Shear modulus and damping ratio of granulated rubber-sand mixtures: Influence of relative particle size

Abstract

Rubber-sand mixtures (RSM) have gained recognition as a valuable, lightweight, and cost-efficient energy-absorbing material with extensive potential application in engineering construction. However, the small-strain dynamic properties and prevailing mechanisms of RSM have not been thoroughly understood. This study conducted a series of resonant column tests on the small-strain dynamic modulus and damping ratio of RSM, considering the effects of particle size ratio (PSR), rubber content (RC), and confining pressure. The results reveal that the dynamic shear modulus of RSM generally decreases with increasing RC and increases with rising confining pressure. For all RC and confining pressure levels, the maximum dynamic shear modulus of RSM reaches the minimum value as the PSR approaches 1.0. In this case, the dynamic shear modulus of RSM decreases most gently with the strain. The addition of rubber consistently augments the damping ratio, whereas the PSR initially diminishes the damping ratio before eventually enhancing it. Simultaneously, as the PSR is nearing 1.0, the damping ratio achieves its lowest point. Furthermore, new empirical equations were developed to quantitatively analyze the dynamic properties of RSM, in which the predicted values of the dynamic shear modulus and the modulus attenuation coefficient show good agreement with the observed values. This work will facilitate the preparation of artificial RSM-cored geotechnical seismic isolation layers tailored to specific engineering requirements.