Sprayed-Polyurea-Modified Asphalt: Optimal Preparation Parameters, Rheological Properties and Thermal Properties

For promoting modifying application of sprayed polyurea (SPUA) in asphalt pavement materials, the effects of sprayed polyurea materials on high-temperature and fatigue performance of asphalt binders were investigated from different aspects. First, the optimal preparation parameters of sprayed-polyurea-modified asphalt binders (SPMAs) were determined by designing an orthogonal test. Then, the high-temperature and fatigue properties of sprayed-polyurea-modified asphalt binders with different contents were characterized by rheological testing methods, including Brookfield rotary viscosity (RV) test, performance grading (PG) test, multiple stress creep recover (MSCR) test, linear amplitude sweep (LAS) test and time sweeping (TS) test. Finally, the thermal properties of the asphalt binders were analyzed by differential scanning calorimetry (DSC) test. The results showed that the optimum preparation parameters were determined by the extreme difference analysis method and analysis of variance (ANOVA) method, and the shearing time was 40 min, the shearing rate was 6000 rpm and the shearing temperature was 150 °C. Sprayed polyurea positively affected high-temperature performance of asphalt binders and could improve fatigue resistance of asphalt binders. Moreover, the Brookfield rotary viscosity test, multiple stress creep recover test and linear amplitude sweep test had high sensitivity to the performance of sprayed-polyurea-modified asphalt binder, which could help to distinguish the effect of sprayed polyurea dosing on performance of asphalt binders accurately. The differential scanning calorimetry test showed that sprayed polyurea was beneficial to high-temperature stability of asphalt binders, which explains the reason why sprayed-polyurea-modified asphalt binders have excellent high-temperature performance from a microscopic perspective.