Calculation of chloride diffusivity in concrete from migration experiments, in non steady-state conditions

Andrade, Carmen; Sanjuán, Miguel Ángel; Recuero, A.; Río, Olga

doi:10.1016/0008-8846(94)90106-6

Cited by 81 publications

(29 citation statements)

References 9 publications

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“…Method h CTH): Described in [8] is based in measuring the depth of colour change of a silver solution [10] and in the application of the following equations: Method II: ACA-NS): Described in [9], it is based in fitting chloride profiles to an analogue diffusion equation to obtain Dmig (equation (3)). calculated by means of the expression [9,12] (equation (4)).…”

Section: A) Migration Testsmentioning

confidence: 99%

“…However, both assumptions do not always happen, as the colour front depends on the concrete quality [11] and the binding is not always produced in a migration test [12]). Another testing procedure has been proposed for the calculation of D,~ by Andrade et al [9], which is bascd in fitting the profiles of chlorides to an analogous diffusion equation to obtain an accelerated coefficicnt, Dmig. The calculation of the D m is made by means of a correction factor which depends on the potential difference applied and the length of the specimen [8,12].…”

Section: Introductionmentioning

confidence: 99%

“…When trying to calculate the diffusion coefficient, the first aspect to be pointed out is the fact that two kind of coefficients are currently used: one of them obtained from steady state experiments using the so-called diffu- sion or migration cell [2][3][4][5][6][7], and the other obtained from non-stationary experiments [8,9]. These coefficients are called in literature reversibly as effective, Deft-, or apparent, Dap p respectively.…”

Section: Introductionmentioning

confidence: 99%

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Non-steady-state chloride diffusion coefficients obtained from migration and natural diffusion tests. Part I: Comparison between several methods of calculation

et al. 2000

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RESUMEThe calculation of non steady state chloride diffusion coefficients by migration tests is a quite controversial subject due on one hand, to the complexity found in describing the penetration of chlorides and on the other hand, to the fact that the different researchers calculate them by different procedures. Therefore, in present work, experimental trials have been carried out performing migration tests following ASTM C1202-91 procedure, and modified by applying 12 Volts. Results from migration methods have been compared with natural diffusion results from tests that were performed in two different experimental conditions. From these tests, calculations of non-steady-state diffusion coefficients, Dns , have been carried out, resulting that migration tests give results in the same order of magnitude than those obtained from natural diffusion tests. However, as it is not known how far the diffusion tests reproduce the real conditions, it has been concluded that, in the lack of a reference method reproducing realistic conditions, either diffusion or migration tests cannot be used more than for comparative purposes. Further research is needed on development of tests able to reproduce real performance.

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Section: A) Migration Testsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Non-steady-state chloride diffusion coefficients obtained from migration and natural diffusion tests. Part I: Comparison between several methods of calculation

et al. 2000

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“…This is accomplished by using the Nernst-Planck equation as proposed e.g. in [1,5,6]. The equation can be solved for steady-state conditions or for transient state, yielding the effective chloride diffusion coefficient (D eff ) or the apparent diffusion coefficient (D app ) respectively.…”

Section: Introductionmentioning

confidence: 99%

RCM: A new model accounting for the non-linear chloride binding isotherm and the non-equilibrium conditions between the free- and bound-chloride concentrations

Spiesz

Ballari

Brouwers

2012

Construction and Building Materials

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a b s t r a c tIn this paper a new theoretical model for the Rapid Chloride Migration test is presented. This model accounts for the non-linear chloride binding isotherm and the non-equilibrium conditions between the free-and bound-chloride concentrations in concrete. The new system of equations is solved numerically and compared to a simplified analytical solution, revealing a good agreement. Subsequently, numerical simulations are applied to experimental data on chloride concentration profiles in concrete obtained elsewhere. The binding parameters, the chloride mass transfer coefficient and the effective diffusion coefficient of chloride are estimated with these simulations. The non-linear binding coefficients correspond well to experimental data found in literature. The chloride mass transfer coefficient reveals a tendency to decrease in time during the application of electrical field across a concrete sample. The effective chloride diffusion coefficient (D eff ) obtained in the present study is found to be in line with data obtained elsewhere. Finally, it is demonstrated that the values of the diffusion coefficient computed from the Rapid Chloride Migration test in the traditional way are overestimated.

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“…3 [4], where the cathode was a stainless steel mesh and the anode was a steel plate. Catholyte was filled with a 0.5 M NaC1 solution while a damp sponge placed between the specimen and the anode allowed the application of the electrical field (12V) between the electrodes.…”

Section: Seriesmentioning

confidence: 99%

Non-steady-state chloride diffusion coefficients obtained from migration and natural diffusion tests. Part II: Different experimental conditions. Joint relations

2001

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A B S T R A C T R I~ S U M !~The complexity of the process of chloride penetration in concrete makes it difficult to define a standard procedure in order to calculate diffusion coefficients. In this paper, an attempt to find joint relations between coefficients calculated from different procedures is made. As a first step, an empirical relation, that allows the conversion of a diffusion coefficient calculated from any experimental conditions to a reference condition (0.5 M NaC1 and 90 days of duration of the test), has been developed and validated with different natural diffusion tests. This relation enables the comparison between different non-steady-state diffusion coefficients. As a second step, the equivalence between migration and natural diffusion tests has been undertaken from different series of migration tests, in steady and nonsteady-state, conditions. The final results have been presented in a graphical form in order to facilitate their application. La complexitd des procedures de pdndtration des chlorures clans le b&on rend di~cile la d~finition d'une proce-

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Calculation of chloride diffusivity in concrete from migration experiments, in non steady-state conditions

Cited by 81 publications

References 9 publications

Non-steady-state chloride diffusion coefficients obtained from migration and natural diffusion tests. Part I: Comparison between several methods of calculation

Non-steady-state chloride diffusion coefficients obtained from migration and natural diffusion tests. Part I: Comparison between several methods of calculation

RCM: A new model accounting for the non-linear chloride binding isotherm and the non-equilibrium conditions between the free- and bound-chloride concentrations

Non-steady-state chloride diffusion coefficients obtained from migration and natural diffusion tests. Part II: Different experimental conditions. Joint relations

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