"Ground Granulated Blast-Furnace Slag" (GGBFS) is produced via the process for grinding "Granulated Blast Furnace Slag" (GBFS) that is a kind of byproduct produced via blast furnace operated in our steel works. GGBFS is hydraulic, mixed in other cement products, and utilized as the material for blast furnace cement, soft concrete mixture material, etc,. As GGBFS is utilized for such a purpose above, compared with ordinary Portland cement, GGBFS utilization dispenses with not only the energy consumed to burn limestone but also CO2 gas emission from burning fuel and limestone itself coincidently.