Geotechnical Behavior of Xanthan Gum-Stabilized Clay Reinforced with Polypropylene Fibers

The use of biopolymers like Xanthan Gum (XG) for soil stabilization offers an eco-friendly alternative, enhancing soil properties while reducing CO₂ emissions, gaining attention in sustainable engineering. This study investigated the interaction and geotechnical improvements of clay mixed with XG and polypropylene fibers (PPF). Biopolymer was used in proportions of 1%, 3%, and 5%, while the PPF percentage was kept constant at 0.5% by weight. Additionally, the molding density was varied at 1.65 g/cm³, 1.70 g/cm³, and 1.76 g/cm³. A total of 108 specimens were prepared using two curing times (28 and 90 days), and the samples were subjected to unconfined compressive strength (UCS) tests, ultrasonic pulse velocity (UPV), and Scanning Electron Microscopy (SEM). The results demonstrate that the addition of XG and PPF in the specified proportions provides significant mechanical improvements to the stabilized soil. The curing time had a notable impact on these improvements; a curing time of 90 days resulted in strength increases of up to 37% compared to 28 days, while the maximum dry density improved this property by up to 87% compared to the minimum density. The incorporation of PPF enhanced strength by 53.93%, while stiffness increased by 63.55%. Additionally, the strength (qu) and stiffness (Go) results were successfully correlated using the porosity/binder index η/Biv, achieving determination coefficients (R²) greater than 0.90 and 0.80, respectively.