Experiment Research On The Corrosion Rule Of Steel Bar In Concrete Under Incursion Of Chloride

The problem of durability of reinforced concrete is one of the extremely important problems which is moreover urgent to be solved at present. The corrosion of steel bar is one of the important factors that lead the concrete structure to failure. For the problem is so serious, based on previous research result, using experiment, the theory of concrete structure, electrochemistry mechanism, material science theory, environment science, structure reliability theory and so on, this dissertation takes comprehensive research on the corrosion rule and temperature effect on the corrosion of steel in concrete under incursion of chloride. Chief works are summarized as follows:(1) The durability of reinforced concrete structures in service under environment of chloride ions' incursion and the research level of its coherent subject at the domestic and foreign correlation are summarized in this dissertation. At the same time, the corrosion mechanism, the condition of steel bar corrosion, the breakage process of reinforced concrete structures and the factors which influence steel bar corrosion rate are investigated in this dissertation.(2) The corrosion effect of chloride ion has been analyzed, including where the chloride origin, the way how the chloride ion invade into the concrete structures, as well as the corrosion mechanism of steel bar under the incursion of chloride ion.(3) The assessment methods of steel bar corrosion status in concrete structure are analysed in chapter three, including half-cell potential, linear polarization, electrochemical impedance spectrum as well as potentiodynamic polarization curve and so on, then points out the advantages and disadvantages, the suitable scope that could be used and the problems that should be solved.(4) The electrochemistry behavior of steel bar in simulated concrete pore solutions with chloride ion in it is studied in experimental methods, the different influences of pH and the chloride ion concentration are considered. Then the critical chloride concentration which could de-passivation are found in simulated concrete pore solutions at different pH values. The dissertation also explored the feasibility of several kind of compound as rebar inhibitors anti steel bar corrosion which could provide the science reference for preventing and controlling the steel bar corrosion problems.(5) The influence of temperature to steel bar corrosion rate is investigated in linear polarization and half-sell potential methods. In view of the concrete characteristic, a batch of mortar specimens are manufactured, and the chloride ion is increased to improve their corrosiveness, controlling other factors to study the influence of temperature to steel bar corrosion rate. The results shows that the steel bar corrosion rate is not unlimited increased along with the temperature increment, but has a critical temperature value, when the temperature is lower than this marginal value, the steel bar corrosion rate elevates along with the temperature increment, but when the temperature surpasses this marginal value the steel bar corrosion rate reduces instead, and stabilizes finally.(6) The influence of water-cement ratio and the content of chloride ion on the the steel bar corrosion are studied. The result shows that the corrosion rate of the steel bar speeds up along with the increment of the chloride ion when the water-cement ratio is unchanged. Reducing the water-cement ratio could lower the corrosion rate of steel bar when the content of the chloride ion is unchanged.