Microscopic Characteristics of a New Type of Sealing Material for Boreholes

The microscopic characteristics of a new type of sealing material, Portland cement and polyurethane for borehole are studied. Based on sealing process in the underground coal mine simulated by experiment, the permeability around boreholes of the new type of sealing material and the polyurethane material are compared through environmental scanning electron microscope FEI QuantaTM250, and T₂ distribution of the new type of sealing material paste and common cement paste are analyzed by means of low field NMR equipment. The results show that the new type of sealing material has a better permeability than polyurethane material, which can effectively eliminate fractures around boreholes and improve the stability of sealing segment. Within 2 hours, due to a better liquidity feature, only micro fissures come out when the new type of sealing material is utilized while cavern porosities come out for common cement.