Find out the latest technology for treating and preventing alkali-silica reactivity (ASR) in concrete at a new workshop series sponsored by the Federal Highway Administration (FHWA). ASR is a pervasive durability problem that strikes beneath the surface of portland cement concrete (PCC), causing premature deterioration of various types of concrete structures across the country and worldwide. It occurs when silica substances in aggregates react with alkali in the cement and absorb water. The result is a gel-like mass that can cause the concrete to expand and eventually crack, potentially causing severe damage. The development of ASR also can expedite other damages to the concrete, such as freeze-thaw or corrosion of reinforcing steel.
As the workshop details, lithium compounds, which have been recognized for more than 50 years as being effective in preventing concrete expansion due to ASR, are now getting increased exposure as a method of both treating existing structures and preventing ASR in new construction. With more state highway agencies setting goals for building longer-life pavements and structures, preventing and treating ASR is becoming even more important. Using lithium compounds, especially lithium nitrate (LiNO3), is a viable approach to controlling ASR-induced damages.
The FHWA workshops provide practitioners with the necessary information and guidance to test, specify and use lithium compounds in new concrete construction, as well as to repair and extend the service life of existing structures. The workshop provides a basic overview of ASR, including information on mechanisms, symptoms of ASR damage in field structures, mitigation approaches, test methods and specifications. The workshop then presents a comprehensive summary of lithium compounds, including information on their production, availability, use in laboratory concrete studies and field applications. In addition, participants can learn from a range of case studies. The workshop also covers:
* Guidelines for using lithium compounds as an admixture in new concrete and as a method of treating existing structures suffering from ASR-induced damage;
* Information on how to assess the effectiveness of lithium compounds in laboratory tests;
* Information on the economics of using lithium both in new concrete and as a treatment for existing structures; and
* A summary of technical and practical issues that should be considered for future laboratory studies and field applications.
To date, workshops have been held in Nebraska, New Hampshire, California and Vermont. A second California workshop will be held in Los Angeles in September. Other states looking at scheduling workshops this fall include Texas and Delaware. There is no charge to highway agencies for the workshop, but they are responsible for hosting the event and providing the necessary facilities.
For more information on the workshop or to find out more about scheduling a workshop in your state, call 202/493-3076; fax: 202/493-3161; e-mail: [email protected].
Information on the use of lithium to combat ASR also is available in a new FHWA publication, Guidelines for the Use of Lithium to Mitigate or Prevent ASR, by K.J. Folliard, M.D.A. Thomas and K. Kurtis. Copies can be requested from FHWA's Product Distribution Center, 9701 Philadelphia Court, Unit Q, Landham, MD 20706 (phone: 301/577-0818; e-mail: [email protected]).
