Experimental Assessment Of Stiffness And Damping In Rubber-Sand Mixtures At Various Strain Levels

The dynamic properties of shredded rubber-soil mixtures (ShRm), comprising a sub-rounded quartz sand combined with small rubber shreds at 0, 10, 20, 30% by mass, were investigated. Testing ranged from small strain, in resonant column apparatus, to large strain, in cyclic triaxial, all at a frequency of 1 Hz with mean stress equal to 100 kPa. As observed by other workers, the shear stiffness of rubber soil mixtures decreases both (i) with rubber content and (ii) with shear strain. In contrast, increases in damping ratio are smallest at higher rubber contents. Shear modulus reduction behaviour for ShRm are shown to fit well for all percentage rubber contents, the functional form put forward by Darendeli (2001). Damping ratio was well-fitted by Darendeli up to a shear strain of about 0.2%, after which the variable trend shown by ShRm has been adjusted using the expression proposed by Phillips & Hashash (2009).