The Study Of Permeability Coefficient Of Lithium Slag Concrete Effected By Multiple Influencing Factors

Lithium slag as a by-product of industrial production of lithium,for a long time it was treated as waste and abandoned,as an utilization of using lithium slag in the concrete is not only conducive to the protection of the environment but also conducive to the development of building structure.Xinjiang belongs to the area of having cold weather and salty soil,and the durability of concrete is inceasingly serious because of the many environmental factors.So under the freeze-thaw cycles and natural soaking,the influence of different amount of lithium slag powder on the permeability of concrete and the permeability of chloride ion was studied,On this basis,the correlation between gas permeability coefficient and electric flux is studied,and the relation between chloride diffusion coefficient and electric flux is discussed.the lithium slag powder on the effect of pore structure and the relationship between permeability of concrete with pore structure parameters by mercury intrusion method;finally with the corresponding formula,the formula is derived about diffusion coefficient applying to the AUTOCLAM permeability tester.Firstly,the change of permeability coefficient of lithium slag concrete at different ages was tested by AUTOCLAM permeability tester,and the compressive strength was studied with C20,C30,C40 and C60 and different lithium powder varying from 0%~30%.Meanwhile the Chloride ion flux is tested at 28 days.Under the condition of a certain amount of lithium slag,the gas permeability coefficient and the electric flux value of the concrete with different strength grades are obviously reduced.And it is found that there is a good relationship between the gas permeability coefficient and the age,and the correlation between the flux and the initial current is also good.Secondly,based on the rapid freezing and thawing method,mass loss,lithium slag concrete compressive strength,gas permeability and flux value are tested,the results show that the lithium slag 10% improve the concrete freeze-thaw cycles and reduce the mass loss rate.And there is a good relationship between the compressive strength and the number of freeze-thaw cycles,that is,with the increase of the number of freeze-thaw cycles,the compressive strength will be lost in a certain proportion.There is a functional relationship between the gas permeability with the number of freeze-thaw cycles,the same in the relationship between the flux value with the number.And the gas permeability coefficient and flux values are both increased with the number of freeze-thaw cycles,with the incorporation of lithium slag,concrete’s flux value are reduced,also lithium slag powder can improve the concrete after freeze-thaw cycles in chloride ion permeability.The gas permeability coefficient is related to the electric flux value,that is,the gas permeability coefficient increases with the increase of the flux.Study on chloride diffusion coefficient based on natural immersion method,The results show that the diffusivity of chloride increases with the increase of NaCl concentration and decreases with the increase of soaking time.When the lithium slag concrete was soaked in NaCl solution for a certain time,the chloride diffusion coefficient and the 28 day flux value of lithium slag concrete decreased with the increase of the amount of lithium slag.Finally,on the basis of the mercury intrusion method,the critical pore size,the pore size,the average pore size and the porosity are tested,the results indicate that the critical pore size and the most probable pore size decrease with the increase of curing age,and the addition of lithium slag powder can reduce the critical pore size and increase the maximum pore size.The C30 and C60,respectively,when the content of 20% and 30%,have the maximum pore tortuosity.