Rheological Characterization and Accumulation Tests for Strong Thixotropic Engineering Slurry.

Area of Science:

• Geotechnical Engineering
• Materials Science

Background:

• Underground void subsidence, particularly from mine goaf, poses significant risks to civilian well-being and development in China.
• Effective filling treatments are crucial for mitigating these hazards and ensuring ground stability.

Purpose of the Study:

• To develop a robust thixotropic engineering slurry and filling treatment for underground void subsidence hazards.
• To optimize the agent ratio for thixotropic cement slurry/mortar using indoor tests.

Main Methods:

• Determining optimal agent ratios through indoor tests: 7.5% rheological agent, 0.7-0.8 water-solid ratio, and 0-1.5 times aeolian sand to cement ratio.
• Analyzing rheological properties of slurry and mortar using a Brookfield RST-SST rheometer.
• Developing new rheological models for yield stress, stress-shear rate, and accumulation law.

Main Results:

• Aeolian sand is suitable for thixotropic cement mortar backfilling of mine goaf.
• Static yield stress exhibits non-linear behavior, deviating from existing models.
• Proposed models accurately describe the material's behavior: logarithmic for yield stress vs. rest time, two-part exponential for stress-shear rate, and exponential for accumulation.

Conclusions:

• The developed thixotropic slurry with aeolian sand provides an effective solution for underground void and mine goaf filling.
• The proposed rheological models offer a simplified yet accurate representation of the material's complex behavior.
• This research contributes to safer and more stable underground environments by addressing subsidence hazards.