Combined Effect of Carbonation and Chloride on Corrosion of Reinforcement in Fly Ash Concrete


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Title: Combined Effect of Carbonation and Chloride on Corrosion of Reinforcement in Fly Ash Concrete

Author(s): S. Nagataki and H. Ohga

Publication: Special Publication

Volume: 132


Appears on pages(s): 227-244

Keywords: carbonation; chloride ions; corrosion; curing; mortars (material); fly ash; reinforcing steels; Materials Research

Date: 5/1/1992

Mortars with and without fly ash are cured initially in distilled water or NaCl solution for 7, 28, 56, and 91 days and then exposed to the accelerated carbonation. The influence of chloride ion on the depth of carbonation is evaluated. Furthermore, mortars initially cured in distilled water are exposed to the accelerated carbonation condition and then immersed in NaCl solution to study the influence of carbonation on penetration of chloride ion. In both cases, electrochemical properties of steel reinforcement embedded in the specimen are measured. The penetration depth of chloride ion in fly ash mortar immersed in NaCl solution is larger at an early age, but becomes almost the same as that of the control mortar later. The depth of carbonation of mortar cured initially in NaCl solution is smaller than that in distilled water, and the same trend is observed, independent of initial curing period and the addition of fly ash. Fly ash mortar shows higher carbonation depth than the control mortar. Corrosion current of steel reinforcement in mortar is affected by both carbonation depth and chloride ion penetration.