Measurement of water resistance of asphalt based on surface free energy analysis using stripping work between asphalt-aggregate system

[Display omitted] •Stripping work of ten asphalts on three aggregates was studied.•Stripping work was used to evaluate degree of water resistance of asphalt.•Aging increased Carbonyl index and sulfoxide index enhancing asphalt stripping work.•Larger ratio of surface free energy component with aging increased stripping work.•ZQ172 silane as coupling agent enhanced water resistance of asphalt-aggregate. In this study, different surface energy parameters of three aggregates i.e. granite, diorite and limestone, and ten types of asphalts along-with their aging versions were measured using surface free energy theory by contact angle method. The water resistance of asphalt and asphalt-water aggregate systems was calculated in terms of stripping work. It was found that with extending aging duration, the ratio of the surface free energy component increases, resulting in greater stripping work between asphalt and aggregate. It was confirmed from Fourier Transform Infra-red spectroscopy characterization that with the aging of asphalt, carbonyl and sulfoxide functionalities increased gradually which in turn increased the polar component of asphalt, enhancing its vulnerability towards water, resulting in higher stripping off of asphalt from the aggregate with low water resistance. This effect was greatly minimized by using carbon-carbon double bond rich ZQ172 silane as a coupling agent and modifier of the aggregate, attributed to decreased polarity of the aggregate after modification. The current study based on the results of stripping of asphalt in terms of water resistance, can be of great help in selection of asphalt and suitable modifier for industrial and practical applications.