Integration of non-destructive testing methods to assess asphalt pavement thickness

The pavement engineering community has consistently drawn its attention to a broadened utilization of advanced Non-Destructive Testing (NDT) systems for pavement evaluation. Amongst these systems, the Falling Weight Deflectometer (FWD) is designed to measure surface deflections and assess the pavement structural condition, while Ground Penetrating Radar (GPR) is utilized to estimate pavement layers' thicknesses. An integration of the capabilities of these two separate systems has been considered a powerful resource in pavement evaluation. With this in mind, the present study aims to investigate whether this integration could result in the utilization of the derived FWD deflection data to directly assess pavement layers thicknesses. For the research, an integrated regression analysis is conducted considering both GPR and FWD data with the aim to develop a relationship between GPR-estimated AC thicknesses and FWD deflection indexes. The developed relationship is calibrated considering both GPR and core thicknesses and further validated yielding an equivalent and satisfactory performance, with thickness prediction errors around 10%. This finding produces evidence in support of the statement that deflection data is capable of roughly producing pavement layer thicknesses. Such an approach could suggest a practical and cost-effective pavement evaluation tool, when the procurement and transportation logistics of implementing multiple and expensive equipment may be a critical issue.