Characterization of the micromorphology of asphalt surfaces using atomic force microscopy

The surface micromorphology (SMM) of asphalt considerably affects its macroperformance. Herein, the SMM of seven types of asphalt was observed using atomic force microscopy. Moreover, the roughness theory was employed to quantitatively analyze and evaluate the surface roughness of the asphalt. The influences of the oil source, grade, styrene–butadiene–styrene (SBS) modification, aging, and water immersion of asphalt on the SMM of five types of matrix asphalt and two types of modified asphalt were elucidated. Results show that the surface roughness of KL-90 asphalt is considerably higher than those of KL-70 and KL-110 asphalts for the same oil sources. The surface roughness of SMM varies with variations in the asphalt oil source, and the surface roughness of ZH-90 asphalt is greater than that of SK-90 asphalt. After SBS modification, the SMM of the asphalt becomes smooth. The surface roughness of the asphalt first gradually increases and then rapidly decreases with aging. After the water immersion of the asphalt, its SMM roughens under the action of “water–asphalt” interfacial tension.