Steel is the most consumable alloy in the industry and its consumption is steadily increasing. One of the most important by-products of steelmaking and refining processes is steel slag. The use of steel slag as an industry waste in geotechnical applications, in order to reduce the problem of slag disposal, as well as preventing the destruction of natural resources, is particular importance. It is necessary to determine the geotechnical engineering properties of steel slag generated from different steelmaking operations and assesses their potential use in road and railways embankment constrictions. In this paper, the physical and compaction properties and California Bearing Ratio (CBR) characteristics of steel slag as a base and sub base road pavement material and sub ballast of railway were studied. Two type of steel slag, Blast Oxygen Furnace (BOF) and Electric Arc Furnace (EAF) slags that generated in Esfahan Steel Company and Mobarakeh Steel Company are use in this research. The grain size distributions range of the test specimens have been selected in accordance with the characteristics of the road pavement as well as the existing laboratory facilities. In this study slag type (BOF, EAF), grain size distribution (G1 and G2), compaction energy (standard and modified compaction) and the effect of saturation in California bearing ratio were evaluated. The results of the atterberg limits test indicate that the material is none plasticity. The results of the tests showed that dry unit weight and optimum moisture content, BOF slag with G1-grain size and standardized compaction, had the lowest dry density, and EAF slag with G2-grain size and compacted by modified density method, has the highest dry unit weight. Based on the California Bearing Capacity test, the highest CBR value is related to the EAF slag with G2 grain size and the dry modified density.