EFFECT OF CONCRETE OVERLAY DEBONDING ON PAVEMENT PERFORMANCE.

The objectives of this paper were to determine the effect of bond loss on response and performance of bonded concrete overlays and to examine present bonding techniques and bond loss detection methodologies. A finite-element model called ILLI-SLAB was used to evaluate pavement response to load, and Westergaard-Bradbury equations were used to determine curling stresses. It was found that loss of bond adversely affects maximum pavement tensile stress (thus fatigue life) and maximum pavement deflections. It is also believed that curling stresses may cause unbonded thin overlays to separate from the underlying slab, causing extremely high stress in the overlay if a load is applied. The only way bond can be obtained is to follow good construction techniques. A summary of these techniques is presented in the paper. On the basis of deflection analysis it was concluded that it may be possible to detect bond loss using nondestructive testing of corner deflections.