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Nowadays an amount of reinforced concrete structures are presenting problems related with corrosion of reinforcement, mainly that induced by chloride ions. So, many studies are being accomplished to predict the necessary time for chloride ions reach the reinforcement, beginning the propagation of corrosive process. In this paper, three models were selected for analysis to determine their ability in properly predicting the chloride penetration in concrete structures: the solution of 2nd Fick's Law, the complete solution of 2nd Fick's Law, considering the variation of diffusion coefficient and the superficial concentration of chlorides in time; and a model proposed. Analysis of the formulations principles and assessment and applicability of equations were made, taking into account the adequate choice of parameters and variables involved, the difficulty to obtain these parameters, and if the models represent properly the natural phenomena. In order to contribute with the service life prediction of the structures when inserted in saline environments, a mathematical model was developed based in a Focus Groups analysis. Some of the main characteristics of the proposed model are the logic applied for its development and the application easiness. This model was applied in a case study to verify the answer in relation to chloride penetration in some points of a reinforced concrete structure inserted in a saline area. The behavior of the model was consistent with the results of experimental investigations accomplished by other researchers.

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From field studies and the literature, it was found that the degradation of concrete over time can be modelled probabilistically using homogeneous Markov Chains. To confirm this finding, this study presents an application of Markov Chains associated with the reliability analysis of experimental results of the degradation of concrete by chlorides. Experimental results were obtained for chloride penetration originating from non-accelerated tests in concretes in which the water/binder ratio was variable (0.40, 0.50 and 0.60) and that were produced with Pozzolanic Portland cement that was exposed for six months to the action of NaCl. Using a simulation process, the failure and safety probabilities were calculated by reliability and using Markov Chains, a service life project was estimated (a period of corrosion initiation). Compared to a concrete structure itself, the average error of service life predicted using Markov was approximately 14%. The results show a promissory methodology, in combination with the determination of concrete cover thickness, according to the required service life.