LONG-TERM SANDY SOIL STABILIZATION USING BIO-BASED POLYMERS AND GEP MODELING

In pursuit of sustainable and biodegradable alternatives for sandy soil stabilization, this study investigates the long-term synergistic effects of polybutylene succinate (PBS) and xanthan gum (XG) on the mechanical performance of sandy soils subjected to a 250-day steam curing at 16°C. Experimental trials were conducted by mixing sandy soil with PBS (0.2%, 0.4%, 0.8% and 1.0% by dry wt.) and 1.5%XG and monitoring the changes in unconfined compressive strength (UCS), alongside other geotechnical indices. After 250 days, untreated soil showed a UCS of 169 kPa, indicating minimal strength development. PBS-only treatments showed modest improvements, with 1.0%PBS reaching 289 kPa. In contrast, 1.5% XG achieved a much higher strength of 622 kPa. The most significant gains were observed in PBS-XG treatments, particularly (0.8%PBS+1.5%XG), which reached 1045 kPa, over six times stronger than untreated soil. Results highlight a strong synergistic effect, with the best long-term stabilization achieved through moderate PBS and high XG concentrations. To model and predict the mechanical behavior based on polymer composition and curing time, a GEP algorithm was deployed that demonstrated high predictive accuracy (R²train= 0.91, R²valid=0.94). Both PBS and XG were chosen for their renewable sources and eco-friendly nature, aligning with the principles of a circular economy.