The “Skin Effect” Assessment of Chloride Ingress into Concrete Based on the Identification of Effective and Apparent Diffusivity

Perkowski, Zbigniew; Szweda, Zofia

doi:10.3390/app12031730

Cited by 4 publications

(9 citation statements)

References 23 publications

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“…On the other hand, chloride extraction from the structure built from this type of concrete should be longer to provide as effective extraction as for concrete with cement CEM I 42.5 R. This effect can be explained by the fact that the majority of chlorides in concrete C2 were probably bounded in the cement matrix, so the real concentration of chloride ions in pore water was lower than in this type of concrete. The effect of binding chloride ions in concrete with cement CEM III/A 42.5 N-LH/HSR/NA was also confirmed in the paper [ 25 ], in which values of diffusion coefficients of chloride ions were determined, taking into account the process of binding chloride ions.…”

Section: Conclusion and Recommendationsmentioning

confidence: 68%

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Evaluating the Impact of Concrete Design on the Effectiveness of the Electrochemical Chloride Extraction Process

Szweda

2023

Materials

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This paper presents a simple comparative method for evaluating the impact of concrete design on the effectiveness of repair with the electrochemical chloride extraction (ECE) process of reinforced concrete structures. This comparison covered two concretes with different types of used cement. Penetration of chloride ions to induce corrosion processes was accelerated with the electric field. However, the corrosion process itself occurred naturally. When the corrosion process was found to pose a risk to the reinforcement, the profile of chloride ion concentration was determined at the depth of concrete cover. Corrosion current intensity during migration and extraction processes of chloride ions was measured with the LPR method. Then, this serious condition for the structure was repaired with electrochemical chloride extraction. Rates of chloride extraction were determined from the derived concentration profiles. It should be noted that the critical concentration Ccrit = 0.4% at the rebar surface was reached after 21 days of the migration process. Moreover, after the same time of extraction, the concentration was reduced by 95% at the rebar surface, which could suggest that extraction rate was slower than chloride ion migration to concrete within the electric field. Using the migration coefficient for predicting the extraction time, as well as ignoring the variability of the extraction coefficient and the initial concentration over time, may result in too short or unnecessarily long extraction times.

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Section: Conclusion and Recommendationsmentioning

confidence: 68%

“…Concretes C1 and C2 were made of ordinary concrete with different type of used cement. Specimens made of the same preparations were used in the work [ 25 ] to determine values of the diffusion coefficient of chloride ions. Concrete C1 contained CEM I 42.5 R cement.…”

Section: Methodsmentioning

confidence: 99%

Evaluating the Impact of Concrete Design on the Effectiveness of the Electrochemical Chloride Extraction Process

Szweda

2023

Materials

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“… By using an electric field in the test method and solving a thermodynamic migration model [ 48 ], the value of the diffusion coefficient is obtained after short-term tests lasting usually 24 and 48 h or 48 and 72 h in the case of concretes with very compact structures. It is based on two measurements that allows one to obtain the mean diffusion coefficient value and to include the effect of diffusion process nonstationarity related to the capacity of chloride ions to bind in the cement matrix [ 59 ]. It requires a greater amount of labor than other rapid migration methods (RCPT1 and RCTP2), but thanks to the use of an electric field, it is shorter than natural penetration-based approaches (CPT, TD1, and TD2).…”

Section: Discussionmentioning

confidence: 99%

“…It is based on two measurements that allows one to obtain the mean diffusion coefficient value and to include the effect of diffusion process nonstationarity related to the capacity of chloride ions to bind in the cement matrix [ 59 ].…”

Section: Discussionmentioning

confidence: 99%

Comparison of Standardized Methods for Determining the Diffusion Coefficient of Chloride in Concrete with Thermodynamic Model of Migration

et al. 2023

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This research paper is the result of observations made during tests according to various standards carried out on behalf of industry. The article presents diffusion coefficient values calculated according to the thermodynamic migration model for twenty different concrete mixes and some selected mixes of the codified approaches known as ASTM 1202, NT BUILD 443, NT BUILD 492, ASTM 1556. The method used here, according to the thermodynamic model of migration, allows determination of the value of the diffusion coefficient after short studies of the migration of chloride ions into concrete and was described in earlier works by one of the authors. Unfortunately, when using standard methods, the values of diffusion coefficients differ significantly from each other. In each concrete, diffusion tests were carried out in the conditions of long-term natural diffusion to verify the values determined by standard methods and according to the thermodynamic model of migration. The analysis conducted for this research paper reveals that the chloride permeability test method according to the standard ASTM C1202-97 has an almost 2.8-fold greater dispersion of the obtained results compared to the thermodynamic model of migration. It was observed that the standard NT BUILD 492 has a 3.8-fold dispersion of results compared to the method with the thermodynamic model of migration. The most time-consuming method is the standard method NT BUILD 443. The largest 3.5-fold dispersion of values concerning the reference value are observed in that method. Moreover, a method based on a thermodynamic migration model seems to be the best option of all analyzed methods. It is a quite quick, but laborious, method that should be tested for a larger number of concrete mixes. A great advantage of this method is that it is promising for a wide range of concrete mixtures, both plain concrete and concrete with various additives and admixtures, as well as high-performance concrete.

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“…The specimens were prepared and every test was conducted at the Laboratory of Civil Engineering of the Silesian University of Technology. Compressive strength, density, and porosity tests were described in [ 47 ] where, among others, C1 and C2 concretes were used in diffusion tests. Properties and compressive strength of the analyzed concrete mixtures from all series are presented in Table 1 .…”

Section: Methodsmentioning

confidence: 99%

The Influence of Corrosion Processes on the Degradation of Concrete Cover

Szweda,

Skórkowski,

Konečný

2024

Materials

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In this work, two methods were used to accelerate the corrosion of concrete. In the first method, chloride ions were injected into the concrete using the migration method. The moment of the initiation of the corrosion process was monitored using an electrochemical method of measuring polarization resistance. In the next step, the corrosion process was accelerated by the electrolysis process. Changes on the sample surface were also monitored using a camera. In the second method, the corrosion process of the reinforcing bar was initiated by the use of the electrolysis process only. Here, changes occurring on the surfaces of the tested sample were recorded using two web cameras placed on planes perpendicular to each other. Continuous measurement of the current flowing through the system was carried out in both cases. It was assumed that in conditions of natural corrosion, a crack would occur when the sum of the mass loss of the reinforcing bar due to corrosion reached the same value in tcr(real) (real time) as it reached in the tcr (time of cracking) during the accelerated corrosion test. The real time value was estimated for C1 concrete with cement CEM I. The estimated value was tcr(real) = 1.1 years and for C2 concrete with cement CEM III, tcr(real) = 11.2 years. However, the main difference that was observed during the tests was the nature of the concrete cracks. In the case of the C1 concrete sample, these occurred along the reinforcing bar, while in the C2 concrete, the failures occurred on a perpendicular plane transverse to the direction of the reinforcing bar.

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The “Skin Effect” Assessment of Chloride Ingress into Concrete Based on the Identification of Effective and Apparent Diffusivity

Cited by 4 publications

References 23 publications

Evaluating the Impact of Concrete Design on the Effectiveness of the Electrochemical Chloride Extraction Process

Evaluating the Impact of Concrete Design on the Effectiveness of the Electrochemical Chloride Extraction Process

Comparison of Standardized Methods for Determining the Diffusion Coefficient of Chloride in Concrete with Thermodynamic Model of Migration

The Influence of Corrosion Processes on the Degradation of Concrete Cover

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