Title:
Investigation of Alkali-Silica Reaction Inhibited by New Lithium Compound
Author(s):
X. Mo, Y. Zhang, C. Yu, M. Deng, M. Tang, K.-J. Hunger, and B. Fournier
Publication:
Materials Journal
Volume:
107
Issue:
1
Appears on pages(s):
37-41
Keywords:
alkali-aggregate reaction; alkali-silica reaction; lithium compounds; performance.
DOI:
10.14359/51663463
Date:
1/1/2010
Abstract:
First, the effectiveness of Li2CO3 against alkali-silica reaction (ASR) associated with a practical reactive aggregate was evaluated. The long-term effectiveness of Li2CO3 in suppressing ASR was confirmed. Furthermore, the effective lithium dosage, as a function of alkali content of cement-based materials, varies from 0.3 to 0.6 Li/(Na + K) molar ratio. Second, the influence of cement types on the effect of Li2CO3 against ASR was also studied. It was found that larger expansion occurred with high-alkali cement than lowalkali cement either with or without Li2CO3, although the final alkali content was increased at the same level by adding KOH. This may be due to a relatively lower proportion of the total alkalis being incorporated in the cement hydrates, then, a higher proportion remains in the cement or concrete pore solution when the high-alkali cement is used versus the low-alkali cement. Third, the influence of Li2CO3 on the strength and setting times of cementbased materials was performed. Results showed that mortar strength would decrease when Li2CO3 was added, and the higher the Li2CO3 dosage, the higher the strength reduction. Moreover, both the initial and final setting time were shortened when Li2CO3 was added, and the higher the Li/(Na + K) molar ratio of Li2CO3, the shorter the setting time. Finally, evidences of effectiveness of Li2CO3 against alkali-silica reaction expansion was examined to confirm the hypothesis that because of having a smaller ionic radius and a higher surface charge density, the Li+ ions are more readily incorporated in the alkali-silica reaction product than Na+ or K+ ions, and the lithium-bearing ASR product is crystalline and nonexpansive.