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The geological condition of Chinese coal mines are complex and high gassy,which account for ffty percent to seventy percent.Because of the abundant pores and cracks around the drainage drilling hole,the gas concentration attenuates rapidly,and the effective gas drainage period is short.The traditional sealing materials of yellow mud and cement-sand grout will readily shrink after the drilling hole is sealed,the sealing length is short and the sealing quality is not satisfactory.Currently widely used polyurethane material will shrink when it comes into contact with water,and the price is also very high.In this study,taking cement as a base material,a novel composite sealing material mixed by expansion admixture,additive,and fbrin and coupling agent was developed and the sealing performance and expansion property of the material were also studied and analyzed.The FEI Quanta TM 250 environmental scanning electron microscope was used to investigate the microstructure of material.The results revealed that the new composite sealing material had a desirable expansion performance and a defnite fluidity convenient for grouting.The solidifed material,combining closely with the drilling wall,possessed an adequate strength and was not easy to shrink.Compared to the conventional polyurethane,the gas drainage concentration by drilling sealing exceeded 40 percent,and the sealing capacity improves5 times,the sealing effect increases signifcantly.
The geological condition of Chinese coal mines are complex and high gassy, which account for ffty percent to seventy percent.Because of the abundant pores and cracks around the drainage drilling hole, the gas concentration attenuator rapidly, and the effective gas drainage period is short. The traditional sealing materials of yellow mud and cement-sand grout will now shrink after the drilling hole is sealed, the sealing length is short and the sealing quality is not satisfactory.Currently widely used polyurethane material will shrink when it comes into contact with water, and the price is also very high. In this study, taking cement as a base material, a novel composite sealing material mixed by expansion admixture, additive, and fbrin and coupling agent was developed and the sealing performance and expansion property of the material were also studied and analyzed. The FEI Quanta ™ 250 environmental scanning electron microscope was used to investigate the microstructure of material. The result s revealed that the new composite sealing material had a desirable expansion performance and a defnite fluidity for forging the solidifed material, combining closely with the drilling wall, possessed an adequate strength and was not easy to shrink. Compounded to the conventional polyurethane, the gas drainage concentration by drilling sealing exceeded 40 percent, and the sealing capacity improves5 times, the sealing effect increases signifcantly.