Accelerated Corrosion Testing Results for Specimens Containing Uncoated Reinforcing Steel and Corrosion Inhibitors

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Title: Accelerated Corrosion Testing Results for Specimens Containing Uncoated Reinforcing Steel and Corrosion Inhibitors

Author(s): I. L. Kondratova, P. Montes, and T. W. Bremner

Publication: Special Publication

Volume: 192

Issue:

Appears on pages(s): 789-806

Keywords: corrosion; cracking (fracturing); high-performance concrete

Date: 4/1/2000

Abstract:
Concrete slabs containing uncoated reinforcing bars were cast with a concrete cover of 20 mm. The W/C was either .25, .40, and .60. A simulated crack .4-mm wide was formed transverse to the axis of the reinforcing bar. Three types of commercial corrosion inhibitors were added to concrete mixtures for corrosion protection. Slabs were placed in an accelerated exposure cabinet with four cycles of wetting and drying per day in simulated seawater. The corrosion rates were measured using the linear polarization technique. Some of the concrete slabs were broken open at the end of the exposure period and corrosion damage was evaluated. Water-soluble chloride content analysis in the rebar trace was performed at the end of the exposure period for all of the examined specimens. The various types of corrosion inhibitors showed a wide variation in performance and their effectiveness was also found to be particularly sensitive to addition rate. In general all had a greater effectiveness in reducing corrosion rate in a higher water-to-cement ratio concrete than in a lower water-to-cement ratio concrete. Only calcium nitrite at an addition rate of 25 L/m3 provided some level of consistent performance in reducing the corrosion rate in .60 and .40 water-to-cement ratio concrete for uncracked and precracked specimens.