This paper studies the reaction between alkaline metal ions Li＋, Na＋ and K＋ and ASR （alkali-silica reaction） reactive aggregates to determine whether Li＋ can substitute Na＋ and K＋ that are unified in cement pa...This paper studies the reaction between alkaline metal ions Li＋, Na＋ and K＋ and ASR （alkali-silica reaction） reactive aggregates to determine whether Li＋ can substitute Na＋ and K＋ that are unified in cement paste. Reactive aggregates use meta-sandstone from eastern Taiwan and Pyrex glass. Non-reactive aggregates use siliceous sand. The results show that the dissolved amount of SiO2 is lower when the reactive aggregates are immersed in an 80 ℃1 N LiOH＇H20 solution than in NaOH and KOH solutions. The reduced amounts of OH and Li＋ in the solution are also higher than those in the NaOH and KOH solutions. These results reveal that reactive SiO2 can react with LiOH to form a reactant with low water solubility. When the powder of the cement paste is immersed in an 80 ℃ 1 N LiOH-H2O solution, the amounts of free Na＋ and K＋ in the solution are higher than those in water. The increased amount increases with the duration of immersion. The amount of Li＋ in the solution also decreases with the duration of immersion. These results reveal that Li＋ can substitute Na＋ and K＋ that are unified in cement paste, which indicates that ASR can be prevented with the existence of Li＋.展开更多
The influences of different alkaline conditions on the kinds and morphologies of steel slag＇s hydration products, Ca（OH）2 con- tent of hydration products, pore stiucture of hardened paste, non-evaporable water cont...The influences of different alkaline conditions on the kinds and morphologies of steel slag＇s hydration products, Ca（OH）2 con- tent of hydration products, pore stiucture of hardened paste, non-evaporable water content of hydration products, and strength of steel slag mortar were investigated by changing the initial alkalinity of the hydration condition of steel slag. The results showed that increasing the initial alkalinity of hydration condition can promote the early hydration of steel slag＇s active com- ponents （e,g., C2S, C3S, and C12A7）, but it has little influence on their late-age hydration degree. The hydration degree of non-active components （e.g., RO phase and Fe304） of steel slag is very low even under strong alkaline condition with pH value of 13.8. The excitation effect of alkaline condition on the early hydration of steel slag is more obvious with the increase of pH value, but the kinds of steel slag＇s hydration products are not influenced by changing the alkaline condition. The amount of steel slag＇s hydration products is limited, so the strength of alkali-activated steel slag mortar is very low though the strong al- kaline condition significantly promotes the early hydration of steel slag. Steel slag is not an ideal raw material for alka- li-activated cementitious material.展开更多
文摘This paper studies the reaction between alkaline metal ions Li＋, Na＋ and K＋ and ASR （alkali-silica reaction） reactive aggregates to determine whether Li＋ can substitute Na＋ and K＋ that are unified in cement paste. Reactive aggregates use meta-sandstone from eastern Taiwan and Pyrex glass. Non-reactive aggregates use siliceous sand. The results show that the dissolved amount of SiO2 is lower when the reactive aggregates are immersed in an 80 ℃1 N LiOH＇H20 solution than in NaOH and KOH solutions. The reduced amounts of OH and Li＋ in the solution are also higher than those in the NaOH and KOH solutions. These results reveal that reactive SiO2 can react with LiOH to form a reactant with low water solubility. When the powder of the cement paste is immersed in an 80 ℃ 1 N LiOH-H2O solution, the amounts of free Na＋ and K＋ in the solution are higher than those in water. The increased amount increases with the duration of immersion. The amount of Li＋ in the solution also decreases with the duration of immersion. These results reveal that Li＋ can substitute Na＋ and K＋ that are unified in cement paste, which indicates that ASR can be prevented with the existence of Li＋.
基金supported by the National Natural Science Foundation of China (Grant No. 51108245)the National Basic Research Program of China ("973" Project) (Grant No. 2009CB623106)
文摘The influences of different alkaline conditions on the kinds and morphologies of steel slag＇s hydration products, Ca（OH）2 con- tent of hydration products, pore stiucture of hardened paste, non-evaporable water content of hydration products, and strength of steel slag mortar were investigated by changing the initial alkalinity of the hydration condition of steel slag. The results showed that increasing the initial alkalinity of hydration condition can promote the early hydration of steel slag＇s active com- ponents （e,g., C2S, C3S, and C12A7）, but it has little influence on their late-age hydration degree. The hydration degree of non-active components （e.g., RO phase and Fe304） of steel slag is very low even under strong alkaline condition with pH value of 13.8. The excitation effect of alkaline condition on the early hydration of steel slag is more obvious with the increase of pH value, but the kinds of steel slag＇s hydration products are not influenced by changing the alkaline condition. The amount of steel slag＇s hydration products is limited, so the strength of alkali-activated steel slag mortar is very low though the strong al- kaline condition significantly promotes the early hydration of steel slag. Steel slag is not an ideal raw material for alka- li-activated cementitious material.
