# A State-of-the-Art Review on the Study of the Diffusion Mechanism of Fissure Grouting
## 2 Current Status of Research on Grouting Materials
### Organic Grouting Materials  
Organic grouting materials (composite materials) can actually have better applicability. Organic materials typically have higher injectability, shorter and more controllable setting times, and higher early strength, but they are expensive. Polyurethane slurries [35; 36] and acrylic slurries [37; 38] have found extensive application in practical engineering.  
With the development of polymer grouting materials, their applications are becoming more and more extensive. The research team led by academic [PERSON] from Zhengzhou University mainly investigates the development and application of new cementitious materials, polymer grouting materials, and geo-environmentally responsive grouting materials in the field of grouting materials. By selecting and blending different raw materials, they achieved the optimization design and preparation process of grouting materials and explored the performance characterization and application fields of grouting material properties. Aiming at the common diseases of road pavements, they independently developed a set of fast and effective grouting techniques and technologies for repairing diseases using the characteristics of polymer materials, which have been widely used in road pavements, pipelines, dams, tunnels, bridges, and other practical engineering fields [39; 40; 41; 42]. This has played a great role in the South-to-North Water Diversion Project, Yi-Wan Railway Sudden Mud Control, Underground Engineering Sudden Water Surge Control, and other major restoration projects. [PERSON] and [PERSON] [43] developed a two-dimensional continuous flow model for high-polymer slurry, considering the geometric shape, chemical reactivity, and time-dependent flow of high-polymer systems. [PERSON] and [PERSON] [44] created a high-polymer slurry diffusion model based on Hele-Shaw flow to simulate the expansion and filling process of high-polymer materials in variously shaped molds, accounting for density changes. [PERSON] et al. [45] examined the toughening effect of in situ-prepared polyacrylamide on sulfoaluminate cement-based grouting material (SCGM), which showed significantly improved toughness compared with standard SCGM. [PERSON] et al. [46] developed a chemical reaction-hydrodynamic model for polymer grout flow and diffusion in planar fissures, utilizing computational fluid dynamics theory and polymerization mechanisms. They achieved a coupled solution for the chemical reaction, temperature field, and flow field. [PERSON] et al. [47] designed a water-soluble epoxy resin to modify cement-based grouting material, demonstrating superior strength, strain, flowability, stability, and bonding capacity compared with pure cement grouts. [PERSON] et al. [48] investigated the influence of polymer concentration, soil moisture, and soaking duration on the strength of silt solidified with permeable polyurethane grouting materials and found significant improvements in silt performance. [PERSON] et al. [49; 50] discussed the application of high-polymer injection technology in the treatment of hidden diseases, such as mud and the overturning of road surfaces, and the restoration of road-bearing capacity based on the performance and technical characteristics of high-polymer injection materials and comprehensive non-destructive testing techniques, such as ground-penetrating radar and hammer-type bending and sinking meters.  
The Current Status of Research on the Theory of Seepage Diffusion of Fissure Grouting in the Rock Body