Study on the mechanical properties and microstructure of a rich-watered grouting material

Abstract

The effective method of mine gas control and efficient development is gas extraction technology. The sealing effect of grouting material on borehole directly affects the efficiency of gas extraction. The new type of rich-watered sealing material with suitable mechanical strength and significant plastic characteristics was developed based on the addition of accelererant, alkali activator, expansion agent and reinforcing agent to Portland cement for mining. The effect of reinforcing agent on the mechanical properties of materials under different w/c ratios was tested by RMT. By means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and other test methods, the microstructure evolution of grouting materials and its influence mechanism on macroscopic mechanics were revealed. The results show that the crystal structures of hydration products AFt, Ca(OH)2 and C-A-H regulate the development of mechanical strength of materials. The uniaxial compressive strength of rich-watered grouting materials can reach 3.5–5.6 MPa and the residual strength is greater than 3 MPa in the range of rich-watered ratio of 0.9–1.3. The new rich-watered grouting material developed has significant plastic deformation characteristics under high rich-watered ratio conditions, which can greatly adapt to borehole deformation and reduce the gap width of slurry-coal interface, and can meet the technical requirements of long-term sealing of gas extraction boreholes.