Improving Concrete Durability through Use of Corrosion Inhibitors

This paper presents results of a 10-year laboratory and field monitoring study to evaluate commercially available corrosion-inhibiting admixtures in terms of effectiveness at preventing or delaying corrosion. The corrosion-inhibiting admixtures used in this study included Xypex Admix C-2000, latex modifier, Kryton KIM, fly ash, silica fume, Darex Corrosion Inhibitor (DCI), Rheocrete CNI, Rheocrete 222+, and FerroGard 901. The laboratory study used accelerated corrosion testing (ASTM G109) to study 656 specimens from 100 different mixtures. Saltwater ponding and drying cycles continued until macrocell current readings indicated initiation of corrosion. Specimens were then removed from cycling and autopsied to determine the extent and location of corrosion on the reinforcing steel. After 10 years of cycling, all remaining specimens were autopsied. The field study included 25 reinforced concrete panels exposed to the tidal zone in the Honolulu Harbor. Panels were tested regularly for chloride penetration and half-cell corrosion potential. After 10 years, the panels were removed from the site and autopsied. Results of the study showed that DCI, CNI, fly ash, and silica fume improved corrosion protection compared to control specimens. Concrete mixtures using Rheocrete 222+, FerroGard 901, Xypex Admix C-2000, or latex modifier showed mixed results. Keywords: admixtures; corrosion; durability; testing.