Prediction of Stress-to-Strength Ratio Using Falling Weight Deflectometer Deflections to Evaluate the Structural Condition of Jointed Plain Concrete Pavement

There are limited methods to interpret the falling weight deflectometer (FWD) data for the structural evaluation of concrete slab due to curling effects and to determine stress in concrete slabs. Thus, this study focuses on developing a more practical and accurate method to estimate structural capacity of concrete slabs using FWD deflection data for in-service pavements. This study adopts the stress-to-strength ratio (SSR) as a structural indicator for concrete slabs and focuses on predicting SSR from FWD deflections. A synthetic database was established to consider various pavement structures and environmental conditions, and it was used for SSR prediction model development. The surface curvature index (SCI) exhibited the strongest correlation with SSR and was selected as an input for the SSR prediction model. The developed model allows for predicting SSR without the need of structural analysis to calculate the maximum stress in the concrete slab. Furthermore, the curling effect on SSR prediction was found to be insignificant, allowing the model to be applied without accounting for curling conditions. Since estimating the curling conditions of in-service pavements is limited, the developed SSR prediction model may be beneficial for pavement management systems to assess structural conditions of in-service concrete pavements.