Aren’t concrete retarder and gypsum retarder a kind of retarder?

the last process of cement production is to grind the cement materials and gypsum together, in which gypsum (calcium aluminate dihydrate) is generally added about 5% (equivalent to 1~3% so3), which acts as a retarder. the mineral tricalcium aluminate (c3a) in cement hydrates very quickly. if gypsum is not added to slow the setting, the…