Aircraft braking forces have increased and will continue to increase in the future. This has resulted in increased shear stresses at the interface between the surface layer and the underlying pavement. An increase in reports of delamination failures has followed. Shear stresses induced by an extreme aircraft braking event were compared to measured interface shear strengths. Interface shear strength was measured from cores recovered from runway surfaces typical of major Australian airports. The runways were exposed to aircraft operations also typical of major Australian airports. The resulting stress-strength ratios identified an area 50 mm in front of the leading edge of the tyre as the critical location for delamination failure where stress-strength ratios approached 1.0. Interface cohesion is provided by tack coat adhesion and contributes to interface shear strength. It is recommended that a premium tack coat material, such as JetBondTM, be specified for future airport overlay projects.
16th Australian Asphalt Pavement Association (AAPA) International Flexible Pavements Conference: Innovation Driving Value, Gold Coast, Australia 13-16 September 2015