Effect of green inhibitor on the corrosion behaviour of reinforced carbon steel in concrete

Abstract

The effect of inhibitors on the corrosion behaviour of carbon steel reinforced in concrete exposed to 3.5% NaCl solution has been studied by electrochemical and weight loss tests. The corrosion potential and concrete resistivity were determined during the immersion time of the concrete specimens. The results show that calcium nitrite and vernonia amygdalina extract reduced corrosion rate compared to sodium nitrite. However, vernonia amygdalina inhibition was more effective in the immersed concrete in simulated seawater. The weight loss results demonstrated that 2% sodium nitrite was more effective with efficiency of 96% in comparison with 2% calcium nitrite and 6% vernonia amygdalina with efficiency of 92% and 75%, respectively. From the results, it is evident that the extract from vernonia amygdalina (bitter leaf) acts as an excellent corrosion inhibitor for rebar steel, efficiency increases with increase in dosage, and the inhibition mechanism was by physical adsorption which is responsible for shielding the specimen from corrosive environment