Influence of Calcium Nitrite Inhibitor and Fly Ash on the Corrosion of High-Performance Concrete Slabs Containing a Construction Joint

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Title: Influence of Calcium Nitrite Inhibitor and Fly Ash on the Corrosion of High-Performance Concrete Slabs Containing a Construction Joint

Author(s): P Montes, T. W. Bremner, and D. Mrawira

Publication: Special Publication

Volume: 217

Issue:

Appears on pages(s): 51-70

Keywords: calcium nitrite corrosion inhibitor; chloride content; cracked concrete; fly ash; high performance concrete; water to cement ratio

Date: 9/1/2003

Abstract:
The effects of calcium nitrite based corrosion inhibitor (CNI) and fly ash on the corrosion of high performance concrete subjected to a simulated marine environment were investigated. Small-scale concrete slabs containing steel reinforcement were cast with a cover depth of 20 mm and with a construction joint intersecting the steel reinforcing at right angles. The slabs were subjected to a simulated marine environment with two cycles of wetting and drying per day. Corrosion activity of the reinforcing bars was evaluated using the linear polarization resistance technique and free water-soluble chloride content at the rebar level was determined at the end of the testing period. Testing in areas away from the construction joint and away from corrosion induced cracking revealed that the water to cementitious materials ratio (w/cm) has a significant effect on the ingress of chlorides. Thus, chloride content obtained for 0.29 and 0.37 w/c were less than one third that of 0.45w/c concrete. Furthermore, a reduction in the amount of chlorides at the rebar level was clearly demonstrated when fly ash was used in 0.45w/c concrete.