Fundamental Investigation of Interaction between Moisture and Asphalt-aggregate Systems

Moisture-induced damage is one of the most common forms of flexible pavement distress which directly causes or exacerbates pavement failure. The intrusion of moisture into the asphalt pavements reduces the overall mechanical properties of the locking structures and gives rise to one or more of the visible forms of distress such as raveling, stripping, permanent deformation and fatigue cracking. This doctoral study is aimed at understanding the detrimental action of water on the asphalt-aggregate systems and the damage mechanism by multi-technique investigation. A thermodynamics framework was considered to characterize the properties of asphalt mix ingredients as well as the engineering performance of mixtures. To facilitate efficient screening of compatible aggregate-asphalt systems, a new digital imaging-assisted test method on loose asphalt mixtures was developed to achieve an objective assessment of moisture susceptibility. Additionally, an innovative aggregate pretreatment technology based on thermoplastic polymeric powder coating was proposed to mitigate stripping of asphalt mixtures.