Time-dependent numerical modelling of corrosion initiation in reinforced concrete structures under projected climate change impacts

摘要

Reinforced concrete (RC) is one of the most popular construction materials due to its versatility and cost efficiency. Environmental exposure can affect the durability and performance of RC structures by initiating deterioration processes leading to significant loss in performance and reduction in service life, with steel corrosion is one of the most concerning deterioration processes. Thus, corrosion evaluation in RC structures is of great importance for sustainable development. This study aims to establish a reliable numerical model for predicting the carbonation progress in concrete using coupled transport equations of heat, moisture and carbon dioxide.Mass and/or energy conservation equations generally follow the transient advection-diffusion-reaction (ADR) equation. The ADR equation is formulated and numerically solved in this study via a novel adaptation of the meshless generalised reproducing kernel particle method (RKPM). In addition, a novel and precise enforcement of the mixed-type boundary condition is introduced by generalising the corrected collocation method. Sensitivity analyses to the main influencing parameters of the ADR equation are carried out to highlight the impact of each parameter on the contamination of field variables.A microstructural model is introduced in this study to mathematically represent the pore structure of cementitious materials and its development in time under continuous hydration reactions. The model is utilised to derive realistic moisture adsorption-desorption isotherms and evaluate the transport properties of liquids, gases and ions into cementitious materials. A reliable microstructure-based hygrothermal model is then established to obtain realistic temperature and moisture responses of concrete to environmental changes that significantly impact on the transport of soluble products that instigate, and accelerate, deterioration mechanisms.A mass conservation based carbonation model is developed in this study through a unified approach to some of the well-known carbonation models. The carbonation model is validated and then utilised to study the impacts of projected climate changes on the progress of carbonation in concrete. The study shows that the so-called greenhouse effect significantly increases carbonation progress and reduces the time to potential corrosion initiation, especially under pessimistic projected scenarios. The influence of global warming also increases the carbonation progress, but with a lesser impact.