Field Validation of Airport Pavement Granular Layer Rutting Predictions

Abstract

This paper presents research findings on the prediction performances and field validations of the recently developed granular base–subbase layer permanent deformation models using the full-scale pavement test section data from the FAA's National Airport Pavement Test Facility (NAPTF). The FAA-designated P209/P154 aggregate materials were used in the construction and testing of the NAPTF flexible pavement test sections with variable-thickness base and subbase courses. To account for the rutting performances of these substantially thick granular layers, a comprehensive set of repeated load triaxial tests, considering both constant and variable confining pressure (CCP and VCP) conditions, were conducted on the P209 base and P154 subbase granular materials. On the basis of the laboratory test results, both CCP- and VCP-type permanent deformation models were developed to predict maximum ruts that occurred at the NAPTF under both six-wheel and four-wheel gear loadings applied following a wander pattern. The developed rutting models were first calibrated for the field conditions and then evaluated for predicting the field accumulation of permanent deformations by properly taking into account the NAPTF trafficking data, effects of stress rotation due to moving wheel loads, and loading stress history effects. A comparison of the measured and predicted permanent deformations indicated that a good match for the measured rut magnitudes and the accumulation rates could be achieved only when the magnitudes and variations of stress states in the granular layers, number of load applications, gear load wander patterns, previous loading stress history effects, trafficking speed or loading rate effects, and finally, principal stress rotation effects due to moving wheel loads were properly accounted for in the laboratory testing and permanent deformation model development.