A model for a long-term diffusion of multispecies in concrete based on ion–cement-hydrate interaction

Kari, Olli-Pekka; Elakneswaran, Yogarajah; Nawa, Toyoharu; Puttonen, Jari

doi:10.1007/s10853-013-7239-3

Cited by 27 publications

(29 citation statements)

References 25 publications

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“…For Cl -/OH -ratio, Cl -is the summation of the total chloride concentration in free solution and in the diffuse double layer, and OH -was calculated based on the pore solution pH. The threshold value of Cl -/OH -to initiate corrosion is 3-5 (Kari et al 2013). The impact of slag addition on the ratio at a depth of 45 mm as a function of exposure …”

Section: Simulation Results On Evaluation Of Reinforcement Corrosionmentioning

confidence: 99%

The Impact of Tortuosity on Chloride Ion Diffusion in Slag-Blended Cementitious Materials

Hatanaka

Elakneswaran

Kurumisawa

et al. 2017

ACT

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The purpose of this study is to determine the tortuosity of cementitious materials containing blast furnace slag (BFS). Furthermore, the influence of tortuosity on multi-species transport into these materials is studied. The porosity and diffusivity of calcium silicate hydrate (C-S-H) were predicted using a three-dimensional spatial distribution model, which were then fitted to Archie's law to determine tortuosity. The tortuosity increased with the slag replacement ratio, suggesting that the diffusion path for ions becomes complicated and lengthy due to slag addition. Thermoporometry was used to determine the pore size distribution of hydrated slag-blended cement. A partial replacement of ordinary Portland cement (OPC) with BFS modified the mineralogy (especially in the types of C-S-H), resulting in changes to the pore structure. The determined tortuosity and porosity were used in a reactive transport model to predict multi-species transport. Experimentally measured and simulated chloride profiles were in good agreement for hydrated OPC and slagblended cements exposed to sodium chloride solutions. The causes for the low penetration rate of chloride in slagblended cementitious materials are discussed considering their pore structure and surface electrical properties. The role of tortuosity on Cl -/OH -for the evaluation of chloride induced corrosion was also discussed.

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Section: Simulation Results On Evaluation Of Reinforcement Corrosionmentioning

confidence: 99%

The Impact of Tortuosity on Chloride Ion Diffusion in Slag-Blended Cementitious Materials

Hatanaka

Elakneswaran

Kurumisawa

et al. 2017

ACT

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“…The simplest and most conservative approach to determine the SL of RC structures is to consider only the initiation period of steel corrosion. For this purpose, predictive models [7][8][9][10][11][12][13][14] take account of microstructure, transport (gas, water, ions) and chemical properties of concrete.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity analysis of chloride ingress models: Case of concretes immersed in seawater

Pradelle

Thiéry

Baroghel-Bouny³

2017

Construction and Building Materials

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Reinforced concrete structures exposed to a marine environment deteriorate as a result of chloride-induced corrosion of the steel rebars. A wide variety of models to predict chloride ingress in water-saturated concretes have already been developed to understand and predict the underlying transport processes. The majority of these models focus on the initiation period of chloride-induced corrosion in order to predict the service life of reinforced concrete structures. They require information on the concrete properties, the concrete cover thickness, the definition of corrosion initiation, etc. These models combine well-known mechanisms, i.e. diffusion of relevant ions, electrical interactions between ions, and interactions between these ions and the solid matrix. As the mechanisms to consider are well identified, the objective here is to perform a probabilistic analysis of some common models. A general framework is proposed to calculate a reliability service life for reinforced concrete structures under chloride attack in case of continuous immersion in seawater. Then a sensitivity analysis is performed in terms of the most relevant mechanisms and influencing input data. The results point out the crucial role of the concrete cover thickness, the critical chloride content and, to a lesser extent, the effective chloride diffusion coefficient. The difficulty to use the Freundlich isotherm for chloride binding is highlighted; it seems to be due to the non-linearity of the description which is still difficult to control. Highlights• A reliability sensitivity analysis of chloride ingress models is performed.• A framework is proposed to calculate a reliability service life for RC structures.

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“…Reactive transport models are an essential tool to evaluate the performance of cementitious materials because the degradation has to be predicted precisely with time at each point of the materials. In recent years, many reports have been published on multispecies transport and coupling of the transport model with chemical reactions (Elakneswaran et al 2010;Hosokawa et al 2011;Kari et al 2013;Marchand et al 2002). The STADIUM model developed by Marchand et al (2002) coupled the mass and energy transport equations with the chemical equilibrium equation at each step of the calculation.…”

Section: Introductionmentioning

confidence: 99%

“…Hosokawa et al (2011) proposed a model for multispecies diffusion (Nernst-Planck-Poisson) by considering the chemical reactions between cement hydrates and the pore solution (coupling phase equilibrium model in PHREEQC externally). Multispecies transport can be simulated in PHREEQC only by using the phaseequilibrium and multi-component diffusion modules (Elakneswaran et al 2010;Kari et al 2013). However, in the existing models, different transport parameters and physicochemical properties of the cementitious material such as cement hydrates, porosity, etc.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, PHREEQC can perform geochemical and speciation calculation (Appelo and Postma 2009;Parkhust and Appelo 1999). Furthermore, it can perform the same kind of calculations in cementitious materials as well (Elakneswaran et al 2010;Hosokawa et al 2011;Kari et al 2013). However, PHREEQC cannot predict the hydration or micro-pore structure formation in cementitious materials.…”

Section: Introductionmentioning

confidence: 99%

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Development and Verification of an Integrated Physicochemical and Geochemical Modelling Framework for Performance Assessment of Cement-Based Materials

Elakneswaran

Ishida

2014

ACT

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In this study, a multi-scale model called DuCOM (Durability COncrete Model), which is developed by the Concrete Laboratory at the University of Tokyo, is extended by coupling the geochemical code PHREEQC. The coupled numerical framework can address physicochemical and geochemical processes such as the hydration of cement particles, pore structure formation, multispecies transport, activity effect, thermodynamic reaction between aqueous solution and solids, etc. in cementitious materials, and therefore, it can potentially be used to assess the long-term durability of concrete structures. The model prediction for the composition of cement hydrates, pore solution chemistry, calcium profiles for the cement paste exposed in pure water, and calcium and sulphur profiles for the cement paste immersed in the sodium sulphate solution are qualitatively and quantitatively compared with experimental results obtained from literature. Finally, the importance of the strong coupling among various processes and mechanisms in the DuCOM-PHREEQC system is discussed.

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A model for a long-term diffusion of multispecies in concrete based on ion–cement-hydrate interaction

Cited by 27 publications

References 25 publications

The Impact of Tortuosity on Chloride Ion Diffusion in Slag-Blended Cementitious Materials

The Impact of Tortuosity on Chloride Ion Diffusion in Slag-Blended Cementitious Materials

Sensitivity analysis of chloride ingress models: Case of concretes immersed in seawater

Development and Verification of an Integrated Physicochemical and Geochemical Modelling Framework for Performance Assessment of Cement-Based Materials

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