Project Details

The three predominant anti-icing and de-icing strategies used in North Carolina are application of sodium chloride in brine form, granular form or as granules mixed with traction enhancing materials. While each of these has its own unique optimal usage for maintaining road safety, there are undetermined consequences associated with the different applications regarding chloride initiated corrosion. This study made an evaluation of the relative impact of each deicing treatment on the ingress of chlorides into concrete surfaces and effect on the corrosion rates of both reinforcing steel and exposed structural steel members. The study included the investigation of a variety of structural surfaces both above and below the deck, including the slab, girder ends, pier caps, guard rails, and barrier walls. An extensive laboratory study employing ASTM and SHRP standardized test methods examined steel corrosion under various concentrations of surface chloride and the ingress rates of chlorides into concrete exposed to each treatment method. Field measurements of the distribution and fluctuation of chloride surface concentrations on bridge components over time were made using a mobile x-ray fluorescence spectrometer. These in-situ measurements were correlated with the laboratory measurements to validate experimental assumptions, determine time-dependent exposure rates specific to the application method, and predict the relative corrosive influence associated with each treatment.