Rheological Properties and Time-dependent Viscosity Evolution of OPC/SAC-sodium Silicate Double Grout
Yinjuan Sun, Fanghao Liu, Zhenxiang Wang, Fei Sha, Yuhang Zuo, Shuo Jiang, Rui FanIntroduction:
Water-rich fractured rock masses often cause water inrush and mud inrush in tunnel engineering. Grouting sealing is a primary control method, requiring accurate characterization of slurry properties. This study investigates rheological and time-dependent viscosity behaviors of single and double slurries to support grouting diffusion analysis.
Methods:
Laboratory tests were conducted on OPC or SAC single slurries (water–cement ratio of 0.8–2.0) and cement–sodium silicate double slurries (volume ratio of 1:1–5:1). A Herschel–Bulkley rheological model was developed for single slurries. For double slurries, a power-law time-varying viscosity model (μ(t)= a·tb) was developed. Grouting diffusion tests were performed under hydrostatic seawater conditions in smooth and rough fractures.
Results:
The Herschel–Bulkley model was fitted with R² > 0.99 for single slurry data; it outperformed the Newtonian and Bingham models. The power-law model for double slurries was achieved with R² > 0.975. At the volume ratio of 1:1, the gelation time of S-S slurry was 6.9–7.9 times that of C-S slurry. All slurries showed circular diffusion patterns, with faster diffusion in smooth fractures.
Discussion:
The Herschel–Bulkley model captured shear-thinning or thickening of cement slurries during bleeding. C-S slurry viscosity rose rapidly due to the sodium silicate–calcium hydroxide reaction forming a viscous gel, while S-S slurry viscosity increased more slowly because sodium silicate interfered with SAC hydration. Fracture roughness delayed diffusion by increasing friction.
Conclusion:
The proposed models effectively characterize OPC/SAC single and double slurries, providing theoretical support for predicting grout diffusion in fractured rock masses and selecting suitable slurries for water-rich tunnels.