Reinforcement Corrosion Assessment Using Linear Polarisation Techniques


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Title: Reinforcement Corrosion Assessment Using Linear Polarisation Techniques

Author(s): S. G. Millard, K. R. Gowers, and J. S. Gill

Publication: Special Publication

Volume: 128


Appears on pages(s): 373-395

Keywords: chlorides; concretes; corrosion; field tests; impedance; polarization; reinforcing steels; General

Date: 11/1/1991

The assessment of reinforcement corrosion in concrete structures before visible cracking and rust stains occur will enable the engineer to take cost-effective and timely remedial action. While half-cell potential mapping techniques have been used very successfully to indicate the location of active corrosion, this method provides no information on the severity of the corrosion rate and hence the scale of the problem. The linear polarization technique provides a means of assessing directly the rate of active corrosion by measuring the response of the reinforcement to a small perturbative signal. The method has generally been restricted to laboratory studies, due to difficulties in evaluating the region of influence of the test by allowing for a relatively high concrete resistance and in the availability of field instrumentation. This paper reports on the development of unique programmable polarization equipment, enabling corrosion rate measurements to be easily collected and stored on site. The results of laboratory studies on control specimens are compared with those taken from structures in aggressive corrosion environments. Guidance is given on the interpretation of linear polarization results from durability studies for those unfamiliar with the technique.