Comparison of the compression and shear behavior of clean and fouled ballast

Univ Lyon, INSA Lyon, GEOMAS, 69621 Villeurbanne, France

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Published online: 1 December 2025

Abstract

The railways are still a highly demanded mean of transportation worldwide, thanks to their cost efficiency, ease of drainage, and capacity to withstand cyclic imposed loadings from trains. The track structures, composed of ballast, frequently undergo deformations of high levels so that the new ballast is progressively degraded and the generated fouling material between ballast particles could cause rail track defects. This paper investigates the influence of fines on the strength properties and deformation characteristics of ballast fouled with two kinds of fines: a fouling made by stone dust of the same parent rock (limestone in our case) and a clay-based fouling with two kinds of tests: oedometric compression and direct shear tests. In the oedometric tests, the ballast fouled with the clay particles results in the reduction of compression strength properties while the natural fouling strengthens the sample. Reduction in the friction angle of the granular assembly with fines is globally measured in both cases, inducing a decrease in the load-bearing capacity of the material. Depending on the loading type, the results don’t show the same tendency for each type of fouling.