Strength characteristics and mechanisms of salt-rich soil–cement

Salt-rich soft soils have not only general characteristics of common soft soils, but also contain high contents of Mg2+, Cl−, and SO42−, which have negative effects on deep mixing method using cement to treat soft soils. Laboratory and field tests were conducted to investigate the effects of changing cement incorporating ratio, water content, cement mixing ratio, and contents of Mg2+, Cl−, and SO42− on the unconfined compressive strength of the salt-rich soil–cement. The microstructure of soil–cement and the mechanism for the strength change of salt-rich soil–cement were investigated using X-ray diffraction, scanning electronic microscopy (SEM), and backscattered diffraction technology. It was found that an increase of cement incorporating ratio enhanced the strength of soil–cement but reduced its strength when water is added. Different amounts of Mg2+, Cl−, and SO42− not only caused the difference in the microstructures of salt-rich soil–cement but also influenced the soil–cement strength.