Effect of anhydrous gypsum on performance of Potland cement

Substitute anhydrous gypsum for dihydrate gypsum in Potland cement production to study the effect of anhydrous gypsum on performance of Potland cement.The result shows that anhydrous gypsum has no harmful effect on setting time of Potland cement, and the effect on 3 d or 28 d compressive strength is less than 5%; If w(C3A) of clinker is less than 11%,anhydrous gypsum has no harmful effect on the setting effect.But if the w(C3A)of clinker is more than 13%,anhydrous gypsum could cause rapid setting, and then it is better to apply mixture of anhydrous gypsum and dihydrate gypsum or apply only dihydrate gypsum.