Artículos de revistas: "Diffusion du chlorure"

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DJERBI, Assia. "Diffusion des ions chlorure dans des bétons fissurés. Application à la durabilité des ouvrages littoraux". Revue Européenne de Génie Civil 10, n.º 8 (septiembre de 2006): 1000. http://dx.doi.org/10.1080/17747120.2006.9692881.

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Cid, M., A. Peñuela y M. C. Petit. "Influence de la Diffusion de L'Oxygene sur L'Initiation et L'Evolution des Phenomenes de Corrosion sur des Aciers en Milieu Chlorure Neutre". Materials Science Forum 8 (enero de 1986): 33–42. http://dx.doi.org/10.4028/www.scientific.net/msf.8.33.

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3

Da Silva, Marly Terezinha Quadri Simões y Wellington Mazer. "Diffusion coefficient and tortuosity: Brownian Motion". CONTRIBUCIONES A LAS CIENCIAS SOCIALES 16, n.º 9 (28 de septiembre de 2023): 18281–302. http://dx.doi.org/10.55905/revconv.16n.9-264.

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The objective of this research is to determine the chloride ion diffusion through Brownian motion using images. The research also aims at the search for diffusional physical tortuosity due to Brownian motion to understand the transport flow of the chloride ion. Through micro-CT scanned images of concrete samples, a 3D reconstruction is performed for the representative element and define its microscopic properties. The implementation of the Brownian motion of the chloride ion particles in the porous network of the representative element considered the initial diffusion coefficient defined by the Stokes-Einstein equation. The diffusion coefficient is an important parameter for predicting the depth of attack of the chloride ion and its displacement due to Brownian motion helps to define the tortuosity of this diffusive transport. The research used computational modeling with MATLAB® software. The results show diffusion due to Brownian motion and tortuousness.

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Qiu, Yinan, Yan Yang, Na Yang, Lige Tong, Shaowu Yin, Lang Yu y Li Wang. "Corrosion of Iron Covered with Iron Oxide Film by Chlorine and Hydrogen Chloride Gases: A Molecular Dynamics Simulation Study Using the ReaxFF". Energies 15, n.º 12 (9 de junio de 2022): 4237. http://dx.doi.org/10.3390/en15124237.

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Flue gas produced by biomass fuel combustion contains various chlorine-containing substances and is an important factor causing biomass boiler corrosion. The corrosion processes of chlorine, hydrogen chloride and water on iron covered with an intact/damaged oxide film were investigated under the high temperature of 1300 K through reactive molecular dynamics simulation. The results show that the diffusion processes of oxygen and chlorine are similar and can be divided into three stages: rapid diffusion, continuous diffusion, and no oxide film (stable). Oxygen diffusion in Fe2O3 into a pure iron layer is the main cause of gas corrosion in iron/iron oxide systems. A complete oxide film can hinder iron corrosion by chlorine and hydrogen chloride. Damage in an oxide film significantly affects oxygen and chlorine diffusion and iron corrosion. However, such influence is gradually reduced. The integrity of a protective film is the key to alleviating corrosion. Water facilitates the dissociation of chlorine and hydrogen chloride, and it reacts with iron at high temperatures to enhance corrosion. This study improves the understanding of the iron oxide/iron corrosion from chlorine-containing gases from a microscopic perspective and is of great significance to metal corrosion protection and biomass combustion technologies.

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5

Hou, Fei, Yu Bai y Jun Dong. "Numerical Analysis of the 2-Dimensional Diffusion Models of Choride Ions Based on the FDM with Alternating Direction Implicit Schemes". Advanced Materials Research 1020 (octubre de 2014): 92–97. http://dx.doi.org/10.4028/www.scientific.net/amr.1020.92.

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Chloride ion etching is a significant reason for the damage of the reinforced concrete structures. Diffusion effect is considered to be the main form of which the chloride ion invades into the reinforced concrete structures. Assuming infinite diffusion medium, based on the Chlorine ion diffusion equation, and accounting for the effects of temperature and moisture, models of chloride diffusion in two-dimensional infinite body with consistent coefficient of diffusion and different coefficient of diffusion in both directions are formulated .Two-dimensional chloride ion diffusion behavior was simulated, which proved the diffusion coefficient has a larger effect on the diffusion behavior of the chloride ion. Through these comparisons, we can analysis that model with different coefficient of diffusion in both directions is more suitable for the actual conditions.

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Li, Pei Hao y Bo Jin. "Modelling of Chloride Diffusion into Surface-Biodeposited Concrete". Applied Mechanics and Materials 164 (abril de 2012): 107–10. http://dx.doi.org/10.4028/www.scientific.net/amm.164.107.

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Chloride diffusuion is regarded as the dominant chloride transport process in concrete and the main cause of the corrosion of steel in concrete structures exposed to chloride-rich environments. Surface biodeposition can be applied to both new and existing concrete structures to restrain this deterioration. To gain comprehensive overview to the protective mechanism of surface biodeposition, a theoretical study of chloride diffusion through surface-biodeposited concrete is required. This paper proposes a physical model for surface biodeposited concrete, and develops a theoretical model to predict chloride diffusion of surface-biodeposited concrete structures. The model describes movement and retention of moisture and chloride by means of balance equations and diffusion laws. The influences of biodeposition and substrate properties on chloride diffusion are studied by a finite difference model. Results indicate that chloride diffusion is controlled by both the biodeposition and the substrate.

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Song, Wen Jie, Jun Dong, Yu Bai, Fei Dong y Wei Ze Sun. "Investigation of Numerical Modeling for Concrete Corroded by Chloride Ion Diffusion". Applied Mechanics and Materials 166-169 (mayo de 2012): 1922–25. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.1922.

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For concrete structure lack of enough durability due to corrosion by chloride ion under chlorine salt environment, and based on the Fick’s Diffusion Law, a mathematical model for concrete corroded by chloride ion diffusion is established and studied. Based on Galerkin FEM with weighted residuals, numerically discrete analysis of the models and final finite-difference-discrete format about time are obtained. Comparisons of PDE models between traditional heat conduction and chloride ion diffusion have been done. According to different parameters and APDL in ANSYS, a program for transformation of parameters including initial and boundary conditions is designed, so as to solve modeling by resolving module of heat conduction in ANSYS. A two-dimensional example from references, namely a concrete plate corroded by chloride ion under chlorine salt environment, is analyzed. All the results show the investigation is reliable and feasible for the research of durability of concrete structure under corrosion environment.

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8

SEUX, R. "Étude expérimentale des facteurs de contamination par le CVM de l’eau des réseaux d’adduction publique". Techniques Sciences Méthodes, n.º 12 (20 de enero de 2021): 105–26. http://dx.doi.org/10.36904/tsm/202012105.

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Depuis fin 2012, en application de l’instruction DGS/EA4/2012/366 du 18 octobre 2012, les premières campagnes de prélèvements, spécifiquement réalisées pour définir les antennes en polychlorure de vinyle (PVC) « à risques chlorure de vinyle monomère (CVM) » des réseaux ruraux des départements du nord-ouest de la France donnent bien souvent des résultats peu cohérents et difficiles à interpréter. Devant les difficultés pour identifier l’origine d’écarts considérables dans les résultats, souvent non reproductibles, obtenus lors de ces campagnes, la section territoriale Ouest – Bretagne, Pays de la Loire de l’Astee a réalisé une étude expérimentale sur deux antennes identifiées pour leur capacité à contaminer l’eau transportée par le CVM, dans des conditions hydrauliques connues et maîtrisées. Cette expérimentation a eu pour objectif de déterminer l’influence du temps de contact et de la température de l’eau sur la diffusion du CVM dans l’eau distribuée par une canalisation en PVC dans deux unités de distribution spécifiques. Les résultats, cohérents entre les deux sites expérimentaux, nous ont permis d’établir une relation entre la teneur en CVM dans l’eau, le temps de contact (tc), la température (θ), la concentration résiduelle (Cm) en CVM dans le matériau de la canalisation et son diamètre intérieur (d). La concentration en CVM dans l’eau est sensiblement proportionnelle au temps de contact pour une température donnée et elle double en passant de 10 à 19 °C. Ce modèle peut également être utilisé pour faire une estimation de l’exportation annuelle en CVM dans l’eau. Après 40 ans de service, elle reste inférieure au millième de la quantité résiduelle emprisonnée dans la masse du matériau de la canalisation.

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9

Xu, Zhiyuan y Guang Ye. "Understanding Chloride Diffusion Coefficient in Cementitious Materials". Materials 16, n.º 9 (29 de abril de 2023): 3464. http://dx.doi.org/10.3390/ma16093464.

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One of the key problems that affect the durability of reinforced concrete structures is the corrosion of rebar induced by chloride. Despite the complicated transport mechanism of chloride ions in cementitious materials, diffusion is still the key mechanism of chloride ingress. The determination of the chloride diffusion coefficient will help to predict the chloride profile inside the cementitious materials and estimate the service life with regard to chloride-induced corrosion. However, this paper shows that the chloride diffusion coefficient in the literature is sometimes misunderstood. Such a misunderstanding results in the overestimation of the chloride resistance of cementitious materials. To clarify the chloride diffusion coefficient, this paper first presents the steady- and non-steady-state diffusion equations in cementitious materials. The factors that influence the diffusive flux are identified. The effective and apparent diffusion coefficients are then clearly explained and properly defined. We also point out the obscure definitions of the effective diffusion coefficient in the literature. The varied definitions of the effective diffusion coefficient are the result of the consideration of different factors affecting the diffusion process. Subsequently, this paper discusses two natural diffusion test methods that are frequently employed in cementitious materials to measure the chloride diffusion coefficient. The influencing factors considered by the measured diffusion coefficients are analyzed in detail. Then, the diffusion coefficients determined in some of the studies are reviewed. It is shown that three typical errors could occur when numerically determining the diffusion coefficients.

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10

Wu, Fu Fei, Ke Bin Shi, Shuang Kuai Dong y Guo Wei Wang. "Based on Maturity of Concrete Chloride Ion Diffusion Model and Life Prediction". Key Engineering Materials 599 (febrero de 2014): 7–10. http://dx.doi.org/10.4028/www.scientific.net/kem.599.7.

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As chloride ion diffusion in concrete theoretical model without considering the shortcomings of the concrete maturity,the improved maturity model is used to establish the relationship between the diffusion coefficient of concrete maturity. With the mathematical derivation, getting new chloride ion diffusion theoretically, which considers the maturity of the concrete, the chloride ion binding capacity, the degradation effects of chlorine ion diffusion equation,and consequently broadens the scope of the fick's second law of diffusion, besides, its form and solution completely consistent with the one in the second law of fick equation. By the calculation example,it can be found that the model is more accurate than the traditional ones, and it also applies to the high content of high-performance concrete.

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11

Yuan, Yezhen, Kaimin Niu, Bo Tian, Lijuan Kong y Lihui Li. "Effect of Metakaolin on the Diffusion Properties of Chloride Ions in Cement Mortar under the Coupling Effect of Multiple Factors in Marine Environment". Advances in Civil Engineering 2023 (25 de mayo de 2023): 1–15. http://dx.doi.org/10.1155/2023/6961234.

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To address the problem of chloride ion transport in cement concrete in marine environment, this study investigates the effect of metakaolin dosage on the chloride ion diffusion resistance of mortar and its mechanism by testing the chloride ion binding capacity and microstructure of mortar under the coupling effect of chlorine salt-sulfate-carbonation multiple factors. The results show that the coupling of sulfate or carbonation reduces chloride ion transport to some extent compared with single chlorine salt attack, while the three-factor coupled environment promotes free chloride ion diffusion. This is because the products of calcium alumina, gypsum, and calcium carbonate grow together and compete with each other to form more large capillaries; thus, accelerating the diffusion of chloride ions in cement mortar. Metakaolin, due to its higher pozzolanic activity, increases the monocarbon aluminate content in the erosion products, promotes F-salt generation, and increases the Al/Si ratio, which strengthens the binding ability of C-S-H gel to chloride ions, so the free chloride ion concentration inside the specimens doped with metakaolin is lower. In particular, the three-factor coupled environment has less 0.05–10 μm capillary pore content and higher F-salt stability in the specimens, which has the strongest effect on chloride ion curing, and the free chloride ion concentration integral in M-SCCl is reduced by nearly 30% compared with MF-SCCl and F-SCCl.

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12

Zhao, Q. L. y Y. Z. Zhang. "Concentration Distribution of Chloride Ion under the Influence of the Convection-Diffusion Coupling". Advances in Materials Science and Engineering 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/2076986.

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The transfer process of chloride ion under the action of the convection-diffusion coupling was analyzed in order to predict the corrosion of reinforcement and the durability of structure more accurately. Considering the time-varying properties of diffusion coefficient and the space-time effect of the convection velocity, the differential equation for chloride ion transfer under the action of the convection-diffusion coupling was constructed. And then the chloride ion transfer model was validated by the existing experimental datum and the actual project datum. The results showed that when only diffusion was considered, the chlorine ion concentration increased with the time and decreased with the decay index of time. Under the action of the convection-diffusion coupling, at each point of coupling region, the chloride ion concentration first increased and then decreased and tended to stabilize, and the maximum appeared at the moment of convection velocity being 0; in the diffusion zone, the chloride ion concentration increased over time, and the chloride ion concentration of the same location increased with the depth of convection (in the later period), the velocity of convection (in the early period), and the chloride ion concentration of the surface.

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13

Barone, F. S., R. K. Rowe y R. M. Quigley. "Laboratory determination of chloride diffusion coefficient in an intact shale". Canadian Geotechnical Journal 27, n.º 2 (1 de abril de 1990): 177–84. http://dx.doi.org/10.1139/t90-021.

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An experimental investigation of diffusive transport of a nonreactive solute (chloride) in saturated, intact Queenston Shale is described. Laboratory tests were performed by placing distilled water in contact with samples of shale having a high initial concentration of chloride in their pore water. Chloride was then permitted to diffuse out of the shale and into the distilled water reservoir for a period of up to 65 days. At the end of each test, the shale sample was sectioned to determine the variation in chloride pore-water concentration with depth through the sample. Fickian diffusion theory was then used to deduce the diffusion coefficient (D). The experimental diffusion coefficient for chloride at a temperature of 22 ± 1 °C ranged from 1.4 × 10−6 to 1.6 × 10−6 cm2/s, which corresponds to a tortuosity (τ) ranging from 0.095 to 0.108. Based on pore size measurements and consideration of the ionic diameter of hydrated chloride, the "effective porosity" available for chloride diffusion is estimated to be greater than 75% of the total porosity calculated from the moisture content of the shale. Key words: diffusion, chloride, rock matrix, Queenston Shale, laboratory study.

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14

Rokon, Rokonuzzaman, Md Shafiqul Islam y Nusrat E. Mursalin. "Effect of w/c ratio and cement content on diffusivity of chloride ion in concrete: A molecular dynamics study". Challenge Journal of Concrete Research Letters 10, n.º 4 (21 de diciembre de 2019): 83. http://dx.doi.org/10.20528/cjcrl.2019.04.002.

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When a reinforced structure is exposed to marine environments, chloride-induced corrosion occurs and it decreases the durability and performance of the structure. The degree of humidity, the presence of cracks, environmental conditions, w/c ratio, and cement content are the influencing factors for chloride ion ingress into concrete. All of them, w/c ratio and cement content are treated as the most crucial factors on diffusion. This paper focus on Molecular Dynamics (MD) simulation method to determine the diffusion coefficient of chloride ion in concrete. The effect of w/c ratio and cement content on the diffusivity of chloride ion is also evaluated. The diffusion coefficients are obtained 2.88x10-12 m2/s, 3.13x10-12 m2/s, and 3.61x10-12 m2/s respectively for different w/c ratio of 0.40, 0.45 and 0.50 with constant cement content. Again the diffusion coefficient are calculated 4.6x10-12 m2/s, 3.13x10-12 m2/s, 2.78x10-12 m2/s respectively for different cement content of 300 kg/m3, 350 kg/m3 and 400 kg/m3 with constant w/c ratio. The simulation results clearly indicate that the diffusion coefficient of chlorine was affected by w/c ratio and cement content significantly.

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15

Leaist, Derek G. "The effects of aggregation, counterion binding, and added NaCl on diffusion of aqueous methylene blue". Canadian Journal of Chemistry 66, n.º 9 (1 de septiembre de 1988): 2452–57. http://dx.doi.org/10.1139/v88-386.

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A simplified version of the Hamed conductimetric technique is used to measure binary diffusion of the self-associating dye methylene blue chloride in water at 25 °C. As the dye concentration is increased from 0.0006 to 0.02 mol dm−3, aggregation of the dye monomers and binding of the chloride counterions cause the dye's binary diffusion coefficient to drop from 0.83 × 10−9 to 0.63 × 10−9 m2 s−1. Ternary diffusion coefficients for aqueous methylene blue chloride +NaCl solutions are also reported. These results show that small amounts of added NaCl (0.005 or 0.01 mol dm−3) sharply reduce the diffusivity of the dye component, and that each mole of diffusing dye cotransports 0.2–0.7 mol NaCl. Diffusion of trace amounts of the dye in the presence of a large excess of an inert supporting electrolyte is discussed briefly.

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16

Zhuravel, Vitalii, Teresa Rucińska y Olga Borziak. "Investigation of the Diffusion of Chloride Ions in Blended Cement Pastes". ce/papers 6, n.º 6 (diciembre de 2023): 1265–68. http://dx.doi.org/10.1002/cepa.2970.

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AbstractWhen exposed to aggressive environments containing chlorides, the chlorine ion partially binds to the usual Portland cement mortar and changes its mineralogy. Chlorine ions entering the system displace sulfate from the monosulfoaluminate. Such systems form Kusel's salt at low chloride concentrations and Friedel's salt at higher concentrations. Unbound chloride ions remain dangerous for reinforcing steel, which diffuse deep into the concrete and destroy the passivating layer on the reinforcement. To assess the protective properties of concrete in relation to metal reinforcement, it is proposed to investigate the process of displacement of the diffusion front in cement composites of various compositions. It is also important to study changes in such characteristics as porosity and filtration properties, which significantly affect the penetration depth of an aggressive medium. The study of the structure, mineral and chemical composition is carried out in layers.

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17

Fiducia, Thomas A. M., Kexue Li, Amit H. Munshi, Kurt Barth, Walajabad S. Sampath, Chris R. M. Grovenor y John M. Walls. "3D Distributions of Chlorine and Sulphur Impurities in a Thin-Film Cadmium Telluride Solar Cell". MRS Advances 3, n.º 56 (2018): 3287–92. http://dx.doi.org/10.1557/adv.2018.449.

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ABSTRACTA cadmium chloride activation treatment is essential for the production of high efficiency cadmium telluride (CdTe) solar cells. However, the effects of the treatment on the distributions of chlorine and sulphur within the device are not fully understood. Here, the detailed locations of chlorine and sulphur in a treated CdTe cell are determined in three dimensions by high resolution dynamic SIMS measurements. Chlorine is found to be present in grain boundaries, grain interiors, extended defects within the grain interiors, at the front interface, and in the cadmium sulphide layer. In each of these regions, the chlorine is likely to have significant effects on local electronic properties of the material, and hence overall device performance. Sulphur is found to have a U-shaped diffusion profile within CdTe grains, indicating a mixed grain boundary and lattice diffusion regime.

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18

Polishchuk, Alexandre Ya, Guennadii E. Zaikov, Lidia A. Zimina, Victor MM Lobo y Artur J. M. Valente. "New Method of Measurement of Thermodynamic Diffusion Coefficients of Electrolytes in Polymers". Engineering Plastics 2, n.º 4 (enero de 1994): 147823919400200. http://dx.doi.org/10.1177/147823919400200405.

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A new application of the open-ended conductimetric capillary cell for measuring thermodynamic diffusion coefficients of electrolytes in polymers of different hydrophilic character is presented. Diffusion coefficients of potassium chloride in hydrophilic (PVA) and hydrophobic (POxB) polymers have been measured and prove the applicability of the cell to measure diffusion coefficients in polymer-solvent-electrolyte systems. The theoretical basis of the method is the formulation of diffusion equations in terms of the chemical potential gradient of the diffusing species, and the validity of this approach has been justified by experimental results.

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Polishchuk, Alexandre Ya, Guennadii E. Zaikov, Lidia A. Zimina, Victor MM Lobo y Artur J. M. Valente. "New Method of Measurement of Thermodynamic Diffusion Coefficients of Electrolytes in Polymers". Polymers and Polymer Composites 2, n.º 4 (mayo de 1994): 247–51. http://dx.doi.org/10.1177/096739119400200405.

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A new application of the open-ended conductimetric capillary cell for measuring thermodynamic diffusion coefficients of electrolytes in polymers of different hydrophilic character is presented. Diffusion coefficients of potassium chloride in hydrophilic (PVA) and hydrophobic (POxB) polymers have been measured and prove the applicability of the cell to measure diffusion coefficients in polymer-solvent-electrolyte systems. The theoretical basis of the method is the formulation of diffusion equations in terms of the chemical potential gradient of the diffusing species, and the validity of this approach has been justified by experimental results.

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20

Feisel, Yves, Jonathan M. Castro y Donald B. Dingwell. "Diffusion of F and Cl in dry rhyodacitic melt". American Mineralogist 104, n.º 11 (1 de noviembre de 2019): 1689–99. http://dx.doi.org/10.2138/am-2019-7095.

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Abstract Chemical diffusion of F and Cl has been experimentally determined in a rhyodacitic melt obtained from remelting a sample of Hekla pumice (Iceland). Diffusion couple experiments were conducted in a vertical tube furnace over a temperature range of 750–950 °C and in air for durations of 1 to 35 days. Concentration profiles of F and Cl were obtained for the quenched samples using an electron microprobe. Fluorine and chlorine exhibit Arrhenian behavior over the range of temperature investigated here. The pre-exponential factors of F and Cl are D0(F) = 4.3 × 10−4 and D0(Cl) = 1.6 × 10−5 m2/s. Fluorine diffusion coefficients vary in the order of 1 × 10−15 to 1 × 10−13 m2/s, whereas Cl diffusivity is up to two orders of magnitude slower. The activation energies for F and Cl diffusivities are equal within error at 223 ± 31 and 229 ± 52 kJ/mol, respectively. The difference in diffusivity between F and Cl is particularly pronounced in the melt of our study, compared to results obtained for other magmatic melt compositions. This means that the potential for diffusive fractionation exists and may occur especially under conditions of magma ascent and bubble growth, as this would favor partitioning of the relatively fast-diffusing halogens into growing bubbles, due to H2O exsolution. A dependence of diffusivity on atomic radius observed here is enhanced over that observed in more basic, less viscous melts, indicating that diffusive fractionation is more likely to be pronounced in more silicic, more viscous systems. A proper parameterization and modeling of diffusive fractionation of halogens in actively degassing volcanic systems thus holds the potential of serving as a tool for quantifying the processes responsible for volcanic unrest.

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21

Vidyasagar, Devthade, Yong-Han Yun, Seunghak Shin, Jina Jung, Woosung Park, Jin-Wook Lee, Gill Sang Han, Changhyun Ko y Sangwook Lee. "In-Situ Nano-Auger Probe of Chloride-Ions during CH3NH3PbI3−xClx Perovskite Formation". Materials 14, n.º 5 (26 de febrero de 2021): 1102. http://dx.doi.org/10.3390/ma14051102.

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Organo-halide perovskite solar cells (PSCs) have emerged as next-generation photovoltaics, owing to their high power-conversion efficiency (PCE), lower production cost, and high flexibility. ABX3-structured methylammonium lead triiodide (CH3NH3PbI3 or MAPbI3) perovskite is a widely studied light-absorbing material in PSCs. Interestingly, a small amount of chlorine incorporation into MAPbI3 increases charge carrier diffusion lengths (from 129 nm to 1069 nm), which enables planar structured PSCs with high PCEs. However, existence of chloride ions in the final perovskite film is still under debate. Contrastingly, few studies reported a negligible amount or absence of chloride ions in the final film, while others reported detection of chloride ions in the final film. Herein, we observed the microstructure and chlorine content of MAPbI3−xClx thin films with increasing temperature via an in-situ nano-Auger spectroscopy and in-situ scanning electron microscopic analysis. The relative precipitation of MAPbI3−xClx films occur at lower temperature and MAPbI3−xClx grains grow faster than those of MAPbI3 grains. Local concentrations of chlorine at intragrain and the vicinity of grain boundary were analyzed to understand the behavior and role of the chloride ions during the microstructural evolution of the MAPbI3−xClx films.

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Zeng, Kelin, Wenjin Sun, Lizhou Sun y Longlong Liu. "Experimental Study on the Effect of Corrosion-inhibiting Admixtures on Chloride Corrosion Resistance of Concrete". Journal of Physics: Conference Series 2736, n.º 1 (1 de marzo de 2024): 012042. http://dx.doi.org/10.1088/1742-6596/2736/1/012042.

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Abstract Compared to the different types of rust inhibitors, The effects of the internal and external coating corrosion inhibitors on the corrosion resistance of concrete were studied. The impact of the mixed rust inhibitor on the working performance, compressive strength and chloride ion permeability coefficient of concrete was investigated. The results show that the working performance, late mechanical properties, and resistance to chlorine salt erosion of concrete are better than those of reference concrete after adding the anti-rust agent. Comparing the effects of 2% and 4% internal rust inhibitors on the corrosion resistance of chloride ions, based on the control group, the chloride ion diffusion coefficient of concrete with 2% and 4% rust inhibitors decreases to the original 15.1% and 37.0%, respectively. Concrete’s chloride ion diffusion coefficient with external rust inhibitor decreases to 62.5%. In addition, the internal corrosion inhibitor has a specific water-reducing component, which reduces the water consumption of concrete and improves the compactness of concrete itself, thus improving the corrosion resistance of concrete.

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Park, JangHyun, JinHo Park y MyeongGyu Jung. "Variation in Service Life on RC Structure According to Concrete Binder Type". Materials 13, n.º 23 (28 de noviembre de 2020): 5430. http://dx.doi.org/10.3390/ma13235430.

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When an additive is used to replace a certain amount of cement, a concrete pore structure becomes dense. Thus, it results in inhibiting the penetration of chlorine ions and suppressing corrosion of reinforcing bars. However, the pH level of the concrete decreases, and it deteriorates the performance of the passive film formed on the surface of the rebars embedded in the concrete. Therefore, in this study, the service lives of reinforced concrete containing different types of concrete binders were predicted and compared. The chloride ion diffusion coefficients of concretes with various binders were measured, and the critical chloride content of the rebar was assessed by the real-time monitoring on the corrosion initiation time of the rebar embedded in concrete. Moreover, Fick’s 2nd law was applied to predict when the chloride content at the 40 mm depth of cover reached the critical chloride content based on the chloride ion diffusion coefficient. It was observed that the service life of S6 (OPC 40% + GGBFS 60%) was the highest, followed by TBC (OPC 40% + GGBFS 40% + FA 20%), S3 (OPC 70% + GGBFS 30%), and OPC (OPC 100%).

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24

Zhang, Jun Zhi, Hua Ting Liu, Zhao Qi Fu, Liang Ying Wang y Sheng Bing Zhou. "Erosion-Resisting Properties for Chloride Ion of Short-Chopped Basalt Fiber Reinforced Concrete". Advanced Materials Research 217-218 (marzo de 2011): 66–70. http://dx.doi.org/10.4028/www.scientific.net/amr.217-218.66.

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According to a test for chloride ion erosion in concrete under designed manual climate environment, distributions of chlorine ion concentration in pure bending concrete of short-chopped basalt fiber RC beam and check RC beam without fiber with different flexural loads are analyzed in this paper, and diffusion coefficients of compression and tensile concrete are fitted on the basis of Fick’s second law. Analysis results show that erosion-resisting properties for chloride ion of the basalt fiber compression and tensile concrete in the pure flexural region are increased

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Xue, Guanming, Zhiguo Wang, Enlei Wang, Yan Tang, Yanhui Zhao, Yihe Wang, Suying Hu, Lin Xiang y Zhiwen Xie. "Enhanced Hot Salt-Water Corrosion Resistance of NiCoCrAlY-AlSiY Coating by Ion-Beam-Assisted Deposition". Coatings 11, n.º 9 (2 de septiembre de 2021): 1062. http://dx.doi.org/10.3390/coatings11091062.

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A promising ion-beam-assisted deposition (IBAD) method was developed to improve the salt-water corrosion resistance of NiCoCrAlY-AlSiY coating. During hot salt-water exposure, hydrochloric acid (HCl) was produced when chloride salt, water, and metal oxide reacted with each other, while HCl was also produced when chlorine reacted with water. The as-deposited AlSiY layer exhibited a loose texture accompanied by numerous pore defects, which triggered the multi-scale diffusion of HCl, resulting in the large-area corrosion degradation of the coating texture and the rapid diffusion of the NiCoCrAlY bonding layer. By contrast, the ion-beam-assisted AlSiY layer showed a dense texture that effectively inhibited the inner diffusion of HCl and suppressed the corrosion reactions as well as the diffusion of the NiCoCrAlY bonding layer. The current results confirmed the significant potential of IBAD in inhibiting corrosion damage and diffusion of thermal protective coatings.

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Liu, Huanqiang y Linhua Jiang. "Influence of Hydrostatic Pressure and Cationic Type on the Diffusion Behavior of Chloride in Concrete". Materials 14, n.º 11 (26 de mayo de 2021): 2851. http://dx.doi.org/10.3390/ma14112851.

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The durability of the concrete in underground and marine engineering is affected by the underground and ocean environment. Chloride diffusion coefficient under hydrostatic pressure is a key parameter of concrete durability design under corresponding conditions. Therefore, this paper studies the diffusion behavior of chloride in different diffusion source solutions by experiment and simulation. Based on the experimental results, this paper proposes a new chloride diffusion model under the coupling effect of diffusion and convection. The interaction of ions and compounds in the diffusion source solutions, concrete pore fluid, and concrete material are considered in the new chloride diffusion model. The experimental results show that chloride diffusion rate is significantly affected by hydrostatic pressure, which increases with the increase of hydrostatic pressure. The chloride diffusion coefficient shows a certain difference in difference diffusion source solutions. The chloride diffusion coefficient in divalent cationic diffusion source solutions is the largest, the chloride diffusion coefficient in the divalent and monovalent cationic compound ones is in the middle, and the chloride diffusion coefficient in the monovalent cationic ones is the smallest. There is a linear relationship between the chloride diffusion coefficient and the hydrostatic pressure whether in single or combined cationic diffusion source solutions.

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27

Huang, Ying, Jun Wei, Rong Zhen Dong y Hui Huang Yan. "Numerical Stimulation Method of Chloride Concentration in the Concrete Structure Exposed to Chloride Aggressive Environment". Applied Mechanics and Materials 193-194 (agosto de 2012): 466–71. http://dx.doi.org/10.4028/www.scientific.net/amm.193-194.466.

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In this paper, based on the similarity between chloride diffusion equation in concrete and heat conduction equation the thermal analysis module of the ANSYS finite element software was used to carry out the numerical simulation for chloride ion diffusion process in concrete. And the numerical results were compared with the analytical solutions of chloride diffusion equation, which showed that the method is effective for the chloride diffusion analysis. Time-dependence of chloride diffusion coefficient in concrete was considered by amending the chloride diffusion coefficient with various parameters. Finally it is a feasible method that the chloride ion concentration in concrete structures was calculated by thermal analysis module of the ANSYS.

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28

Chen, Ruige, Xiaoli Wei, Fawang Liu y Vo V. Anh. "Multi-term time fractional diffusion equations and novel parameter estimation techniques for chloride ions sub-diffusion in reinforced concrete". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, n.º 2172 (11 de mayo de 2020): 20190538. http://dx.doi.org/10.1098/rsta.2019.0538.

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In this paper, searching for a better chloride ions sub-diffusion system, a multi-term time-fractional derivative diffusion model is proposed for the description of the time-dependent chloride ions penetration in reinforced concrete structures exposed to chloride environments. We prove the stability and convergence of the model. We use the modified grid approximation method (MGAM) to estimate the fractional orders and chloride ions diffusion coefficients in the reinforced concrete for the multi-term time fractional diffusion system. And then to verify the efficiency and accuracy of the proposed methods in dealing with the fractional inverse problem, two numerical examples with real data are investigated. Meanwhile, we use two methods of fixed chloride ions diffusion coefficient and variable diffusion coefficient with diffusion depth to simulate chloride ions sub-diffusion system. The result shows that with the new fractional orders and parameters, our multi-term fractional order chloride ions sub-diffusion system is capable of providing numerical results that agree better with the real data than other models. On the other hand, it is also noticed from the numerical solution of the chloride ions sub-diffusion system that setting the variable diffusion coefficient with diffusion depth is more reasonable. And it is also found that chloride ions diffusion coefficients in reinforced concrete should be decreased with diffusion depth which is completely consistent with the theory. In addition, the model can be used to predict the chloride profiles with a time-dependent property. This article is part of the theme issue ‘Advanced materials modelling via fractional calculus: challenges and perspectives’.

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29

Wang, Xiao Yong, Han Seung Lee y Hai Moon Jung. "Analysis of Chloride Penetration into the Corner Zone of Concrete Structure Member". Key Engineering Materials 348-349 (septiembre de 2007): 397–400. http://dx.doi.org/10.4028/www.scientific.net/kem.348-349.397.

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Chloride penetration into concrete is the main cause of steel corrosion in concrete structures exposed to chloride-rich environments. In general, conditions on the diffusion process are dominant among various penetration mechanisms, such as ionic diffusion, capillary sorption, and so on. In recent analysis of current literature, chloride diffusion is as a simplified one-dimensional diffusion process. However, for the rebar in the corner zone of concrete beam, the diffusion belongs to a two-dimensional diffusion. Based on a galerkin finite element method, a two-dimensional diffusion differential equation is built and solved numerically and the different chloride concentration is compared to one dimensional diffusion and two-dimensional diffusion process. The service life of concrete structure members under two-dimensional chloride penetration is predicted by compared with a critical threshold chloride concentration. Compared with general one-dimensional chloride attack, the service life is considerably reduced in a corner zone due to two-dimension penetration.

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30

Wang, Qiannan, Wei Sun, Liping Guo, Chunping Gu y Jinyu Zong. "Modeling Chloride Diffusion Coefficient of Steel Fiber Reinforced Concrete under Bending Load". Advances in Civil Engineering 2018 (2018): 1–6. http://dx.doi.org/10.1155/2018/3789214.

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The chloride diffusion coefficient is the most important parameter when predicting chloride ingress in concrete. This paper proposed a model for calculating the chloride diffusion coefficient of steel fiber reinforced concrete (SFRC). Considering the concrete structures in service are usually subjected to external loads, the effect of bending load was discussed and expressed with a stress factor ks in the model. The chloride diffusion coefficient of cement paste was calculated with capillary porosity and then used to predict the chloride diffusion coefficient of SFRC. Some factors in the model were determined with experimental results. Chloride bulk diffusion tests were performed on SFRC and plain concrete (without fiber) specimens under bending load. SFRC showed slightly better chloride resistance for unstressed specimens. The compressive stress decreased the chloride diffusion coefficient of SFRC, while it caused no change in plain concrete. For the tensile zone, the chloride resistance of concrete was improved significantly by adding steel fibers. Overall, SFRC performed better chloride resistance, especially under bending load. The proposed model provides a simple approach for calculating the chloride diffusion coefficient of SFRC under bending load.

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31

Moreira, Ramón, Francisco Chenlo, N. Vallejo y Lionel Gerbet. "Mass Transfer Analysis during Osmotic Dehydration of Eggplant Using Binary Solutions of Sucrose and Sodium Chloride". Defect and Diffusion Forum 273-276 (febrero de 2008): 413–18. http://dx.doi.org/10.4028/www.scientific.net/ddf.273-276.413.

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Osmotic dehydration of eggplant slices in sucrose and sodium chloride solutions at different solution concentrations, stirring levels and time of process is studied. Water loss and solids gain kinetics were experimentally determined and modelled using a diffusional model and equilibrium values were predicted by means of Azuara model. Modelling was satisfactory and involved effective coefficients of diffusion useful to quantify the different mass transfer fluxes.

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32

Shabliy, Tetyana, Olena Ivanenko, Sergii Plashykhin, Nonna Pavliuk, Artem Safiants y Dmytro Sidorov. "New Approaches to Comprehensive Electrochemical Processing of Sulfate-Chloride High-Mineralized Wastewater Treatment Residues". Architecture, Civil Engineering, Environment 16, n.º 3 (1 de septiembre de 2023): 171–80. http://dx.doi.org/10.2478/acee-2023-0044.

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Abstract The results of electrochemical processing of spent acidic, neutral, and alkaline sulfate-chloride-containing regenerative solutions in two- and three-chamber electrolyzers are presented. It has been determined that the highest current efficiency for the products of electrodialysis can be achieved in the presence of hardness ions when processing acidic sulfate-containing solutions using three-chamber electrolyzers. It has been established that during electrodialysis of alkaline solutions after regeneration of anionites containing chloride ions, accumulation of alkali occurs in the cathodic region, and in the anodic region, chloride ions accumulate due to diffusion through the anion exchange membrane during the first stage, followed by preferential oxidation of chloride ions with liberation of free chlorine during the second stage. It has been shown that electrodialysis can effectively solve the problem of comprehensive processing of neutral, alkaline, and acidic regenerative sulfate-chloride-containing solutions, with the production of alkali and acid at concentrations suitable for reuse in regeneration processes.

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33

Yu, Bo, Zhong Hui Huang, Ming Wu, Hui Liang Sun, Lu Feng Yang y Bin Hong. "Concentration Distribution of Chloride Ion in Cracked Concrete". Applied Mechanics and Materials 351-352 (agosto de 2013): 1581–84. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.1581.

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Cracks provide diffusion path for chloride ions transport from the external environment into the concrete, resulting in the durability degradation of concrete structures. In this paper, the boundary condition of cracked concrete and chloride diffusion coefficient in crack were analyzed. The time-dependent chloride diffusion model was established based on the time-dependent chloride diffusion coefficient and the Ficks second law of diffusion. The influence of crack on the concentration distribution of chloride ion in cracked concrete was quantificationally investigated.

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34

Mayor, Luis, Ramón Moreira, Francisco Chenlo y Alberto M. Sereno. "Mass Transfer Analysis during Osmotic Dehydration of Pumpkin Fruits Using Binary and Ternary Aqueous Solutions of Sucrose and Sodium Chloride". Defect and Diffusion Forum 258-260 (octubre de 2006): 213–18. http://dx.doi.org/10.4028/www.scientific.net/ddf.258-260.213.

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Osmotic dehydration experiments of pumpkin with binary aqueous solutions of sucrose, sodium chloride and ternary solutions with both solutes at 298 K were carried out. Weight reduction, water loss and solute acquisition kinetics were determined. Experimental data were fitted employing a diffusional model considering samples as spheres and the external resistance to the mass transfer negligible. The model gave as parameter of fitting an effective diffusion coefficient for each component transferred (water, sucrose and sodium chloride) for each experimental condition assayed. Correlations between the effective diffusivity and solute concentration were established for binary and ternary systems.

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35

Zhu, Jin Song y Li Kun He. "Cellular Automata-Based Chloride Ion Diffusion Modelling of Concrete Bridge under Multifactor Coupling Action". Advanced Materials Research 368-373 (octubre de 2011): 1407–10. http://dx.doi.org/10.4028/www.scientific.net/amr.368-373.1407.

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In order to accurately simulate the diffusion of chloride ion in the existing concrete bridge and acquire the precise concentration of chloride ion at any time, a Cellular Automata(CA)-based model is proposed. Firstly, the process of chloride ion diffusion is analyzed by the CA method and a nonlinear solution to the Fick’s second law is obtained. Secondly, considering the impact of various factors such as stress states, temporal and spatial variability of diffusion parameters and water-cement ratio on the process of chloride ion diffusion, the model of chloride ion diffusion under multifactor coupling is presented. Finally, a chloride ion penetrating experiment is used to prove the effectiveness and reasonability of this present method. A T-type beam is taken as an illustrative example to analyze the process of chloride ion diffusion.

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36

Cheng, Xiaokang, Jianxin Peng, C. S. Cai y Jianren Zhang. "Experimental Study on Chloride Ion Diffusion in Concrete under Uniaxial and Biaxial Sustained Stress". Materials 13, n.º 24 (15 de diciembre de 2020): 5717. http://dx.doi.org/10.3390/ma13245717.

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The existence of axial and lateral compressive stress affect the diffusion of chloride ions in concrete will lead to the performance degradation of concrete structure. This paper experimentally studied the chloride diffusivity properties of uniaxial and biaxial sustained compressive stress under one-dimensional chloride solution erosion. The influence of different sustained compressive stress states on chloride ion diffusivity is evaluated by testing chloride concentration in concrete. The experiment results show that the existence of sustained compressive stress does not always inhibit the diffusion of chloride ions in concrete, and the numerical value of sustained compressive stress level can affect the diffusion law of chloride ions in concrete. It is found that the chloride concentration decreases most when the lateral compressive stress level is close to 0.15 times the compressive strength of concrete. In addition, the sustained compressive stress has a significant effect on chloride ion diffusion of concrete with high water/cement ratio. Then, the chloride diffusion coefficient model under uniaxial and biaxial sustained compressive stress is established based on the apparent chloride diffusion coefficient. Finally, the results demonstrate that the chloride diffusion coefficient model is reasonable and feasible by comparing the experimental data in the opening literature with the calculated values from the developed model.

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37

Chen, Zheng, Xi Bin Zhao, Yan Hua Yuan, Zhong Hua Wang, Lu Feng Yang y Qiong Ming Jiang. "On the Time Dependency of the Chloride Diffusion in High Performance Concrete". Advanced Materials Research 721 (julio de 2013): 148–52. http://dx.doi.org/10.4028/www.scientific.net/amr.721.148.

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The chloride diffusion coefficient of concrete is time dependent. The high performance concrete (HPC) was prepared and the specimens were tested by ASTM C1202 and the durability of HPC in long period is analyzed with the time dependency of diffusion in this paper. The results show that the chloride diffusion coefficients of the HPC with only fly ash are large than those of the HPC with multi-admixtures, but the attenuation of the chloride diffusion coefficients of the formers are faster than the latters. The analysis results show that the chloride concentrations in concrete is over estimated when time-dependence of chloride diffusion is not considered, and the durability of concrete in long period is determined by both chloride diffusion coefficient and age factor.

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38

Rawat, Garima, Sumit Gandhi y Yogesh Iyer Murthy. "Influence of nano-TiO₂ on the chloride diffusivity of concrete". Emerging Materials Research 11, n.º 4 (1 de diciembre de 2022): 1–13. http://dx.doi.org/10.1680/jemmr.22.00056.

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In this research, the benefit of nano-TiO2 concrete over pure concrete in resisting the impacts of chloride diffusion was investigated. An increasing accelerative effect the chloride diffusion was experimentally discovered, which coincided with the movement in the exposed concrete surface caused by diffusion and the damage in concrete microstructure caused by chloride salt accumulation. The “time lag” and “equivalent time” between diffusion and migration tests were used to calculate the steady and non-steady-state chloride diffusion coefficients. Concrete containing 2% nano-TiO2 in the weight of cement demonstrated improved impermeability when compared to pure concrete, owing to improvements in microstructure and porosity. In comparison to pure concrete, the concrete containing nano-TiO2 had a superior performance in resisting the effects of chloride diffusion. Because of its superfine particle size distribution and “filler” effect, nano-TiO2 appeared to assure decreased chloride diffusion in the investigated mixes, test findings revealed that adding supplemental cementitious elements to mortar enhanced its resistance to chloride penetration.

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39

Zhang, Qing Zhang, Xiang Lin Gu, Wei Ping Zhang y Qing Hua Huang. "Study on Effect of Soaking Time on the Transmission of Chloride Ion in Concrete under Drying-Wetting Cycles". Advanced Materials Research 261-263 (mayo de 2011): 61–68. http://dx.doi.org/10.4028/www.scientific.net/amr.261-263.61.

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Acceleration penetration tests of chloride ion were conducted for typical diurnal and semidiurnal tidal types in China with consideration of various values of soaking time. It was found that the content of chloride ion from shallow area near the surface of concrete to the pure diffusion area of concrete reduced more significantly with the depth than that in the pure diffusion area of concrete. Based on Fick’s second law, the variation laws of chloride ion content at the edge of the pure diffusion area and chloride ion diffusion coefficient in the pure diffusion area under different soaking time ratios were identified by using the chloride ion content distributions that were established based on the test results of concrete in the pure diffusion area. It was found that the chloride ion content and the apparent chloride ion diffusion coefficient in pure diffusion area may be very high when the ratio of soaking time ratio is between 0.3 and 0.42 or 0.6 and 0.7 for diurnal tidal type and 0.83 for semidiurnal tidal type, which will cause severe erosion in concrete structures in tidal zone.

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40

Hajikhani, Aidin, Franca Scocozza, Michele Conti, Michele Marino, Ferdinando Auricchio y Peter Wriggers. "Experimental characterization and computational modeling of hydrogel cross-linking for bioprinting applications". International Journal of Artificial Organs 42, n.º 10 (3 de julio de 2019): 548–57. http://dx.doi.org/10.1177/0391398819856024.

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Alginate-based hydrogels are extensively used to create bioinks for bioprinting, due to their biocompatibility, low toxicity, low costs, and slight gelling. Modeling of bioprinting process can boost experimental design reducing trial-and-error tests. To this aim, the cross-linking kinetics for the chemical gelation of sodium alginate hydrogels via calcium chloride diffusion is analyzed. Experimental measurements on the absorbed volume of calcium chloride in the hydrogel are obtained at different times. Moreover, a reaction-diffusion model is developed, accounting for the dependence of diffusive properties on the gelation degree. The coupled chemical system is solved using finite element discretizations which include the inhomogeneous evolution of hydrogel state in time and space. Experimental results are fitted within the proposed modeling framework, which is thereby calibrated and validated. Moreover, the importance of accounting for cross-linking-dependent diffusive properties is highlighted, showing that, if a constant diffusivity property is employed, the model does not properly capture the experimental evidence. Since the analyzed mechanisms highly affect the evolution of the front of the solidified gel in the final bioprinted structure, the present study is a step towards the development of reliable computational tools for the in silico optimization of protocols and post-printing treatments for bioprinting applications.

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41

Yao, Ling, Lixia Ren, Guoli Gong y Jianqiang Zhang. "Simulation of Chloride Diffusion in Concrete Based on a New Mesoscopic Numerical Method". Advances in Civil Engineering 2020 (18 de agosto de 2020): 1–10. http://dx.doi.org/10.1155/2020/5318106.

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Chloride diffusion-induced corrosion is a major factor that affects the durability of concrete structures. Thus, the study of chloride diffusion in concrete is important. In this study, a mesoscopic structure model is proposed and used to investigate chloride diffusion in concrete. The concrete is assumed to be a heterogeneous material composed of two phases of aggregate and mortar matrix. The aggregates are randomly distributed convex polygons. The chloride diffusion is assumed to occur only in the mortar matrix phase. The modified chloride diffusion coefficient in the mesoscale model is proposed. The effect of a single aggregate in chloride diffusion in concrete is analyzed. The present numerical model is validated on the basis of the experimental data. The influence of aggregate in the presented model, including aggregate random distribution form, aggregate content, and the validity of polygonal aggregate based on circle, is explored further. The simulation results indicate that the polygonal aggregate random distribution has a negligible influence on chloride diffusion in concrete, the polygonal aggregate content has a certain effect, and the presented mesoscale numerical model is an effect method for predicting the chloride diffusion in concrete.

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42

Liu, Jing, Xuandong Chen, Hua Rong, Aiping Yu, Yang Ming y Ke Li. "Effect of Interface Transition Zone and Coarse Aggregate on Microscopic Diffusion Behavior of Chloride Ion". Materials 15, n.º 12 (12 de junio de 2022): 4171. http://dx.doi.org/10.3390/ma15124171.

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Concrete is a multiphase composite material composed of coarse aggregate, cement mortar, and interface transition zone (ITZ). It is of great significance to study the effect of ITZ and coarse aggregate on chloride microscopic diffusion behavior for predicting the service life of reinforced concrete (RC) structures. By introducing the random distribution function, a random coarse aggregate model considering the randomness of the thickness of the ITZ was established. Furthermore, a two-dimensional (2D) chloride ion diffusion mesoscopic model was developed by specifying different diffusion properties for different phase materials of concrete. Moreover, the effects of coarse aggregate rate, ITZ thickness, and ITZ diffusion property on chloride ion diffusion behavior were investigated in this paper. The research showed that the aggregate has hindrance and agglomeration action on chloride ion diffusion. Although the volume content of the ITZ was very small, less than 0.2% of the total volume of concrete, the effect of the ITZ on the chloride diffusion in concrete cannot be ignored. More importantly, the mechanism of promoting chloride diffusion in the ITZ was revealed through the chloride diffusion trajectory. The research revealed the transmission mechanism of chloride ions in the meso-structure of concrete and provides theoretical support for the design of RC structures in coastal areas.

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43

Matseevich, Tatyana A. y Ilya F. Andreev. "The finite element model of chloride diffusion in pre-stressed corroded reinforcement bars of reinforced concrete structures". Vestnik MGSU, n.º 11 (noviembre de 2022): 1462–70. http://dx.doi.org/10.22227/1997-0935.2022.11.1462-1470.

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Introduction. The general corrosion model, made for reinforced concrete structures, must include the initiation of environmental influences such as carbonation, cracking and chloride ion penetration. It depends on the rate and degree of corrosion, corrosive effects in reduced areas, as well as the lower strength of bond between pre-stressed and unstressed reinforcement bars and concrete. The majority of earlier studies were focused on one-dimensional diffusion problems with an assumed constant corrosion rate. Materials and methods. In the aftermath of general corrosion, localized corrosion is accompanied by a release of hydrogen and alkaline water, chlorine ions. Crack propagation in reinforcement wires is calculated using the transient finite element software for chloride diffusion, which is time-dependent. Results. In most cases, the diffusion equation does not have a closed form solution, and therefore, the finite difference method can be used. The authors have shown that the corrosion rate decreases with time if current density has different water-cement ratios. If the water-cement ratio increases, the corrosion rate increases, as well. Conclusions. In a pre-stressed reinforced concrete beam, the corrosion of one bar affects the total corrosion of all bars and the reduction in the cross-sectional area of bars that does not exceed 15 %.

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44

HIGASHIYAMA, Hiroshi, Manote SAPPAKITTIPAKORN, Mutsumi MIZUKOSHI y Osamu TAKAHASHI. "Time Dependency on Chloride Diffusion of Ceramic Waste Aggregate Mortars Containing Ground Granulated Blast-Furnace Slag". Journal of the Society of Materials Science, Japan 64, n.º 7 (2015): 591–98. http://dx.doi.org/10.2472/jsms.64.591.

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45

Ma, Junjun y Pengzhen Lin. "Simulation Approach for Random Diffusion of Chloride in Concrete under Sustained Load with Cellular Automata". Materials 15, n.º 13 (21 de junio de 2022): 4384. http://dx.doi.org/10.3390/ma15134384.

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Steel bar corrosion caused by chloride is the major reason for concrete structure durability failures in a corrosive environment. An accurate simulation of chloride ion diffusion in concrete is hence critical to durability design, maintenance, and reinforcement of concretes in erosive environments. To accurately simulate actual chloride ion diffusion in concretes, an improved three-dimensional neighborhood type is proposed according to the mechanism of chloride ion diffusion in concrete, and a three-dimensional cellular automaton model (3D CA model) for describing the diffusion process of chloride in concrete is established based on this neighborhood type. The accuracy and correctness of simulation results obtained from the 3D CA model were verified by comparison with Fick’s second law analytical solutions. Based on the 3D CA model, an improved modified 3D CA model is developed (3D RTCA model) which takes into account random chloride ion distribution in concrete, the time dependence of the coefficient of chloride ion diffusion, and the structure stress level effect on chloride ion diffusion. Numerical simulation results reveal that the 3D RTCA model has higher calculation accuracy in predicting long-term concentration of chloride in concretes, and the simulation results are closer to experimental findings than analytical results obtained based on Fick’s second law. Compared with Fick’s second law analytical solutions, the 3D RTCA model can reflect more truly the cross-sectional stress level effect on chloride ion diffusion through simple local evolution rules. Besides, the 3D RTCA model can genuinely describe the randomness and uncertainty of the chloride diffusion process. The 3D RTCA model developed in the current study provides a novel perspective and method to investigate chloride ion diffusion in concrete from structural level.

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46

Zhu, Yun Dong, Yang Li y Zhuo Zhao. "Correlation Test between Chloride Diffusion Coefficient and Microcosmic Pore Structure of Mineral Admixture Concrete". Applied Mechanics and Materials 438-439 (octubre de 2013): 81–86. http://dx.doi.org/10.4028/www.scientific.net/amm.438-439.81.

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Cube crushing strength, resistance to chloride penetration and gas adsorption analysis of mineral admixture concrete are tested to analyze the effect of raw material on chloride diffusion coefficient and its regression relationship with concrete microcosmic pore structure index. Test results show that chloride diffusion coefficient at different age increased with the increase of water-binding material ratio, decreased with the increase of cement dosage and both appeared a good nonlinear regression relationship. Chloride diffusion coefficient at different age increased with the increase of concrete microcosmic pore structure index. 56d chloride diffusion coefficient has a good linear correlation with microcosmic pore structure index, and 84d chloride diffusion coefficient has a good nonlinear regression relationship with microcosmic pore structure index.

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Balcone-Boissard, Hélène, Don R. Baker, Benoit Villemant, Jean Cauzid, Georges Boudon y E. Deloule. "Br diffusion in phonolitic melts: Comparison with fluorine and chlorine diffusion". American Mineralogist 105, n.º 11 (1 de noviembre de 2020): 1639–46. http://dx.doi.org/10.2138/am-2020-7372.

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Abstract Bromine diffusion was measured in two natural phonolitic melts: (1) a K2O-rich (~10 wt%) one synthesized from the white pumice phase of the 79 AD eruption of Vesuvius (Italy), and (2) a Na2O-rich (~10 wt%) one corresponding to the most differentiated melt of the 12 000 BC eruption of the Laacher See (Germany). Experiments were performed at 0.5 and 1.0 GPa, 1250 to 1450 °C, at anhydrous and hydrous (2.65 ± 0.35 wt% of dissolved water) conditions. Experiments conducted with the diffusion-couple technique in the piston cylinder were performed with only bromine diffusing and with the simultaneous diffusion of a halogen mixture (F, Cl, Br) to evaluate the interactions between the halogens during diffusion. The diffusion profiles of Br were measured by X-ray fluorescence using synchrotron radiation microprobe (SYXRF), ID18F, at the European Synchrotron Radiation Facility (ESRF, France). Bromine diffusion displays Arrhenian behavior under anhydrous conditions that is similar when it diffuses alone and when it diffuses with F and Cl. The Br diffusion coefficients range between 2 × 10–12 m2/s at 1250 °C and 1.5 × 10–11 m2/s at 1450 °C for the Na-rich melt and between 3 × 10–12 m2/s at 1250 °C and 2.5 × 10–11 m2/s at 1450 °C for the K-rich melt, at 1.0 GPa. Although Br mobility is independent of F and Cl in anhydrous phonolitic melts, its behavior may be dependent on the dominant alkali in the melt, as previously observed for Cl, but not F. For hydrous experiments, although the data are scattered, the Br diffusivity increases slightly with water and the Na/K ratio seems to influence Br diffusivity. Similarly to noble gases, halogen diffusivity at a given temperature in the phonolitic melts appears related to the ionic porosity of the silicate structure. Compared to basaltic melt, Br diffusivities are approximately one order of magnitude lower in the Na-phonolite melt, because of the difference of the pre-exponential factor. Br mobility appears to be decoupled from melt viscosity, considering the results here.

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Khan, Muhammad Umar, Shamsad Ahmad y Husain Jubran Al-Gahtani. "Chloride-Induced Corrosion of Steel in Concrete: An Overview on Chloride Diffusion and Prediction of Corrosion Initiation Time". International Journal of Corrosion 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/5819202.

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Initiation of corrosion of steel in reinforced concrete (RC) structures subjected to chloride exposures mainly depends on coefficient of chloride diffusion, Dc, of concrete. Therefore, Dc is one of the key parameters needed for prediction of initiation of reinforcement corrosion. Fick’s second law of diffusion has been used for long time to derive the models for chloride diffusion in concrete. However, such models do not include the effects of various significant factors such as chloride binding by the cement, multidirectional ingress of chloride, and variation of Dc with time due to change in the microstructure of concrete during early period of cement hydration. In this paper, a review is presented on the development of chloride diffusion models by incorporating the effects of the key factors into basic Fick’s second law of diffusion. Determination of corrosion initiation time using chloride diffusion models is also explained. The information presented in this paper would be useful for accurate prediction of corrosion initiation time of RC structures subjected to chloride exposure, considering the effects of chloride binding, effect of time and space on Dc, and interaction effect of multidirectional chloride ingress.

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WANG, Jian, Pui-Lam NG, Weishan WANG, Jinsheng DU y Jianyong SONG. "MODELLING CHLORIDE DIFFUSION IN CONCRETE WITH INFLUENCE OF CONCRETE STRESS STATE". Journal of Civil Engineering and Management 23, n.º 7 (13 de julio de 2017): 955–65. http://dx.doi.org/10.3846/13923730.2017.1343203.

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Under coastal or marine conditions, chloride erosion is the major accelerating factor of reinforcement corrosion. Therefore, it is of vital importance to investigate the chloride diffusion model. Research reveals that the concrete stress state has great influence on chloride diffusion; therefore a stress influence coefficient was incorporated in chloride diffusion coefficient model by many researchers. By referring to the experimental data from eight different researchers, the law between stress influence coefficient and concrete stress ratio is studied in detail, and equations relating the stress influence coefficient with the concrete stress ratio are established. Compared with three typical existing groups of equations, it is found that the proposed equations give the most accurate estim.ation of the stress influence coefficient. Hence, the proposed equations can be adopted to improve the valuation of chloride diffusion coefficient, and a modified chloride diffusion model is put forward. Three groups of experimental data are used to validate the modified chloride diffusion model, which is shown to be reasonable and having high prediction accuracy.

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Chen, Jianlan, Jiandong Wang, Rui He, Huaizhu Shu y Chuanqing Fu. "Experimental Study on Effective Chloride Diffusion Coefficient of Cement Mortar by Different Electrical Accelerated Measurements". Crystals 11, n.º 3 (27 de febrero de 2021): 240. http://dx.doi.org/10.3390/cryst11030240.

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This study investigated the effective chloride diffusion coefficient of cement mortar with different water-to-cement ratio (w/c) under electrical accelerated migration measurement. The cumulative chloride concentration in anode cell solution and the cumulative chloride concentration drop in the cathode cell solution was measured by RCT measurement and the results were further used to calculate the chloride diffusion coefficient by Nordtest Build 355 method and Truc method. The influence of w/c on cement mortar’s chloride coefficient was investigated and the chloride diffusion coefficient under different determination methods were compared with other researchers’ work, a good consistency between this work’s results and literatures’ results was obtained. The results indicated that the increased w/c of cement mortar samples will have a higher chloride diffusion coefficient. The cumulative chloride concentration drop in the cathode cell solution will have deviation in early stage measurement (before 60 h) which will result in overestimation of the effective chloride diffusion coefficient.

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