Influence of particle breakage on the resilient modulus of railway ballast

Numerous research studies have been carried out in the recent past to determine the influence on the resilient modulus of railway ballast of parameters such as stress history, number of loading cycles, density, grading, fines content, maximum grain size, aggregate type, particle shape and moisture content. However, the influence of particle breakage on the resilient modulus has not been described in depth. The current study highlights the influence of particle breakage on the resilient modulus of latite ballast (commonly used in railway track in New South Wales, Australia). Aggregate degradation is represented by the ballast breakage index (BBI). Laboratory test results indicate that the BBI has a profound influence on the resilient modulus of ballast. The resilient modulus increases with BBI, irrespective of the effective confining pressure. In addition, a simple hyperbolic relationship has been proposed between the resilient modulus M_R and the bulk stress φ for latite ballast.