Fatigue Modeling as Related to Flexible Pavement Design

ABSTRACT A literature study of rheological and fatigue modeling of asphalt mixtures is presented. Theoretical aspects on structural modeling, rheological behavior and the fatigue integration in design procedures are reviewed. In principle, pavement design methods can be categorized in three broad groups: empirical, semi-mechanistic and fully mechanistic methods. Pavement design is generally performed using semi-mechanistic methods comprising analytical or numerical structural response models and deterioration modeling based on transfer functions and shift factors. In the case of fatigue deterioration, several approaches have been elaborated e.g. classical models, fracture mechanics and damage mechanics. The approaches differ regarding theoretical foundation and evaluation methods used. Recognizing significant limitations concerning theoretical basis as well as lack of empirical support for current design methods, a shift in paradigm from semi-empirical methods towards more advanced fully mechanistic methods have been initiated. According to this approach, improved pavements are achieved by appropriate design methods which are capable of predicting fatigue resistance in the actual pavement environment, and thus taking into account complex stress conditions, influence of temperature and material characteristics, such as aging and healing. KEYWORDS: Flexible Pavement DesignFatigueRheologyViscoelasticityAsphalt Concrete