The Box Test apparatus plays a crucial role in simulating large-scale railway pavements, providing valuable insights into material performance under conditions closer to reality. This study utilizes the Box Test to comprehensively analyze the potential use of steel slag as a material for railway ballast, focusing on its characterization and evaluation of the resilient modulus for sustainable railway pavement viability. The research involved conducting various tests in accordance with Brazilian and American standards to assess the feasibility of steel slag as a ballast material. The results revealed that, while the slag meets certain regulatory limits, it exceeds specified limits for porosity and absorption. The study also assessed the elasticity modulus of the steel slag ballast, confirming its positive outlook and contribution to the feasibility of sustainable railway pavement. The article emphasizes the significance of large-scale experiments in simulating railway pavements, providing valuable insights into the potential of steel slags as ballast material. The research is ongoing, with the completion of full-scale tests to fully simulate the pavement and observe layer interactions under more representative conditions. It is anticipated that the Box Test experiments results will provide a more comprehensive understanding of material performance in realistic conditions, contributing to a better understanding of railway pavement and offering insights into the feasibility of steel slags for the desired applications.