Development of asphalt material specification requirements to prevent slippage failure of airfield pavement

Slippage failure has been observed on asphalt runway pavements at high-speed exits, due to either asphalt mixture instability or delamination at layer interface. This study aims to develop material and construction specification requirements to prevent slippage failure. Airfield asphalt mixtures were collected from the field for testing of dynamic modulus, triaxial shear strength, and interface shear strength. On the other hand, numerical modeling is used to predict normal and shear stresses at pavement near-surface and layer interface under free rolling and braking of aircraft tire. The results from laboratory characterization and mechanistic modeling were used to evaluate shear failure potential of surface mix and layer interface under multi-axial stress states. Furthermore, cyclic loading tests were performed to obtain fatigue life before rapid permanent deformation for asphalt mix and interface delamination at different shear stress ratios, which was used to determine the critical shear stress ratio and the corresponding requirement on shear strength. Finally, the critical pavement temperatures for shear strength requirements are determined by using machine learning models with the inputs of climate variables. The analysis results recommend the thicker asphalt overlay is beneficial for mitigating interface delamination. The required minimum high-temperature indirect tensile (HT-IDT) strength is 22–49 psi to prevent shear flow of asphalt mix with a high value required for the mixture having a lower friction angle. The required minimum interface shear strength is 17 psi (without confinement) to prevent interface delamination. These strength tests need to be tested at the representative high temperature experienced in the airport pavement that can be predicted from site-specific climate data. Full-scale pavement tests are recommended to validate the proposed specification requirements.