A Conceptual Approach to Estimating the In-situ Layered Elastic Moduli for Flexible Pavements

The evaluation of the structural condition of a pavement is of great importance, since pavements are important transportation infrastructures that should have an adequate bearing capacity. For this reason, the use of Non-Destructive Testing (NDT) systems has gained worldwide acceptance as an effective tool for determining pavement condition. Various indices from deflection measurements using systems such as the Falling Weight Deflectometer (FWD) can provide an overview of the structural condition of the pavement. However, detailed and accurate information about the mechanical properties of the individual layers of a pavement can be obtained using advanced analysis tools such as the back-analysis method. The back-analysis method usually requires extensive experience and additional computational resources, which makes it unattractive for general use. With this in mind, the present study attempts to develop a simplified method for a quick and reliable estimation of the mechanical properties of a flexible pavement using established indices such as Surface Modulus calculated directly from deflection measurements with a view to expediting the pavement condition assessment procedures without the need of time-consuming analyses. To this end, NDT data collected along a flexible pavement are analyzed and the correlation of the Surface Modulus with the elastic modulus of each layer of the pavement is investigated. The study demonstrates the potential of using the Surface Modulus to predict the elastic modulus for evaluating the structural condition of a flexible pavement bypassing the use of sophisticated tools.