The Multiple Corrosion Experimental Study Based On The Corrosion Test Of Sulfate About Lanzhou Underground Reinforced Concrete

Lanzhou subway has a variety of corrosive ions and the content is very high in groundwater and soil environment.The main ion is chloride ion corrosion, sulfate ions and magnesium ions, and they have reached the strong corrosive. The subway engineering as a national large engineering, the concrete structure durability requirements is very high, general design service life of 100 years, so the research in lanzhou subway sulfate in the durability problem of multi-factor corrosive environment problem is not only important to Lanzhou subway,but also has great significance to the same type of soil and water environment in northwest of subway construction.In reinforced concrete corrosion resistance research, the more is about single factor corrosion study of sulfuric acid root ion and chloride ion, under the condition of dry-wet circulation and sulfuric acid root ion corrosion is more as well,but dual factors of magnesium ion and sulfate ion corrosion research is less, chloride, sulfuric acid root ion and the multi-factor corrosion study of magnesium ions is much less. With the actual situation in lanzhou subway environment, we adopted the long-term immersion method, the interior circulation rapid test method and electrochemical workstation to study the reinforced concrete corrosion problem about various factors based on sulfate corrosion.In the research of concrete resistance to sulfate ion and magnesium ion of double factors corrosion test, in this paper,we designed five kinds of proportioning of concrete specimen,which long-term immersion in the 5000 mg/L magnesium sulfate solution.We used long-term immersion method and the interior circulation fast test method for experimental study, as the ?1, ?2, ? to evaluation index for analysis of the concrete resistance to sulfate ions and the corrosion behavior of magnesium ions,and determined the corrosion conditions the best ratio of concrete corrosion resistance at the same time.In the research of concrete resistance to the chloride ion, sulfate ion and magnesium ion of double factors corrosion test, we designed three kinds of proportioning of concrete specimen,respectively soaked in four different concentrations of coupling in the solution, their are 5000mg/L respectively magnesium sulfate solution, 5000 mg/L magnesium sulfate solution with200,2000, 20000 mg/L sodium chloride solution in the coupling of fluid.,through on a regular study of the electrochemical detection of reinforced concrete, analysis of test data, We can have a research of concrete resistance to chloride ion, sulfate ions and the corrosion behavior of magnesium ions, and determine the best ratio of concrete corrosion resistance at the sametime. In addition, combined with the SEM scan images, We can further verify its corrosion mechanism.Through the above experimental research, it is concluded that for the durability of sulfate ion and magnesium ion in concrete the effect of admixture ratio influence is more obvious than the water cement ratio; Sulfate ions and magnesium ions did not directly cause corrosion of steel, and can only be achieved through the destruction of the passive film to achieve the purpose of corrosion, and even if the passive film was damaged to a certain extent, steel is still not the occurrence of significant damage without the participation of chloride ions; The durability of reinforced concrete resistance to chloride ion, sulfate ion and magnesium ions were concerned, when the chloride concentration reached 2000mg/L, corrosion will mutate.