Bond strength and chloride resistance of epoxy and concrete overlays on bridge decks

The deteriorating condition of infrastructure, combined with fiscal limitations experienced by many agencies, necessitates increased service life of bridges. Maintenance and preservation methods such as overlays and sealers have been known to protect bridge decks from deterioration, while also extending a bridge's service life. It is important to understand the characteristics of various overlay types to make informed maintenance decisions, thus assessing and comparing the performance of thin epoxy overlays and low slump dense concrete (LSDC) overlays is desirable. To evaluate the performance of these two overlay types, the chloride resistance and long-term bond strength of the overlays were assessed. Three bridges were chosen to install each overlay type, with corresponding field and laboratory evaluations performed. The above tests results indicated that the initial bond strength of both overlays is good, but that the thin epoxy overlays showed decreased performance after 300 F/T cycles. The bond performance of the LSDC remain unchanged for the duration of the freeze-thaw testing, indicating superior long-term performance. As expected, the epoxy overlay performed much better than the LSDC overlay with respect to chloride resistance. These performance metrics are important to keep in mind when selecting maintenance and rehabilitation methods for bridges.