Modeling of Effective Diffusion Coefficient of Substances in Concrete Considering Spatial Properties of Composite Materials

Kato, Yoshitaka; Uomoto, Taketo

doi:10.3151/jact.3.241

Cited by 13 publications

(8 citation statements)

References 7 publications

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“…When the crack opening displacement increases from 50 to 200μm, the cracked concrete permeability increases rapidly with a great magnitude in comparison with that corresponding uncracked concrete. Based on the similar test method, Kato and Uomoto (2005) concluded that the diffusion coefficient of chloride ions through a crack (D cr ) increased with increases in the crack width and is almost constant when the crack width becomes wider than approximately 75μm. In the simulation model of Takewaka et al (2003), if W cr is less than 50μm, the cracks seldom affect diffusivity, but when the W cr is between 50μm and 100μm, D cr was set 10 times of sound part (1×10 -12 m 2 /s), and when W cr is larger than 100μm, D cr was set as 10 3 times.…”

Section: Review Of Previous Studiesmentioning

confidence: 99%

“…3.1 Diffusion coefficient of concrete To a conventional concrete, the diffusion coefficient D c is not a real physical constant since the process of chloride ion transportation in concrete is considered to be governed by a number of factors such as diffusion, ionic interaction, water transportation, and chloride ion fixation (Kato and Uomoto 2005). However, according to the extensive experimental investigations, it has been concluded that the most important factors are the water-to-cement ratio (w/c) and the temperature.…”

Section: Statistics Of Diffusion Coefficient Of Concrete (D C ) and Mmentioning

confidence: 99%

“…The testing schemes for evaluation transport property of cracked concrete can be divided into three kinds based on the loading method: uniaxial compressive test (Saito and Ishimori 1995;Lim et al 2000;Samaha and Hover 1992 splitting test (Wang et al 1997;Aldea et al 1999;Kato et al 2005) and flexural test Xing et al 2005a). The effect of microcracking on transport property under uniaxial compression has been studied by several researchers.…”

Section: Review Of Previous Studiesmentioning

confidence: 99%

“…Therefore, in the study of diffusivity or substances transportation characteristics of concrete, cracks must be taken into account correctly to cover the practical working condition of structures. However, due to difficulties in generating desirable crack patterns in concrete specimens and availability of appropriate methods for concrete diffusivity measurements, a limited number of studies have been done on the transport property of cracked concrete (Wang et al 1997), so till now the characteristics of chloride ions transportation in cracked concrete have not yet been made clear (Kato and Uomoto 2005).…”

Section: Introductionmentioning

confidence: 99%

“…Second, the presence of porous and connected ITZ probably contributes to facilitating the movement of ions. In order to investigate the effect of aggregate content and ITZ on the transport properties, usually the mortar or concrete is treated as a three-phase composite material in which aggregates are embedded in a matrix of hardened cement paste, and the ITZ is around the aggregates (Yang 2003;Care and Herve 2004;Kato and Uomoto 2005) (see Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

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Simulation of Chloride Diffusivity for Cracked Concrete Based on RBSM and Truss Network Model

Wang

Soda²,

Ueda

2008

ACT

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For concrete structures exposed to salt environment, the microstructure and cracks play a crucial role in the ingress of chloride ions into concrete. In this study, concrete is simulated on the meso scale as a three-phase composite, i.e., aggregate particles, mortar and the interfacial transition zone (ITZ). Because of the advantages in predicting cracks behavior in concrete, Rigid Body Spring Model (RBSM) is employed to carry out the mechanical analysis to simulate the distribution and width of microcracks. And then, the truss network model is adopted to evaluate the chloride diffusivity of the cracked concrete. On the basis of the statistics analysis of diffusion coefficients of concrete and mortar determined experimentally, the diffusivity of ITZ is analytically clarified. The range of diffusion coefficient of ITZ estimated in this paper is approximately 3-16 times of that of mortar depending on the different assumed thickness, which agrees well with that of the previous experimental results. With the aim to validate the effect of microcracks on the diffusivity of concrete, a series of the chloride ions penetrating analysis is numerically carried out on the concrete specimen under different stress levels. The axial compressive and tensile loading conditions are investigated respectively and the effects of stress level on chloride diffusivity of cracked concrete are examined. Results indicate that the chloride diffusivity is significantly dependent on the stress level, but only considering the effect of cracks predicted by RBSM is not sufficient. So an empirical equation which can account for the microstructure variation of concrete under loading is proposed. With it, a reasonable estimation for chloride diffusivity of cracked concrete is achieved.

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Section: Review Of Previous Studiesmentioning

confidence: 99%

Section: Statistics Of Diffusion Coefficient Of Concrete (D C ) and Mmentioning

confidence: 99%