Electrochemical Treatment: Extending the Life of a Historic Viaduct Structure, Ball
Completed in 1915, the historic 12th Street Trafficway Viaduct is a 2,300-foot long reinforced concrete structure that was constructed to link the industrial district in the bottom land along the confluence of the Missouri and Kansas rivers to the commercial district along the bluffs 200 feet above. The Viaduct is undergoing a major restoration program to extend the service life of the 90-year old structure. In 2005, ECE was used to treat the large concrete columns as part of an overall rehabilitation. (read more)
Norcure® and Galvashield® Extend Service Life of I-480 Bridge, Bridge Builder Magazine, 2004
Constructed in the early 1970′s, the mainline structure of the I-480 viaduct through downtown Omaha, Nebraska to the Missouri River consists of 1.5 miles of concrete deck and steel box girders supported by 66 large conventionally reinforced concrete piers. By the mid-1990s, the 30 year-old structure was experiencing deterioration of the concrete deck and concrete substructure. This deterioration was due to chloride-induced corrosion of the reinforcing steel.
In 2002, Norcure Electrochemical Chloride Extraction was used on twenty-six of the piers with the highest chloride contamination levels (approximately 16,000 ft2) and Galvashield XP embedded galvanic anodes were used in the patch repairs on the remaining piers. All piers were then coated to prevent future chloride contamination. (read more)
FDR Drive Rehabilitation: New York Construction Magazine, Best of 2004 “Project of the Year”
Rehabilitating a major thoroughfare in New York City is not a minor event. The Franklin Delano Roosevelt Drive, also knows as East River Drive, carries up to 150,000 vehicles daily along the east side of Manhattan. Built as part of the FDR’s New Deal Program, the FDR Dr. structure from 54th to 63rd was showing signs of age including severe concrete deterioration and extensive water leakage, and was in need of seismic upgrades.
Closing this major traffic artery during rehabilitation was not an option. Therefore, to minimize disruption to the public, the $136 million project required a half-mile outboard detour to be built over the East River from 53rd to 60th streets. This temporary detour will stay in place during the duration of the rehabilitation project which is scheduled to be completed in 2007.
This project was recognized by New York Construction magazine as its Project of the Year for 2004 for ingenuity and innovative engineering.
With the major investment being made to rehabilitate the structure, the New York State DOT was searching for a long-term fix to mitigate on-going corrosion of the reinforced concrete retaining wall which was to remain in place. Their answer was Electrochemical Chloride Extraction, deemed to be one of the most promising technologies to come out of the Strategic Highway Research Program authorized by Congress in 1987. After the damaged concrete sections are repaired, approximately 9,000 ft2 of the reinforced concrete is being electrochemically treated using the Norcure® Chloride Extraction (ECE) process.
Norcure ECE is a temporary electrical treatment that addresses on-going corrosion activity and mitigates future corrosion. By applying a temporary electric field to reinforced concrete, aggressive chloride ions are drawn away from the reinforcing steel. This process also increases the alkalinity of the concrete around the steel thus rebuilding the steel’s natural corrosion-resistant barrier. The ECE process is to be followed by application of a FRP (Fiber Reinforced Polymer) strengthening system to complete the seismic retrofit of the retaining wall. By electrochemically treating the wall, corrosion activity beneath the FRP strengthening system will be minimized thus extending the life of the overall repair.
Additionally, Vector® Galvashield® XP embedded galvanic anodes were used to help mitigate corrosion in the areas surrounding all patch repairs in the roof structure and retaining wall. Galvashield XP consists of a sacrificial zinc core encapsulated in a specially formulated mortar, and is quickly and easily attached to exposed reinforcing steel. Once installed, the zinc core corrodes preferentially to the surrounding rebar, thereby providing galvanic corrosion prevention to the adjacent reinforcing steel.
