<p>Three phase granular mixes consisting of soft (recycled tyre aggregates) and rigid (crushed rock) materials bonded with flexible or semi-flexible binders are gaining momentum as a solution for waste tyre crisis. Experimental works suggest macro-scale responses of these mixes are dependent on both soft and binder content in the mix. However, the underlying mechanisms governing these responses remain unclear. The present study focuses on exploring the contact mechanics of three-phase granular mix composed of soft and rigid particles bonded with flexible binders. Conventional contact laws for particle-scale study of bonded materials have limitations, as they are primarily formulated for rock-like materials. Therefore, advanced contact models are necessary to understand the macroscopic behaviour of these three-phase granular media. Given the flexible nature of the binder in this study, the ‘softbond model’ is employed to simulate the behaviour of the three-phase mix. However, the softbond model overestimates the strength of these granular mixes by assuming identical contact stiffness for bonded and unbonded conditions. The compressibility of unbonded contact is significantly different from the bonded contacts due to the presence of soft particles. To address this contact stiffness disparity, the softbond model is enhanced to better simulate the contact behaviour of these mixes. The new modified model can accurately predict the constrained modulus evolution against axial stress as found in one-dimensional compression experiments in the literature. Microstructural analysis of these mixes provides valuable insights into bond breakage, force distribution, and strong force chains. Bond breakage alters the force chain distribution in these mixes, and despite the presence of bonds with higher stiffness, unbonded contacts begin to dominate the force chain. The variation in microstructural properties indicates that the behaviour of these mixes depends not only on the binder content but also on the proportion of soft particles in the mix. The new microstructural understanding will ultimately help proposing better hypothesis to explain the complex material response for different soft and binder contents under applied loading.</p> Graphical Abstract <p></p>