The National Academies

NCHRP 10-45 [Completed]

Procedures for Evaluating Corrosion-Inhibiting Admixtures for Structural Concrete

  Project Data
Funds: $274,848
Research Agency: CC Technologies Laboratories, Inc.
Principal Investigator: Neil G. Thompson
Effective Date: 12/1/1995
Completion Date: 3/31/1999

The project evaluated potential procedures for evaluating corrosion-inhibiting admixtures for structural concrete, and documented state departments of transportation use of corrosion-inhibiting admixtures.

During the past 20 years, corrosion-inhibiting admixtures have become increasingly popular for long-term protection of reinforced and prestressed concrete components of highway bridges and other structures. However, there has been considerable debate recently about the benefits of corrosion-inhibiting admixtures in concrete. In 1992, a Joint Committee of the American Association of State Highway and Transportation Officials (AASHTO), the Associated General Contractors (ACG), and the American Road and Transportation Builders Association (ARTBA), through Task Force Number 32, prepared a Manual for Corrosion Protection of Concrete Components in Bridges. The manual addresses the various systems, including corrosion-inhibiting admixtures, available to provide corrosion protection for bridge components. However, neither this manual nor other publications provide specifications or guidelines to help engineers evaluate and compare corrosion-inhibiting admixtures. In the absence of such information, engineers frequently rely on information provided by product manufacturers when making evaluations and recommendations. This information, in many cases, is not based on well-defined, consistent procedures; therefore there is a need to develop a set of tests for evaluating corrosion-inhibiting admixtures to enable engineers to make more rational product comparisons and recommendations.

The research included a review of relevant domestic and foreign literature and current practices relative to use, testing, and evaluation of corrosion-inhibiting admixtures; a survey and documentation of state departments of transportation use of corrosion-inhibiting admixtures; and the conduct of laboratory tests to evaluate potential methods for evaluating corrosion-inhibiting admixtures. The research revealed that the evaluated procedures exhibited certain inconsistencies and raised concerns about their applicability; a validated procedure for evaluating corrosion-inhibiting admixtures was not developed. The agency final report has been distributed to all members of the AASHTO Highway Subcommittee on Materials, and is available on the NCHRP website as NCHRP Web Document 29.

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