Desiccation cracking behavior of xanthan gum admixed clay

This study investigates the desiccation cracking properties of xanthan gum (XG)-treated clay and its effectiveness in repairing cracked clay by examining their evaporation characteristics, crack propagation, patterns, and the related micro-mechanisms were discussed with the aid of micro examination. Results show that (i) the evaporation rate curve of untreated and XG-treated clay exhibits a Z-shape with three stages, and the latter possesses higher water content, smaller evaporation rate, and longer evaporation durations. (ii) The crack development in both untreated and treated clay follows identical four stages, and the sample treated with higher XG content showed better resistance to wet-dry (W-D) cycles. The R_c, W_av and L_to roughly reduce as XG content increases, and are also impacted by W-D cycles. The optimal XG content was considered as 1.5% and 2%. (iii) The cracked sample repaired by XG exhibited satisfactory crack resistance after the 1st and 2nd W-D cycles, and the R_c, W_av and L_to obviously reduced, and the higher sand content promotes this effect. (iv) XG treatment reduces the clay voids, enhances the elastic connection between inter-particles, and entraps water within XG molecular structures, by its coating, bridging, and filling effects, thus enhancing clay water retention capacity and resistance to desiccation cracking.