Alkali-Silica Reaction Prevention by Lithium Salts

Paper by ANDIÇ RAMYAR from ISCR 9th 2004 Instanbul Turkey

After the exploration of damages caused by alkali-silica reaction (ASR) on highway bridges in Turkey recently, the usage of reactive aggregate on highway construction was prohibited. However, this does not seem to be the proper solution, because natural aggregate leads to an increase in workability of concrete due to its round shape. Reducing the alkali content of cement or preventing highway bridges and concrete roads from moisture are not economical solutions. Thus, the effects of mineral and chemical admixtures on ASR expansions are being studied. In this study, ASTM C1260- Accelerated Mortar Bar Test was used to evaluate the effects of lithium salts on ASR expansions. For this purpose, two types of reactive aggregates and Li2CO3, LiF and LiNO3 salts were used. Li2CO3 salt was used as 0.5%, 0.75%, 1%, 2% and 3%; while LiF and LiNO3 salts were used as 0.5%, 0.75% and 1% by weight of cement. The expansions less than 0.1% in 14-days as specified by the standard were evaluated as effective. The test results revealed that Li2CO3 salt was effective when used as beyond 1%, while in lower percentages of usage the expansions were above the limit. LiF was effective in all percentages used; while LiNO3 was not effective in all of the percentages of usage.

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