Multi scale investigation on the failure mechanism of adhesion between asphalt and aggregate caused by aging

Abstract The micro- and nano-surface properties of asphalt obviously affect the macro-bonding of asphalt and with aggregates, which is influenced by aging. In this study, the surface morphology and force curves of two asphalts for different degrees of aging (matrix asphalt and SBS modified asphalt) and macro-bonding with the mineral aggregate were measured. Moreover, the micro-nano surface morphology and surface energy were quantitatively evaluated. Furthermore, the micro-nano surface properties of asphalt and the macro-bonding were correlated. Then the evolution mechanisms of asphalt adhesion with aging were revealed by gray correlation analysis on the nano, micro and macro scales. The results showed that the number of microscopic bee-like structures and the nano-roughness of asphalt increased initially and then decreased, the area and maximum length of microscopic bee-like structures, micro-surface energy gradually decreased as the aging time prolongs. Macro-bonding of asphalt with mineral aggregate gradually decreased. The results of grey correlation analysis showed that the attenuation of micro-surface energy caused by aging is the main factor to reduce the value of macro-bonding, further indicating that the main reason for the bonding failure of aged asphalt with aggregate is the weakening of interface chemisorption. The results will provide a good reference for understanding the multi-scale evolution of asphalt performance with aging.