Chloride Corrosion Threshold Dependence on Steel Potential in Reinforced Concrete

Abstract

Abstract In reinforced concrete structures exposed to marine environments, corrosion initiates when the chloride ion concentration at the surface of the embedded steel bar exceeds a chloride corrosion threshold (CT) value. CT is generally assumed to have a conservatively fixed value between 0.2-0.4% by weight of cement. However, over the last 40 years there have been extensive experimental investigations on chloride corrosion threshold confirming that CT is not a fixed value and depends on many variables, one of which is the potential of the steel while it is in its passive state. Marked increases in CT are associated with more negative pre-activation potentials. Experimental measurements of the effect can be found in the literature but for a limited set of conditions. Experiments were designed and conducted here for more detailed assessment. The results were analyzed along with previous data to identify trends and corresponding descriptive parameters. A formulation with CT = CT0 10^(E-E0)/ βCT was used and values generally consistent with previous tentative trends were obtained.