Influence of LiOH on the expansive behavior of alkali-silica reaction product

Water absorption rate of products of silica reaction with KOH, NaOH and LiOH was studied. Test results show that the water absorption rate of KOH-silica reaction products is the highest followed by NaOH-silica reaction products, the water absorption rate of LiOH-silica reaction products is the lowest. The expansion of siliceous aggregate was compared in different solutions such as LiOH, KOH, LiOH+KOH and the products were studied by SEM/EDS. The results show that LiOH-silica reaction gives rise to less-expansive lithium silicate L-S-H which is fine and close in texture and unreacted aggregate is wrapped up in new-formed lithium silicate and alkali-silica reaction is prevented. LiOH-silica reaction process itself does not lead to expansion. When there is LiOH, K-S-H produced by KOH-silica reaction is transformed into L-S-H because K⁺ in K-S-H is replaced by Li⁺, therefore LiOH can inhibit the expansion due to alkali-silica reaction.