Rutting of Airport Pavement Granular Layers

This paper focuses on predicting rutting performances of airport pavement granular layers from laboratory testing. Typical field stress states occurring in the granular layers of the Federal Aviation Administration's (FAA's) National Airport Pavement Test Facility (NAPTF) flexible pavement sections were realistically assessed from finite element analyses. The granular specimen tested was the FAA's P209 base course material, a crushed aggregate, also used in the NAPTF test sections. Using an innovative repeated load triaxial testing device with the capability to apply multidirectional stress pulsing on laboratory specimens, permanent deformation accumulation was studied for various applied stress levels, stress ratios, and stress loading paths. The test results indicated that an increase in the applied stress levels/ratios, or a decrease in the confinement, mainly resulted in a higher rate of permanent deformation accumulation. Such high stress levels/ratios and the rotating nature of applied principal stresses under a moving aircraft wheel are the primary factors that contribute to significant rutting in airport pavement granular layers. Models were developed from the test results to predict the accumulation of permanent deformation.