- Author
- Clifton, J. R. | Knab, L. I.
- Title
- Selection of Siliceous Aggregate for Concrete.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Sponsor
- Nuclear Regulatory Commission, Washington, DC
- Report
- NISTIR 4327, June 1990, 21 p.
- Distribution
- Available from National Technical Information Service
- Keywords
- aggregates | alkalies | alkali-aggregate reaction | concretes | durability | siliceous aggregate | testing
- Abstract
- Alkali-aggregate expansion reactions are one of the potentially serious degradation problems that could affect the structural stability of underground concrete structures for disposing of low-level radioactive waste (LLW). It appears that all aggregates react to some degree with alkalies in cement. In the majority of cases the reactions are beneficial (e.g., increasing the bond between aggregate and hydrated cement paste) or innocuous. In some cases, however, the reactions result in the formation of expansive products which can cause serious cracking of the concrete. This report deals with the selection of siliceous aggregates to avoid deleterious alkali-aggregate expansions. Current proactices used to prevent expansive alkali-silica reactions and the standard test methods used to identify reactive aggregates are first discussed. Then the results of a study on using a new alkali-silica reactivity test to select siliceous aggregates for use in the concrete of LLW storage structures are presented. It is recommended that siliceous aggregates, selected for constructing underground vaults for disposal of LLW, have an expansion of less than 0.10 percent using the new test.