Study On Strength And Permeability Characteristics Of Red Mud,Carbide Slag And Fly Ash Mixture

The development of the industrial field will inevitably produce some solid waste,including red mud,carbide slag and fly ash.If these wastes are not properly disposed of,they will not only take up a lot of valuable land resources,but also pollute the environment.In order to explore effective ways to eliminate three kinds of solid waste,this thesis studied the main technical indexes of three kinds of waste composition mixtures through indoor experiments,including electrical resistivity,unconfined compressive strength and permeability coefficient.In this thesis,the electrical resistivity of the mixture was measured by different current frequencies.The effects of current frequency,mix proportion,age and molding method on the electrical resistivity of the mixture were studied.Then,the unconfined compressive strength test was carried out.The effect of age,mix proportion and molding method on the unconfined compressive strength was studied.Finally,the effect of seepage pressure,mix proportion and age on the permeability coefficient of the mixture was studied by the penetration test.Through the above research,this thesis establishes the correspondencebetween the electrical resistivity of the mixture and the unconfined compressive strength,the electrical resistivity and permeability coefficient,which provides a reference for future research.After systematic research and analysis,the main research results of this thesis are as follows:(1)When the current frequency is in the range of 0-50 kHz,the electrical resistivity of the mixture decreases continuously with the increase of the current frequency.When the current frequency is in the range of 50kHz-1MHz,with the increase of the current frequency,the change in electrical resistivity of the mixture is small and gradually stabilizes.Therefore,the current frequency is suitable to be selected in the range of 50kHz-1MHz.(2)As the content of carbide slag and fly ash increases,the red mud content decreases,and the electrical resistivity of the mixture increases first and then decreases.When the mass proportion of red mud,carbide slag and fly ash is40:30:30,the electrical resistivity of the mixture reached a maximum.As the age increases,the electrical resistivity of the mixture increases and the growth rate slows down after 14 days due to the weakening of the chemical reaction.The molding method does not change the trend of the influence of age and the mix proportion on the electrical resistivity,but changes the numerical value of the electrical resistivity.(3)As the content of carbide slag and fly ash increases,the red mud content decreases,the unconfined compressive strength of the mixture increases first and then decreases.When the mass proportion of red mud,carbide slag andfly ash is 40:30:30,the strength of the mixture reaches the maximum.When the content of carbide slag and fly ash continues to increase,the strength decreases due to excess of carbide slag.As the age increases,the unconfined compressive strength of the mixture increases continuously.After the age is greater than 14 days,the strength growth slows down due to the weakening of the chemical reaction.The molding method does not change the trend of the influence of the mix proportion and age on the unconfined compressive strength,but changes the numerical value of the strength.(4)Under different mixing proportions,the permeability coefficient of the mixture increases or slightly increases as the seepage pressure increases due to the difference in structural stability.The permeability coefficient of the mixture decreases first with the increase of carbide slag and fly ash content.Small and then increased.When the mass proportion of red mud,carbide slag and fly ash is40:30:30,the permeability coefficient of the mixture is the smallest,and the impermeability is the best.When the content of carbide slag and fly ash continues to increase,the structure is destroyed,and the permeability coefficient increases.As the age increases,the permeability coefficient of the mixture decreases as the structure becomes dense.(5)The electrical resistivity of the mixture is positively correlated with the unconfined compressive strength.When the electrical resistivity increases,the unconfined compressive strength also increases.The electrical resistivity of the mixture exhibits a negative correlation with the permeability coefficient,whenthe resistivity increases,the permeability coefficient decreases.Therefore,by measuring the electrical resistivity,it is possible to predict the unconfined compressive strength and permeability coefficient of the mixture.