Abstract:

To improve coalbed methane extraction efficiency in deep mines, a high-flow sealing hole grouting material was developed using superfine cement as the base material to overcome issues of commonly used high polymer sealed materials such as high cost and flammable, low permeability of ordinary cement materials, and insufficient strength of paste materials such as fly ash. The hydration mechanism of the developed high-flow sealing grouting material was explored by an experimental study on the material's mechanical properties, combined with the measurements by scanning electron microscope(SEM)and X-ray diffraction(XRD). The results indicated that a large amount of calcium silicate hydrate (C-S-H) gel and ettringite (AFt) crystals were generated in the high-flow sealing grouting material during the initial phase of hydration. Furthermore, the gel particles of hydration products filled the pores of the material with the hydration reaction. Compared to commonly used cement sealing grouting material, the hydration reaction of the developed material was much faster and more complete, and the overall structure was more denser. Moreover, the compressive strength was increased by 3.68%. Therefore, the developed high-flow sealing hole grouting material can maintain the stability of gas extraction boreholes and improve gas extraction efficiency.

Key words: high-flow sealing, grouting material, drainage borehole, hydration reaction, hydration product