Shear modulus and damping characteristics of uniform and layered sand-rubber grain mixtures

Large numbers of vehicles manufactured annually result in massive traffic and in turn creates huge numbers of waste tires entering into the environment and causing problems. Therefore, it is necessary to find reasonable applications for waste tires. They may be used to reduce seismic effects on structures due to their damping characteristics and energy absorption. Although comprehensive research studies have been carried out on static and dynamic properties of soil mixed with waste rubber, dynamic tests on layered mixtures of sand and rubber are highly demanding due to their easy to perform for practical applications. In this study, dynamic properties of sand mixed with different percentages of waste tire grains in uniform and layered forms were studied using a series of consolidated drained cyclic triaxial tests. The results show that for a given rubber percentage, layered mixtures have less shear modulus and more damping ratio than rubber-sand mixtures with uniform distribution. It has also been observed that for 50% tire content in layered sand-rubber mixtures, the Sand-Tire-Sand (STS) configuration offers lower shear modulus and a greater damping ratio than the Tire-Sand-Tire (TST) arrangement.