Early Age Stresses and Debonding in Bonded Concrete Overlays

Abstract

Bonded concrete overlays are a cost-effective strategy for rehabilitating and strengthening old concrete pavements. Volume changes of the over lay concrete may cause debonding at the interface between old and new concrete or surface cracking, detrimentally affecting long-term performance of the pavement. Experimental measurements and numerical analyses were pursued to understand distribution of stress arising from thermal change or drying shrinkage under restrained conditions. Laboratory overlay specimens were made to measure opening displacement at the interface. Debonding profiles at the interface were determined by using a dye technique. A finite element model was developed to study debonding behavior and crack tendency due to volume changes. Physical experiments were used to define nonlinear gradients of drying shrinkage and bond strengths for input into the model. The model was validated by comparing the predicted opening displacements and debonding profile with the experimental measurements. The results indicate how high-performance concrete mixtures may be problematic for overlay applications if full wet curing is not used.