Influence of Waste Rubber Powder on the Physical and Mechanical Behavior of Clay Soils

transportation networks. One major challenge is the presence of weak soils. Clayey soils, due to their high plasticity and deformability, are considered problematic, and improving their geotechnical properties remains a key issue in civil engineering. Recently, the use of waste materials, especially waste rubber powder, as sustainable soil stabilizers has gained attention.This study examines the influence of different contents (5%, 10%, and 15%) and particle sizes (0.5, 1.3, and 3.5 mm) of waste rubber powder on the strength and mechanical behavior of clayey soils. Untreated clay was used as a control, and standard laboratory tests—including Atterberg limits, compaction, consolidated drained direct shear, and unconfined compressive strength—were conducted according to ASTM standards.The results show that adding rubber powder lowers the liquid limit, plastic limit, optimum moisture content, and maximum dry density. Higher rubber content reduced unconfined compressive strength, while the internal friction angle increased and cohesion decreased.Overall, incorporating waste rubber powder offers a sustainable approach to improving the engineering performance of clayey soils while reducing the environmental burden of rubber waste.