Influence of curing conditions on the strength of xanthan gum-stabilised sand

Biopolymer-stabilised soil holds great promise as an environment-friendly material suitable for sustainable pavement construction. However, the impact of curing conditions, a vital aspect that can influence the mechanical properties of biopolymer-stabilised sand, remains uncertain. In this study, the influences of curing time and relative humidity on the compressive strength of the xanthan gum-stabilised sand were investigated through macroscopic and microscopic laboratory tests. The results indicate that the compressive strength of xanthan gum-stabilised sand is closely correlated with its residual moisture content. As the curing time increases, the residual moisture content gradually decreases, signifying the attainment of different specific residual moisture conditions. This reduction in moisture content is accompanied by an increase in compressive strength. And the strengths of stabilised specimens, tested after the final attainment of equivalent moisture content, are similar in both short-term and long-term curing. Furthermore, an optimal curing humidity of around 40% was identified. SEM test results demonstrate that under the optimal curing condition, thicker and more widely distributed gels bond adjacent sand particles, thereby contributing to the improved strength.