Sponsor: North Carolina Department of Transportation
Project has focused on evaluating the relative impact of anti-icing and de-icing strategies used in North Carolina on the ingress of chlorides into concrete surfaces and the effect of corrosion rates on both reinforcing steels and exposed structural steel members. A multi-bridge, multi-regional field study investigated chloride concentrations and seasonal variations across a variety of structural surfaces both above and below the deck, including the deck slab, girder ends, pier caps, guard rails, and barrier walls using field x-ray fluorescense measurements. Within a separate controlled-application field study, initial dispersion and transport of the chloride ion associated with brine anti-icing, granular deicing, and salt-sand mixes were experimentally monitored over sequential days to examine treatment specific characteristics. A suite of laboratory tests have also been conducted to quantify corrosive impacts of the chloride-based treatment strategies on exposed and coated steel coupons and reinforced concrete specimens.
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The research will provide information to bridge maintenance officials for determination of the appropriate level and associated level of economic cost for corrosion mitigation practices applied in response to the different winter road maintenance strategies. Effective corrosion mitigation must be determined based on service life expectations as well as data regarding the susceptibility of various bridge components. This research will indicate the contribution of each application method to the chloride-driven deterioration of the bridge. If this data is used in conjunction with a lifecycle model, the most economical mitigation strategies can be planned based on the nature of the ice clearance program. For instance, the data may lead maintenance officials to assign a higher priority to cleaning and painting steel beam-ends and repairing leaking joints. Alternatively, washing of bridge surfaces or application of protective overlays may be deemed more appropriate based on the research results and economic factors.
Prah-Ennin, Papa Kwesi (2013) “Quantifying Corrosive Potential of De-Icing and Anti-Icing Solutions to Steel and Concrete Bridge Components,” Masters of Science Thesis, University of North Carolina at Charlotte, Department of Civil and Environmental Engineering.