Behavior of fresh and recycled slag ballast under cyclic and post-cyclic monotonic loadings using large-scale triaxial tests

This paper aims to evaluate the behavior of fresh and recycled Electric Arc Furnace (EAF) slag materials as railway ballast using large-scale cyclic triaxial tests. Recycled slags are materials that were previously subjected to cyclic and monotonic loadings and Los Angeles abrasion. These materials were cleaned and re-grained. Grain size of recycled ballast was similar to fresh ballast, from 19 to 50.8 mm. All the specimens with a diameter of 30 cm and a height of 60 cm were tested in dry conditions. Based on the results, there is no limitation in the use of EAF slag as ballast in terms of quality control criteria. However, the cyclic stress amplitude applied to the EAF slag should be limited to 210 kPa to prevent progressive deformations. An increase in the maximum ballast size and the quantity of recycled ballast can increase the resilient modulus and the ultimate permanent axial deformation. The resilient modulus at the confining pressures of 60 and 30 kPa is at least 400 and 300 MPa, respectively. The resilient modulus reaches less than 300 MPa at the failure stage.