Morphological and rheological property analysis of polyphosphoric acid modified asphalt

To get macro and micro-properties of polyphosphoric acid (PPA) modified asphalt, pure asphalt, 4 wt% styrene-butadiene-styrene blockcopolymer (SBS) modified asphalt and 2 wt% PPA modified asphalt were test by AFM and DSR based on morphology and rheology. The topography images and phase images of three types of asphalt were obtained from AFM, in which the size of "bee-like" structrue of PPA modified asphalt is a bit larger than that of pure asphalt asphalt and SBS modified asphalt, moreover, the whole image brightness of PPA modified asphalt is higher than that of pure asphalt and SBS modified asphalt. The PPA modified asphalt shows a stiffer and more uniform surface according to surface bearing index (S_bi) and the density of summits(S_ds) analysis. The complex shear modulus(G^*), phase angle(δ) and rutting factor(G^*/sin δ) of three types of asphalt gotten from DSR indicate that PPA modified asphalt is better to resist the transformation from high temperature than the other two types of asphalt.