PURPOSE: To produce a cement clinker excellent in high-early-strength properties and expandability without any unfavorable effects such as deterioration in fluidity in kneading the cement clinker with water due to an excess of 3CaO.Al2 O3 and further enable the production of the cement clinker without causing the generation of sulfurous acid gas.

CONSTITUTION: A pulverized mixture containing gypsum in an amount of 15-35 pts.wt. based on 100 pts.wt. coal ash and calcium in an amount of 120-250 pts.wt. expressed in terms of CaO is used as a raw material and burned to afford this cement clinker containing 3-12wt.% 3CaO.Al2O3 and 5-20wt.% 3CaO.3 Al2O3.CaSO4.