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 setting time of the cement will be very short or even…