Correlating laboratory and full-scale reflective cracking tests for airfield pavements

Asphalt overlays minimize moisture infiltration and help in restoring the smoothness and structure of existing airfield concrete pavements, but due to reflective cracking, the new asphalt overlay often fails before achieving its design life. In airfields, the potential for reflective cracking presents a major challenge for rigid pavement rehabilitation involving asphalt overlays. To assist airport engineers and others concerned with the temperature-induced reflection cracks, several full-scale test pavements have been constructed, instrumented, and tested at the Federal Aviation Administration (FAA) National Airport Pavement Test Facility (NAPTF). The main objective of this study was to identify and develop correlations between full-scale and laboratory reflective cracking tests. A customized Overlay Tester (COT) and Cyclic Disc-Shaped Compact Tension (CDCT) Test were used evaluate the fracture and fatigue performance of hot mix asphalt (HMA) materials at low temperatures. The COT was conducted at the same conditions as the full-scale tests and test results were analyzed using several parameters. Temperature effect was pronounced in strain parameters (initial strain, failure strain, and strain at Nf(NLC)). Further fatigue parameters (Nf(crack) and Nf(NLC)) indicated a swifter deterioration of HMA mixture at a higher displacement (cooling) rate. Fracture parameter (Gfini) was found to decrease with the increase of displacement rate due to the brittleness of HMA at low temperatures as excepted. A two-term exponential function from the CDCT tests demonstrated the fracture behavior of HMA under cyclic loading. The released energy rate factor (R2) correlated well with the fatigue life. Finally, a set of shift factors were derived between the full-scale, OT, and CDCT tests. Valuable data obtained from this study provides immediate support to the future FAA reflective cracking research.