehensively studied. The results show that the PPA additive can improve performances of matrix asphalt and polymer modified asphalt at the high and low temperature. The modification mechanism had more different performance between PPA and SBS modified asphalt at high temperature, and PPA using can significantly increase the viscosity of asphalt, and PPA has less influence on the elastic deformation recovery ability of asphalt, but SBS can greatly improve the elastic recovery of asphalt. The modification mechanism of PPA modified asphalt was analyzed by nuclear magnetic resonance (NMR) test, and the results show grafting, phosphating and cyclization reactions are happened between asphalt and PPA, which changes the carbon chain structure and chemical structure of asphalt, and asphalt become more viscosity.

Key words:road engineering; poly phosphoric acid; modified asphalt; rheological properties; modified mechanism