Innovative Agricultural Soil Management: Geotechnical Utilization of Recycled Plastic Waste to Improve Soil Strength, Stability and Resistance to Desertification

Abstract

Background: Muthanna Governorate in southern Iraq is characterized by Gelic Andosols that are highly susceptible to drought and erosion. The accumulation of polyethylene terephthalate (PET) bottles, which are rarely discarded, poses an environmental concern due to their persistence and greenhouse gas emissions. Addressing both soil weakness and plastic waste management is therefore critical. The Samawah desert soil, being saline, is unsuitable for construction purposes. This study investigates the potential enhancement of Samawah desert soil with PET strips as a reuse strategy. Methods: PET bottles were cut into 15 mm × 20 mm strips and incorporated into soil at weight ratios of 5%, 10% and 15%. Laboratory tests, including shear strength, plastic limits, Proctor compaction and California bearing ratio (CBR), were conducted to evaluate the performance of the reinforced soils and determine the effectiveness of PET strips in improving soil properties. Result: The findings indicate that PET strips enhanced soil behaviour by increasing shear strength and specific gravity, while reducing swelling and desiccation cracking. Compaction characteristics were improved, with a marginal increase in maximum dry density and a slight decrease in optimum moisture content, reflecting improved load bearing capacity. Evidence suggests that recycled PET strips are an inexpensive and environmentally friendly alternative for reinforcing weak soils and combating erosion in arid regions such as Samawah. Additionally, their use provides a practical pathway for reducing plastic waste accumulation.