Effect of Saturation on Performance of Steel Slag Ballast under Cyclic Rail Loads

Abstract

Steel slag is becoming a popular alternative to conventional natural ballast in a ballasted rail track under a circular economy paradigm. The mechanical behavior of ballast has a significant impact on the overall performance of the track, particularly during monsoons due to heavy rain or flooding, which may further alter the track performance. The present study aims to investigate the effect of saturation on the performance of steel slag ballast under monotonic and cyclic loading. The performance is quantified in terms of shear strength, resilient modulus, permanent deformation, damping ratio, and crushing strength behavior. A comparative study of four different steel slag ballasts and granite (one of the most commonly used ballast materials) was conducted using laboratory tests, including the monotonic triaxial test, cyclic triaxial test, and single-particle crushing strength test for dry and saturated conditions. The results show that the presence of free lime content and saturation adversely affect the behavior of steel slag. Empirical relations are proposed for assessing the resilient modulus and damping ratio of steel slag ballast from single-particle crushing strength, abrasion resistance, free lime content, and water absorption value. A prediction model is proposed to predict the permanent strain accumulation taking into account key factors such as water absorption, specific gravity, and free lime content, which can be helpful in the construction and maintenance of railways.