| A systematic and robust method for predicting chloride and carbonation-induced steel corrosion in reinforced concrete structures under prescribed exposure conditions is developed. The significant phenomena that contribute to the rate and amount of corrosion of reinforcement; i.e. heat and moisture transfer, chloride, CO2 and O2 transport, are modeled by the two-dimensional time-dependent nonlinear finite element method. The governing equations of the various transport phenomena are solved numerically in the time and the space domains. Where appropriate, the coupling effects among the different transport phenomena and the chloride binding/release mechanisms as well as the carbonation process are modeled in order to simulate the field conditions reasonably closely. The proposed finite element model and its associated computer program, CONDUR, are capable of handling any geometry (including cracks), prescribed initial and boundary conditions and pertinent material nonlinearities. Since mass transport in concrete is the subject of on-going research, the computer program is designed to be flexible enough to accommodate improvements and modifications to the adopted models. By using a two-dimensional time-dependent nonlinear finite element method, the corrosion of the reinforcement is treated as an electrochemical process and is modeled as a spatial and temporal function of temperature, moisture, and ionic or molar concentration of various chemicals within the pore solution. The corrosion analysis provides the rate and amount of reinforcement corrosion in a reinforced concrete structure operating within a prescribed environment. To verify the finite element model and its associated computer program, the numerical results are compared with available experimental data, with reasonable agreement between them. Further numerical simulations have been carried out to demonstrate the capabilities of the developed methodology and the computer program. |
