The Ohio Department of Transportation (ODOT) has constructed over 350 lane miles of Unbonded Concrete Overlays (UBCO). For the most part these overlays have performed as expected. However, occasionally an UBCO is constructed which performs below expectations. The objective is to determine the mechanisms of failure responsible for each distress evident at the time of the study. The goal being to tie these mechanisms to the design, construction and/or materials practices or standards that can be modified to gain better performance and eliminate or delay these types of problems in the future. The research is expected to result in a better understanding of how to design and construct an unbonded concrete overlay. Ultimately, this research is expected to produce cost savings by preventing premature distress formations in unbonded concrete pavement overlays and reducing future maintenance costs to those projects through improved performance of the overlays.