Title : ISSUES WITH THE APPLICATION OF POTENTIAL GRADIENT IN EVALUATING THE PERFORMANCE OF CORROSION INHIBITORS IN STEEL-CEMENTITIOUS SYSTEMS
Authors : Jayachandran Karuppanasamy, Radhakrishna G. Pillai
Publication : 8 - 10, October 2015
Volume : 2
Pages :
Price : 250
Abstract : The critical chloride threshold (Clth) of steel-cementitious system is defined as the concentration of chloride ions required at the surface of embedded reinforcement to initiate corrosion. The Clth can be increased by using integral corrosion inhibitors (say, calcium nitrite). The testing procedures can have significant influence on the measured Clth values – leading to possibly erroneous conclusions. Many researchers have used external potential to accelerate and drive chlorides towards the embedded steel during various corrosion tests. This paper briefly explains one such test procedure followed to detect the corrosion initiation and the issues/drawbacks in using such external potential while testing Clth in systems with calcium nitrite inhibitors. A separate set of tests found that the Cl- and (NO2)2-concentrations at the steel surface can significantly increase and the value of [Cl-]/[(NO2)2-] at the steel surface can significantly decrease upon the application of external potential. Therefore, Clth determined will not be realistic. Thus, the test method in which an external potential is applied across the cover concrete/mortar is not recommended to determine the Clth of steel embedded in complex cementitious system with corrosion inhibitors.