In this study, activator, metakaolin, and silica fume were used as a compound activator to improve the activity of steel slag powder. The influence of activator, steel slag powder, metakaolin, and silica fume on the resulting strength of steel slag cement mortar was investigated by orthogonal experiments. For four weight fractions of steel slag powder (10%, 20%, 30%, 40%), the experimental results indicate that the compressive strength of mortar can reach up to more than 85% of the control group while the flexural strength can reach up to more than 90% of the flexural strength of the control group. Through orthogonal analysis, it is determined that the activator is the primary factor influencing the mortar strength. According to the result of orthogonal analysis, the optimal dosages of activator, steel slag powder, metakaolin, and silica fume are suggested. The GM (0, N) prediction model of compressive strength and flexural strength was established, and the compressive strength and flexural strength of mortar with the optimal dosage combinations were predicted. The prediction results show that by using the optimal dosage combination, the mortar strength can reach the level of P·O·42.5 cement. Considering the different strength and cost requirements of cementitious materials in practical engineering, the economic benefits of replacing cement with steel slag powder activated by compound activator in various proportions and equal amounts were presented. The results show that the method proposed in this study can reduce the cost of cementitious materials.

Acrylic materials exhibit favorable grouting repair performance. However, their curing products are easily inclined to drying shrinkage, and their concrete impermeability repair characteristics have seldom been investigated. To improve material properties, reveal the impermeability repair mechanism, and address drying shrinkage, this study proposed the addition of styrene–acrylate copolymer emulsion (styrene–acrylic emulsion) to the grouting material to prepare two-component acrylate grouting materials. Using orthogonal and single-factor tests combined with physical and mechanical properties, the mechanical properties and impermeability repair performance (physical and mechanical properties combined) of grouting materials were analyzed and studied, and the optimal ratio of each component of acrylate grouting materials was determined. Results show that (1) the hydrogel produced by the reaction of sodium methacrylate with hydroxyethyl acrylate has good physical and mechanical properties. (2) With the increase in the accelerator dosage, the setting time of slurry initially decreases and then increases; as the initiator dosage increases, the setting time of slurry decreases, which is negatively correlated with the initiator dosage. (3) Talcum powder can improve the physical and chemical properties of gel and enhance the reliability and durability of acrylate grouting materials, and the comprehensive performance is the best at a dosage of 3%. (4) Styrene–acrylic emulsion can increase the solid content and reduce the volume drying shrinkage when added to grouting materials. The fractured impermeable specimens were repaired by grouting with prepared acrylate grouting materials and cured for 24 h for the impermeability test, and the water pressure for the 24 h impermeability repair was 1.0 MPa. This study’s results provide important reference and basis for revealing the impermeability principle of acrylate grouting materials and evaluating their impermeability.

In this study, a series of tribological tests were conducted on a pin-on-disc tester to study the lubrication mechanism of SiO₂ nanoparticles under different surface roughness considering various loads and velocities. For a comprehensive understanding of the mechanism of SiO₂ nanoparticles, base fluid was also employed as a contrast. Results show that the reductions of friction coefficients and wear scar widths increase with the decrease of surface roughness, due to the increase in rolling effect and self-repairing mechanism of SiO₂ nanoparticles. The lubrication mechanism of SiO₂ nanoparticles is the rolling effect when the height-diameter ratio (λ) is less than 6, and the self-repairing mechanism at λ of 6 and 10, whereas, there is no obvious difference by adding nanoparticles when λ is 20. When the height-diameter ratio is less than 6, surface wears show an increasing trend as the load increases due to the high hardness of nanoparticles, while it is the opposite at λ of 10 and 20 because of the self-repairing mechanism.

The inlet elbow pipe of a double-suction pump in solid–liquid two-phase flow can easily lead to a variety of unstable flow conditions, such as flow asymmetry, turbulence intensity, and vortex formation. Additionally, the inertia and aggregation effects of particle movement complicate this phenomenon further, significantly affecting energy performance and causing erosion damage. This study explores the relationship among elbow curvature, solid–liquid two-phase flow characteristics, entropy production distribution, and wear patterns in a double-suction centrifugal pump. The interaction between inlet vortex evolution and particle movements is elucidated, followed by an exploration of the spatial energy performance and erosion distribution within the double-suction pump. The results indicate that a rise in elbow curvature has a significant effect on the flow field, intensifying flow asymmetry, enhancing turbulence and vortex formation, which, in turn, leads to greater energy loss and entropy production rate, while diminishing pump efficiency. The influence of elbow curvature on energy loss is determined through the entropy production theory. In solid–liquid two-phase flow, the inertia and aggregation effects of the particles intensify wall friction and turbulent dissipation, resulting in a greater localized wear intensity. Under conditions with greater curvature, the effects of particle aggregation are enhanced, resulting in a more pronounced erosion intensity. This study offers a comprehensive insight into the pump performance in terms of the interplay of inlet vortex characteristics and the particle migration process.