Cracking and Chloride Contents in Reinforced Concrete Bridge Decks [Final Report]

015365892005Final Report May 2001 \u2013 February 2005PDFTech ReportK-TRAN: KU-01-9C1267Bridge decksChloride contentDelaminationGirder bridgesReinforced concreteReinforced concrete bridgesBridges and other structuresHighwaysMaterialsI24: Design of Bridges and Retaining WallsI32: ConcreteKansasUnited StatesKansas. Dept. of TransportationLindquist, WillDarwin, DavidBrowning, JoAnn P.University of Kansas. Dept. of Civil, Environmental and Architectural EngineeringKansas. Dept. of Transportation. Bureau of Materials & ResearchUS Transportation CollectionThe effects of material properties, design specifications, construction practices, and environmental site conditions on the performance of reinforced concrete bridge decks were evaluated. Field surveys were performed on 59 bridges to measure deck cracking, chloride ingress, and delaminated area. The surveys were limited to steel girder bridges \u2013 bridges that are generally agreed to exhibit the greatest amount of cracking in the concrete decks. The study includes two bridge deck types with silica fume overlays. The performance of silica fume overlay decks relative to conventional overlay and monolithic decks is of particular interest due to the widespread use of silica fume overlays in the state of Kansas. The results of the study indicate that chloride contents increase with the age of the bridge deck, regardless of deck type. In addition, concrete for all bridge deck types sampled in the same age range exhibit similar chloride contents for samples taken both at and away from cracks, regardless of deck type. For bridges within the same age range, the average chloride concentration taken away from cracks at the level of the top transverse reinforcement rarely exceeds even the most conservative estimates of the corrosion threshold for conventional reinforcement. Chloride concentrations taken at crack locations, however, can exceed the corrosion threshold in as little as nine months. Based on these observations, it appears clear that attention should be focused on minimizing bridge deck cracking rather than concrete permeability.93