Jun 20, 2015 After cooling, the clinker may be stored temporarily in a clinker store, or it may pass directly to the cement mill. The cement mill grinds the clinker to a fine powder. A small amount of gypsum - a form of calcium sulfate - is normally ground up with the clinker. The gypsum controls the setting properties of the cement when water is added. 4.A. Cementitious Materials Portland cement alone or in combination with one or of blended hydraulic cement, fly ash and other pozzolans, ground granulated blast-furnace slag, and silica fume. 1.03 SUBMITTALS A. Product Data For each type of manufactured material and product indicated. B. Design Mixes For each concrete mix.