Experimental assessment of cyclic behavior of sand-fouled ballast mixed with tire derived aggregates

Abstract

This study deals with the application of tire derived aggregate (TDA) mixed with ballast material as an approach for enhancing the ballasted track performance in the presence of sand fouling. In order to assess the TDA influence on sand-fouled ballast, a series of ballast box tests was conducted on various mixtures of TDA, ballast material with AREMA 4A gradation and the Tabas desert windy sand with particle size range of 0.075–4.75mm. A total number of 36 cyclic uniaxial tests were performed by considering four TDA weight percentages of 0%, 5%, 10% and 15% as well as three weight percentages of 0%, 50% and 100% for windy sand as the contaminant. The gradation of TDAs was similar to that of ballast particles so as not to disturb the ballast layer drainage. On the basis of the laboratory outputs, the settlement, ballast breakage and damping ratio of samples were discussed. The experimental results indicate that increasing the sand percentage decreases the damping ratio, while leading to an increase in the settlement and ballast breakage of samples. Alternatively, these parameters escalated with the increase of TDA percentage. Overall, the 5%-TDA sample was determined as the most suitable mixture in terms of breakage and stiffness, whereas the more TDAs continuously increased the damping ratio of samples. Three regression equations were also derived to evaluate these parameters as functions of the number of loading cycles, TDA and sand percentages.