Abstract
The use of vapour phase inhibitors is an effective method for protecting steel bar embedded in concrete. The major cause of corrosion damage to steel in RCC, even for high quality concrete is chloride ion attack. The use of VCI could enhance service life of RCC even under chloride attack. The method of application differs. In new structures inhibitors are admixed in sufficiently high concentration to the fresh concrete, whereas in existing structures surface application or even injection of VCI into concrete can be done. The science and technology of VCI is a developing area and mechanism of migration, adsorption on steel surface, interaction with corroded steel, etc., have not been fully explained. However, the surface application of VCI for repairs to existing structure has been accepted as part of repair scheme in European Standards. In Indian tropical conditions the VCI has been evaluated at elevated temperatures by subjecting RCC specimens to thermal cycles at 60°C. The evaluation of VCI for steel in concrete suffers for want of proper standards. Only two standards ASTM G 109 & JIS-A-6205 are available for evaluation. The development of standards could pave way for large-scale use in the field.
