The Effect Analysis Of Rebar Corrosion Rate On Durability Of Bridge Structures

Reinforcement corrosion is one of the most important factors of the damage of reinforced concrete structures. It brings incalculable economic losses and huge potential safety hazard to a large number of buildings of reinforced concrete structure. To explore the mechanism of reinforcement corrosion in concrete has become a problem to be solved. On the basis of that, we can obtain the Impact analysis of the durability of reinforced concrete which has huge engineering practical value.This article selects steel type, the concrete cover thickness, pH value of concrete simulated liquid and chloride ion concentration from main influence factors as the experimental factors. Use some methods to accelerate the corrosion of reinforcing steel experiment. Then reinforcement corrosion conditions were evaluated by electrochemical methods and mechanical properties testing. The effect law of the influencing factors on reinforcement corrosion has been researched.(1)The pH value and the invasion of chloride ion are main influencing factors for corrosion. With the loss of the pH value of concrete simulated liquid, the steel corrosion current density increases. For bare steel, the corrosion current density when pH value is9.7is2～4times than the corrosion current density when pH value is11.5, is15～25times than the corrosion current density when pH value is12.5. For concrete sample, the corrosion current density when pH value is9.7is4-5times than the corrosion current density when pH value is11.5.(2)The invasion of chloride ion can not only make corrosion rate increasing, but also can accelerate the destruction of passivation membrane on the steel surface. That makes the time of corrosion rates rising sharply shorten from45days to3days, corrosion rate increase4-5times. Weightlessness rate is sensitive to the invasion of chloride ion. The weightlessness rate of rebar in corrosive liquid which has chloride ion and pH value is9.7is15%difference than the rebar which do not contain chlorine ion. The number is4times when pH value is12.5.(3)In the experiment factors, the effect on corrosion rate of steel surface thread and concrete cover thickness are less than other factors. The corrosion current density of deformed steel bar is slightly higher than plain round bar. For the specimens which have same pH value and different concrete cover thickness the reinforced current density when concrete cover thickness is10mm is1-2times than the reinforced current density when concrete cover thickness is50mm. Meanwhile, the weightlessness rate of deformed steel bar is1-3times than round steel bar. Other mechanical performance index basic remained stable when weightlessness rate is less than1.2%.(4)On the basis of previous studies, correct the Xiao Cong Zhen’s theoretical model and China University of Mining Technology’s theoretical model by using collecting the data. Add two influencing factors:pH value of concrete simulated liquid and etching time of Reinforced accelerated corrosion experiments. The revised model is more in line with reinforcement corrosion rule.(5)In the end, a quantitative evaluation method based on electrochemical detection and finite element analysis technology was raised. The feasibility of this method was tested by an actual example firstly. Then modeling simulation is made for reinforced concrete specimens of this experiment. Strain values change forecast empirical formula of10mm and50mm concrete cover thickness is developed, which can be used to relate the corrosion rate and structural deformation.