New Warping and Differential Drying Shrinkage Models for Jointed Plain Concrete Pavements Derived with Nonlinear Shrinkage Distribution

Warping can be quantified by the equivalent temperature difference required to deform a theoretically flat slab to the same shape as the actual slab. In the Mechanistic Empirical Pavement Design Guide (MEPDG), the current warping model for jointed concrete pavements uses a triangular shrinkage distribution within the shrinkage zone near the surface of the slab as well as modification factors to account for ambient relative humidity (RH) and the amount of total shrinkage that is expected to be reversible. The current warping model was evaluated and found to predict improbable values. A new warping model based on an assumed nonlinear shrinkage distribution that followed the curve described by one-quarter of an ellipse was proposed. The elliptical shrinkage distribution was found to agree well with predicted moisture distributions through the depth of the slab at various locations around the United States. A new factor accounted for the fact that only drying shrinkage contributed to warping, and changes were made to the RH adjustment factor. The proposed model was derived from plate theory, rather than beam theory, to account for the two-way bending behavior of a slab. Only parameters that were currently inputs in the MEPDG were required for the new proposed warping model. With slight modification, the model could be used to predict differential drying shrinkage levels in jointed concrete pavements.