Temperature Correction of HWD Deflections and Backcalculated Asphalt Modulus for Airfield Pavements

Abstract: Nondestructive testing methods, such as heavy/falling weight deflectometer (H/FWD) testing, are widely used to estimate in-situ pavement layer moduli through backcalculation analysis. The layer moduli are sensitive to environmental conditions, particularly the asphalt concrete modulus is highly affected by seasonal and daily temperature variations. Pavement structural evaluations typically require the asphalt modulus at a reference temperature (e.g., 70°F). Numerous models have been developed to correct asphalt modulus for temperature effects, primarily based on data from instrumented highway test sections, yet few studies focus specifically on airfield pavements. This paper examines temperature effects on airfield asphalt concrete mixture P-401 using data from Construction Cycle 7 (CC7) asphalt test sections at the Federal Highway Administration (FAA)’s National Airport Pavement Test Facility. The CC7 full-scale experiment included instrumented pavement sections with varied asphalt thicknesses, with HWD tests conducted over a wide temperature range across two years. HWD tests on non-trafficked areas were analyzed to develop temperature correction factors for both HWD deflections and the backcalculated AC modulus, enabling adjustments from the test temperature to a reference temperature. The models incorporate the test temperature, measured at the mid-depth of asphalt layer, and asphalt layer thickness. The FAA’s BAKFAA computer program was used for backcalculating the modulus of asphalt layers.