Reinforcing soil with 22.5% PET plastic waste can improve its bearing capacity and CBR. The soil-22.5% PET plastic waste composite can be applicable in civil engineering applications like as material for foundation bearing strata, light road sub-base or subgrade, and as backfill materials for foundations, embankments, and retaining walls. Additionally, the study has established that reinforcing soil with 22.5% PET plastic waste is sustainable, hence mitigating the social, economic and environmental impacts by reducing need for natural resources, no land filling of PET plastic waste, and increased utilization of poor quality construction soils like sand. Furthermore, calculations were done and found out that reinforcing sand with 22.5% reduced the width of the foundation by 3% which made it more economical compared to unreinforced sand.