Performance of Bridge Deck Overlays in Virginia: Phase I: State of Overlays

About the report:

Maintaining the existing transportation infrastructure is a major concern of the Virginia Department of Transportation (VDOT). The increased user travel costs, safety concerns, and financial burdens involved in replacing deteriorating decks are reasons for finding appropriate rehabilitation actions that can safely extend the service life of structures.

Virginia has been a leader in employing overlays as a rehabilitation method for bridge decks. VDOT’s Manual of the Structure and Bridge Division contains guidance for the decision-making process related to maintenance and repair of structures. Yet there is a need to update the guidelines based on contemporary experience and the knowledge gained through technological advances.

This report presents and discusses the preliminary findings of Phase I of a multi-phase study to determine the performance of bridge deck overlays in Virginia. Phase I focused on obtaining information regarding the experiences of VDOT’s nine districts with regard to their use of different kinds of overlays and the factors that influence which overlays are used. In addition, VDOT’s bridge inventory was analyzed to gain an understanding of the types of overlay systems used in Virginia.

The overlay types identified to be the most commonly used by the nine VDOT districts were latex-modified concrete, epoxy concrete, silica fume concrete, very-early-strength latex-modified concrete, and hot-mix asphalt concrete with a water-resistant membrane. From interviews, wide ranges in service life, even for the same overlay type, were found in every VDOT district. The performance of overlays, irrespective of the type, was highly dependent on the construction workmanship and the attention paid to the crucial details. Another commonly observed influential factor was the degree of deck damage (i.e., deterioration) that existed when the overlay was installed, the higher the pre-overlay deck damage, the worse the performance of the overlay.

The study recommends that a Phase II study be conducted that will involve an investigation of the overlays for bridges in VDOT’s bridge inventory, including a review of inspection reports and a field survey of a selected number of bridge decks. The study further recommends that factors identified in the Phase I study, such as age of overlays, traffic volume, and salt usage, be taken into account when the bridges are selected. The results will support appropriate modifications to the bridge maintenance guidelines as they pertain to deck overlays in VDOT’s Manual of the Structure and Bridge Division.

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