Mechanical behaviour of loess soil stabilised with natural biopolymers

Abstract

Collapsible loess soils are a major geotechnical concern due to their high sensitivity to moisture and structural instability upon wetting. This study evaluates the potential of two natural biopolymers, xanthan gum (XG) and guar gum (GG), as sustainable soil stabilisers aimed at improving the mechanical behaviour of compacted loess under variable moisture and curing conditions. Compaction and unconfined compression tests were conducted on soil-biopolymer mixtures with 1% and 2% content, cured for up to 56 days. The results show that biopolymers reduce dry unit weight and increase optimum moisture content, with XG yielding unconfined compressive strengths up to 466 kPa. GG, although less effective in strength, led to greater stiffness gains under specific conditions. Scanning electron microscopy revealed distinct microstructural improvements, including gel bonding and matrix densification. These findings support the technical feasibility of using biopolymers for environmentally friendly ground improvement in collapsible soils, particularly in arid and semi-arid regions where moisture variation is a critical design factor.