Shear Strength of Large-Size Shredded Scrap Tires

Abstract

One application for recycling large (1.4-m top size) shredded tires is as an intermittent stream or ravine crossing in place of a culvert. To measure the shear strength of large-size shredded scrap tires for use in slope stability analyses, a large-scale direct shear box (0.91 0.91 m in plan) was constructed. Two failure criteria were used, yielding similar results. A friction angle of 37° and a cohesion intercept of 3.1 kPa were obtained for large shear displacements, and the same friction angle of 37° and a zero cohesion intercept were interpreted using the 10 percent displacement failure criterion as defined by AASHTO. When shear-strength data on shredded tires from this and previous studies are analyzed, there is no apparent relationship between shred size and strength. The shear strength of the combined data, however, are well represented by the power function τ = 1.68σ0.74, where both τ and σ are in kPa. It is suggested that this nonlinear relationship, independent of shred size, can be used in stability analyses where the shear strength of shredded tires is needed.