Seasonal and Diurnal Variations of Backcalculated Layers Moduli in Flexible Pavements and FWD Testing Guidelines

The seasonal and diurnal changes impact the backcalculated layer moduli for flexible pavements in different climatic regions. HMA showed minimal variation spring fall seasons every area. Also, were consistently higher, based on deflections measured before noon. However, temperature correction, generally applied to moduli, can eliminate season, time, impacts of FWD measurements. Since base subgrade are from single deflection basins surface, temperatures moisture conditions at time measurements affect those material properties. Temperatures may potentially result values that close their representative in-field conditions. Based results, preferred ranges 55 70?F 65 75?F freeze non-freeze regions, respectively, during any day.