Characterization of Coupled Aging-Moisture Degradation for Hot Mix Asphalt Concrete

Durability of asphalt concrete is significantly influenced by aging and moisture damage. These two phenomena occur simultaneously in the field, resulting in early degradation of asphalt pavements. Although there exists a significant number of studies in the literature addressing these phenomena individually, research efforts to characterize the coupling effect of aging-moisture degradation in asphalt concrete are very limited. This was the main motivation for conducting the study presented in this dissertation. The focus of this study is to formulate an Integrated Aging-Moisture Predictive model (IAMP) for dynamic modulus of asphalt concrete as a function of aging temperature, loading frequency, and exposure time. The integrated model combines a predictive kinetic-based aging model with a moisture damage one. The aging model characterizes the dynamic modulus master curve of an aged asphalt concrete based on aging properties (i.e., activation energies and preexponential), temperature, and exposure time. This model is then modified by incorporating the moisture damage model, which is developed based on intermolecular bond energy/force, and the mechanisms of cohesive and adhesive failures. The moisture damage model assumes water vapor diffusion, which is the dominant moisture transport mode in asphalt pavements. Parameter calibration and model validation for a Superpave mixture is done through performing dynamic modulus tests (on fine-aggregate and full mixture specimens), as well as Bitumen Bond Strength test (on the adhesive bond between aggregate and asphalt binder). Validation results show the competence of the proposed model in predicting the dynamic modulus of asphalt concrete under simultaneous effect of aging and moisture damage