The design and construction phases of a research proqram to develop an effective cathodic protection system for use on bridge substructures are described. Construction of four experimental systems on columns of the Burlington Bay Skyway Bridge was completed in 1982, One sacrificial anode system and three impressed-current systems were installed, each covering approximately 38 m2 of column surface. The sacrificial anode system used zinc ribbon anodes with a shotcrete overcoat. A conductive polymer concrete was used as the primary anode in all the impressed-current systems. In System 1 the anodes were used with a shotcrete overcoat. System 2 consisted of the primary anodes with an exposed secondary anode of conductive paint. System 3 employed a secondary anode network of multifilament carbon strand, also with a shotcrete overcoat. A range of instrumentation was designed and installed to determine the effectiveness and efficiency of the four systems.

Considerable efforts have been expended in recent years to develop methods for the rehabilitation of highway bridges that have deteriorated as a result of the corrosion of embedded reinforcement. Most of this work has concentrated on bridge decks<.! 11_), but similar deterioration is present in substructure elements where it is more difficult and expensive to repair.