Characterising the modifying efficiency of polyphosphoric acid to bitumens with different oil sources

Abstract

ABSTRACT To explore the properties and mechanism of different polyphosphoric acid (PPA)-modified bitumen, this research selected three bitumens with different oil sources and two PPAs with different relative H3PO4 contents (which are 105%, 115%, namely 105 and 115 grade PPA, respectively). A succession of tests and analyses was conducted to explore the performance of the PPA-modified bitumens. The physical performance test results show that PPA improves the high-temperature performance of the bitumens, and it has different modification effects on the three bitumens. When PPA reacted with the bitumen that has a higher content of polar components, the performance variation of the bitumen was higher than the other two kinds of bitumens. Furthermore, the 115-grade PPA seemed to have a better modified efficiency than that of the 105-grade PPA due to the longer molecular chain length. This also leads to the entanglement of molecular chains of PPA-modified bitumen was more significant with the 115-grade PPA. Therefore, the 115-grade PPA-modified bitumen shows a large asphaltene agglomeration in the AFM diagram.