Cyclic loading effects on flexible-bonded soft-rigid granular mixes

The mechanical response of flexible bonded soft (waste tyres)-rigid (crushed rock) is studied under cyclic loading. The use of waste tyres for different transportation infrastructure has attracted the attention of the engineers to understand the behaviour of these materials mixed with different geotechnical material like soil and crushed rock. Discrete Element Method (DEM) is employed to understand the behaviour. A coherent contact model is used in DEM with modelling strategy, developed for these materials. The contact parameters were calibrated against oedometric test responses for various mix combination. Two samples with varying soft contents are considered in this study, while keeping the binder content in the mix constant. The samples are subjected to strain and stress-controlled loading. The macroscopic stress-strain behaviour varies with changes in the soft and binder content percentages in the mix. The stress reduction for a strain-controlled test is higher for a mix containing higher soft content. Similarly for a stress-controlled test, the strain accumulation happens at a much higher rate for higher soft content mix. The current study involves loading beyond the yield. It is observed that stress reduction is influenced not only by the soft and binder content but also by bond breakage leading to stress reduction during the first loading cycle. Furthermore, a logarithmic function is proposed for both strain and stress-controlled tests to relate the modulus with the number of cycles.