Thermal sensitivity of Falling Weight Deflectometer deflections in full-depth asphalt pavements: a model-driven parametric analysis

Accurate pavement structural evaluation using falling weight deflectometer (FWD) testing is strongly affected by pavement temperature, yet field tests cannot cover the full range of thermal conditions. This study integrates field FWD data with a parametric finite element (FE) model to examine temperature-dependent responses of full-depth asphalt pavements. A refined pavement temperature gradient model was used to generate realistic thermal profiles and evaluate the effects of asphalt layer thickness and subgrade stiffness on deflections. Results show that temperature effects are greatest near the load center and diminish with distance. Thinner asphalt layers and weaker subgrades exhibit higher temperature sensitivity, whereas thicker asphalt layers and stiffer subgrades reduce temperature-induced deflection through insulation, load distribution, and enhanced structural support. Among the evaluated deflection basin parameters, the proposed Asphalt Curvature Index (ACI) and Subgrade Curvature Index (SubCI) are particularly sensitive to temperature. These findings support improved temperature correction for FWD-based pavement assessment.