Effects of soluble soybean polysaccharides on solidifying aeolian sand by soybean urease-induced carbonate precipitation

The soybean urease-induced carbonate precipitation is potentially valuable for solidifying desert aeolian sand. In order to improve the uniformity and effects of solidification, the soluble soybean polysaccharide (SSPS) is added to the extracted soybean-urease solution to induce carbonate precipitation. Firstly, the impact of SSPS on the characteristics of soybean-urease solution and the formation of calcium carbonate in soil-free solution are analyzed. Then, the one-phase injection method is used to solidify the aeolian sand in the soil environment. The unconfined compressive strength and triaxial consolidated undrained shear characteristics of the cemented samples are tested, and the solidification mechanism is explored with SEM. The results show that the addition of SSPS at 1 g/L and 3 g/L lightly inhibits soybean-urease activity but hardly affects the viscosity of soybean-urease solution, and more calcite crystals are generated in soil-free solution. At the same time, the strength and uniformity of the solidified aeolian sand are improved. The effects are better when the additive amount of SSPS is 3 g/L. The SEM results show that after adding SSPS, larger and more compact calcium carbonate crystals are formed in soil-free solution, and more and more compact calcium carbonate crystals are distributed at the contact points between the sand particles in the soil environment, thus enhancing the solidification effects.