Investigation of the Moisture Susceptibility of Nanocomposite-Modified Asphalt Mixture Using Surface Free Energy Theory

Moisture damage is a form of distress of asphalt pavement due to the presence of water and its impact on the mechanical characteristics of the asphalt mixture. One of the strategies delaying this event is to use a polymer-nanocomposite as an additive. In the present study, the effect of polyethylene (PE)/montmorillonite nanocomposite (NC) on the moisture susceptibility of asphaltic mixtures has been investigated using surface free energy (SFE) theory and indirect tensile strength (ITS) test. The results of SFE tests indicated that the acid component of SFE was decreased and its base component was increased through modifying the asphalt cement with PE/NC, and this increased the adhesion between asphalt cement and aggregates in the presence of water. In addition, the de-bounding energy between asphalt cement and aggregates has been decreased in modified mixtures, hence it can be expected the resistance of these mixtures to improve against stripping. Moreover, the cohesion-free energy and thus the resistance to rupture of the modified asphalt cement increased by increasing the nonpolar component. Furthermore, the results of experiments on asphalt samples indicated that the addition of PE/NC to asphalt mixtures has increased the tensile strength ratio, which increases the durability of the asphalt pavement.