Electrode Potential Monitoring of Effect of Plants Extracts Addition on the Electrochemical Corrosion Behaviour of Mild Steel Reinforcement in Concrete

摘要

The corrosion and protection of a mild steel reinforcement in concrete, partially immersed in 5% sodium chloride solution, was investigated at ambient temperature by potential monitoring technique. The work was carried out using a digital voltmeter and a copper sulphate electrode (CSE) as the reference electrode. Extracts of kola plant and tobacco in different concentrations were used as ‘green’ inhibitors. This paper reports the observed electrochemical response from the electrode potential monitoring of the reinforcing mild steel during the experiments. A reduction in the active corrosion reactions behaviour of the embedded mild steel in sodium chloride solution was obtained with the addition of different concentrations of the plants extracts. This behavior was attributed to the protective film provided on the steel’s surface in the concrete by the complex chemical compounds of the plants extracts, which prevented and/or reduced the chloride ions penetration through the film to the steel surface. Effective protection of the embedded steel was achieved in nearly all the extracts for the greater part of the experimental period. However, the most effective results were obtained from the tobacco extract and from the combination of other individual extracts concentrations by synergistic effect.