Mechanistic-Empirical Faulting Prediction Model for Unbonded Concrete Overlays of Concrete

Abstract

Transverse joint faulting is a distress that develops in unbonded concrete overlays (UBOL). Historically, faulting models used for predicting the performance of a UBOL have not accounted for the effects of the interlayer between the overlay and the existing pavement on the development of faulting. This is a significant limitation since characteristics of the interlayer play a primary role in the rate at which faulting develops in UBOLs. To develop a more robust faulting prediction model for UBOLs, enhancements were made to the current process to address this limitation. This includes the use of a structural response model that can account for the effects of the interlayer properties on the response of the UBOL. Additional enhancements include the use of a deflection basin of the overlay (in lieu of corner deflections of an equivalent slab system for accumulating differential energy [DE]), the incorporation of an erosion model that can account for the erodibility of the interlayer material, the adjustment of the incremental faulting equations to accommodate small slab sizes that are common in UBOLs, and a national calibration using faulting data from in-service UBOLs. This enhanced faulting model has been implemented in the mechanistic-empirical design tool Pitt UBOL-ME.