The diffusion and sealing mechanisms of cement-sodium silicate grout (C-S grout), which is widely used in flowing water sealing projects, are complicated. Based on a large-scale quasi-three-dimensional simulation test platform of fracture dynamic water grouting, an orthogonal experiment of flowing-water sealing of C-S grout was performed. The grout was shown to diffuse in the form of an asymmetric ellipse. The flowing-water sealing process consists of three stages: (1) the grout diffuses to the fracture boundary in an asymmetrical ellipse; (2) the solidified body of grout develops; (3) the stable solidified body forms. The sealing efficiency was evaluated and graded by the reduction of water drainage through the fracture after grouting. Based on the test data, the factors that affect sealing efficiency can be listed in the following order from strong to weak: grout gel time, flowing water velocity, grout take, fracture plane width, and fracture aperture. Finally, a fitting equation was acquired to provide a reference for practical engineering applications.

Grouting is the effective method to prevent water inrush and reinforce fractured surrounding rocks in the construction of the submarine tunnel. The seawater intrusion will lead to obvious changes in the rheological properties of slurries, which can be adverse for the diffusion properties of slurries. This study aimed to identify the impact of seawater intrusion on the constitutive relationship of superfine cement–sodium silicate slurry (SC-S slurry). The chemical gelling time, viscosity, and rheological model of the slurry were studied. The concentrations of seawater ranged from 0% to 100%. The water–cement ratio ranged from 0.6 to 2.0. This study revealed that seawater significantly shortened the chemical gelling time of the slurry. The effect was more pronounced as the concentration of seawater increases. Furthermore, it was observed the rheological model of SC-S slurry will change from Bingham model to Herschel–Bulkley model with the increase in concentration of seawater. Rheological parameters that vary with time were also studied. The rheological constitutive models of slurry under seawater intrusion were established.

The time-varying viscosity of quick-setting slurries will cause the spatial variation of slurry viscosity, which has an important impact on the diffusion mechanism of infiltration grouting. With the time-varying Bingham fluid constitutive model and the uniform capillary group theory, a cylindrical–hemispherical slurry infiltration diffusion model was established, considering the time-space variation of slurry viscosity. According to the soil parameters and slurry rheological parameters, the slurry pressure can be calculated at different diffusion radius and times. The effects of the permeability, porosity, and grouting rate of the injected medium on the grouting pressure and grouting diffusion radius were analyzed. The medium porosity is very critical for the design of the slurry diffusion radius. A 3-dimensional infiltration grouting test was carried out. The infiltration grouting pressure under different grouting rates and soil parameters were obtained. The results obtained from theoretical model were compared and verified with the test results. The results show that the grouting pressures calculated from the infiltration diffusion model proposed in this paper are in agreement with the experimental results. The grouting pressure calculated by the theoretical model is 1.05–1.25 times of the experimental value.

The appropriate use of industrial solid waste is an effective method for alleviating environmental pollution. In this study, the potential of using desulfurized gypsum (DG), phosphogypsum (PG), gypsum dihydrate (G), and calcium carbide slag (CS) in the production of supersulfated cement (SSC) was investigated. The effects of various types of gypsum and their dosages on the performance and hydration process of SSC were thoroughly examined. The results indicate that as the ratio of CS to gypsum (CS/G) increased, the pH of SSC increased, whereas fluidity and setting time decreased. For the same CS/G ratio, SSCs activated by DG and CS (D-CSSC) and by PG and CS (P-CSSC) exhibited longer setting times and lower pH values than those activated by G and CS (G-CSSC). Mineralogical analysis and microstructural characterization revealed that the type of gypsum influenced the hydration rate, microstructure, and hydration products (type and quantity) of the SSC, thereby affecting its compressive strength. The loose pore structure of G-CSSC significantly reduced its compressive strength. Owing to the formation of a significant amount of Calcium aluminum hydrate (C-A-H) gel, D-CSSC demonstrated greater early strength; however, hannebachite hindered its late strength development. PG continuously participated in hydration, leading to more hydration products and a denser microstructure in P-CSSC, which significantly increased its late strength. This study elucidates the effect of gypsum type on SSC performance and offers valuable insights for enhancing it.