Alkali-silica reactivity (ASR), a chemical reaction between portland cement concrete and certain aggregates, can directly cause severe damage in concrete pavements and structures or can expedite other reactions that in turn cause damage, such as freeze-thaw or corrosion related damage. The Lead States Team for ASR helped other States understand this chemical reaction and learn how they can take preventive and remedial actions.
From 1995 to 2000, the members of the Lead States Team for ASR, with the assistance of partners from universities, industry, and the Federal Highway Administration, was engaged in several projects to accomplish its goals of increasing awareness of ASR; developing guidelines and encouraging use of technologies for treating and preventing ASR; and completing research projects begun under the Strategic Highway Research Program. These projects included testing new in-service pavements to determine which concrete mixes and additives prevent ASR-related damage and developing a new, environmentally safe screening test for ASR in existing concrete.
In September 2000, the Alkali-Silica Reactivity Team transferred its responsibilities to the Subcommittees on Materials and Construction of the American Association of State Highway and Transportation Officials (AASHTO). The Team prepared a Transition Plan detailing the results of their work and recommendations for the future.
The AASHTO subcommittees will assume responsibility for continuing/follow-on work of the ASR Lead States team. The Team reports that the following tasks need additional work:
- Provide construction guidance for designing ASR-resistant Portland cement concrete and managing ASR in existing concrete.
- Continue to collect and distribute ASR information under one umbrella.
- Develop methods that will rapidly and reliably evaluate performance of concrete mixtures for ASR susceptibilitiy.