Cement-Based Rock Grouting: Shear Rate Dependencies-PPT Presentation

PPT Presentation

Pdf Summary

The presentation examines how shear-rate-dependent behavior affects cement-based rock grouting. Its focus is on two rheological issues: wall slip and a critical shear rate, and how they influence predictions of grout propagation through fractures.<br /><br />Cement grouts have complex flow behavior, including thixotropy, wall slip, hydration, sedimentation, and particle migration. The researchers measured flow curves using a rotational rheometer, testing grouts with water-to-cement ratios of 0.6 and 0.8. They varied measurement geometry and measurement intervals, and used creep tests to assess the critical shear rate. Results showed that measured flow curves depend on both geometry and measurement time.<br /><br />The study applies these findings to idealized two-dimensional radial flow in rock fractures, a model used for theoretical grouting analyses. A practical design nomogram was developed to link required grout propagation with relevant grouting variables. An illustrative example showed that neglecting wall slip can substantially affect estimated flow rate and penetration length, with differences of about 50%.<br /><br />The authors conclude that grout rheology should be characterized with attention to measurement conditions and shear-rate effects. Future work should improve analytical models to account for wall slip and thixotropy, and use visualization methods such as in-line UVP measurements.

Keywords

cement grouting

shear-rate dependence

wall slip

critical shear rate

rheology

thixotropy

rotational rheometer

fracture propagation

grout penetration

rock fractures