Evaluation of corrosion inhibiting admixtures for steel reinforcement in concrete

Abstract

Inhibitors are added to concrete to improve its quality and integrity. The various inhibitors used in the construction industry to salvage the book or service life of steel reinforcement in concrete structures are broadly classified into organic and inorganic corrosion inhibitors and other methods which include cathodic protection, coatings to the reinforcement, penetrating sealers and chloride removal. In recent years, the use of these inhibitors in producing high performance concrete has increased significantly. Organic base (Amine) and inorganic base (Nitrite) have been known for protection of concrete structures but are not commercially indigenous to most developing economies due to manufacturing difficulties and are toxic to the environment. Also the inhibitors are not known to stop chloride attack in concrete. Hence, the objective of the present investigation was to study a novel, eco-friendly and hydrophobic green plant extracts inhibitor and compares its effectiveness with calcium nitrite and ethanolamine inhibitors. Bambusa arundinacea (Green plant extracts), calcium nitrite and ethanolamine corrosion inhibitors were selected for the present investigation. Compressive strength, electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) technique were used for 180 days of exposure. The results of the inhibitors studied showed that B. arundinacea has superior compressive strength and the corrosion rate was the lowest compared to calcium nitrite and ethanolamine. B. arundinacea may be considered a better substitute for nitrite and amine- based corrosion inhibiting admixtures for durable concrete structures due to its hydrophobic effects and environmentally benign.