SPR 14-484 Chloride Contamination Remediation on Steel Bridges

Objectives: 1) Review current processes for surface preparation including blasting with various abrasive media, such as sponge jets and dry ice, and water jetting, hot pressure washing and steam cleaning combined with conventional abrasive blasting. 2) Treat uncoated steel panels by cyclic salt fog testing to promote corrosion and charge them with chlorides. Subject painted panels with chloride contamination to UV/condensation to promote weathering. 3) Clean the corroded steel panels and weathered painted panels with candidate surface preparation methods identified in 1). 4) Subject the cleaned/prepared panels to Bresle testing to measure retained chlorides. Subject samples from those panels to scanning electron microscopy (SEM) to evaluate surfaces created by the various cleaning methods. Use SEM to detect the quantity and disposition of any retained chlorides on the resulting substrates. 5) Provide recommendations for future surface preparation methods for steel bridge maintenance painting and 6) Work with KYTC officials to incorporate the use of these methods on an experimental basis.