Sand–tyre chips mixtures in undrained and drained cyclic triaxial tests

This paper deals with the stress-controlled cyclic triaxial response of saturated sand rubber chips (RC) mixtures at different gravimetric contents. Three types of sand were utilised, namely, uniform medium and coarse sands, as well as a combination of the two at two relative densities. A series of consolidated undrained and drained single-stage cyclic triaxial tests was performed using standard equipment to evaluate the development of the accumulated excess pore-water pressures, permanent axial and volumetric strains. Samples were anisotropically consolidated prior to cyclic loading. The results showed that for all sands adding 10% RC increases the liquefaction potential. Compared to pure sand, increasing the chips content beyond 20–30% generally yields an improvement as long as the sand is not too coarse. Expressions have been derived for the evolution of accumulated pore-water pressure and the relation between excess pore-water pressure from the undrained test and cumulative volumetric strain from drained tests. Although the findings were derived for a single set of loads, they reveal the basic characteristics of the cyclic composite material behaviour.