The Research Of Influence Of Lithium Slag Powders On Chloride Penetration Of Concrete Under Load Or Freeze-thaw Cycles

Xinjiang lithium salt plant is Asia’s largest manufacturer which produces lithium saltproducts with ore as raw materials. At present, the international market demands for lithiumseries products rising at an annual rate of15%~20%, but every tons of lithium carbonateproduction would discharge about ten tons of lithium slag waste. Rational use of lithium slagnot only can reduce cost, but also is conducive to protect the environment. Meanwhile,Xinjiang region widely distributes saline soil and has cold climate, and concrete structures inservice are subjected to chloride ion erosion, freeze-thaw damage and load. As a result, itsdurability is more complex and severe. Therefore, this paper carried out the experimentalstudy on the influence of lithium slag powders upon the chloride penetration of concreteunder load and freeze-thaw cycles respectively, to provide a reference for the durabilityevaluation of reinforced concrete structures in Xinjiang area.Firstly, according to the "Specification for mix proportion design of ordinary concrete"(JGJ55-2011), the strength grade of C40mix proportion design was obtained, and then thebasic properties of concrete were determined. The results show that with increasing lithiumslag powder content, concrete cubic compressive strength of28d increases first and thendecreases and it is maximum when the content is20%, and change trends of cylindercompressive strength and cubic compressive strength are similar and the relationship betweenthe two has a good linear correlation. The test also finds that changes of hydration products ofcement-based materials observed by scanning electron microscope can better explain thevariations of the cubic compressive strength of concrete.Secondly, electric flux of concrete under once loading and cyclic loading was determinedby test method for coulomb electric flux. The test results indicate that load has a significantimpact on the chloride penetration of concrete and electric flux increases with increasingstress ratio by the exponential function under once loading and cyclic loading. Addition oflithium slag powder into concrete can significantly reduce its chloride penetration and electric flux decreases with increasing lithium slag powder content by the quadratic function. The testalso concludes that electric flux and initial current has a good linear correlation.Finally, electric flux of concrete under freeze-thaw cycles was determined by test methodfor coulomb electric flux. The test results show that electric flux increases with increasingfreeze-thaw cycle number by the linear function. When the freeze-thaw cycle number is75,the concrete with different lithium slag powder content still has a high resistance to chloridepenetration. Addition of lithium slag powder into concrete can significantly reduce itschloride penetration and electric flux decreases with increasing lithium slag powder contentby the negative exponential function. The test also finds that the relationship between electricflux and initial current, electric flux and chloride ion penetration depth, initial current andchloride ion penetration depth all have a good linear correlation.