Nanosized morphology and mechanical properties of recovered binders from weathered asphalt mixtures

Aging of asphalt binders can be more accurately simulated in the laboratory by an accelerated weathering machine (AWM) considering most of the weathering factors, and the nanosized properties of the aged binders can be examined at the nanoscale level by Atomic Force Microscopy (AFM). In this study, two gradations of asphalt mixtures, i.e., stone matrix mixture (SMA) and asphalt concrete (AC), were at first weathered by the AWM, and then asphalt binders were recovered. AFM technologies were applied for measuring the nanomorphology and nanomechanical properties of the recovered binders. The results are the following: (1) the roughness of morphology of recovered binders was gradually reduced, indicating a flattening asphalt surface phenomenon as the weathering time increased; (2) the average roughnesses of both adhesion and nanomodulus of the recovered binders increased as the weathering time increased because of the increased polymerization and the macromolecule; (3) there were fairly good linear correlations between the nanomorphology and the nanomechanical properties of the aged binders.