| In order to control environmental pollution,many regions in China have implemented mountain closures and mining bans,which has caused difficulties for the supply of concrete aggregates supported by mines.Non-spontaneous coal gangue is solid waste generated during coal mining and washing and processing.It is also one of the largest industrial solid wastes in China at present,which seriously pollutes the mine environment.In order to turn waste into treasure,control environmental pollution and solve the problem of shortage of raw material supply for underground concrete,this paper carried out related basic research work of non-spontaneous combustion coal gangue used in coal mine concrete aggregate.The thesis adopts non-spontaneous coal gangue as coarse and fine aggregate instead of natural aggregate and mixes it into concrete.The basic mechanical properties test,drop weight impact test,SHPB test and screening test are used to test and analyze non-spontaneous coal gangue concrete To study and compare the effects of single and mixed non-spontaneous coal gangue coarse and fine aggregates on the main mechanical properties of concrete.The main contents are as follows:(1)The test results of different non-spontaneous combustion coal gangue fine aggregates and the compressive strength of concrete at different ages show that the 28d compressive strength of C30 and C40 concrete are different from those of non-spontaneous combustion coal gangue fine aggregates.The trend is to increase first and then decrease.The optimal dosage is 30%.(2)The basic static mechanical performance test of non-spontaneous coal gangue concrete shows that adding non-spontaneous coal gangue coarse aggregate concrete to non-spontaneous coal gangue coarse aggregate concrete can improve aggregate grading and reduce internal pores of concrete,Reduce the adverse effect of non-spontaneous coal gangue coarse aggregate on concrete strength.When the configuration strength is C30 and C40,the compressive strength of the coarse aggregate concrete with non-spontaneous combustion coal gangue is 39.07MPa and 47.34MPa,the split tensile strength is 3.583MPa and 4.205MPa,and the flexural strength is 3.527MPa,respectively And 4.121MPa;the compressive strength of concrete mixed with non-spontaneous coal gangue coarse and fine aggregate is 41.83MPa and 49.79MPa,the splitting strength is 3.782MPa and 4.386MPa,and the bending strength is 3.73 1MPa and 4.318MPa,respectively.Compared with ordinary concrete,the compressive strength of C30 and C40 mixed with non-spontaneous coal gangue coarse and fine aggregate concrete was increased by 4.7%and 2.4%,the split tensile strength was increased by 1.8%and 0.2%,and the flexural strength was basically equal.(3)The drop weight impact test of non-spontaneous coal gangue concrete shows that when the configuration strength is C30 and C40,the initial cracking impact energy of the single-spontaneous coal gangue coarse aggregate concrete is 201.5J and 223.7J,The final impact energy is 197.5J and 207.6J,and the average failure energy is 199.5J and 215.7J,respectively.The initial cracking impact energy of coarse and fine aggregate concrete mixed with non-spontaneous coal gangue was 243.9J and 270.1J,the final cracking impact energy was 219.7J and 229.9J,and the average failure energy was 231.8J and 250J,respectively.Compared with ordinary concrete,the initial cracking impact energy of concrete mixed with non-spontaneous coal gangue coarse and fine aggregates was increased by 2.6%and 2.3%,the final cracking impact energy was increased by 0.9%and 0.1%,and the average damage energy was increased.1.7%and 1.3%.(4)The SHPB test of non-spontaneous coal gangue concrete shows that when the impact gas pressure is 0.4 MPa,0.5 MPa,0.6 MPa and 0.7 MPa respectively,the dynamic resistance of coarse and fine aggregate concrete mixed with non-sponfaneous gangue under the C30 configuration strength The compressive strengths are 45.654MPa,47.789MPa,50.773MPa,54.545MPa,and the dynamic compressive strength of non-spontaneous coal gangue coarse and fine aggregate concrete under C40 configuration strength is 55.276MPa,58.756MPa,60.907MPa and 62.807MPa,respectively.Compared with ordinary concrete,the dynamic compressive strength of C30 concrete is increased by 2.8%,3.1%,1.6%,and 4%,respectively.The dynamic compressive strength of C40 concrete is basically the same as that of ordinary concrete;Compared with aggregate concrete,the dynamic compressive strength of C30 concrete increased by 5.7%,8.2%,6.3%,and 9.0%,respectively,and the dynamic compressive strength of C40 concrete increased by 3.2%,5.9%,6.5%,and 5.5%,respectively.(5)The research results of fractal characteristics of non-spontaneous combustion gangue concrete at different impact pressures show that with the increase of impact pressure,the degree of crushing,crushing particle size and fractal dimension of non-spontaneous combustion gangue concrete are also increasing..According to the test data,the higher the dynamic compressive strength of concrete mixed with non-spontaneous coal gangue coarse and fine aggregate,the greater the fractal dimension.The concrete fractal dimension has a good positive correlation with the dynamic compressive strength.The above test research shows that the test prepared C30 and C40 non-spontaneous coal gangue concrete can be used in the supporting project of the mine under dynamic and static load to reduce environmental pollution and solve the problem of shortage of natural sand and stone materials supply.Figure 51 Table 16 Reference 81... |
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