This study presents the behavior of soils reinforced with crushed PET (Polyethylene Terephthalate) residue through experimental study. Three soils were used: a coluvionar soil, a clean and poorly graduated sand and a bentonite. Physical characterization, chemical and mechanical tests (isotropically consolidated-drained triaxial and direct shear) were performed for each material and mixtures. The triaxial test was performed on samples of clayey soil compacted within the maximum dry density and optimum moisture content with ratios of 0, 10, 20 and 30 per cent of fine crushed PET and 3,0 and 5,0 per cent of PET flakes, by dry weight of soil. The triaxial tests on sand samples were made to a relative density of 50 percent and 10 per cent of water content, and with 0, 10 and 20 percent fine crushed PET, by dry weight of soil. The direct shear tests with bentonite were made with ratios of 0 and 30 percent of fine crushed PET and 3,0 and 5,0 percent of PET flakes, by dry weight of soil. The results have shown that the PET content and level of confining stress have influence on the final mechanical behavior of the mixtures. With both residue of PET, the mixtures present a satisfactory behavior, increasing or maintaining the shear strength parameters similar to the pure soil. Thus, for the clayey mixtures, the fine crushed PET content of 30 percent and the PET flakes content of 5 percent are more effective, once they increase the strength parameters. For sandy mixtures the PET inclusions is more effective with 10 percent of fine crushed PET at lower confining stresses and the optimum content is 10 percent. For bentonite mixtures the PET inclusions is more effective for PET flakes and the optimum content is 5. Therefore, the use of PET waste for soil reinforcement could minimize the current problems of waste disposal, contribute with the reduction of consumption of natural resources and give a noble use for this material.