Chloride penetration in concrete under varying humidity and temperature changes
A numerical study
Liang yu Tong (Shanghai Jiao Tong University)
Branko Šavija (TU Delft - Materials and Environment)
M Zhang (TU Delft - Materials and Environment, University College London)
Qing Xiang Xiong (Shanghai Key Laboratory for Digital Maintenance of Buildings and Infrastructure)
Qing-feng Liu (South China University of Technology, Shanghai Key Laboratory for Digital Maintenance of Buildings and Infrastructure)
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Abstract
When serving in the marine environment, reinforced concrete structures are prone to be attacked by chloride ingress, which generally co-occurs with varying humidity and temperature changes. Therefore, considering the interaction between moisture transport and heat transfer, and their individual and coupling effects on chloride transport, this paper presents a novel numerical modelling framework for chloride penetration in concrete under different environmental conditions. In this framework, a novel thermal conductivity model and temperature-depended chloride binding isotherms are also developed, considering the heterogeneous characteristics of concrete. The proposed model is validated against a series of experimental data. By assuming the cyclic humidity and temperature boundary conditions as trigonometric type, this study further discusses the effect of average value, amplitude value and period length of cyclic environmental changes on the chloride transport in concrete. The results indicate that variation in humidity and temperature averages can alter the peak values of chloride content but have less effect on the chloride penetration depth. However, the increased humidity amplitude could significantly promote both the peaks and the penetration depths due to intensive chloride convection caused by moisture transport. This paper is supposed to provide a better understanding of chloride penetration in concrete under a realistic engineering environment.