Title: Influence of Cation on Corrosion Behavior of Reinforcing Steel in High-pH Sulfate Solutions

Author(s): Laura Mammoliti and Carolyn M. Hansson

Publication: Materials Journal

Volume: 102

Issue: 4

Appears on pages(s): 279-285

Keywords: corrosion; durability; reinforcement

DOI: 10.14359/14622

Date: 7/1/2005

Abstract:
It is well accepted that exposure of hardened concrete to sulfate salts can lead to degradation of the cement paste matrix. Limited studies, however, have examined the effect of sulfate salts on the corrosion behavior of the embedded reinforcing steel, and in these studies, the sulfates are usually in combination with other aggressive species such as chlorides. The present investigation aims to isolate the influence of the sulfate cation (Na+ or Mg++) on reinforcement corrosion in lime water with varying Ca(OH)2 concentrations and in a NaOH/KOH solution with and without Ca(OH)2. Surprisingly, corrosion was only induced in solutions containing MgSO4 and was initiated at lower sulfate levels in lime-water solutions than in the NaOH/KOH solutions. In addition, the mechanism of corrosion is different in the different solutions, emphasizing the importance of selecting the appropriate medium for simulating the corrosion of steel in concrete.