Investigation of alkali-silica reaction inhibited by new lithium compound

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 Li ₂CO₃ dosage, the higher the strength reduction. Moreover, both the initial and final setting time were shortened when Li ₂CO₃ 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.