Durability of reinforced concrete structures including electric arc furnace slag as aggregate in chloride environment is a significant topic to enable their performance stable in their service period. In this study, chloride penetration in recycled concretes including gradation of fine and coarse aggregate that is electric arc furnace (EAF) slag is tested and compared with that of reference concrete including just natural aggregate gradation. To observe chloride penetration effect, concrete samples are exposed to a saline attack firstly; and then, total chloride content and chloride penetration profiles are tested. The Part I of the study argues the effect of aggregate of electric arc furnace slag on durability of reinforced concrete structures in chloride environment in the Introduction and Background section and the Materials and Methods section. Second part of the study is going to present the Results and Discussions section and the Conclusions section. Both part have the Abstract section and Reference section differently each other.