Effects of Chloride Contamination - Winter Bridge Painting on Coatings Performance KY SPR Study No. 08-366

KYfC roads receive de-icing salt applications during the winter. This can result in significant chloride concentrations on bridges. One area that is commonly 8.ffected is that under deck joints (including bearings and beam ends) which are subjected to high chloride concentrations due to joint leakage. These concentrations decrease considerably after the spring rains when they are flushed by subsequent leakage. Over the past few yean, KYTC bas discontinued paint season restrictions allowing contractors to paint in winter when chloride concentration on bridge steel under joints is high. Cotrosion under deck joint was observed by KYTC officials on bridges that were recently painted. KYTC field and laboratory analyses have pinpointed cbIorides IS the cause of these premature failures. Since KYTC bridge painting operations cum::ntly have no seasonal restrictions, KYfC officials are concerned that excessive chlorides on steel prior to painting can cause significant problem with paint dmability. Work is needed to determine ~table dlloride limits on bridge steel prior to painting and 2) to assess seasonal (winter) chloride contamination on bridge steel. The laboratory tests are required to determine the tolerance ofKYI'C-qualified mAinternmcecoatings for withstanding surface chloride CODtamination.The field chloride measurements are to determine if winter painting poses an undue risk fur premature ~nJl)t failures.