ABSTRACT:Railway ballast deforms and degrades progressively under heavy train (cyclic) loading. Ballast degradation is
influenced by several factors including the amplitude and number of load cycles, density of aggregates, track confining pressure, angularity, and most importantly, the fracture strength of individual grains. The degraded ballast is usually cleaned on track, otherwise fully or partially replaced by fresh ballast, depending on the track settlement and current density. The disposed waste ballast may be cleaned, sieved and re-used in the track. However, due to the breakage of the sharp edges and the development of micro-cracks during the previous loading cycles, recycled ballast is generally subject to excessive settlement and particle breakage. Therefore, the settlement and degradation aspects of recycled ballast must be carefully examined before recycling to the track. This paper investigates the deformation and degrada tion characteristics of recycled ballast under field-simulated loading conditions. Cyclic triaxial tests were conducted on both fresh and recycled ballast. The potential of recycled ballast as an alternative track construction material has been examined using geosynthetic technology, and the results are discussed in detail.

Key words: ballast, cyclic load, deformation, geosynthetics, particle breakage, stabilisation (IGC: D6/K14)