Evaluating the Effect of Breakdown Fouling and Water Content on the Ballast Degradation Characteristics

Railroad ballast as a layer of track substructure performs important tasks such as increasing the bearing capacity of the sleepers, providing large voids for drainage and resisting the forces applied to the super-structure. Contamination of ballast as the result of ballast breakdown known as breakdown fouling can prevent ballast from performing its job and also affects the engineering properties of ballast. This paper discusses the drained static triaxial testing on granite ballast material with different amount of breakdown fouling and water content. Large-scale triaxial equipment was used for this testing program at the University of Massachusetts, Amherst. These tests were performed to study the effect of fouling and water content, on the strength properties and degradation characteristics of railroad ballasted track. Ballast with three different fouling percentages from clean to highly fouled ballast (<5%, 15% and 30%) and four water contents from dry to field capacity were tested under three different confining pressures. The results show that although an increase in moisture degrades the fouled ballast, increase in breakdown fouling at constant moisture conditions increases the strength of the ballast.