Corrosion of Coated and Uncoated Reinforcing Steel in Concrete

Abstract

An experimental program designed to investigate the effects of various material properties on the corrosion of reinforcing steel in concrete was conducted at the University of Minnesota. The test specimens were constructed to promote macrocell corrosion. A total of 96 prism and cracked slab specimens were subjected to an accelerated corrosion process for periods ranging from 35 to 48 weeks. The impact of the following variables on the corrosion of reinforcing steel in concrete was monitored in this program: 1) water/cementitious ratio; 2) addition of condensed silica fume; 3) percentage of entrained air in the concrete; 4) type of reinforcing steel and coating; 5) cracked concrete. The corrosion current, specimen resistance, driving potential, and CuCuS04 half-cell potential were monitored regularly to follow the corrosion process. The most significant variables determined in the University of Minnesota experimental program were the concentration levels (7.5% vs. 10%) of condensed silica fume (CSF), the significance of cracked concrete on the corrosion of reinforcing steel, and the lack of any notable corrosion resulting in concrete specimens containing bars with significantly damaged epoxy-coatings, despite high levels of chloride contamination.