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Federal Highway Administration > Publications > Focus > July 2009 > FHWA Launches Online ASR Reference Center
Publication Number: FHWA-HRT-09-015
Date: July 2009

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FHWA Launches Online ASR Reference Center

The Federal Highway Administration (FHWA) launched a new online Alkali-Silica Reactivity (ASR) Reference Center this spring, providing users with one-stop access to ASR-related information. Located at, the site features an overview of ASR, as well as research reports, specifications, guidance documents, case studies, and links to other useful Web sites.

ASR occurs when silica in some aggregates and alkalis in cement 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 a reduction in service life.

Users can provide feedback on information they would like to see included in the ASR Reference Center by contacting Gina Ahlstrom at FHWA, 202-366-4612 (email: More information on ASR is also available in FHWA's free quarterly newsletter, Reactive Solutions. To subscribe to the newsletter, send an email to Past issues of Reactive Solutions are available online at

Figure 6. Screenshot. A screenshot of FHWA's new Alkali-Silica Reactivity (ASR) Reference Center Web site (

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Updated: 02/20/2015

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