Performance Evaluation of Protective Coatings on Corrosion resistance in Transmission Line Tower foundations

Corrosion of steel angles in concrete has become one of the menacing problems on durability aspects, which influence the service life of the structures. The life cycle cost of transmission tower foundations, which are corrosion prone has increasingly, become difficult to manage. Failures in their transmission line components amounts to thousands of dollars only in maintenance costs apart from other related expenditures. Many of these failures are corrosion related due to the exposure of the system materials to aggressive atmospheric and/or soil environments.

Transmission line towers running close to coastal area are attacked by chlorides and sulphates and the towers in the vicinity of chemical, petro chemical, fertilizer and other industries are subjected to aggressive chemical attacks. Because of the extreme climate conditions prevailing in certain areas, transmission line tower stubs/coping/muffing concrete have been severely deteriorated and stub angle were corroded very much. During submergence of stub steel above concrete chimney for some period in rainy season, water acting as salt dissolved electrolyte, the corrosion process is aggravated particularly in the presence of chlorides and phosphates. A mechanism of pitting or crevice corrosion will initially occur in the presence of aggressive chloride ions. Application of Protective coating to steel angles and addition of admixtures to the concrete is one of the best method of controlling corrosion in steel angle. Effect of providing coatings on stub angle, addition of admixtures in stub concrete, corrosion inhibitors and barrier coatings onstub concrete against corrosion had been investigated in the laboratory under accelerated environmental condition.