Physical Model for Steel Corrosion in Concrete Sea Structures—Application

by Zdeněk P. Bažant, (M.ASCE), Prof. of Civ. Engrg.; Northwestern Univ., Evanston, Ill.,

Serial Information: Journal of the Structural Division, 1979, Vol. 105, Issue 6, Pg. 1155-1166

Document Type: Journal Paper


The theoretical physical model developed in a companion paper, is applied to a simplified calculation of corrosion rates and times to corrosion cracking of concrete cover. Setting up approximate estimates of effective resistance of the corrosion cell, and treating oxygen and chloride ion transport through concrete cover as quisi-stationary and one-dimensional, the corrosion problem is reduced to ordinary differential equations in time. For determining the extents of cathodic and anodic areas and the thickness of the rusting layer, a new principle stating that the actual corrosion current is maximum is postulated. Various steady-state corrosion processes are then analyzed, and after developing approximate formulas for the time of steel depassivation due to chloride ions and for cover cracking due to volume expansion of rust, a number of illustrative numerical examples are given. Diffusivities for chloride ions and oxygen are shown to be usually the controlling factors.

Subject Headings: Steel structures | Chloride | Physical models | Structural models | Corrosion | Concrete | Seas and oceans | Concrete structures

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