Behavior of HMA Surface under Full-Scale Testing at the FAA NAPTF

The Federal Aviation Administration (FAA) National Airport Pavement Test Facility (NAPTF) is located at the FAA William J. Hughes Technical Center, Atlantic City International Airport, New Jersey. The primary objective of the testing performed at the NAPTF is to generate full-scale pavement performance and response data for development and verification of airport pavement design criteria. A construction cycle at the NAPTF includes test pavement construction with embedded instrumentation, traffic tests to failure, posttraffic tests (includes trenching activities and other tests), and pavement removal. Four construction cycles (CC1, CC2-OL, CC3, CC5 Test Strip) to test flexible pavements under heavy aircraft loading have been completed, and a fifth one is under way. The primary objective for flexible pavement testing has been to generate shear failure in subgrade, as evidenced by subgrade flow and upheaval outside the traffic path. The research results have been widely published and accepted. This paper documents the behavior of Hot Mix Asphalt (HMA) concrete surface behavior during flexible pavement test construction cycles. The most common distresses observed in the HMA surface layer were shoving at the longitudinal joint, fatigue (alligator) cracking, and tearing in the surface layer. Rutting in the HMA layer was minimal. Alternate mix designs and longitudinal joint construction techniques were tried and were quite successful. Results from trenching studies have been useful in quantifying HMA layer behavior.