Experimental Study Of Polymer Powder Modified Cement Used In Borehole Sealing

Gas drainage is the guarantee of safe-mining.The concentration of gas extraction is less than 30% in about 65% working face of our country,which fully reflects the present situation of bad sealing quality.Sealing quality has directly effect on the result of gas drainage meanwhile it depends on hole sealing materials and methods largely.Therefore,it is very important to take study on hole sealing materials.Polymer modified cement has a combined performance of both polymer and cement,but its application and research of underground hole sealing are very few.Meanwhile,the modification is happened mostly in single and emulsion polymer.So we study the combined modification of polymer powder and other adding contents and develop a kind of polymer powder modified cement,which is very meaningful to improving the efficiency of gas drainage and ensuring safe-mining.(1)This article adopts the method of theoretical analysis,puts forward that the drainage rate has influence on hole sealing quality and establishes drainage rate-air leakage model based on the present study of drilling leakage mechanism.Analyzes the reaction mechanism of cement materials and the theory of composite material interface,calculates the optimum proportioning of cement composition.(2)During the process of research and development,we determine the initial water cement ratio of hole sealing material,study the effect of polymer powder on drainage rate,viscosity and macroscopic fracture,explain the influence of polymer powder on the macro-performances of hole sealing material by SEM and FTIR.(3)Study the effect of polymer powder together with coal ash on compressive strength.Introduce the concept of fractal box dimension,study mechanical behavior of hole sealing material from micro-view.Take research on the dynamic process of the crack development under the pressure of surrounding rock.This is very meaningful for revealing mechanism of air leakage comprehensively and for the optimization of hole sealing material.The thesis studies the sealing property of three kinds of materials comparatively,examine the hole sealing performance of the material developed by experiment.The study accelerates the process of its using under coal mines.During my graduate studies in CUMT,I published a piece of Chinese core journal and applied for 11 patents,including 8 patents of invention in the stage of substantial examination and 3 patents of utility model authorized.