The increasing demand for sustainable civil engineering solutions requires balancing present-day infrastructure needs with environmental preservation for future generations. This study explores the potential of xanthan gum, an eco-friendly biopolymer, for stabilizing clayey sand as an alternative to traditional soil stabilizers. Various concentrations of xanthan gum (0.25 % to 1.5 %) and curing durations (7, 14, and 28 days) were evaluated using standard geotechnical testing methods, including compaction, unconfined compressive strength (UCS), indirect tensile strength (ITS), ultrasonic pulse velocity (UPV), and scanning electron microscopy (SEM) analysis. The soil samples comprised 80 % poorly graded sand and 20 % high-plasticity clay. Results showed a significant improvement in soil properties, with just 0.25 % xanthan gum after a 7-day curing period leading to notable increases in UCS and tensile strength. However, further increases in xanthan gum concentration yielded diminishing returns in strength enhancement. Extending the curing time from 7 to 28 days improved compressive strength and stiffness. Additionally, xanthan gum-enhanced samples exhibited increased energy absorption, stiffness, and brittle behavior, forming a denser soil matrix and improving the particle bonding, supported by UPV results and SEM imagery. Also, the relationship between the stiffness from UCS tests and the ultrasonic pulse velocity was obtained. The findings underscore xanthan gum's potential as a sustainable and effective soil stabilizer for geotechnical applications.
