Mechanical behavior of inert steel slag ballast for heavy haul rail track: Laboratory evaluation

The ballast mechanical behavior is one of most important aspects governing the performance and safety conditions of railway track lines. Usually comprised of natural crushed rock, the research for alternative ballast materials becomes interesting both environmentally and economically. This paper presents a comparison between aggregates of steel slag and granite by means of monotonic and cyclic triaxial tests carried out on scaled down ballast specimens. The monotonic triaxial tests were conducted at three different confining pressures to failure and to critical state. The long-term cyclic tests (at least 106 cycles) were conducted in two stress paths compatible with heavy haul loadings. The results showed that the steel slag aggregate has higher values of strength parameters compared to the granite aggregate and better long-term deformability behavior, expressed by lower degradation and particle breakage and a faster tendency for stabilization the permanent deformation.