Shearing Behavior of Interfaces between Tire-Derived Aggregate and Three Soil Materials

When tire derived aggregate (TDA) is used as a lightweight monolithic fill in civil engineering applications, such as embankments and retaining walls, the shearing behavior of TDA-interfaces with different materials should be carefully considered. This paper presents results from large-scale direct shear tests performed on interfaces between Type B TDA and layers of sand, aggregate, and clay for initial normal stress ranging from 19.0 to 76.7 kPa. To match field conditions, a separation nonwoven geotextile was used at the TDA-sand and TDA-clay interfaces, and a separation woven geotextile was used at the TDA-aggregate interface. Large shear displacements, typically between 200 and 350 mm, were required to fully mobilize the secant friction angle. Peak secant interface friction angles range from 26° to 32°, and peak strength envelopes are linear for the sand interface and nonlinear for the aggregate and clay interfaces. Failure envelopes for the TDA-soil interfaces are bounded above by the Type B TDA internal failure envelope and below by the Type B TDA-concrete interface failure envelope. A pair of replicate tests using woven and nonwoven geotextiles for the TDA-aggregate interface indicated that geotextile type had little effect on measured shear behavior as they only provide separation.