Corrosion Resistance Of Stainless Steel In Cracked Concrete And Bonding Degradation Between Corroded Rebar And Concrete

Corrosion of reinforced steels is the most important and common factor that threatens the durability of reinforced concrete structures.Accurately predicting the corrosion rate of steels in concrete and their mechanical properties after corrosion are significant for estimating the remaining service life of structures.The existing corrosion rate prediction models are mostly based on the test data.These empirical models are lack of theoretical basis,and most of them do not consider the quantitative impact of cracks on the corrosion rate.Unlike carbon steels,stainless steels have excellent corrosion resistance,however few studies focued on the prediction models of the corrosion rate of stainless steel in concrete and the bond performance after steel corrosion.Therefore,taking the process from the steel corrosion in concrete to the degradation of bonding performance as the main research object,the steel corrosion regulation of different types of steels and the steel corrosion in different erosion environments were studied in this paper.The main research contents are as follows:(1)Based on the electrochemical principle,the effects of various factors such as the type of steel bar,the longitudinal crack width,and the erosion environment on the corrosion rate were explored through two types of steels corrosion experiments under different erosion conditions.By qualitatively and quantitatively comparing the test results of chloride ion concentration,polarization curve,corrosion potential,corrosion current density,and polarization resistance of the carbon steels and stainless steels in the corrosion process,the differences in the corrosion resistance of these two types of steels were analyzed.Finally,relevant durability parameters were obtained as the basis for numerical simulation of steel bar corrosion in cracked concrete.(2)Based on the chloride diffusion and the steel corrosion electrochemical principles,an electrochemical model of steel corrosion in concrete with crack was established by considering the coupling effects of the chloride ion,the oxygen diffusion process in concrete and the electrochemical process of steels corrosion.In the simulation,the effects of crack width,chloride ion diffusion coefficient,chloride ion binding capacity,and concrete resistivity on the corrosion rate of two different steel bars in concrete were explored.Finally,the corrosion time of cover cracking of the reinforced concrete structure in different steel types and different erosion environments was obtained by the coupled corrosion electrochemical model and cracking process of concrete cover.(3)The central pull-out test of stainless steel bar concrete specimens with different corrosion ratio was carried out to figure out the influence of corrosion ratio and surface crack width on the degradation of bond behavior.Through this pull-out test,a prediction model of bond strength between corroded steel and concrete was proposed on the basis of the corrosion ratio and the surface crack width.Furtherly,the difference between the bond strength degradations of corroded stainless steels and ordinary carbon steel bars was compared.