Deformation and degradation behaviour of Rubber Intermixed Ballast System under cyclic loading

In recent years, there has been an increasing interest in the use of rubber aggregates derived from waste tyres in order to improve track performance, and Rubber Intermixed Ballast System (RIBS) demonstrated some of the important geotechnical properties that reduce ballast deterioration by partially replacing ballast particles using rubber granules ranging from 9.5 to 19.5 mm. This paper focuses on evaluating the characteristics of RIBS subjected to cyclic loads by conducting large-scale triaxial tests for changing rubber contents (0–15% by weight) under confining pressures (30–60 kPa) and a loading frequency of 20 Hz following a monotonic conditioning phase. The results indicate that irreversible rearrangement of grain configurations was pronounced in RIBS with increased rubber at the conditioning phase leading to a reduction in particle deformation during the cyclic loading. It was also demonstrated that the increased rubber content in RIBS increases the energy absorption capacity and damping properties, reduces ballast breakage and resilient modulus. In addition, the study confirmed 10% by weight as the optimum rubber content in RIBS, considering the overall deformation and degradation performance of ballast.