Influence of corrosion rates on polarization and current distribution of ICCP in concrete

Abstract

Corrosion rate is known to be a factor affecting the distribution of current in cathodic protection (CP) applications. This paper demonstrates the effect of different corrosion rates of embedded steel in concrete on the polarization and distribution of current during CP application. A concrete specimen was cast with separate steel bars at a fixed distance from a centralised anode. The bars are embedded in sections containing different admixed chloride concentrations to create varying corrosion rates. The specimen was conditioned to allow development of corrosion followed by application of short-term CP at a constant current of 20mA/m2. The magnitude of current flowing to each section was logged along with corresponding potential shifts. Trends were then correlated to the corrosion rates together with circuit resistance. Circuit resistance was shown to predominantly control current distribution whereas corrosion rates had a significant influence on polarization.