The effect of PPA on performances and structures of high-viscosity modified asphalt

polyphosphoric acid (ppa) was used to improve the physical and rheological properties of high-viscosity modified (hvm) asphalt and decrease the styrene–butadiene–styrene (sbs) content. the sample preparation technique was optimized further by blending furfural extract oil and asphalt in advance. with the optimized preparation process, the major physical and rheological properties of hvm asphalt were improved further by adding the same amount of ppa comparing with other preparation processes; however, the motive viscosity, toughness and tenacity of hvm asphalt still depended on the sbs content. various rheological tests were adopted to investigate the effect of ppa on the rheological behaviours of hvm asphalt before and after ageing. the suitable gelation accused by ppa not only improved the high-temperature rheological performances of hvm asphalt, but increased the low-temperature rheological performances. morphology observation by using optical microscope showed the effect of vulcanization and ageing on the outline and distribution of sbs in hvm asphalt. fourier transform infrared analysis indicated the difference of sbs content under different modifications. thermal analysis displayed the effect of ppa on the thermodynamic behaviours of hvm asphalt and demonstrated the declined ageing susceptibility of hvm asphalt after ppa modification.