Steel Corrosion in Concrete at the Marine Tidal Zone: The Roles of Crack Width and Organic Corrosion Inhibitors

Abstract

Organic corrosion inhibitors (OCI) have been widely accepted as a reliable method for enhancing the durability of marine reinforced concrete structures. However, the effect of OCI on steel corrosion is not clear in the case of cracks appearing in the concrete cover. In this paper, steel corrosion behaviors in cracked concrete with different crack widths, intact concrete containing OCI, and cracked concrete containing the OCI exposed to the marine tidal zone were investigated through open-circuit potential tests and EIS measurements. The obtained results illustrate that the corrosion rate of steel in cracked concrete is reduced with the decrease of crack width having an initial width of less than less than or equal to 200 μm in the marine tidal zone. Based on the Rf and Rct values, it is found that the alcohol amine-based OCIs can improve the corrosion resistance of steel in intact concrete and concrete with microcracks (with a width of less than 100 μm) exposed to the marine tidal zone. The carboxylic acid-based OCIs aggravate the steel corrosion due to the hydrophobicity provided by carboxylic acids for seawater transport through cracks. The ester-based OCIs also increase the steel corrosion rate as it accelerates concrete carbonation.