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7342209 
Journal Article 
Corrosion of reinforcing steel evaluated by means of concrete resistivity measurements 
Morris, W; Vico, A; Vazquez, M; De Sanchez, SR 
2002 
Yes 
Corrosion Science
ISSN: 0010-938X
EISSN: 1879-0496 
44 
1 
81-99 
WOS:000172339500007 
The corrosion behaviour of reinforcing steel bars (rebars) in four different concrete mix designs commonly used at coastal cities in Argentina is studied. The investigation has two basic objectives: (1) to evaluate the influence of certain local variables that affect the rebar corrosion process, among which the common practice of using sea sand as a fine aggregate, exposure conditions and typical mix designs are the most important, and (2) to establish a rebar corrosion evaluation criterion based on measurements of concrete electrical resistivity. Two exposure conditions were investigated: seashore environment and partially immersed in a saline solution. Two water to cements and various chloride ions additions were selected for the study. Electrochemical parameters characteristic of the corrosion process were evaluated together with mechanical, chemical and physical properties of the concrete mixes. Rebars in contact with a good quality concrete (f(c) approximate to 30 MPa) exposed for 1000 days to the seashore environment remained in the passive state, even when its surface chloride concentration reached 0.75% with respect to cement content. This behaviour was even better than that observed on a standard-quality uncontaminated concrete (f(c) approximate to 20 MPa). When immersed in a saline solution, all rebar segments presented an active behaviour (E-corr < -0.35 V vs. copper sulphate electrode and i(corr) > 0.2 muA cm(-2)). although the CR depended primarily on the concrete quality and the initial chloride concentration. The electrical resistivity of concrete has proven to be an effective parameter to evaluate the risk of reinforcing steel corrosion independently of mix design and exposure condition. Rebars are likely to achieve an active state of corrosion when rho is lower than 10 k Omega cm, and likely to present a passive behaviour when concrete resistivity is higher than 30 k Omega cm. (C) 2001 Elsevier Science Ltd. All rights reserved.