Performance of Overlays Placed Over Sealed Decks under Static and Fatigue Loading

Abstract

In order to enhance the effectiveness of portland cement overlays placed over existing bridge decks, the deck may be sealed with an acceptable sealer before placing the overlay. The main purpose for such a treatment of the deck is to seal the existing cracks, and prevent penetration of chlorides into the deck if the overlay cracks. The presence of a sealer at the deck-overlay interface is expected to reduce the available bond strength. The reported research was carried out to investigate the performance of overlays placed over sealed bridge decks, examine the level of bond strength, and develop simple yet effective means to restore the bond strength as much as possible. Test results indicate that the sealer reduces the available bond strength by as much as 50%. Up to 85% of the bond strength can be restored if sand is broadcast over the sealer while it is curing or if the dried sealed surface is lightly sanded. These observations were validated through fatigue loading and loading to failure of a one-third-scale subassemblage of a steel stringer bridge.