Performance evaluation of bonded concrete overlay

Asphalt concrete overlay rather than bonded concrete overlay is used as a typical rehabilitation method for deteriorated concrete pavement in Korea, since asphalt concrete overlay requires a shorter construction time. Asphalt concrete overlay on existing concrete pavement, however, often undergoes various types of early distress, such as reflection cracking, pothole and rutting due to the different physical characteristics between the asphalt concrete overlay and the existing concrete pavement. Recently, bonded concrete overlay has been considered as a possible alternative, since its material properties are similar to existing concrete pavements in Korea. This study investigates the service life of bonded concrete overlay based on an analysis of distress data in USA LTPP sections. Although a considerable numbers of early distressed sections were found, the measured service life shows a good relationship with the predicted service life by the AASHTO design method when early distressed sections are excluded from the comparison. Generally, poor construction or bonding is doubted as the major cause of early distress in bonded concrete overlay. In this study, another potential source of early distress that occurs due to excessive bond stress in spite of the achievement of an adequate level of bond strength is investigated by a numerical analysis. The result of this study indicates that the bond stress may exceed the bond strength in the critical conditions of a high coefficient of thermal expansion of the overlay material and a thin overlay thickness.