AWARD OF MERIT: Transportation Category

GARDEN CITY SKYWAY SUBSTRUCTURE CORROSION MITIGATION

Downsview, Ontario, Canada

Submitted by Vector Construction Group

Deteriorated and open deck joints allowed chlorides to penetrate and contaminate the substructure of the Garden City Skyway over the years. By 2005, the Garden City Skyway was exhibiting significant deterioration of the concrete pier caps and columns. Reinforcing steel corrosion was causing concrete delamination and spalling. Previous conditions surveys carried out on the substructure indicated some degree of defects in all piers surveyed. The condition of the piers varied from acceptable to poor, with the majority in fair condition.

The Ministry of Transportation Ontario (MTO) decided to undertake a major rehabilitation program for the pier caps and columns. Passive cathodic protection was considered by MTO to address the corrosion problem and prolong the service life of the structure.

In 2006, activated arc spray zinc was used as part of an overall repair and corrosion protection strategy to extend the life of the Garden City Skyway substructure. The activated arc spray zinc was used to provide passive cathodic protection to the piers with less than 15% of the concrete surface area having concrete damage (such as delamination and spalling) and greater than 20% of the sound concrete surface area with high corrosion potentials.

Based on data collected from a monitored section, the activated arc spray zinc is estimated to provide over 35 years of passive cathodic protection, thus significantly prolonging the service life of the structure.

Owner
Ministry of Transportation Ontario
Downsview, Ontario, Canada

Project Engineer/
Designer
Totten Sims Hubicki Associates
Whitby, Ontario, Canada

Repair Contractor
Vector Construction Group
Stoney Creek, Ontario, Canada