ABSTRACT
The ballast layer is one of the most important elements of the railway track playing a key role in its behavior, concerning vertical and horizontal stability. Physical-mechanical properties of ballast material influence track’s performance and its life cycle cost. Intensive studies on the most relevant properties of the ballast material have been performed, considering the basic functions of this layer, particularly its resilience, load distribution and drainage capacities. The behavior of this layer is essentially influenced by compaction, as well as by the characteristics of its particles. The characteristics of the track superstructure, traffic loads and maintenance operations can also influence the behavior of the ballast layer. This paper presents a brief review on aspects determining ballast behavior, focusing on particle and aggregate characteristics. Laboratory results regarding particle shape characterization and cyclic load tri axial tests on large specimens are presented and discussed. Regarding the ballast drainage capacity, the Ground Penetrating Radar can be an important tool for in situ assessment. Tests in laboratory aiming at supporting the in situ ballast fouling evaluation are also referred herein
