Title: Standardizing Test to Quantify Chloride Threshold of Steel in Concrete
Author(s): David Trejo, Naga Pavan Vaddey, and Ceki Halmen
Publication: Materials Journal
Appears on pages(s): 177-187
Keywords: critical chloride threshold; instantaneous corrosion current density; macro-cell current density; open circuit potential
The corrosion performance and service life of reinforced concrete systems exposed to chlorides are commonly assessed using the critical chloride threshold, Clcrit, which represents the chloride concentration required to initiate corrosion at the steel-concrete interface. There is a lack of consensus on an acceptable Clcrit value and this challenge is mainly attributed to the lack of a standard laboratory test method for quantifying Clcrit. This paper introduces a new test method, OCcrit, for quantifying Clcrit. A preliminary study was conducted to evaluate various aspects of the OCcrit test to develop an optimal corrosion test method. Results indicate that the measurement of open circuit potential (OCP) of the reinforcing steel using a Cu-CuSO4 electrode is a quick and reliable way to detect corrosion. Results also indicate that for the test specimens used in this study, a cyclic chloride exposure can be aggressive and can overestimate the chloride concentration at the steel surface needed for corrosion initiation.