Deformation Mechanism of Bound Soft-Rigid Granular Mixtures

Recycled tyre aggregates (soft particles) mixed with common granular material such as crushed rock (rigid particles) are considered effective solutions for a range of applications in transportation geotechnics in recent years. While extensive research has been conducted on the mechanical properties and behaviour of sand-rubber combinations as unbound soft-rigid mixtures, most studies on bound soft-rigid mixtures have focussed on utilizing brittle binders like Portland cement. On the other hand, there have been only a few studies in recent years exploring the behaviour of soft-rigid mixtures bonded with non-brittle binders. This study aims to enhance our understanding of the impact of binder elasticity and stiffness on the compressibility mechanism of soft-rigid granular mixtures. One-dimensional compression tests complemented with shear wave velocity measurements were conducted on bound samples, using different types of binders, to investigate how the characteristics of binders influence the fabric of the mixture and, consequently, its behaviour. The findings indicate a multiphase behaviour of bound mixtures, in contrast to the single-phase behaviour of unbound mixtures, particularly for higher contents of binder and for brittle and semi-flexible binders.