U.S. Department of Transportation
Federal Highway Administration
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Washington, DC 20590
Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
This magazine is an archived publication and may contain dated technical, contact, and link information.
|Publication Number: Date: November/December 2003|
Issue No: Vol. 67 No. 3
Date: November/December 2003
Below are brief descriptions of products recently published online by the Federal Highway Administration's (FHWA) Office of Research, Development, and Technology. Some of the publications also may be available from the National Technical Information Service (NTIS). In some cases, limited copies are available from the Research and Technology (R&T) Product Distribution Center.
When ordering from NTIS, include the NTIS publication number (PB number) and the publication title. You also may visit the NTIS Web site at www.ntis.gov to order publications online. Call NTIS for current prices. For customers outside the United States, Canada, and Mexico, the cost is usually double the listed price. Address requests to:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Toll-free number: 800-553-NTIS (6847)
Address requests for items available from the R&T Product Distribution Center to:
R&T Product Distribution Center, HRTS-03
Federal Highway Administration
9701 Philadelphia Court, Unit Q
Lanham, MD 20706
For more information on research and technology publications from FHWA, visit the Turner-Fairbank Highway Research Center's (TFHRC) Web site at www.fhwa.dot.gov/research/tfhrc/, FHWA's Web site at www.fhwa.dot.gov, the National Transportation Library's Web site at http://ntl.bts.gov, or the OneDOT information network at http://dotlibrary.dot.gov.
Guidelines for the Use of Lithium to Mitigate or Prevent ASR
Publication No. FHWA-RD-03-047
Alkali-silica reaction (ASR) is a significant durability problem that results in premature deterioration of various types of concrete structures in the United States and throughout the world. Although several viable methods exist to prevent ASR-induced damage in new concrete structures, few methods mitigate further damage in structures already affected by expansion and cracking due to ASR. For more than 50 years, researchers have recognized that lithium compounds effectively prevent expansion caused by ASR, and in recent years there has been renewed interest in using lithium compounds either as an admixture in new concrete or as a treatment for existing structures. This report provides practitioners with the necessary information and guidance to test, specify, and use lithium compounds in new concrete construction and in applications to repair and extend service life.
First, the report provides a basic overview of ASR, including information on mechanisms, symptoms of damage in field structures, mitigation approaches, test methods, and specifications. A comprehensive summary of lithium compounds follows, including information on their production, availability, and use in concrete studies in the laboratory and in field applications (including a range of case studies). Next, the authors present guidelines for using lithium compounds as an admixture in new concrete and for testing existing structures suffering from ASR-induced damage, including information on how to assess the efficacy of lithium compounds in laboratory tests. Some basic information also is provided on the economics of using lithium in new concrete and as a treatment for existing structures. Finally, the report provides a summary of conclusions and identifies several technical and practical issues that should be considered for future laboratory studies and field applications.
Optimal Procedures for Quality Assurance Specifications
Publication No. FHWA-RD-02-095
This manual is a comprehensive guide that a highway agency can use when developing or modifying specifications for acceptance plans and quality assurance. It provides necessary instruction and illustrative examples to lead the agency through the entire process of developing acceptance plans, including:
Long-Term Effectiveness of Cathodic Protection Systems on Highway Structures
Publication No. FHWA-RD-01-096
Based on extensive study, FHWA researchers conclude that cathodic protection-the technology used to mitigate corrosion of metals embedded in concrete-is the only rehabilitation technique that has proven to stop corrosion in salt-contaminated bridge decks regardless of the chloride content of the concrete. This technology is based on applying an external source of current to counteract the internal corrosion current produced in reinforced concrete components. During cathodic protection, current lows from an auxiliary anode material through the electrolyte (concrete) to the surface of the reinforcing steel. Assorted materials in different configurations are used as auxiliary anodes for cathodic protection, resulting in various types of systems. The selection of the anode material and its configuration is paramount to the success of the system. The primary objective of this 5-year study was to determine the effectiveness of various materials and configurations when used as auxiliary anodes on highway structures during a long-term evaluation.
In this study, researchers looked at 20 highway structures (19 bridges and 1 tunnel) protected by one or more cathodic protection systems. The structures, located in 11 States and 1 Canadian Province, were protected by a total of 19 impressed-current and 5 galvanic systems. FHWA selected most of the structures based on previous studies performed under the Strategic Highway Research Program; the current study was funded under the continuation of that program.
The findings of the study summarize the protection provided by the systems evaluated and estimate the expected service life for the anode materials in similar environments. On some structures, the systems were operated at insufficient output current, resulting in poor performance. If these systems had been operated at higher output currents, their performances would have been rated higher.