Are Two Coats as Effective as Three?
Until the late 1970s, virtually all steel bridges in the United States were protected from corrosion by paint systems that consisted of 3 to 5 thin coats of alkyd paint containing toxic lead and chromate. Because the majority of the steel bridges in the interstate system were built between 1950 and 1980, many outlasted their useful service lives. Often, harsh environments and exposure to roadway deicing chemicals (salts) intensify the effects of the natural aging process. Nearly 20 years ago, research led to the current standard, which is a 3-coat system of zinc-rich primer/epoxy/polyurethane paint. Many states use the 3-coat paint system as the preferred method of protection. A new class of coating systems consisting of a zinc-rich primer topcoated with fast-dry, high-build polyaspartics, polyurethane, or polysiloxane promises anti-corrosive results comparable in some situations with the 3-coat systems. These 2-coat systems eliminate the intermediate epoxy layer, so that painting a steel overpass can be completed overnight. When application specifications are followed, 2-coat systems can reduce labor as well, increasing worker productivity and decreasing the overall cost of coating applications. This article discusses how, in order to assess the performance of these new 2-coat systems, the Federal Highway Administration recently conducted a series of lab and outdoor tests that compared the performance of 11 rapid deployment, 2-coat paint systems with that of traditional 3-coat systems.
- Record URL:
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Availability:
- Find a library where document is available. Order URL: http://worldcat.org/oclc/1586080
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Authors:
- Chong, Shuang-Ling
- Yao, Yuan
- Publication Date: 2006-9
Language
- English
Media Info
- Media Type: Print
- Features: Figures; Photos; Tables;
- Pagination: pp 32-38
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Serial:
- Public Roads
- Volume: 70
- Issue Number: 2
- Publisher: Federal Highway Administration
- ISSN: 0033-3735
- Serial URL: https://www.fhwa.dot.gov/publications/publicroads/
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Publication flags:
Open Access (libre)
Subject/Index Terms
- TRT Terms: Anticorrosion coatings; Coatings, fillers and paints; Corrosion protection; Corrosive materials; Maintenance practices; Metal bridges; Protective coatings; Structural deterioration and defects; Zinc rich paint
- Uncontrolled Terms: Bridge maintenance
- Subject Areas: Highways; Maintenance and Preservation; I61: Equipment and Maintenance Methods;
Filing Info
- Accession Number: 01041351
- Record Type: Publication
- Files: TRIS
- Created Date: Jan 30 2007 1:28PM