Large-scale combination direct shear/simple shear device for tire-derived aggregate

This paper describes a novel large-scale device capable of performing both direct shear and simple shear tests to evaluate shear deformation and strength properties of Type B tire-derived aggregate (TDA). The device consists of stacked tubular steel members that can be locked as upper and lower rigid sections to displace relative to one another in direct shear or pinned at the ends to translate in simple shear. For both configurations, the TDA specimen has a length of 3,048 mm, a width of 1,220 mm, and an initial height up to 1,830 mm. The upper rigid section of the device can also be used to conduct interface direct shear tests. Vertical stress is applied to the top surface of the specimen using deadweights and horizontal shearing force is applied using two hydraulic actuators in displacement-control mode. Typical results from internal direct shear, concrete interface direct shear, and cyclic simple shear tests are presented. In direct shear mode, the device allows for mobilization of peak shear strength and, in simple shear mode, for evaluation of shear stiffness and damping ratio under large strain conditions for TDA with large particle size.