Full-Scale Tests of Unbonded PCC Overlays at the FAA's National Airport Pavement Test Facility

摘要

Full-scale tests of unbonded concrete overlays were completed in February 2018 at the Federal Aviation Administration's (FAA) National Airport Pavement Testing Facility (NAPTF). The objective was to gain full-scale data to improve the FAA's FAARFIELD design procedure for PCC-on-rigid airport pavement overlays. The overlay experiment of Construction Cycle 8 (CC8) included two test items, each consisting of ten slabs. The north test item was trafficked by a four-wheel (2D) gear configuration, and the south test item by a six-wheel (3D) gear. Underlying slabs had existing damage, but still retained significant structural integrity. A thin asphalt interlayer was used as a bond breaker between two concrete layers. Both concrete layers were instrumented with embedded sensors to measure dynamic (strain and deflection), and static (temperature) pavement responses during trafficking. In contrast to previous Construction Cycle 4 (CC4) test results at the NAPTF, the 2D loaded test item failed earlier than the companion 3D item. The dominant distress types in both test items were corner breaks and linear reflection cracks. Longitudinal cracks were reflected from the doweled longitudinal joints of the underlying PCC slabs. In addition, the observed crack pattern suggests that some transverse cracks may have initiated from the instrumentation channels in the asphalt interlay; however, this remains to be confirmed by post-traffic forensic investigations. Pavement deterioration was characterized using the structural condition index (SCI) and crack density (CD). The rate of SCI deterioration remained nearly constant with coverages, confirming results from previous CC4 tests.