Liquefaction Resistance of Silty Sand with Ground Rubber Additive

The contractive behavior and flow failure in saturated binary granular soils have been studied by many as functions of their physical properties [gradation, mean particle size, fines content (FC), and packing quality] and mean effective stress, stress history, and cyclic stress amplitude. Nevertheless, little is known on the interplays between frame elements and fines in loose saturated geocomposite mixtures and also between virgin and added frame elements under cyclic loading. That knowledge shortfall has lent uncertainty to flow potential and compressibility predictions for saturated sands in their natural and engineered forms. In this paper, 36 cyclic undrained triaxial-compression tests were performed to investigate the cyclic behavior and properties of saturated loose sand-silt-tire-derived ground rubber (GR) mixtures and to determine the effects of the GR and almost nonplastic fines on the rate of pore-water pressure buildup. The complex interplay among the angular sand, fines (silt) and GR solids, and pore spaces of varied shape, size, and rigidity are discussed at a microscale and invoking the framework of two conceptual models, small silt and large silt. The control of FC on liquefaction resistance was found to be dependent on the sand and GR particle sizes. The relatively greater elasticity of GR than sand lends a damping effect to frame elements and further improves the liquefaction resistance through relaxation of skeletal stresses and reduces the chance of contact destruction for sand particles.