A review of biopolymers in geotechnical engineering: Mechanical properties, dynamic behavior, applications, and mechanisms

This review comprehensively analyzes the applicability of biopolymers in geotechnical engineering and highlights their value as eco-friendly alternatives that can contribute to the development of sustainable infrastructure. Biopolymers derived from renewable resources offer advantages in enhancing the physical and mechanical properties of soils while minimizing environmental impacts. This study classified biopolymers into hydrocolloid-based (e.g. xanthan gum (XG) and guar gum (GUG)) and stimuli-responsive (e.g. agar gum (AG), and gellan gum (GG)) types, and systematically examined the physical properties and applicability of each type. Biopolymer-treated soils demonstrated significant improvements in geotechnical performance, including increases of up to 200% in shear strength, 150% in unconfined compressive strength (UCS), and reductions in hydraulic conductivity to below 10 –9 m/s, thereby significantly enhancing impermeability. Furthermore, biopolymer treatments reduced the swelling potential of expansive soils by 40%, maintained stiffness, and increased damping ratios under cyclic loading, thereby improving dynamic stability. The liquefaction resistance was markedly enhanced through increased shear strength and suppressed pore water pressure, demonstrating stability under dynamic loads, such as earthquakes. Biopolymers exhibit outstanding performance in various applications, including road pavements, slope stabilization, erosion control, landfill liners, and liquefaction mitigation. This study elucidates the mechanisms by which biopolymers interact physically and chemically with soil, block pore spaces, and enhance interparticle cohesion via hydrogen bonding and electrostatic interactions. These findings validate biopolymers as environmentally friendly and sustainable alternatives to conventional chemical stabilizers, suggesting their potential for broader industrial applications through improved long-term durability and cost efficiency. Future research should focus on ensuring the long-term durability of biopolymers and developing customized formulations and technologies for large-scale applications that will serve as critical foundations for the sustainable advancement of geotechnical engineering.