Evaluation of sandy soil stabilized with Tragacanth gum biopolymer for geotechnical applications

• TG stabilized sand as a sustainable construction material is evaluated. • The influence factors include TG content, density and time. • UCS improvement ranged from 177 % to 259 %, depending on the dry unit weight. • Cohesion increased up to 562 %, while internal friction angle boosted up to 51 %. • SEM images show formation of biopolymer network, reducing void spaces. Environmentally friendly soil improvement approaches are recently a global interest due to their lower environmental impact compared to traditional stabilizers. The traditional stabilizers, such as cement, contribute significantly to greenhouse gas emissions and soil degradation. Tragacanth Gum (TG), a carbohydrate polymer, is an eco-friendly additive, which offers a more sustainable and less polluting alternative. Only a few studies on the strength behavior of TG stabilized soils have been conducted. This study investigates the effect of TG addition in improving low-strength sandy soil. Unconfined compressive strength (UCS), direct shear, and scanning electron microscopy (SEM) tests were carried out on stabilized sandy soil with TG at 0.5 %, 1 %, and 2 % by weight after curing times of 1, 3, and 7 days to evaluate their short-term performance. UCS values increased from 20 kPa to 72 kPa, depending on the dry unit weight of sandy soil. The TG stabilization improved cohesion value from 8 kPa to 53 kPa and internal friction angle from 30.88° to 46.64°, for dry unit weights of 16 and 17 kN/m 3 , respectively. This study shows the prospect of using TG as a greener additive in geotechnical and pavement applications.