Corrosion characteristics of straight and bent epoxy-coated reinforcing steel were studied under accelerated southern exposure (se) cycling as described in nchrp report 244. Variables included seven different suppliers, bend diameter, coating thickness, coating application before and after fabrication of the bar, rate of bending, temperature of steel during bending, and patching of damaged areas before installation into concrete slabs. Specimens with uncoated steel were included as controls. A total of 40 small-scale concrete slabs, each consisting of two independent specimens--one bent-bar and one straight-bar specimen--were tested. Results after completion of 47 se cycles for some specimens and 70 cycles for others are reported. Results indicate that straight and bent epoxy-coated bars provide significantly better resistance to chloride-induced corrosion than uncoated bars. Out of the 36 sets of epoxy-coated specimens tested, only seven showed measurable macrocell corrosion currents. The macrocell corrosion currents on the control slabs were more than an order of magnitude higher than the epoxy-coated bar slabs. Corrosion rates calculated from three-electrode linear polarization data correlated withmacrocell current data. Ac resistance data indicated that the coatings did not deteriorate or disbond with time. Autopsy testing revelaed little corrosion damage on epoxy-coated rebars. Corrosion found on epoxy-coated rebars initiated only at damaged areas and at holidays. The effects of various coating parameters on the ability of the epoxy coating to provide corrosion protection was not distinguishable. There were no differences discernible between the bent and straight epoxy bars, other than visible coating damage. This paper appears in transportation research record no. 1268, Highway maintenance operations and research 1990.
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