Mechanistic-Empirical Modeling of Permanent Deformation in Asphalt Concrete Layers

Three mechanistic-empirical permanent deformation models were evaluated under Swedish conditions with respect to traffic, climate and materials using accelerated pavement testing and long-term pavement performance studies. The mechanistic-empirical pavement design guide (M E PDG), the incremental-recursive mechanistic-empirical CalME model (CalME), and the PErmanent Deformation of asphalt concrete layer for ROads (PEDRO) model generally showed both useful features and limitations. The M E PDG results were more accurate at the lowest material input data quality level (level 3) than at the highest (level 1). The main cause was probably the demonstrated inaccuracy of the predicted dynamic modulus at level 3 compared with measured level 1 results, and the M E PDG calibration at level 3. The CalME underestimated the permanent deformation in the semi-rigid section due to its response modeling sensitivity to overall pavement stiffness. Further, the results indicated that the relation between elastic and plastic material properties may change throughout the pavement life. The PEDRO model behavior due to lateral wander and observed field temperatures was reasonable. The zero shear rate viscosity assessment method for asphalt concrete, utilized in PEDRO, should be further evaluated. All models produced reasonable permanent deformation results although further validation and calibration is recommended before employment for pavement design purposes in Sweden.