Abstarct: One of the problematic soils in geotechnical engineering is Collapsible soils, that is changed in volume suddenly due to moisture absorption and low shear strength. These properties lead to asymmetric settlement in the soil, which can cause irreparable damage to the structures located on it. One of the methods to improve soil resistance parameters, which is often considered by engineers, is mixing soil with additive materials such as polymeric materials. In this study, waste UPVC granules have been selected as additive polymeric materials to significantly reduce construction costs and preserve environment with UPVC waste. In the research process, direct Shear test were performed on reconstituted soil samples without granules and soil samples with different percentages of UPVC granules then triaxial test were performed on reconstituted soil samples without granules and soil samples with the optimal percentage of UPVC granules obtained from direct shear test. For proper comparison, direct shear and triaxial test have been performed in similar conditions. To investigate the effect of this material on soil collapsibility behavior, collapsibility tests were performed on undisturbed and reconstituted samples without granules in natural conditions and samples with different amounts of granules. The results indicate the optimal amount of 3% granules in improving soil strength and also the optimal amount of 5% granules in improving soil collapsibility behavior.