Ultra-High Performance Concrete (UHPC) Bridge Deck Overlays as a Corrosion Mitigation Strategy

Title: Ultra-High Performance Concrete (UHPC) Bridge Deck Overlays as a Corrosion Mitigation Strategy to Ensure Longer Service Life Presented By: Naveen Saladi and Scott Muzenski, Genex Systems Description: Corrosion of steel reinforcement is one of the primary contributing factors to bridge deck deterioration. Depending on the extent of corrosion, different corrosion mitigation strategies can be used to extend the deck’s service life. Overlays are one such corrosion mitigation measure. Traditionally, deteriorated bridge decks were repaired using localized patches or thin, bonded overlays composed of conventional concrete materials. UHPC overlays gained traction from the bridge owners in recent years, in part due to their superior mechanical and durability properties. Previous research has demonstrated that UHPC overlay can be a low impact option compared to conventional concrete and latex-modified concrete overlay when considering a cradle-to-grave life cycle assessment for a service life of 50 years. As such, it is important to evaluate the long-term performance of UHPC overlays in order to ensure extended service lives of bridge decks and thereby their value in the context of sustainability. This study evaluates different corrosion mitigation strategies to evaluate the effects of such techniques on the bond between UHPC overlay and the substrate concrete. The corrosion mitigation strategies include use of sealers, corrosion inhibitors and overlays by themselves or in conjunction with sealers, corrosion inhibitors or both. Corrosion activity was monitored using half-cell potential and cyclic polarization using standardized test protocols. Furthermore, the effect of corrosion mitigation measures on the bond performance is assessed using direct tension bond testing. UHPC overlays were found to be effective in reducing corrosion rates by more than 50 percent. Sealers and corrosion inhibitors applied to the concrete substrate in combination with placing a UHPC overlay reduced the corrosion rates even further. However, sealers and corrosion inhibitors appeared to negatively affect bond strength and potentially increasing the likelihood of overlay delamination.