Research On Chloride Ion Transmission, Steel Corrosion And Bonding Relationship In Concrete

Today,concrete structures are widely used,and the disadvantages of concrete structures in industrial and agricultural buildings are further highlighted,such as concrete carbonization,steel corrosion,cracking of protective layer and so on.In this context,the transport of chloride ions in loaded concrete,the process of concrete expansion and cracking in cylindrical structures,the bond constitutive relationship of concrete members under tensile load and the corrosion rate of steel bars have been studied,and some research results have been obtained.The results of this study are as follows:1.Considering the actual situation of coastal concrete structures under load during service,based on the theory of composite medium,the expressions of chloride diffusion coefficient and water cement ratio,aggregate volume fraction,environmental relative humidity,erosion time,diffusion coefficient ratio of interface zone and mortar,stress level are established,and the factors affecting the diffusion coefficient are studied.The degree of influence.The conclusions are as follows: chloride diffusion coefficient increases with the increase of water cement ratio,decreases with the increase of aggregate volume fraction,increases with the increase of environmental relative humidity,decreases with the increase of erosion time,increases with the increase of diffusion coefficient ratio of interface zone and mortar,decreases with the increase of compressive stress and increases with the increase of tensile stress.2.Based on the thick-walled cylinder model,the formulas for calculating the critical corrosion rate of steel bars with the thickness of protective layer,diameter of steel bars and Poisson's ratio of corroded materials are established.The following conclusions are drawn: the critical corrosion rate decreases with the increase of volume expansion rate of corroded objects,decreases with the increase of diameter of steel bars,and basically does not change with the increase of thickness of protective layer and with mixing.The tensile strength of concrete increases with the increase of Poisson's ratio of rust,but decreases with the increase of Poisson's ratio of rust.Based on the above formulas,considering the existence of the void area between reinforced concrete,it is revised.In addition,considering that the corrosion will enter the concrete protective layer after the cracking of the protective layer,the expansion process of the corrosion is further analyzed.3.Through a series of theoretical analysis,the bond-slip constitutive equation of cylindrical reinforced concrete members under tension load is established,which takes into account the corrosion of steel bars in the members,and draws the following conclusions: from the end of the members to the middle of the members,the relative slip gradually decreases,the stress of steel bars basically does not change,and the bond stress gradually decreases;The slip and bond stresses increase with the increase of reinforcement stress at the loading end.4.Considering the power of corrosion,i.e.the potential difference of the equilibrium potential of the anode-cathode reaction and the resistance of corrosion,i.e.the polarization of the anode-cathode and the resistance of concrete,a calculation model of the corrosion rate of steel bar is established,and the rule of steel bar corrosion under tension load is studied by experiments.