No abstract

The Delta Pier located at Naval Base Kitsap in Bangor, Washington has served as the West Coast drydock for the U.S. Navy's Ohio Class submarines since its completion in 1979. A flame-sprayed thermoplastic coating was applied to the sheet piles of the pier in 2000, and that coating system quickly failed. In January 2007, the sheet piles of Delta Pier were inspected for corrosion damage. In concert with the inspection, the Navy requested that a replacement coating system be recommended. Many of the sheet piles on Delta Pier are located behind a relatively dense section of concrete piles that support concrete piers.The close proximity of the concrete piles so severely limits construction access that traditional coating systems, such as high performance organic coating systems or thermal spray aluminum with a sealer, may be economically infeasible. This paper discusses several rehabilitation strategies, the construction constraints, and how these divergent factors were resolved to allow clear recommendations to be made. Additional strategies include covering the sheet pile tidal and splash zone areas with cast-in-place concrete or cladding with a copper nickel alloy.

Cathodic protection (CP) systems were installed on a viaduct in Ketchikan, Alaska, in 2001. Three CP styles were implemented to meet the changing protection needs in several marine environments over varying elevations. The systems installed included galvanic thermal spray zinc metallizing installed on cast-in-place pile caps and precast deck panels in the upper splash and atmospheric zones; fiberglass-reinforced plastic jackets with embedded galvanic zinc mesh anodes installed on the pile caps and piling in the tidal and lower splash zones; and submerged aluminum anodes protecting the piling in the submerged zone. A 2017 inspection found that the systems were still providing protection to most of the cathodically protected areas. In contrast, areas not originally protected with CP showed severe cracking and delamination exacerbated by corrosion of the reinforcing steel. Depolarization testing of CP systems in concrete is often a lengthy process that can take weeks to months to fully achieve. The extreme tidal changes in Ketchikan provided further challenges as measured corrosion potentials in many areas were influenced by tide level. As a result, passivation verification technique (PVT) testing was utilized to provide additional support to the depolarization data. PVT is an alternating current technique that provides a qualitative analysis of the condition of the reinforcing steel by measuring changes in phase angle over a partial spectrum—100, 10, 1, 0.1, and 0.01 Hz. These PVT and depolarization measurements are used to determine if the reinforcing steel is exhibiting passive or active behavior and whether the reinforcement is corroding or protected.