On the novel approach of sacrificial cathodic protection of mild steel in simulated concrete pore solution and concrete mortar by high phosphorus pig iron anodes

Abstract

The effectiveness of high phosphorus pig iron (1.5 wt% P, 3.5 wt% P, and 8.0 wt% P) as sacrificial anode for the cathodic protection of mild steel was investigated in simulated concrete pore solution and concrete mortar. Electrochemical tests were carried out in both chloride-free and chloride-contaminated pore solution under freely aerated and deaerated environments. Linear and dynamic polarization, electrochemical impedance spectroscopy and zero resistance ammeter tests were performed to compare the electrochemical behavior of the pig iron samples to the mild steel. Laboratory and field tests were also conducted by galvanically coupling the mild steel to the pig iron samples in the concrete mortar and monitoring the polarization shift. The polarization results indicate that all three different pig iron samples show more active potential as compared to the mild steel in both chloride-free and chloride contaminated pore solutions. The open circuit potential and polarization resistance for all the pig iron samples decrease with an increase in the P content. The more active galvanic potential and positive galvanic current density for the pig iron and the mild steel couple show the effectiveness of the pig iron as a sacrificial anode in simulated concrete pore solution. The laboratory and field studies also suggest that the 100 mV polarization shift criterion has been established, and the pig iron samples are effective in preventing the corrosion of the mild steel in concrete. The first time use of iron based sacrificial anode for the cathodic protection of reinforcing steel embedded in concrete defines the novelty of the present work.