Performance Monitoring Of Ultra-Thin Whitetopping At A General Aviation Airport

Abstract

The first ultra-thin whitetopping (UTW) project in the United States on a general aviation (GA) airport runway was built at the Savannah-Hardin County Airport (SNH) in Tennessee. The asphalt concrete (AC) surface at SNH Runway 18-36 was aged and had significant amounts of cracking. Existing surface conditions were assessed using the pavement condition index procedure and pavement structural capacity was estimated using the falling weight deflectometer and dynamic cone penetrometer; insitu and laboratory CBR tests were also conducted. Current pavement conditions, structural capacity, and subsurface soil conditions were evaluated to determine pavement design parameters. UTW deflection and bending stresses (estimated using 2-D ILLI-SLAB code), because of FAA C-2 classification aircraft, were used in the Portland Cement Association fatigue law to determine the allowable number of load repetitions. A 100-mm thick UTW on top of the existing AC surface with a 1220-mm joint spacing was recommended. Strain gages were installed near the surface and bottom of the Portland cement concrete (PCC), and on the top of the milled AC surface for performance monitoring by determining if the UTW is completely bonded, completely unbonded or partially bonded to the milled AC surface. Strains were measured in the winter and summer seasons during both morning and afternoon hours using a loaded dump truck. A paper presented at the 2001 ASCE Airfield Pavement Specialty Conference in Chicago, Illinois, described the UTW design process and the results of the field-testing conducted during the summer months. This paper provides results of winter and summer testing and compares the summer and winter test results. Analysis of both summer and winter field test data indicated that the UTW is performing satisfactorily and is adequately bonded to the existing AC surface.