Sensitivity of Predicted Flexible Pavement Performance to Unbound Material Hydraulic Properties

The analysis methodology developed in new AASHTO mechanistic-empirical pavement design guide (MEPDG) includes the influence of diurnal and seasonal temperature and moisture variations on material and pavement behavior. However, the sensitivity of predicted flexible pavement performance to variations in the thermo-hydraulic input properties of the unbound pavement materials is not well established. The sensitivity of predicted pavement distresses to subgrade type, groundwater table depth, saturated hydraulic conductivity, and soil water characteristic curve parameters are quantified for three flexible pavement sections in four climate locations. Overall, the unbound material environmental inputs related to groundwater depth, soil water characteristic curve parameters, and saturated hydraulic conductivity all had slight to negligible influence on the predicted distresses for the cases considered in the study. The influences of climate and subgrade type predicted performance were sensible in their trends.