Characterization of asphalt concrete and asphalt binder for moisture damage using nanoscale testing

Asphalt and bituminous materials have been characterized for moisture damage at traditional laboratory (macro) scales. The problem is yet to solve for the moisture damage in asphalt concrete. Macro and microscales scales testing are not sufficient for developing an understanding of the bond damage phenomena that occurs between asphalt-asphalt and asphalt-aggregate bonding. In this study atomic force microscopy (AFM) and nanoindentation techniques are employed to evaluate the moisture damage in asphalt binder and asphalt concrete. AASHTO T-283 method is used to condition the dry asphalt concrete samples. In this study, moisture damage is quantified in performance grade (PG) asphalt binders using different functionalized AFM measured adhesion values. This study finds the asphalt binder and asphalt concrete to be susceptible for moisture action. The results show that PG 76-28 binder is more resistant to moisture damage as compared to PG 70-22 binder. Using nanoindentation, it is shown that in asphalt concrete, hardness increases due to wet conditioning of aggregate, whereas hardness decreases due to wet conditioning of mastic, which is a mixture of fines and asphalt binder. Nanoindentation results shows that the aggregate sample is much stronger than the mastic sample as little deformation is observed. Also the percentage of fines may have some reasonable effect on modulus and hardness values.