Abstract
Epoxy coated reinforcing (ECR) steel was acquired from ten sources and characterized with regard to coating thickness, hardness and defects. Subsequently, specimens were prepared from these; and electrochemical impedance spectroscopy (EIS) scans were performed for baseline characterization purposes in either distilled or tap water. Exposure testing was conducted in either distilled water or an aqueous 3.5 w/o NaCl solution at 80°C with EIS scanning at 1, 7 and 14 days. It was determined that impedance decreased with time in association with development of either coating defects or conductive pathways through the coating (or both) with ECR specimens from individual source typically exhibiting similar behavior. Because most of the impedance decrease occurred in the initial day of testing, the procedure is considered to have utility as an in-plant quality control test for epoxy coatings on reinforcing steel. The results of this research are discussed within the context of alternative short-term testing procedures and the need for predicting long-term ECR performance based upon results of accelerated testing.
