I Indonesia is a country with a various kind of ressources from nature, such aspetroleum, coal, nickel and etc. So,no wonder if we often found several miningaround us. The irony is that mining itself causes a lot of wastes, which willbecome B3 waste. For example, nickel slag is a waste from the result of smeltingore. Based on annually report from PT. Aneka Tambang, the amount of nickelslag is increasing, because 1 ton of nickel ore refining results 1,8%-2% nickelslag. In other hand, researchers who are focusing on Global Warming, estimatethat 5% CO2 in atmosphere are the result of production of Cement. In order toreduce it, the actual composition of cement should be partialy substitued by ecoregionmaterials. Thus, we tried to use nickel slag powder in the production ofcement, but we need to test their physical properties by using picnometer andblaine test, then their mechanical properties of concrete with nickel slag powderincluding compressive strength and workability, with ratio of water-cement 0,4and 0,6 and finaly to compare this experimental investigations with Tiga RodaOPC Type 1 used as a reference. The compressive strengh of the created concreteafter 28 days may reach fc’ 30 MPa. The results show that nickel slag powder hasthe potential to be used as partial replacement of cement, with fineness valueshigher than referenced cement, 4360 cm2/gr. Based on mechanical properties,nickel slag powder is generally able to replace cement by 25% and 0%,respectively.