COMPARATIVE STUDY ON ENHANCING THE MECHANICAL PROPERTIES OF CLAYEY SAND WITH WASTE PLASTIC FIBERS AND LIME

Introduction. The stabilization of clayey soils remains a dynamic and evolving field, with ongoing research exploring new materials, techniques, and sustainable practices to address the challenges posed by problematic soils in construction and infrastructure development. The aim of the study is to investigate the improvement of compaction and mechanical properties of clayey sand by reinforcing its structure with polyvinyl chloride (PVC) plastic fibers of varying sizes and proportions, and/or by applying lime treatment at a minimal dosage. Methods. The different mixtures were evaluated through a series of tests, including Proctor compaction tests, California Bearing Ratio (CBR) tests, and direct shear tests conducted under unconsolidated undrained conditions, to assess their mechanical behavior and strength enhancements. Results indicated that larger PVC fibers yielded the highest CBR values, even surpassing those achieved through lime treatment alone. Furthermore, the CBR index of the soil increased proportionally with the amount of PVC fibers added. It was also observed that the short-term behavior of clayey sand is significantly improved when reinforced with plastic fibers, whether used independently or in combination with lime treatment. This improvement can be attributed to the combined effects of lime, which strengthens the soil by reducing plasticity and increasing cohesion, and the structural contribution of larger plastic fibers, which promote better interlocking and reinforcement. These findings suggest that stabilizing clayey soils using PVC waste fibers and/or minimal lime treatment offers a technically effective and economically viable solution, while also supporting sustainable development goals.