Abstract

The Burlington Skyway consists of two parallel high-level bridges that allow Great Lakes cargo ships to cross under the Queen Elizabeth Way highway in Burlington, Ontario. The first bridge opened to traffic in 1958 and was the site of the first Electrochemical Chloride Extraction (ECE) project in North America. Years of leaking joints had allowed salt-contaminated water to penetrate the large concrete piers with chlorides to initiate corrosion of the reinforcing steel.

The ECE process uses an impressed current power supply and a temporarily installed anode system to electrochemically treat reinforced concrete structures. As with any impressed current system, the ECE process generates hydroxyl ions at the steel surface and reduces the concentration of chlorides around the steel such that the structure is left in a passive, non-corroding condition at the end of the treatment process.

In 1989, the Ministry of Transportation Ontario (MTO) authorized a demonstration of a relatively new technology which can passivate corroding steel and has subsequently become known as Electrochemical Chloride Extraction (ECE). This process is more accurately described as Electrochemical Passivation of Chloride-contaminated Concrete (EPCC). After monitoring the original pilot installation for eight years, MTO proceeded to implement the ECE process on major substructure rehabilitation projects on the Burlington Skyway in 1997 and 1999. These projects included application of the EPCC process to approximately 20,000 ft2 of chloride-contaminated, reinforced concrete bridge substructure components. MTO has also applied the process to five other bridges in Ontario.

The initial area treated in 1989 has been monitored for 30 years and the other EPCC rehabilitated substructure components have been in service for 22 and 20 years since they were treated. All treated sections were inspected in 2020, more than 30 years after the initial area was treated and are in in good condition.

This paper provides an overview of the electrochemical passivation process, history of the Burlington Skyway, description of the installation process, treatment results and up to 30 years of monitoring results for the structure.

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