The utilization of lunar in-situ resources is an important way to realize the construction and operation of Moon scientific research base. The effect of alumina-alkali activator on the mechanical properties of solidified lunar soil simulant was studied by using basaltic lunar soil simulant as raw material, adding alumina and alkali activator for solidification treatment. Characterisation of hydration products in the simulated lunar soil using X-ray diffraction (XRD), scanning electron microscopy with energy spectroscopy (SEM-EDS), fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG-DTG) and X-ray photoelectron spectroscopy (XPS). The solidified mechanism of lunar soil simulant under the synergistic effect of aluminaalkali activator was discussed. The results showed that the compressive strength and splitting tensile strength of the solidified lunar soil simulant show an increasing trend, and the highest compressive strength was 17.29 MPa, which was 57% greater than that of the control group. The energy evolution process inside the specimen can be divided into four stages: damage initiation, damage increase, damage mutation and damage acceleration. The incorporation of alumina can promote the geopolymerization reaction between the alkali activator and the lunar soil's mineral composition to generate plenty of (N,C)-A-S-H gels that can fill the pores in the particles, thereby improving the mechanical strength of the solidified lunar soil simulant. Finally, the microscopic reaction mechanism model of alumina-alkali activator synergistic solidified lunar soil simulant was established.

Loess has the characteristics of loose, large pore ratio, and strong water sensitivity. Once it encounters water, its structure is damaged easily and its strength is degraded, causing a degree of subgrade settlement. The water sensitivity of loess can be evaluated by permeability and disintegration tests. This study analyzes the effects of guar gum content, basalt fiber content, and basalt fiber length on the permeability and disintegration characteristics of solidified loess. The microstructure of loess was studied through scanning electron microscopy (SEM) testing, revealing the synergistic solidification mechanism of guar gum and basalt fibers. A permeability model was established through regression analysis with guar gum content, confining pressure, basalt fiber content, and length. The research results indicate that the addition of guar gum reduces the permeability of solidified loess, the addition of fiber improves the overall strength, and the addition of guar gum and basalt fiber improves the disintegration resistance. When the guar gum content is 1.00%, the permeability coefficient and disintegration rate of solidified soil are reduced by 50.50% and 94.10%, respectively. When the guar gum content is 1.00%, the basalt fiber length is 12 mm, and the fiber content is 1.00%, the permeability of the solidified soil decreases by 31.9%, and the disintegration rate is 4.80%. The permeability model has a good fitting effect and is suitable for predicting the permeability of loess reinforced with guar gum and basalt fiber composite. This research is of vital theoretical worth and great scientific significance for guidelines on practicing loess solidification engineering.