Experimental Study On Coagulation Mechanics And Durability Damage Deterioration Mechanism Of Coal Gangue Mixed Aggregate

Based on the background of slope protection and restoration of typical mine dump in Wuhai city,Inner Mongolia,the thesis takes local accumulated coal gangue and natural pumice as the main raw materials.The experimental study of gangue mixed aggregate concrete is divided into two stages.In the first stage,gangue mixed aggregate concrete is prepared by replacing pumice coarse aggregate with coal gangue coarse aggregate with equal volume gradient,and the macroscopic mechanical properties of concrete are analyzed accurately through compression test and splitting tensile test.The mass loss rate and relative dynamic elastic modulus of concrete subjected to freezing-thawing cycle were used to characterize the macroscopic frost resistance of concrete.The damage constitutive model was established by uniaxial compression test of concrete after freezing-thawing cycle,and the damage degradation process,damage mechanism and durability of concrete were analyzed.According to the mechanical properties and durability deterioration law,combined with the microscopic characteristics,the comprehensive performance of gangue mixed aggregate concrete with different amount of gangue was analyzed,and the optimal gangue mixed proportion was determined.Phase two is based on the optimal replacement ratio,the additive 120 mesh powder to improve coal gangue concrete comprehensive performance,analysis of coal gangue powder mixture aggregate concrete macroscopic mechanical properties,freeze-thaw damage characteristics and microscopic pore structure,grey correlation model is set up based on nuclear magnetic resonance(NMR)technology,studies macro mechanical properties and pore structure,the conclusion is as follows:1.With the increase of gangue substitution rate,cube compressive strength increases first and then decreases,and 60% substitution rate reaches the peak value.The exponential function fitting accuracy of splitting tensile strength and substitution rate is high,and the established stress-strain curve model can better describe the load-bearing deformation process of concrete.With the increase of coal gangue replacement rate,the proportion of micro pores in concrete increases,while the proportion of large and medium pores decreases.The mixing of coal gangue and pumice weakens the material defects of pumice and coal gangue,reduces the internal pores of concrete and optimizes the pore structure.It was determined that the optimal replacement rate was 60%,with the highest strength,maximum initial stiffness,the strongest resistance to elastic deformation and good internal pore structure.2.Under freezing-thawing cycle,the mass loss rate increases and the relative dynamic elastic modulus decreases with the increase of gangue substitution rate,and the increase of substitution rate degrades the frost resistance of gangue mixed aggregate concrete to a certain extent.The stress-strain damage degradation constitutive model of gangue mixed aggregate concrete under different gangue replacement rates was established to better reflect the strength deterioration law of gangue mixed aggregate concrete under different gangue replacement rates.3.The addition of 120 mesh rubber powder improves the tensile and compression ratio of concrete,reduces the brittleness of concrete and improves the toughness of concrete.The colloidal particles can fill pores,reduce the generation of harmful pores and optimize the pore structure.The GM(1,3)model was established,and the average error between the predicted value and the experimental value was 3.60%.The durability of gangue mixed aggregate concrete can be improved by adding 120 mesh rubber powder,and the best content is 12%.4.Determine the water-ash ratio of 0.43,and the gangue 60% equal volume to replace the pumice coarse aggregate to prepare gangue mixed aggregate concrete.Provide a slope protection concrete material that can be used in situ for large drainage yards in the mining area,reduce economic costs,reduce solid waste gangue accumulation area,natural pollution of the environment and other issues.1 20 mesh glue powder with 12% mass of the externally incorporated cement material can improve the pore structure and freeze resistance of the concrete,and improve the performance of the concrete.