Determining Pavement Layers Thickness and Moduli According to Non-Destructive Testing and Back Analysis (Case Study: Azadegan Freeway-Tehran)

Background/Objectives: The engineers are permanently looking for a way to be informed and evaluate current conditions of pavement in order to estimate structural pavement conditions and the remained lifetime. Methods/Statistical Analysis: Present study aimed to conduct a back analysis on pavement layers moduli of elasticity in one of sections of Azadegan Freeway through the data obtained from an assessment on pavement status by DCP and GPR tests as well as the deflection results of FWD device for 9 sensors on the desired section. Back analysis of pavement layers moduli was carried out using the Software ELMOD. Results: The results from this study can be summarized as follows: 1. For both loading levels of 49.2KN and 58.42KN, asphalt layer moduli has the highest changes. 2. Changes trend of the rigid layer depth is in a direct proportion with subgrade moduli. 3. Rigid layer has a direct effect on moduli-related results of other pavement layers. 4. Geophone D3 has the highest mean differential deflection. Conclusion/Application: In conclusion, this study indicates that for both load levels, asphalt layer moduli has the highest changes and the moduli changes are less in lower layers.