Influence of the chromate content in cement on the corrosion behaviour of steel in concrete

✍ Scribed by P. Schieß; T. F. Mayer; K. Osterminski

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: German
• Weight: 360 KB
• Volume: 59
• Category: Article
• ISSN: 0947-5117
• DOI: 10.1002/maco.200804160

✦ Synopsis

Abstract

Chromate, which is known to be an effective corrosion inhibitor in various applications, is contained in cement as a trace element. So far its influence on the corrosion of steel in contact with concrete has not been investigated. However, as the introduction of chromate‐reduced cements has coincided with an increase in corrosion phenomena occurring on steel moulds in precast concrete plants, the question has been raised whether chromate might as well have an influence on the corrosion of reinforcement in hardened concrete.

Against this background different experiments for examining the influence of chromate on the corrosion behaviour of steel in synthetic pore solution, fresh and hardened concrete have been carried out. The results showed that the reduction of chromate has different consequences for the time periods of fresh and hardened concrete. During early hydration within the first 12–24 h the natural chloride content of the concrete constituents may be sufficient to start corrosion. Experiments yielded a higher corrosion risk for steel embedded in chromate‐reduced concrete. This first stage is followed by a repassivation as pH rises and chlorides are bound in the course of cement hydration. In hardened concrete no significant influence of the chromate content in the cement on the corrosion behaviour could be found.