Condition Assessment of Field Structures With Calcium Nitrite

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Title: Condition Assessment of Field Structures With Calcium Nitrite

Author(s): N. S. Berke, M. C. Hicks, and R. J. Hoopes

Publication: Special Publication

Volume: 151

Issue:

Appears on pages(s): 43-72

Keywords: bridge girders; calcium nitrite; chlorides; corrosion; harbor structures; parking facilities; structures; tests; Structural Research

Date: 7/1/1994

Abstract:
Calcium nitrite corrosion inhibitor has been commercially available in the U.S. since 1978. In that period of time, over 200 parking structures, 100 marine structures, and more than 230,000 m 3 (300,000 yd 3) of precast/prestressed bridge girders have been constructed with concrete containing calcium nitrite. In this paper, several of the oldest structures, along with several test sites, were evaluated to determine the corrosion performance. The condition assessment included a visual evaluation of the structure, determination of chloride and nitrite contents in the concretes, and determination of the corrosion activity. The corrosion tests consisted of corrosion potential mapping and polarization resistance testing to determine the corrosion rates at the time of the evaluation. These assessment techniques are applicable to all steel reinforced concrete structures with or without some modifications. The assessment showed that all of the structures with calcium nitrite are performing well. In two cases, there is evidence that corrosion is in progress on adjacent structures that were not protected with calcium nitrite. The nitrite analyses document that calcium nitrite is stable in concrete and remains at the reinforcing bars. Diffusion of chloride is not increased in the concretes with calcium nitrite, and there is evidence of a reduction in chloride penetration in some cases.