Effect of gypsum cement on performance of aluminoferriate cement with Barium element

The effect of gypsum content on the hydration,compressive strength and setting time of Ba-bearing aluminoferriate cement was presented.The proportion of gypsum added into cement was 0%,1%,3%,5%,7%,10% and 12% respectively.The results showed that gypsum restrained early hydration speed of C2.75B1.25A3S and C4AF,lowered the early compressive strength of the cement and prolonged the setting time of cement.AFt was formed by the reacting between gypsum and CxAHy(including CAH10,C2AH8,C4AH19,etc.).The transformation from CAH10,C4AH19 and C2AH8 to C3AH6 was prevented by the reaction.Therefore,the later compressive strength of the cement could be increased stably.And the optimal proportion of gypsum in cement was 7%.