Exploration for Cohesion and Adhesion Characteristics of High Viscosity–Modified Asphalt: Impacts of Composition-Associated Factors and Thermal Aging

Abstract

To analyze the impacts of composition-associated factors of high-viscosity asphalt mixtures and thermal aging on the cohesion and adhesion characteristics of high viscosity–modified asphalt (HVMA), neat asphalts (NAs), high-viscosity additives, and aggregates were selected, and several HVMAs were first prepared. Then, the prepared HVMAs were subject to contact angle testing, and their cohesion and adhesion behaviors and influencing factors were explored by multifactor orthogonal testing coupled with the surface free energy (SFE) concept. Further, the variations and influencing factors of cohesion and adhesion properties of relevant HVMAs under aging were analyzed in comparison with styrene-butadiene-styrene (SBS)-modified asphalts (SBSMAs) and NAs. Lastly, under aging, the change behaviors of microscopic phases of HVMAs were contrastively investigated using atomic force microscopy (AFM) testing, and the relationship between the microscopic phases and the cohesion and adhesion properties was illustrated. Results showed that NA type, high-viscosity additive dosage and type, and aggregate type notably influenced the cohesion and adhesion of HVMAs, and the high-viscosity additive dosage influenced their cohesion the most. Aging weakened the cohesion and adhesion of asphalts, and the HVMAs possessed the superior cohesion and adhesion at each aging period. Under aging, the NA type, aggregate type, and aging level remarkably affected the cohesion and adhesion of HVMAs, among which the NA type affected their cohesion most prominently. Besides, the aggregate type was the most influential variable on the adhesion of HVMAs whether the HVMAs were aged or not. AFM testing demonstrated that aging reduced the component of microscopic phase structures of HVMAs and the amount of their bee structures, and diminished the surface roughness Ra of asphalt binders; in contrast, aging did not alter the component of microstructural morphology of SBSMAs and NAs. The cohesion and adhesion indexes of HVMAs under aging obeyed the high Pearson correlation and the moderate linear correlation with the Ra index.