Particle morphology’s influence on the rail ballast behaviour of a steel slag aggregate

The ballast railway layer is one of the main applications of crushed rocks in civil engineering. Environmental concerns have influenced the use of by-products and recycled materials as alternatives to the exploitation of new quarries. One of the main industrial by-products available near railways is steel furnace slag. Mechanical tests performed by monotonic and cyclic triaxial loading showed that this material can perform better than a granite aggregate traditionally used in the ballast layer. The work presented in this paper intends to be a contribution explaining the influence of the individual particles’ morphology on the mechanical ballast behaviour. The results obtained by the Aggregate Image Measurement System show that the superior performance of steel slag aggregate is probably influenced by its higher particle angularity, this being one of the parameters that define its morphology.