Rubber-soil mixtures are known to have mechanical properties that enable their use in backfills, road construction or geotechnical seismic isolation systems. The complexity of these mixtures comes from adding soft (i.e. rubber) particles that increases the number of particle properties to consider when studying the macroscopic behaviour. The distinction between sand-like and rubber-like behaviour is normally presented in relation to the rubber content and size ratio between particles. It is however unknown how the change on the mixture gradation affects the mechanical behaviour of RSm. Entropy coordinates condense the entire particle size distribution (PSD) to a single point on a Cartesian plane, accounting for all the information in the gradation. Grading entropy coordinates have been used to study typical geotechnical behaviours of mostly incompressible (i.e. sand) soils. In this study, entropy coordinates are used to analyse the correlation between the small-strain stiffness and liquefaction susceptibility of RSm and their PSDs. The results suggest that entropy coordinates can be used effectively on RSm as an alternative means of assessment of typical soil behaviours, being also able to distinguish between sand-like and rubber-like behaviours. Based on the 30 PSDs analysed, it is also evidenced that internal stability criterion proposed by Lőrincz (1986) can be used to predict the liquefaction susceptibility of RSm. The normalised base entropy (A) has also been shown to increase with the rubber content, which is linked to a lower liquefaction susceptibility, due to the supporting effect of rubber particles on strong-force chains formed of sand particles.
Bernal-Sanchez, J., Barreto, D., & Leak, J. (in press). Rubber-soil mixtures: use of grading entropy theory to evaluate stiffness and liquefaction susceptibility. Bulletin of Earthquake Engineering, https://doi.org/10.1007/s10518-023-01673-3