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Federal Highway Administration > Publications > Focus > November 2008 > FHWA Develops Resources to Prevent and Mitigate ASR in Concrete
November 2008Publication Number: FHWA-HRT-09-008

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FHWA Develops Resources to Prevent and Mitigate ASR in Concrete

Opportunities to learn more about preventing and mitigating alkali-silica reactivity (ASR) in portland cement concrete pavements and structures are now available through the Federal Highway Administration's (FHWA) ASR Development and Deployment Program. Established and funded by the 2005 Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU), the program is designed to increase the durability and performance of concrete pavements and structures and reduce life-cycle costs.

ASR occurs when silica in some aggregates and alkalis in concrete combine with water to form a gel-like substance. As the gel absorbs water and expands, it causes the concrete to crack. Over time, the cracks enable other forms of distress to occur, such as freeze thaw damage or corrosion, leading to premature deterioration and loss in serviceability.

Figure 1. Photo. A close-up of a concrete structure exhibiting cracking as a result of alkali-silica reactivity.
ASR in pavements and structures can lead to premature deterioration.

A primary focus area of FHWA's ASR program is the implementation of field application and demonstration projects. "Deploying both new and currently underutilized technologies and methods for the prevention and mitigation of ASR will allow States to address their ASR issues in a more cost-effective manner and will allow the engineering community to gain valuable data on the long-term performance of these methods and techniques. These efforts will help to significantly advance the state of the practice," says Gina Ahlstrom of FHWA's Office of Pavement Technology. Demonstration projects for pavements and structures wi ll begin in 2009. FHWA will provide technical assistance to States participating in the field demonstrations, including installing instrumentation for data collection and evaluating and analyzing data. FHWA will also develop individual project reports and a final program report based on the results and analysis of all of the field trials. ASR treatments to be used in the field trials will include lithium technologies, silanes, coatings, and fiber-reinforced wraps.

As part of the Development and Deployment Program, FHWA is conducting a parallel ASR research initiative. The research program will develop improved methods to predict and prevent ASR in new construction and mitigate ASR in existing pavements and structures, as well as improve fundamental understanding of the ASR process.

FHWA has launched a free quarterly newsletter, Reactive Solutions, to provide general information on ASR, as well as updates on the ASR Development and Deployment Program. Features include an "Ask the Experts" column, which offers readers the opportunity to submit questions about ASR. The newsletter is available online at www.fhwa.dot.gov/pavement/concrete/asr.cfm. To be added to the mailing list, send an email to Gina Ahlstrom at FHWA, gina.ahlstrom@fhwa.dot.gov, or asrnewsletter@transtec.us.

Two new publications on ASR will be available from FHWA this winter: Report on Determining the Reactivity of Concrete Aggregates and Selecting the Appropriate Measures for Preventing Deleterious Expansion in New Concrete Construction and Report on Diagnosis, Prognosis, and Mitigation of Alkali-Silica Reaction in Transportation Structures. The reports will be available at www.fhwa.dot.gov/pavement/concrete/asr.cfm.

FHWA is also developing an online ASR Reference Center. "The goal of the reference center is to provide State engineers and other practitioners with resources and information on ASR that are readily accessible," says Ahlstrom. Resources will include ASR research reports and guidance documents; information on various State ASR specifications; and details on past, current, and planned field trials. FHWA expects to launch the reference center online by spring 2009.

For more information on the ASR Development and Deployment Program or hosting a field trial in your State, contact Gina Ahlstrom in FHWA's Office of Pavement Technology, 202-366-4612 (email: gina.ahlstrom@fhwa.dot.gov). To learn more about the research portion of the program, contact Paul Virmani at FHWA, 202-493-3052 (email: paul.virmani@fhwa.dot.gov). Information on the program is also available at www.fhwa.dot.gov/pavement/concrete/asr.cfm.

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Updated: 04/07/2011

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