Improving the performance of loess is of significant importance for lowering its collapsibility and water sensitivity to construction requirements and for geohazard mitigation. The present paper studies the changes in mechanical, structural, and mineralogical properties of nano-SiO₂-treated loess with different contents and curing days. The mechanical behavior was examined by unconfined compressive strength (UCS) of untreated and treated loess. To better understand the mechanisms of stabilization, particle size distributions, scanning electron microscope (SEM) images, and X-ray diffraction (XRD) analyses were carried out. The results show that the UCS increase with increasing contents and curing days due to nano-SiO₂ addition produced coarser particles, denser packing, and smaller pores in treated loess. The changes in the properties can be attributed to the formation of aggregation and agglomeration, with greater particle sizes and more interparticle contact. In addition, the results from mineralogical component analysis further confirm that physical structure modification controls the changes in mechanical and fabric properties, rather than chemical component alteration. Even small nano-SiO₂ additions can also provide great improvement when curing days are enough for the treated loess. These findings reveal that nano-SiO₂ has the potential to serve as a cost-effective stabilized additive that treats the universal loess.

Understanding property changes in soil improvement using a new technique is critical for enhancing engineering activity. However, little is known about nano-SiO₂pile-induced changes in soil properties due to its excellent properties as an alternative new additive material. This study aims to examine the changes in properties of loess stabilized with nano-SiO₂pile after curing for 28 days. Using samples taken from four desired radii (i.e., 5, 10 15, and 20 cm), we tested their mineralogical, structural, physicochemical, and index properties and analyzed the relationship of these properties to strengthen the link between microscopic characteristics and macroscopic behaviors. We then discussed the mechanism of the changes in the treated loess properties. The test results show that nano-SiO₂pile induced a physical structure modification in the treated loess and, consequently, an isotropic process with coarser particles due to crystallinity. This resulted in a solidification process in loess with nano-SiO₂pile, causing a decrease in water content and void ratio as well as an increase in natural density, thereby improving its mechanical strength. Meanwhile, the specific surface area (SSA)and cation exchange capacity (CEC) of treated loess were smaller than those of original loess, and there were slight changes in chemical properties. The disintegration rate of treated loess decrease compared with the original loess. The interactional relationship of the microscopic and macroscopic observation was facilitated to better understand the mechanism of changes in nano-SiO₂pile-treated loess properties. This finding reveals that nano-SiO₂pile has the potential as an alternative stabilized technique in loess improvement due to its obvious performance improvement and slight chemical changes.