Considerations about the service life prediction of reinforced concrete structures inserted in chloride environments

Abstract

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.

Evaluation of service-life prediction model for reinforced concrete structures in chloride-laden environments

“…The lack of data on the penetration of chlorides in concrete structures exposed in a marine atmosphere zone during high exposition periods, which makes it difficult to monitor the progress of the critical concentration of chlorides along the concrete depth and, consequently, the validation of the model proposed by Andrade. In relation to the previous works that evaluated the application of the model in question, it was verified that the behavior of the model was consistent with the results of experimental investigations accomplished by other researchers [38][39][40].…”

“…Various models are available for the prediction of servicelife of reinforced concrete structures that consider the reinforcement depassivation by chlorides [18][19][20][21][22][23]41]. The proposed formulations vary in complexity, but most are based on the assumption that part of the process is controlled by diffusion [38]. Thus, most of these models result from the resolution of the Fick's 2nd Law, which considers different boundary conditions [42].…”

“…In this context, we highlight the model for the prediction of service life of concrete structures proposed by Andrade [37][38][39], which has simple input data and easy to obtain, such as w/c ratio of the cement matrix, cement type, type of mineral addition used, among others. This model was obtained through a Focus Group experiment conducted with specialists in the area of materials durability structures and technology.…”

Análise da vida útil de estruturas de concreto armado sob corrosão uniforme por meio de um modelo com RNA acoplado ao MEF

“…Entretanto, esses sistemas estruturais são vulneráveis a processos de deterioração resultantes de agressões químicas e danos físicos, que, ao longo do tempo, podem conduzir a um desempenho estrutural insatisfatório sob cargas de serviço ou ações acidentais. Diante do exposto, nos últimos anos houve avanços significativos nas áreas de modelagem, análise e projeto quanto a deterioração em estruturas, assim como novas abordagens foram propostas quanto à avaliação de vida útil das estruturas (Ellingwood, 2005;Biondini et al, 2017, Andrade et al, 2017. A corrosão das armaduras apresenta-se como a patologia com o maior índice de ocorrência em estruturas de concreto armado (KARI et al, 2014).…”

Análise paramétrica da carbonatação em estruturas de concreto armado via Redes Neurais Artificiais

“…A corrosão das armaduras apresenta-se como a patologia com o maior índice de ocorrência em estruturas de concreto armado (Taffese et al, 2013;Kari et al, 2014;Possan, Andrade, 2014;Andrade et al, 2017). No Brasil, por exemplo, este índice varia de 14 a 64% a depender da região de análise (Dal Molin, 1988;Andrade, 1992;Aranha 1994).…”