Characterization of asphalt materials' moisture susceptibility using multiple methods

Moisture damage seriously deteriorates asphalt pavement's performance and durability and is therefore one of the major problems of asphalt pavements. Currently, researchers pay most attention to macro investigation of moisture damage in asphalt materials. However, moisture damage in asphalt materials can be attributed to the complex interactions between water, asphalt and aggregates occurring at the micro level so that macro tests cannot provide precise insight into this process and its mechanisms. To this end, two promising micromechanical tests, atomic force microscopy (AFM) and nanoindentation, were used in this paper to capture the micromechanical properties of asphalt binder and mixture samples before and after moisture damage. For data comparison, surface energy method and freeze-thaw splitting test were also used. Results show that AFM and nanoindentation are promising methods in investigation of asphalt materials' moisture damage because they can quantitatively determine the loss of asphalt samples' strength and also determine their damage types (adhesion or cohesion failure). Results of surface energy method and freeze-thaw splitting test correlate well with AFM and nanoindentation results in characterization of moisture susceptibility of asphalt binder and mixture samples respectively. It is concluded that these four testing methods can achieve a systematic and accurate evaluation of asphalt materials' moisture resistance.