The increase of rubber wastes, especially in the form of used tires has become a serious environmental challenge. In this research, the effect of granular rubber particles (GRP) as an additive (up to 50%) was investigated on the behavior of clayey soil under repeated loading using direct shear apparatus. Effect of different parameters were investigated such as GRP percent, unloading/reloading amplitude, number of cycles, normal stress and compaction. With increasing GRP, cohesion constantly decreases but internal friction angle raises at first and slightly decreases after 20% weight fraction of GRP. It was observed that increasing GRP weight percentage leads to higher permanent horizontal displacement and increase of hardening behavior under high normal stresses. The study also revealed that compaction has a negative effect on post-repeated loading shear strength which is an economical point in projects.

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