The Long-Term Monitoring of Large-Scale Concrete Specimens Containing Lithium Salts to Mitigate Alkali-Silica Reaction

摘要

The effectiveness of lithium salts to prevent alkali-silica reaction (ASR) in laboratory samples has been known since the early 1950s; however, the long-term effectiveness of lithium on concrete in the field has not yet been established. This paper details the long-term exposure of large-scale concrete specimens and one monitored concrete pavement section subjected to outdoor field conditions containing either lithium hydroxide (LiOH) or lithium nitrate (LiNO3) as an admixture to control ASR. Four different locations were chosen to investigate the impact of varying climatic conditions on the progression of ASR in concrete, including three land-based sites: Austin, Texas (USA), Ottawa, Ontario (Canada), and one marine site at Treat Island off the coast of Eastport, Maine (USA). A concrete pavement containing lithium (LiOH) in New Mexico, USA, was also monitored for 18 years since placement. The results of these studies confirm that different dosages are needed depending on the aggregate mineralogy, based on realistic exposure conditions, and it may take up to 16 years (or even more) for some concretes to begin deteriorating based on exposure conditions and the reactivity of the aggregate. Combinations of lithium and fly ash have shown that both synergistically beneficial and detrimental effects (e.g. increased expansion) may occur.