Reinforcement Corrosion And Sensor Monitoring In Cement-based Materials

At present,it is known that the corrosion of steel bars is an important reason for the early failure of reinforced concrete structures.After investigation and research,there are many factors that affect the corrosion of steel bars,such as chloride ion concentration,temperature and humidity,crack width and so on.The development of steel corrosion and the design of a multi-factor sensor can be used to evaluate the corrosion of steel bars,to predict the service life of concrete structures,and to ensure the development of reinforced concrete structures.Structural safety has far-reaching significance.At first,this paper investigates and analyzes the design principle and monitoring principle of monitoring sensors at home and abroad,it also discusses its advantages and disadvantages,and makes a thorough discussion on its application in practical engineering.Secondly,the effects of chloride ion content and crack width on the corrosion of steel bars were studied.Then,the anode ladder and chloride ion sensor were self-made and their reliability was studied.Fianlly,the self-made multi-sensor monitoring was used to study the corrosion development of steel bars embedded in cement-based materials under dry and wet cycles.The basic research includes:(1)The effects of different kinds of chloride ions on the corrosion process of steel bars were studied by studying the effects of two different water-cement ratio mortar and strain hardening cement-based composites(SHCC),the results show that the higher the chloride content is,the higher the content of chloride is easy to occur rust;curing early humidity and free chlorine ion content is high,the steel is easy to rust,followed by the late high humidity and the low free chloride ion content,and finally the medium-term low humidity,free chloride ion content is low,the steel is not easy to rust;the same chloride ion content,0.55 water-cement ratio under the steel than 0.4 water-cement ratio is more prone to corrosion.(2)By studying the effects of different crack widths on capillary absorption,capillary water absorption and air corrosion in the steel,it is found that the increase of the crack width in the process of capillary salt absorption and water absorption is more prone to corrosion.In the air environment,the effect of crack width on the corrosion of steel bars is not obvious.Under the same crack width,the corrosion of steel bars is most likely to occur during the salt absorption process,followed by the water absorption environment and finally the air environment.(3)Comparison of the trend of electrochemical parameters in self-made anodic ladder and German anode ladder in cement-based materials,self-made anodic ladder has a certain reliability in predicting corrosion of steel bar.(4)Compared with the chloride ion content of the self-made chloride ion sensor and the core powder,the self-made sensor has a certain reliability in describing the chloride ion trend.(5)By studying the electrochemical parameters of self-made anodic ladder,chloride ion sensor and temperature and humidity sensor in concrete under dry and wet cycle,it can be seen that when the concrete surface humidity is large,the outside oxygen is not easy to spread to the cathode surface,then the steel is not easy to rust,and when the steel surface chloride content is far greater than the standard critical chloride content,the steel will rust at this time.(6)By studying the electrochemical parameters of the German anode ladder,chloride ion sensor and temperature and humidity sensor under the wet and dry cycle of mortar,it is known that the steel bar is also less susceptible to corrosion when the surface humidity is large.When the chloride ion content around the steel bar exceeds the standard,it may be rusted.