Dynamic characterization of tire derived aggregates using cyclic simple shear and bender element tests

The relatively recent use of tire-derived aggregates (TDA) in civil engineering applications makes it necessary to thoroughly understand and characterize its behaviour under static and dynamic loads. Only a limited number of experimental studies have investigated the dynamic behaviour of TDA with large aggregate sizes. This paper aims to investigate the dynamic and cyclic behaviours of TDA and factors that could affect the characterization of TDA using cyclic simple shear tests. A comprehensive series of cyclic direct simple shear tests were performed in this study on TDA under vertical stress and shear strain amplitude ranges of 15–400 kPa and 0.01–10%, respectively. Small-strain shear moduli (Gmax) of TDA were also determined from shear wave velocities measured at vertical stresses of 15–800 kPa using bender elements. The results were used to study the effects of cyclic loading frequency, drainage condition, fabric anisotropy, shear strain amplitude, and vertical stress on the dynamic behavior of TDA. Shear modulus and damping ratio of TDA ranged from 85 to 4290 kPa and 7–25%, respectively. While the shear modulus of TDA was found to be strongly influenced by the loading frequency, drainage condition, anisotropy, shear strain amplitude and vertical stress, these testing parameters had little or reduced effects on the damping ratios of TDA specimens. Finally, shear modulus reduction curves were obtained by combining the results of cyclic simple shear and bender element tests.