Analytical Model for Square Root Increase of Surface Chloride Concentration and Decrease of Chloride Diffusivity

Zhou, Shengjun

doi:10.1061/(asce)mt.1943-5533.0001483

Cited by 18 publications

(16 citation statements)

References 10 publications

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“…When the surface chloride content is considered, the analytical solution of Equation (3) can be still found, but with a much more complex expression. For C s = kt 0.5 e , the analytical solution is [6],…”

Section: Effect Of Surface Chloride Contentmentioning

confidence: 99%

“…These models and methods can be categorized into two types. One is to develop empirical or semi-empirical models based on the analytical solution of Fick's 2nd law [6,7], which is preferred in engineering practice owing to its simple expression and convenience to use. This approach, however, is only applicable under typical assumptions, e.g., homogeneous material, consistent environmental conditions, semi-infinite domain.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Seasonal Characteristics of Temperature and Relative Humidity on Chloride Diffusion Process in Concrete: A Preliminary Theoretical Study

Pan

Li²,

Ruan

2019

Sustainability

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The chloride diffusion process can be greatly affected by the temperature and relative humidity. Annual average temperature and relative humidity are often adopted in analytical models to calculate chloride profiles. These models, however, cannot consider the seasonal characteristics of temperature and relative humidity. This paper presents a theoretical study to solve the above problem. The temperature and relative humidity in several major cities in China are first collected. Then, the governing equation of one-dimensional chloride diffusion is solved by both analytical and numerical methods using the annual and monthly average temperature and relative humidity, respectively. Based on these two methods, a parameter called “seasonal correction coefficient” is introduced into the analytical models. The values of the coefficient for major cities in China are obtained. Based on the results, it is found that: (1) the analytical solution with annual average temperature and relative humidity is questionable to calculate chloride profiles for typical cities, (2) the seasonal correction coefficient is independent on the apparent chloride diffusivity, affected slightly by the activation energy of chloride ions during diffusion and greatly by the critical relative humidity for common water-to-cement ratios of ordinary Portland cement (OPC) mortar and concrete.

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Section: Effect Of Surface Chloride Contentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Seasonal Characteristics of Temperature and Relative Humidity on Chloride Diffusion Process in Concrete: A Preliminary Theoretical Study

Pan

Li²,

Ruan

2019

Sustainability

View full text Add to dashboard Cite

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“…Experimental studies demonstrate such observation [16], [17], which make the deterministic approach inefficient. The random behaviour governs, for instance, the chloride concentration values at the structural surface [18], [19] and the threshold chloride concentration for the reinforcements' depassivation [20]. Besides, the concrete mixture components are essentially random in space [21], [22], which introduces important randomness on the coefficient of diffusion.…”

Section: Introductionmentioning

confidence: 99%

The cover thickness design of concrete structures subjected to chloride ingress from RBDO solution technique

Pellizzer

Leonel

2020

Rev. IBRACON Estrut. Mater.

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Diffusion is the principal transport mechanism of chloride ions into concrete pores. The chlorides trigger the reinforcements’ depassivation when its concentration at the concrete/reinforcement interface reaches the threshold level. Thus, the depassivation defines the initiation stage end and the propagation stage start. The structural safety reduces widely during the propagation stage because of the various deleterious mechanisms triggered by reinforcement’s corrosion. Therefore, the engineers should accurately predict and prevent the propagation stage start. The literature describes several models for evaluating the end of the initiation stage. However, few of them applies the Boundary Element Method (BEM) for this purpose, despite its known accuracy. Besides, enormous randomness affect the phenomenon. Thus, it is adequately handled solely in the probabilistic context. Optimisation techniques may be coupled in the problem modelling to propose adequate cover thickness values accounting for probabilities of failure. This study presents a Reliability-Based Design Optimisation (RBDO) approach for designing accurately the cover thickness of concrete structures subjected to chloride ingress. The BEM handles the diffusion modelling whereas the Monte Carlo simulation assesses the probabilities of failure. The RBDO is formulated in the context of Weighted Average Simulation Method (WASM), which requires only one assessment of the reliability analysis. It leads to a reliable and computationally efficient solution technique. The problem formulation and the implemented solution scheme are described herein. Moreover, one application is presented, in which the design results are interpreted properly.

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“…To estimate the approximate initiation time of rebar corrosion induced by the chloride ingress, the analytical models are usually adopted in engineering practice due to the convenience to use [2,3]. The prototype of these analytical models is based on the analytical solution of the Fick's law, ( , ) = 0 + ( s − 0 ) *1 − erf ( 2 √ app )+ (1) where is the chloride content, 0 and s are initial and surface chloride contents, respectively.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of chloride diffusion in cementitious materials by lattice type model

Li¹,

Pan

Bai³

et al. 2019

MATEC Web Conf.

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The chloride ingress is one of the most significant problems to reinforced concrete structures in coastal areas and cold regions where the de-icing salt is commonly used. In this paper, the lattice type model which has been widely used in fracture analysis of brittle materials is applied to simulate the chloride diffusion process in cementitious materials. The theoretical background of the lattice type model in solving the mass transport problem is briefly presented. The analytical solution of the Fick’s law is adopted to theoretically validate the developed lattice type model. After that, two typical case studies are included to demonstrate the application of the lattice type model in the chloride ingress issue. In the first case, the tortuosity effect of the aggregates on the chloride diffusion front at meso-scale is studied by the lattice model. In the second case, the lattice model is applied in the simulation of the chloride diffusion in cracked concrete. The results show that the lattice type model can be a useful tool to simulate the chloride ingress in the cementitious materials.

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Analytical Model for Square Root Increase of Surface Chloride Concentration and Decrease of Chloride Diffusivity

Cited by 18 publications

References 10 publications

Effect of Seasonal Characteristics of Temperature and Relative Humidity on Chloride Diffusion Process in Concrete: A Preliminary Theoretical Study

Effect of Seasonal Characteristics of Temperature and Relative Humidity on Chloride Diffusion Process in Concrete: A Preliminary Theoretical Study

The cover thickness design of concrete structures subjected to chloride ingress from RBDO solution technique

Numerical simulation of chloride diffusion in cementitious materials by lattice type model

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