This thesis explores the sustainable utilization of recycled plastics in geotechnical engineering, focusing on soil stabilization and geosynthetics. The study begins by examining the use of recycled plastics in soil stabilization, analyzing their effects on geotechnical properties. It provides a comprehensive literature review, highlighting the advantages and limitations of incorporating recycled plastic materials into soil improvement techniques. It was found that the geotechnical properties of soil mixed with plastic waste are influenced by factors such as the type, shape, content, and source of the plastic material. The thesis also explores sustainable practices for utilizing recycled plastics in geosynthetics by investigating innovative approaches to developing eco-friendly reinforcement materials. A significant portion of the research is dedicated to evaluating, through laboratory testing, the performance of 3D-printed model geogrids manufactured from recycled plastics. Tensile tests on 1:10 scale 3D-printed samples made from recycled PET bottles demonstrated tensile strengths comparable to those of conventional benchmark geogrids at a strain rate of 10% per minute. Additionally, the feasibility of producing 3D-printed aggregates, perforated drainpipes, and corrugated drainage pipes from recycled plastics is examined. An online questionnaire was developed to identify recycled plastic materials, suppliers, and potential companies producing geosynthetics from recycled plastics. Findings indicate that sustainable geosynthetics produced from recycled plastics are feasible for practical applications, showcasing the potential for integrating recycled materials in soil stabilization. The research provides valuable insights into the potential of recycled plastics as a viable alternative to traditional materials in soil stabilization and geosynthetic applications, offering both environmental and economic benefits
