Development of a Permanent Deformation Model to Predict Rutting Performance in Substandard Airfield Pavements

This paper discusses a permanent deformation model (PD model) developed with data collected from previous full-scale pavement testing experiments to improve the prediction of rutting development on airfield asphalt pavements. The data, including rut depths, pavement stiffness, and instrumentation, were collected from 34 different test items trafficked with a heavy vehicle simulator and deployable load-cart. The loading conditions of the test traffic corresponded to heavy aircraft including the C-17 (single wheel load of 45,000 lb), C-130 (single wheel load of 35,000 lb), and P-8 (total gear load of 89,000 lb). Pavement-Transportation Computer Assisted Structural Engineering (PCASE) version 7.0 was used to determine the predicted passes to failure based on measured pavement layer thickness and material properties and compare the predicted and measured passes to failure. It was observed that approximately 75% of the data fell below the line of equality, indicating that the current design methodology underpredicts passes to failure. A PD model was developed that computes a mechanistic response at predefined points within a theoretical unsaturated poroelastic multilayered structure caused by an aircraft load and then relates these responses to progressive rutting performance through an incremental-recursive rutting model. The performance of the PD model was verified with the data collected from full-scale test experiments. Results showed that the PD model consistently performed well over a range of different passes to failure.