Toward a Fracture Mechanics–Based Design Approach for Unbonded Concrete Overlay Pavements

AbstractAn illustrative fracture mechanics–based design paradigm is proposed for unbonded concrete overlays (UBCOs), an increasingly popular pavement rehabilitation system, with the ultimate goal of establishing a more rational design procedure than those currently available. To illustrate the advantages of the fracture mechanics–based approach to design, specific attention is paid to one type of failure associated with pavement structures, reflection cracking. The design formulas derived from the results of a large number of crack propagation simulations of both the UBCO composite and a reference single-layer new pavement quantify the dependence of the required overlay thickness and load-carrying capacity on all relevant material and geometric parameters. Preliminary comparisons of the results with field observations suggest that the fracture mechanics paradigm offers a promising procedure for improved design of UBCOs.