Galvanic coupling in concrete

Galvanic coupling in concrete

Reference [10]

Concrete reinforced partly with carbon steel (CS) and partly with stainless steel (SS) will not suffer from rebar corrosion in a chloride environment if SS rebar only is in contact with chlorides. In real situations, such as that of repairs, or when the CS rebar is too close to the surface, some corrosion of the CS rebar may take place. There will be three CS corrosion mechanisms involved (5)

  1. non-galvanic corrosion, representing about 97% of the overall corrosion rate
  2. galvanic coupling of corroding CS with passive CS, a counter intuitive form of corrosion, which contributes to about 2% of the corrosion rate
  3. last, galvanic coupling of corroding CS with passive SS which accounts for about 1% of the corrosion rate. SS is a poorer cathode than passive CS due to the poor conductivity of the chromium oxide passive layer

All studies support the conclusion that galvanic corrosion between SS and CS is negligible.

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