Study On Frost Resistance And Damage Rule Of Steel Fiber Reinforced Coal Gangue Concrete

Coal gangue concrete not only can consume large amounts of industrial waste,but also conforms to the national economic development direction of energy conservation,emission reduction and consumption reduction,and is of great significance to the utilization of coal gangue resources.This project uses coal gangue as coarse aggregate to replace ordinary gravel to prepare concrete.Acoustic emission technology is used to combine experimental research with theoretical analysis to study the damage evolution of coal gangue concrete and steel fiber reinforced coal gangue under freeze-thaw conditions law.This article first studied the frost resistance of coal gangue concrete.The test replaced crushed stone with 0%,20%,40%,and 60%of coal gangue to prepare concrete.Exploring the frost resistance of coal gangue concrete with different coal gangue replacement rate;and based on the behavior of coal gangue concrete under different freezing and thawing cycles.The change of elastic modulus,the basic theory of macroscopic phenomenological damage mechanics,establishes the freeze-thaw damage evolution equation of coal gangue concrete.The results show that the frost resistance of concrete decreases significantly with the increase of coal gangue substitution rate;the damage evolution equation of gangue concrete established based on the dynamic elastic modulus is in good agreement with the experimental data and can be used for coal gangue concrete under freeze-thaw conditions,which can provide the theoretical basis for the durability design of coal gangue concrete.Acoustic emission technology was used to dynamically monitor the uniaxial compressive strength of coal gangue concrete after freeze-thaw cycles.Based on the acoustic emission energy released during the compressive failure process of coal gangue concrete,the internal damage degree was qualitatively analyzed;and the damage evolution model of coal gangue concrete was built based on the cumulative count of acoustic emission events during the compression process.The study shows that with the increase of the number of freeze-thaw cycles,the initial damage value of coal gangue concrete is bigger,the peak stress is smaller,and the brittleness performance is more obvious.The damage evolution model established by accumulative counting of acoustic emission events in this paper is in good agreement with the test results,and can provide a theoretical basis for the evolution of axial compressive damage of gangue concrete under freeze-thaw conditions.In order to further improve the frost resistance of coal gangue concrete,0%,0.5%,1%,and 1.5%of steel fibers were blended into the coal gangue concrete to prepare steel fiber reinforced coal gangue concrete.Through rapid freeze-thaw tests,the changes of apparent morphology,mass loss,relative dynamic elastic modulus and compressive strength of steel fiber gangue concrete with different contents were studied.The damage variable was defined by the change of the dynamic elastic modulus of steel fiber reinforced coal gangue concrete,and the damage evolution model of steel fiber reinforced coal gangue concrete under freezing and thawing environment was established.The results show that the addition of proper amount of steel fiber under freeze-thaw environment can reduce the loss of mass and relative dynamic elastic modulus of coal gangue concrete and improve the frost resistance of coal gangue concrete.The damage model presented in this paper is in accordance with the experimental data better,which can provide a theoretical reference for the study of the durability of steel fiber reinforced coal gangue concrete in freeze-thaw environment.In order to study the relationship between the compression damage damage process and acoustic emission characteristic parameters of steel fiber reinforced coal gangue concrete,acoustic emission technology was used in the test,and the gangue concrete with steel fiber content was 0%,0.5%,1%,and 1.5%.The axial compression test is dynamically monitored.According to the count of acoustic emission ringing,the whole process of compressive damage of steel fiber coal gangue concrete is inversed.The damage variable of steel fiber reinforced coal gangue concrete is defined according to the acoustic emission energy,and the damage evolution model of steel fiber reinforced coal gangue concrete with different content is established.Experimental studies show that acoustic emission parameters are closely related to the formation,expansion and penetration of internal cracks in steel fiber reinforced coal gangue concrete;the addition of appropriate steel fibers can delay the development of cracks in the coal gangue concrete;the establishment of damage variables based on the definition of acoustic emission energy is in good agreement with the experimental data and can provide a theoretical reference for the study of the damage law of steel fiber reinforced coal gangue concrete.