Location
University of Leeds
Keywords
fractal dimension, tortuosity, calcium silicate hydrate (C-S-H), chloride ion, transport
Abstract
The durability performance of cement-based materials in service environments is affected by numerous factors, many of which involve attacks due to ionic transport, leading to reduced service life. The durability must be ensured in both an economically and environmentally responsible manner. Chloride-induced steel corrosion is a serious threat to the durability of reinforced concrete structures in marine environments, and the diffusion is the dominant transport mechanism of chloride ingress into concrete. Therefore, clear understanding of chloride transport mechanism, particular the diffusion path, is important for designing the durability performance of reinforced concrete structures. The purpose of this study is to determine tortuosity of cement-based materials and to predict the chloride ingress using the tortuosity values. The pore-structure model to obtain capillary pore was extended by introducing fractal dimension which represents microstructural complexity. The fractal dimension was determined by fitting experimental data to simulation results considering two types of C-S-Hs (low and high density) or two types of products (inner and outer), and it was used as tortuosity to determine effective diffusion coefficient of chlorides in the reactive transport model. The chloride ingress was simulated using the transport model and verified with experimental data for hydrated cement having water to cement (W/C) ratio of 0.5 and cured for 28 days. A good agreement between experimental data and simulated chloride profiles demonstrates that the diffusion path is influenced by presence of C-S-H types (HD-CSH and LD-CSH) and their pore structure characteristics.
Revised manuscript
Elakneswaran_1192_ICDCS2018_paper.docx (249 kB)
Included in
Estimating Fractal Dimension of Cement Matrix for Predicting Chloride Ingress into Cement-Based Materials
University of Leeds
The durability performance of cement-based materials in service environments is affected by numerous factors, many of which involve attacks due to ionic transport, leading to reduced service life. The durability must be ensured in both an economically and environmentally responsible manner. Chloride-induced steel corrosion is a serious threat to the durability of reinforced concrete structures in marine environments, and the diffusion is the dominant transport mechanism of chloride ingress into concrete. Therefore, clear understanding of chloride transport mechanism, particular the diffusion path, is important for designing the durability performance of reinforced concrete structures. The purpose of this study is to determine tortuosity of cement-based materials and to predict the chloride ingress using the tortuosity values. The pore-structure model to obtain capillary pore was extended by introducing fractal dimension which represents microstructural complexity. The fractal dimension was determined by fitting experimental data to simulation results considering two types of C-S-Hs (low and high density) or two types of products (inner and outer), and it was used as tortuosity to determine effective diffusion coefficient of chlorides in the reactive transport model. The chloride ingress was simulated using the transport model and verified with experimental data for hydrated cement having water to cement (W/C) ratio of 0.5 and cured for 28 days. A good agreement between experimental data and simulated chloride profiles demonstrates that the diffusion path is influenced by presence of C-S-H types (HD-CSH and LD-CSH) and their pore structure characteristics.
