Investigation of the static and dynamic characteristics of TDA-subballast mixtures

TDA (tire-derived aggregate) has great potential in ballasted railway engineering due to its excellent wear resistance and vibration absorption capacity. Thus, engineering insight into the effect that TDA has on the static and dynamic behavior of TDA-subballast mixtures is in high demand. In this investigation, different size ratios and shapes of TDA were used, and a series of large-scale monotonic and cyclic triaxial tests with different confining pressures and tire contents were conducted to evaluate the mechanical properties of the TDAsubballast mixtures. The experimental results indicate that TDA leads to a decrease in the stiffness, shear dilatancy, and modulus of resilience and an increase in the energy dissipation capacity of the mixtures. Then, the equivalent intergranular void ratio eeq is introduced to further evaluate the contribution of TDA granules to the shear behaviors of mixtures. A series of equations were established to discuss the evolution of the peak deviatoric stress, energy dissipation, and resilient modulus with eeq. Furthermore, based on the test indexes, the performance of mixtures with different TDA shapes and contents was comprehensively evaluated, and the optimal volumetric content of tires was found to be approximately 20%. The test results further promote the application of TDA in railway engineering and the effective use of waste tires.