Corrosion Mechanism And Practical Corrosion Rate Prediction Model For Steel In Concrete

Carbonation or chloride intrusion can induce steel corrosion in concrete structures, which is one of the main causes of concrete structure performance degeneration. Corrosion not only incites rebar cross-section loses, but also causes crack and spalling of concrete cover. Finally structure will be destroyed for inadequate load capacity. Steel corrosion rate shows structural performance degeneration rate. So it is important to study steel corrosion for capacity evaluation, maintenance plan and residual life prediction of existing concrete structure.In combination of steel corrosion mechanism with electrochemical corrosion principle in concrete, this paper established a macrocell corrosion model. Then, a practical corrosion rate prediction model was set up with relevant physical factors as control parameters, including water-cement ratio, chloride content, cover depth and relative humidity, which can be easily determined. Main contents includes:1. Based on the corrosion mechanism and the electrochemical corrosion principle, a macrocell steel corrosion model in concrete was established.2. Relying on the macrocell corrosion model, influences of electrochemical parameters, structural parameters and environmental parameters on steel corrosion rate were analyzed quantitatively. Especially the influence rule of corrosion process control mode was uncovered concerning relative humidity, cover depth, and concrete resistivity.3. Depending on the macrocell corrosion model, a practical corrosion rate prediction model was established considering water cement ratio, chloride content, cover depth and relative humidity as control parameters, which can be easily determined. Mass loss and cross-section loss of rebar were deduced. Besides, flexural strength of reinforced concrete beam under the influence of steel corrosion were studied to provide a scientific foundation for the capacity evaluation of existing concrete structure.