51313-02747-Critical Localized Corrosion Penetration of Steel Reinforcement for Concrete Cover Cracking

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Product Number: 51313-02747-SG

ISBN: 02747 2013 CP

Author: Ezeddin Busba

Publication Date: 2013

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Corrosion of steel in concrete causes cracking of the concrete cover C when the metal loss reaches a critical penetration depth Xcrit. The value of Xcrit is important to formulate reliable models of the propagation stage. Corrosion of steel in concrete is commonly localized especially in high quality concrete structures. Localized corrosion can occur due to preexisting cracks in cover concrete concrete joints or defects in steel coatings. It has been shown previously that the value of Xcrit increases as corrosion becomes more localized but scarce data did not enable reasonable extrapolation to the case of small corroding lengths as may be encountered at the intersection of rebar with preexisting narrow cracks. This investigation determines Xcrit for cases of small corroding lengths (L) down to L/C=0.2 including tests with conditions overlapping those of the earlier work to provide the basis for a more precisely established relationship. The tests were conducted with reinforced concrete cylinders having a central composite reinforcement rod of diameter D with a short plain steel central segment bounded by highly corrosion resistant Alloy 22 bars. Corrosion was induced by impressed anodic current and quantified by total charge and gravimetric determinations. The present results confirmed the trend of increasing values of Xcrit as L/C decreased. A refined functional relationship was proposed for Xcrit D C and L based on the added findings. A modeling simulation was implemented using a thick-walled cylinder approach to obtain insight on the phenomena responsible for the relationship.