Effect Of Spontaneous Combustion Coal Gangue Powder On Mechanical Properties And Permeability Of Steamed Concrete

Coal gangue refers to carbon-bearing rocks and rocks discharged from coal mines during well construction,mining,coal mining and coal washing.It is the general term for solid waste discharged from coal mine construction and coal production.There are a large number of coal gangue hills in China.The random stacking of these coal gangues will pollute the air,water source,geology,etc.,and bring serious environmental problems.Therefore,a rational method is needed to treat coal gangue.The use of coal gangue as a mineral admixture for cement concrete is an effective way.This can reduce the environmental pollution caused by the production and use of cement.Second,it can generate huge economic benefits from turning waste coal gangue into treasure.At the same time,with the development of industrialization of buildings,more and more concrete components are required to achieve factory prefabrication,and the most common curing method for prefabricated components is steam curing.It is unclear how the performance of concrete mixed with gangue powder under different steam curing conditions is developing.Based on this,the research has important theoretical and practical significance.In this paper,the concrete with the coal gangue content of 0%,10%,20%,30%,40%is designed,and the three water-cement ratios are designed to be 0.31,0.36 and 0.43,and under different curing systems?normal temperature curing,steam curing?Firstly,the development law of compressive strength of coal gangue powder concrete was studied,and the relationship between compressive strength and ultrasonic sound velocity was studied.Secondly,the chloride ion permeability,gas permeability and surface water absorption of concrete were passed.The permeability of coal-doped vermiculite powder concrete was studied in three aspects.Finally,the microstructure of coal-filled vermiculite concrete was studied by means of XRD,MIP and thermal analysis.The results show that with the increase of coal gangue content,the compressive strength of normal temperature curing concrete decreases continuously.At 28d and 90d age,the compressive strength of concrete with 10%coal gangue is 1.5%and 1.2%;after the steam curing temperature is 60°C,after 18 h of curing,the compressive strength of the coal-filled vermiculite concrete reaches 87.6%of the 3d strength of the normal temperature curing concrete,63%of the 28d strength,and reaches 90d when the age is90d.The normal temperature curing concrete is 80%of the same age,and when the steam curing temperature is 80°C,this value is 90.4%,65%and 76.1%;the strength of concrete increases with the increase of ultrasonic sound velocity,both There is no linear relationship,but a relationship of power functions.Adding self-ignited coal gangue powder to concrete will greatly improve the permeability resistance of concrete:the test results of electric flux and gas permeation test show that the permeability of coal gangue concrete is lower than that of pure cement concrete,when coal gangue is mixed.When the amount is 20%,the chloride ion permeability and surface water absorption performance of the concrete are the best,and when the content is 30%,the gas permeability of the concrete is optimized;in order to obtain concrete with better permeability,When the steam curing temperature is 60°C and80°C,the steaming time is preferably 24 h.In terms of microstructure,the steam curing method has obvious effect on the microstructure improvement of coal-filled vermiculite concrete.In the steam curing mode,the peak of Ca?OH?₂ in the XRD pattern is significantly reduced,and 400°C in the TG-DTA spectrum.The weight loss peak of nearby Ca?OH?₂ is obviously reduced,the pores in the concrete are refined,and many harmless pores appear,and harmful pores and harmful pores are greatly reduced.