Aging-Effect Incorporation into the Fatigue-Damage Modeling of Asphalt Mixtures Using the S-VECD Model

This work focuses on modeling fatigue for aged asphalt mixtures. This is accomplished by combining existing models and adapting asphalt mixture aging laboratory procedures. The aging model used is based on the evolution of an internal state variable, and it is capable of taking into account the effect of aging temperature. The simplified viscoelastic continuum damage (S-VECD) model was selected for representing the fatigue damage behavior. Results at four aging states were analyzed, including the unaged mixture. Aged mixtures were obtained by heating loose asphalt mixture in an oven for two periods (2 and 45days) and two temperatures (85 and 135 degrees C). Based on the results from linear viscoelastic and S-VECD characterization, it was concluded that aging produces less damage tolerant materials; i.e.,fatigue failure is observed for less evolved damage states. However, depending on the pavement conditions and on the pavement cross section geometry, because of the increase in material stiffness, aging may not be responsible for a decrease in fatigue life.