Effect of different varieties of gypsum on performance of low-heat Portland cement and its mechanism

The physical properties and hydrated rates of low-heat Portland cement prepared with different varieties of gypsum were tested.The influence of varieties and amount of gypsum on the performance of low-heat Portland cement was analyzed by means of XRD and ion chromatography.The results showed that when the anhydrous gypsum was used as setting retarder,the cement strength gradually improved along with the augment of anhydrous gypsum.And the more the augment was,the more obvious the function of enhancing strength was.The influence of dehydrate gypsum on the strength of the cement appeared the shape of wave.The SO42- concentration of solution increased by adding anhydrous gypsum,so the rate of hydration of silicate minerals accelerated,the strength of the cement improved obviously.