Basic Study on Corrosion Controlling Mechanism of Nitrite Ion and Its Effectiveness in Concrete
Satoshi TAKAYA, Yuhji SUDOH, Tomohiro NAITO, Kazunori ERA, Takashi YAMAMOTO and Toyoaki MIYAGAWA
Abstract:Lithium nitrite injection method has been employed in recent years to prevent ASR due to the presence of lithium ion. Meanwhile, in the presence of nitrite ion, lithium nitrite is also expected to inhibit steel corrosion in concrete when water, oxygen and chloride ion may ingress through ASR-induced cracks. Consequently, lithium nitrite is applied to repair concrete section either combined in patching material or being a coating material. Despite of its widespread application, quite a few problems on corrosion-inhibiting mechanism of nitrite ion have not been fully understood yet. How to evaluate the effect of nitrite ion and its related risk of macro-cell corrosion is among them. Purpose of this study is to investigate the corrosion-inhibiting mechanism of nitrite ion based on polarization tests of steel bars corroded under various kinds of corrosion conditions. A further discussion on the application of nitrite ion is present upon the test results. Key Words:Concrete, Reinforcement steel, Corrosion, Corrosion prevention, Repair