Effect of anisotropic consolidation and rubber content on dynamic parameters of granulated rubber-sand mixtures

Abstract

To investigate the shear modulus and damping ratio of granulated rubber-sand mixtures, cyclic triaxial tests were conducted on specimens prepared with different granulated rubber content (by weight) and consolidated under different consolidation ratios. The specimens were then sheared under two cyclic shear strain amplitudes of 0.002 and 0.004 up to 300 cycles. The results show that adding granulated rubber has decreased shear modulus (G) and increased damping ratio (D) under both shear strain amplitudes, but rubber has been helpful in reducing the degradation rate of the shear modulus irrespective of the initial consolidation state. Overall, anisotropic consolidation has had little effects on the variations of shear modulus and damping ratio of granulated rubber-sand mixture (GRSM) compared to clean sand. The sand-rubber mixtures have become more isotropic by increasing the rubber percentage even under anisotropic consolidation. The point that the granulated rubber has significantly contributed to reducing the degradation potential of G with number of cycles makes it attractive in executing backfills and earth structures using rubber-sand mixtures in seismically active zones. The results of this study are also promising in efficient application of granulated rubber-sand mixtures as an isolation system under the foundation of buildings.