Effect of dry-wet cycles on the mechanical properties of saline soil solidified with sulfur-free lignin and hydrophobic polymer

In response to the increasing problem of rainfall-induced erosion-concomitant slope failure in saline soil areas, environmentally friendly and recyclable bioethanol by-product sulfur-free lignin (SFL) and green pollution-free hydrophobic polymer (HP) were used to improve the engineering performance of saline soil. The effect of dry-wet cycles on the physicochemical properties of solidified saline soil was investigated by performing unconfined compressive strength tests (UCS) and microscopic analyses. The results showed that the optimal mixture of solidified soil was 5% SFL and 12% HP, which increased the strength by 274.29% compared to plain soil (PS). The drywet cycle leads to the deterioration of the microstructure and pore characteristics of the soil, with a strength deterioration rate (SDR) of 45.1% after 10 dry-wet cycles. And the solidification mechanism was attributed to the hydrophobic matrix and ion exchange generated by SFL and HP, which enhanced the particle aggregation and microstructural strength of saline soil.