Thesis (D.Eng.)--Chulalongkorn University, 2008

In marine environment, the deterioration of concrete structures is mainly due to chloride induced corrosion. With real concrete structures, the deterioration is controlled by the combination of mechanical load and climatic load. The mechanical load results cracks in concrete structures. The cracks accelerate the chloride penetration into concrete structures. As a result, the service life of concrete structures will be reduced considerably. There were many models proposed to predict the deterioration of concrete structures. However, these models are not reliable due to not having simultaneous combination of mechanical and climatic loads. In this research, a model, which simulates the chloride ingress into plain concrete, using different cement types, under flexural cyclic load and tidal environment, was proposed. This model is based on theoretical analysis and experiments of chloride diffusion test, chloride content test and flexural cyclic loading test. Flexural cyclic load is applied from 50% to 80% of to ultimate bending load. Fictitious crack model is adopted to predict fatigue crack growth of plain concrete beam under flexural fatigue. Experimental results show the linear relation between results of short-term and long-term test of chloride diffusion coefficient. Of the four common cement types, Ordinary Portland cement is the best cement type using for concretes in term of the chloride induced corrosion resistance because of the highest capacity to bind chloride ions. The proposed model shows that the flexural cyclic load accelerates chloride penetration into concrete. The higher the flexural load level, SR, the faster chloride penetration occurred. The model predictions fit well with experimental results when the crack density parameter, and the tortuosity parameter, are introduced.