The Mechanism Of Effect Of Metakaolin On Cement Hydration Process

This paper is about the effect of the strength of cement mortar on different calcining temperature(650 ℃, 750 ℃, 850 ℃) of metakaolin. On the premise of the same fluidity, The best content of metakaolin in cement mortar is 10% and need to increase the amount of water. It can improve the strength of cement mortar. The metakaolin of ZGE650 and JY750 works best. After adding metakaolin can increase the hydration rate of cement, Especially in the early hydration.The induction period of the end of the time in advance and Hydration exothermic quantity(3d) have different degree of reduced. Including ZGE650 and JY750 promotion effect is best, The second is GH650 and GH850. Differential thermal test of metakaolin results show that improve the endothermic peak of Ca(OH)2 in the early hydration(2d).First the endothermic peak of Ca(OH)2 of ZGE650 and JY750 is higher, it can promote the hydration. Three days after hydration, the endothermic peak of Ca(OH)2 of metakaolin decreased significantly,its show that a certain amount of secondary hydration. In this paper, the hydration kinetics were studies. Five groups of gelled material sample(Cement,GH650,GH850,ZGE650,JY750) are controlled by NG- I- D process. Cement、GH650 and GH850 have longer time through the process of the I,but ZGE650 and JY750 have short time through the process. After mixed with ZGE650 and JY750, the hydration of composite gelled material becomes strong, control mechanism is also changing, reaction process is accelerated and the acceleration effect of these two kinds of metakaolin has strong. Metakaolin and silica fume can improve the compressive strength of concrete. or silica fume, content of 10% is for the most appropriate. For activity characteristics of two different kinds of metakaolin(MKA、MKB), MKA is more active than the MKB(content of 8%); MKBis more active than the MKA(content of 10%).