Measuring Long-Term Performance of Unbonded Concrete Overlay Pavement in Florida

Concrete overlays have gained more attention due to their ability to extend the service life of deteriorated pavements and provide a smooth riding surface. This study focused on investigating the long-term performance of unbonded concrete overlay pavements in terms of structural performance, cracking performance, faulting performance, and smoothness (IRI) by utilizing the falling weight deflectometer (FWD) and laser crack measurement system (LCMS). The field data was collected over the last thirty-five years on an unbonded concrete overlay testing road on US-1 between Daytona Beach and Titusville. The test road was constructed by Florida Department of Transportation (FDOT) in 1988. A total of 3.06 km of concrete overlay was included in a 12.9 km milling and resurfacing project for a deteriorated asphalt pavement. The concrete overlay test sections were divided into three groups based on design thickness. Each group had subsections with three joint spacing levels and two dowel bar configurations (standard 30.5-cm spacing and wheel path only). It was found that the studied experimental concrete overlay sections outlived the design life with only minor repair and rehabilitation requirements after 35 years of service with more than 2.95 million truck passes. Thicker concrete overlay slabs provided better overall performance. Shorter slab lengths mitigated slab cracking. The slabs with dowels in the wheel path configurations could not provide comparable performance to the slabs with standard dowel bar configuration. A five-point rating scale was employed to assess long-term pavement performance with various design configurations. A multiple regression analysis was performed to identify significant pavement design parameters that affect pavement performance in terms of structural capacity, corner deflection, load transfer efficiency (LTE), cracking, international roughness index (IRI), and faulting. The findings from this study can support the development of comprehensive concrete overlay design approaches in Florida.