I Indonesia is one of the countries with the largest nickel reserves in the world. in the nickel smelting process produces solid waste called nickel slag. In nickel smelting can produce up to 50 times the nickel slag waste. The purpose of this research is to determine the mechanical characteristics of concrete and durability of concrete that uses nickel slag as a substitute for coarse and fine aggregates and replaces cement as much as 20% with GGBFS or iron slag. The concrete mixtures in this study were normal concrete as reference concrete and concrete with 20% GGBFS mixture with variations of nickel slag as much as 10% of fine aggregate (FA) 30% of coarse aggregate (CA), 30% FA 10%CA, 20%FA 20%CA, 40%FA 40%CA, 60%FA 60%CA, 80%FA 80%CA, and 100%FA, 100%CA. The results of the compressive strength of normal concrete in this research amounted to 62.24 MPa and obtained the optimum compressive strength results in the BTN 40FA 40CA mixture of 69.43 MPa. The split tensile strength results ranged from 3.33 MPa to 5.27 MPa. The porosity percentage of concrete obtained in this research ranges from 6.52% to 9.162% and has a permeability coefficient ranging from 4.20E-8 to 5.08E-8.