Salinized loess exhibits poor engineering properties, including low strength, salt migration, and instability, due to the combined characteristics of loess and saline soil. This poses serious threats to the safety and stability of buildings, roads, and other infrastructure. To address this issue, this study aims to solidify salinized loess using geopolymer produced through alkali activation of industrial waste, including slag powder and fly ash. An orthogonal experimental design was used to systematically investigate the mechanical properties, microstructural characteristics, and solidification mechanism of geopolymer solidified salinized loess. The tests included unconfined compressive strength (UCS), direct shear, pH, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) to evaluate the influences of different factors on the solidification effect. The results showed that the sodium silicate solution modulus was the primary factor affecting the strength of solidified salinized loess, followed by the amounts of fly ash and slag powder. The Baume degree (degrees Be) had the least impact. Under the optimal conditions (1 modulus, 35 degrees Be, slag powder and fly ash ratio of 1:0), the UCS of the sample at 28 days reached 3204.06 kPa, which increased by 16.32 times compared with the unsolidified sample. Lowering the modulus and increasing the proportion of slag powder and the Baume degree increased the sample pH. Micro-analysis revealed that the strength increase was mainly due to the bonding of soil particles by gel substances (C - S - H, N - A - S - H, and C - A - S - H) formed during alkali activation, as well as the filling effect of unreacted slag powder and fly ash. The findings of this study provide valuable theoretical and practical insights for treating salinized loess in engineering, offering essential references for optimizing geopolymer solidifier ratios.

Ferronickel slag is the solid waste slag produced by smelting nickel-iron alloy. After grinding ferronickel slag into powder, it has potential chemical activity. It can partially replace cement and reduce the amount of cement, and is conducive to environmental protection. The mechanical properties of soil cement were investigated through the compressive strength test and inter-split tensile test of ferronickel slag powder soil cement with different dosages. To further study the mechanism of ferronickel slag powder's action on soil cement microscopically, the microstructure of soil cement was analyzed by using a scanning electron microscope and nuclear magnetic resonance equipment. The results of the study show that the incorporation of ferronickel slag powder can enhance the compressive and tensile strength of soil cement. The best performance enhancement of ferronickel slag powder was achieved when it was doped with 45% of its mass. The hydration products of soil cement increased with the increase in the doping amount, but the excessive doping of ferronickel slag powder would lead to a weakening of the hydration reaction and a decrease in the strength of the soil cement. At the same time, ferronickel slag powder plays the role of filling the void of soil cement. With the increase in ferronickel slag powder, the large pores inside the soil cement are reduced and the structure is denser.