Evaluation of Corrosion Protection Systems and Testing Methods for Conventional Reinforcing Steel

Abstract

The performance of several corrosion protection systems for conventional reinforcing steel are evaluated. These include a lower water-cement ratio, two different corrosion-inhibiting admixtures, Rheocrete (an organic corrosion inhibitor) and DCI-S (an inorganic corrosion inhibitor), and an alternative deicer CMA (calcium magnesium acetate). The systems are evaluated using rapid macrocell tests developed at the University of Kansas, as well as two bench-scale techniques, the Southern Exposure (SE) and cracked beam (CB) tests, that are generally accepted in United States practice. Macrocell tests are conducted on bars symmetrically embedded in a mortar cylinder. Specimens are exposed to a simulated concrete pore solution with 1.6 molar ion concentration of sodium chloride. For the bench-scale tests, a 6.04 m ion concentration deicer solution is ponded on the top of both SE and CB specimens. The performance of the systems using the rapid macrocell tests and bench-scale tests is also compared. The results indicate that in a salt environment, based on the SE and rapid tests, the higher water-cement ratio, the higher corrosion rate and the more negative the anode corrosion potential. Based on the SE tests, both inhibitors used in this study, Rheocrete and DCI-S, significantly reduce the corrosion rate of the steel. In the CB tests, however, neither a low water-cement ratio nor the corrosion inhibitors protect the reinforcing steel. The results also indicate that in a CMA environment, for SE tests and CB tests, corrosion rates were extremely low. CMA, however, causes concrete to undergo severe surface deterioration in both tests. For the rapid macrocell tests, no conclusion iii can be drawn because of corrosion that occurred on the exposed portion of the steel in the specimens. The rapid macrocell test appears to provide an efficient method for evaluation steel performance in uncracked concrete exposed to a salt environment.