RESUMEN
In this study, we evaluated the impact of xanthan gum biopolymer (XG) on kaolinite fabrics using X-ray diffraction (XRD) and the ensuing changes in the compaction behavior and shear resistance of kaolinite soils. The XRD peak analysis revealed that XG changed kaolinite fabrics into face-to-face associations. Moreover, environmental scanning electron microscopy showed the formation of XG-bridges between kaolinite particles, resulting in the change in fabrics and subsequently improving the resistance of kaolinite to external forces. Consequently, as XG content increased, the maximum dry density decreased, and the undrained shear strength increased. The viscous XG hydrogels produced a higher optimal moisture content and increased resistance to shear force. This study showed that XG affects the mechanical properties of kaolinite through changing kaolinite fabrics (up to 0.5% of the XG-to-kaolinite mass ratio) and absorbing pore-fluids (excess XG over 0.5% of the XG-to-kaolinite mass ratio).
RESUMEN
Biopolymers have recently shown great potential to replace traditional binding materials in geotechnical engineering; however, more research is required to reach a deeper understanding of biopolymer-treated soil behavior. The objective of this study was to investigate the most important parameters that affect the behavior of biopolymer-treated soil, including biopolymer content, dehydration time, soil type effect, and durability. Sodium alginate and agar biopolymers were used due to their stability under severe conditions and the reasonable costs to study these parameters. A broad range of soil particle sizes was used to optimize the kaolinite-sand combination. As one of the main concerns in the behavior of biotreated soils, durability was investigated under five cycles of wetting and drying. In addition, a comprehensive microstructural study was performed by FTIR analysis and SEM images, as well as chemical interaction analysis. The results indicated that the optimized biopolymer content was in the range of 0.5-1% (to soil weight) and the dehydration time was 14 days. A soil combination of 25% kaolinite and 75% sand provided the highest compressive strength. Under wetting and drying conditions, biopolymers significantly increased soil resistance against strength reduction and soil mass loss. This study provides an understanding how agar and sodium alginate changes the behavior of the soil and can be used as a reference for further studies in the future.
RESUMEN
Biopolymer-based soil treatments have shown effectiveness in soil improvement, with successful field-scale implementation. In this study, we explored the effect of cyclic wetting-drying (W-D) and freezing-thawing (F-T) on the strength durability of biopolymer-treated soils. The results indicate that cyclic W-D and F-T gradually degrade soil strength owing to water adsorption and local biopolymer dilution. Poorly graded sand was highly vulnerable to these weathering effects; however, this problem was mitigated when the soil contained a fines content of 15-25%. These biopolymer-treated soils effectively resisted numerous cycles of both W-D and F-T, indicating that biopolymer-treated soils are suitable for earthen slope reinforcement.