• Computers and Concrete
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• v.10 no.1
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• pp.79-93
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• 2012

This paper estimates theoretically the diffusion-reaction behaviour of sulfate ion in concrete caused by environmental sulfate attack. Based on Fick's second law and chemical reaction kinetics, a nonlinear and nonsteady diffusion-reaction equation of sulfate ion in concrete, in which the variable diffusion coefficient and the chemical reactions depleting sulfate ion concentration in concrete are considered, is proposed. The finite difference method is utilized to solve the diffusion-reaction equation of sulfate ion in concrete, and then it is used to simulate the diffusion-reaction process and the concentration distribution of sulfate ion in concrete. Afterwards, the experiments for measuring the sulfate ion concentration in concrete are carried out by using EDTA method to verify the proposal model, and results show that the proposed model is basically in agreement with the experimental results. Finally, Numerical example has been completed to investigate the diffusion-reaction behavior of sulfate ion in the concrete plate specimen immersed into sulfate solution.

• Bulletin of the Korean Chemical Society
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• v.5 no.6
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• pp.249-253
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• 1984

Mutual diffusion coefficients of choline chloride were determined by using the diaphragm cell method in aqueous solutions of chondroitin sulfate A at $25^{\circ}C$. The diffusion coefficients of choline chloride in 0.1g/100ml, 0.5g/100ml and 1g/100ml respectively of chondroitin sulfate solutions were compared with those of binary systems of water-choline chloride. At low concentrations, the diffusion coefficients of the choline chloride in the presence of chondroitin sulfate were significantly smaller than the values obtained in the absence of chondroitin sulfate, indicating a strong interaction between these solutes. The effect of this interaction on the diffusion of choline ion is largest at higher chondroitin sulfate concentrations and at lower choline chloride concentrations. The influence of chondroitin sulfate is overcome at higher choline chloride concentrations. Self-diffusion coefficients of choline ion in the presence of chondroitin sulfate are also obtained. Excellent agreements were obtained between the experimental data and the calculated values obtained by using the Manning's equations. These observations suggest that the interaction between choline chloride and chondroitin sulfate involves primarily a long range electrostatic effect and there is no appreciable "condensation" or binding of choline ion to the chondroitin sulfate.

• Computers and Concrete
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• v.4 no.2
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• pp.157-166
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• 2007

The paper considers a theoretical model to study sulfate ion diffusion in saturated porous media - cement based mineral composites, accounting for simultaneous effects, such as filling micro-capillaries (pores) with ions and chemical products and liquid push out of them. Pore volume change and its effect on the distribution of ion concentration within the specimen are investigated. Relations for the distribution of the capillary relative radius and volume within the composite under consideration are found. The numerical algorithm used is further completed to consider capillary size change and the effects accompanying sulfate ion diffusion. Ion distribution within the cross section and volume of specimens fabricated from mineral composites is numerically studied, accounting for the change of material capillary size and volume. Characteristic cases of 2D and 3D diffusion are analyzed. The results found can be used to both assess the sulfate corrosion in saturated systems and predict changes occurring in the pore structure of the composite as a result of sulfate ion diffusion.

• Computers and Concrete
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• v.4 no.4
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• pp.273-284
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• 2007

The paper considers a theoretical model for the study of the process of transfer of sulfate ions in saturated porous media - mineral composites. In its turn, the model treats diffusion of sulfate ions into cement based composites, accounting for simultaneous effects such as filling of micro-capillaries with ions and chemical products and liquid push out of them. The proposed numerical algorithm enables one to account for those simultaneous effects, as well as to model the diffusive behavior of separate sections of the considered volume, such as inert fillers. The cases studied illustrate the capabilities of the proposed model and those of the algorithm developed to study diffusion, considering the specimen complex configuration. Computations show that the theoretical assumptions enable one to qualitatively estimate the experimental evidence and the capabilities of the studied composite. The results found can be used to both assess the sulfate corrosion in saturated systems and predict and estimate damage of structures built of cement-based mineral composites.

• Computers and Concrete
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• v.16 no.6
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• pp.847-864
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• 2015

This study aimed to develop models of sulfate diffusion and ettringite content profile in cement paste for the predication of the damage behavior in cement paste subject to external sulfate. In the models, multiphase reaction equilibrium between ions in pore solution and solid calcium aluminates phases and the microstructure changes in different positions of cement paste were taken into account. The distributions of expansive volume strain and expansion stress in cement paste were calculated based on the ettringite content profile model. In addition, more sulfate diffusion tests and SEM analyses were determined to verify the reliability and veracity of the models. As the results shown, there was a good correlation between the numerical simulation results and experimental evidences. The results indicated that the water to cement ratio (w/c) had a significant influence on the diffusion of sulfate ions, ettringite concentration profile and expansion properties in cement paste specimens. The cracking points caused by ettringite growth in cement paste specimens were predicted through numerical methods. According to the simulation results, the fracture of cement paste would be accelerated when the specimens were prepared with higher w/c or when they were exposed to sulfate solution with higher concentration.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.508-513
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• 2001

Recently, ground granulated blast-furnace slag (GGBFS) has been increasingly used as additive for concrete. Many researchers reported that concrete using GGBFS had a better resistance under severe environments, such as marine or sulfate-rich soils, than Portland type cement concrete. The aim, therefore, of this study is to evaluate on the effectiveness of concrete using GGBFS when the concrete exposes to sulfate-rich environment. The detailed items for experiments show 2 series consisted of sulfate immersion test with mortar and sulfate diffusion test with concrete. The sulfate immersion test was performed for 400 days and contained reduction of compressive strength, length change and XRD analysis. For sulfate diffusion test, sulfate ions diffusivity was calculated on tile consideration of electrochemical theory by the diffusion cell test. As the results of this study, it was found that the concrete using GGBFS as additive was superior to portland type cement concrete. Consequently, the use of concrete with GGBFS for recycling may expect the durable and economical benefits.

• Computers and Concrete
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• v.30 no.6
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• pp.409-419
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• 2022

The purpose of this study is to examine the effectiveness of biological repairing mortars on restoring the structural performance of a sewage culvert deteriorated by sulfate attack. The biological mortars were developed for protecting concrete structures exposed to sulfate attack based on the block membrane action of the bacterial glycocalyx. The diffusion coefficient of sulfate ions in the biological mortars was determined from the natural diffusion cell tests. The effect of sulfate-attack-induced concrete deterioration on the structural performance of culverts was examined by using the moment-curvature relationship predicted based on the nonlinear section lamina approach considering the sulfuric-acid-induced degradation of the structure. Typical analytical assessments showed that biological mortars were quite effective in increasing the sulfate-resistant service life of sewage culverts.

• Textile Coloration and Finishing
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• v.7 no.1
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• pp.72-79
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• 1995

The effect of copper sulfate/thiourea on the diffusion and the dye exhaustion of two dyes, C. I. Acid Orange 7 and C. I. Food Yellow 3 in nylon 6 fiber has been studied. The results obtained from the experimetal are as follows : 1) Copper sulfate reacted with thiourea at constant temperature and then generated the colorless trasparent coordination compound, and then combinated end group of carboxyl of nylon 6 fiber. 2) The coordination compound [$Cu_{2}$($TU_{6}$)] ($(SO_{4})_2$) is conducted at pH 5-6 in solution intensity and repulsed the sulfonic acid group of dyes, and therefore the diffusion of dyes is restraint. 3) Dye uptake and diffusion coefficient were decreased in the order of untreated > copper sulfate/thiourea-treated > tannin-treated.

• Korean Journal of Crystallography
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• v.5 no.1
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• pp.33-38
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• 1994

'Heterogeneous' vapor diffusion experiments were carried out using hen egg white Iysozyme and equine serum albumin as model proteins: droplets were equilibrated against reservoir solutiorls containing an alternative precipitant which is different from results showed that the use of polyethylene glycol as an alternative precipitant instead of NaCl or ammonium sulfate reduces equilibration rate between droplet and reservoir solution. By using the heterogeneous vapor diffusion techniqlue it is possible to control the equilibration rate by adjusting the relative amounts of ionic salts and nonionic yecipitants in reservoir solutions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.3
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• pp.169-176
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• 2004

The Mechanistic model, considering expansion stress, coefficient of diffusion etc. to time, is applied to predict the deterioration of concrete structures of the nuclear power plant(NPP) due to sulfate attack. Mix design for the test was three kinds of specified compressive strength 385, 280 and $210kgf/cm^2$ which are used to construct NPPs and cement was type I and V. The immersion test was performed with 10% $Na_2SO_4$ solution to cement type and strength for a year. The coefficient of diffusion on each concrete mix is calculated based on the results of immersion test, and it is used for predicting the sulfate attack of the concrete structures of NPP. The coefficient of diffusion of the target concrete ranged $0.5763{\sim}3.9002{\times}10^{-12}m^2/sec.$, and the sulfate attack rate of concrete structures of the NPP was predicted as 0.1~7.1 mm/year.