• International Journal of Highway Engineering
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• v.17 no.1
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• pp.59-67
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• 2015

PURPOSES : In this study, an image analysis method is used to evaluate the pore structure characteristics and permeability of hybrid concrete. METHODS : The binder weight of hybrid concrete is set to $400kg/m^3$, $370kg/m^3$, and $350kg/m^3$, and for each value of binder weight, the pore structure and permeability of concrete mixture is evaluated. The permeability of hybrid concrete is evaluated using a rapid chloride penetration test(RCPT). RESULTS : The concrete pore structure characteristics of hybrid concrete reveals that as the binder weight is reduced, the entrained air is reduced and the entrapped air is increased. The permeability of the hybrid concrete for all values was measured to be below 1000 C, which indicates a "Very Low" level of permeability relative to the evaluation standard of KS F 2711. Additionally, as the binder weight is decreased, there is a significant increase in the permeability of chloride ions. CONCLUSIONS : In this study, the pore structure characteristics of hybrid concrete at different binder weights shows that as the binder weight is reduced, the entrained air is reduced and the entrapped air is increased. Consequently, chloride ion penetration resistance of the hybrid concrete is diminished. As a result, it is expected that this will reduce the concrete's durability.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.207-212
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• 2002

Reportedly, the use of mineral admixtures make concrete more durable and tighten against water. But, it is needed to study more about the relationship between the admixtures and the chloride ion diffusion. When concrete is mixed with fly-ash, pozzolanic reaction occur to time. So we should consider the factors that can evaluate inner structure of concrete in order to evaluate the chloride diffusion of the concrete more accurately. Therefore, in this study, we analyzed the correlation between chloride ion diffusion and physical properties such as compressive strength, void ratio, air permeability of the concrete, and tried to use them as fundamental data for analyzing chloride ion diffusion mechanism of the concrete mixed with fly-ash.

• Journal of Environmental Science International
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• v.12 no.5
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• pp.559-564
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• 2003

The specific ion effects are observed in the alumina-metal EDTA(Ethylene Diamine Tetraacetic Acid) system. These effects seem to be associated with the fluidity of the metal ion in the complex. A consideration of the order of adsorption of the complexes on alumina indicates that a specific ion effect also affects the stability of the system. It is clear that EDTA and its heavy metal complexes have a significant effect on the dewaterability of alumina. These effects are not well represented by zeta potential measurements, especially for EDTA alone. With the nonspeciating complexes, though, the maximum permeability is predicted by the pH$\_$zpc/ from zeta potential measurements. At other pH value, the refiltration rate is better predicted by the state of coagulation as measured by log W.

• Membrane Journal
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• v.27 no.1
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• pp.84-91
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• 2017

In this study, heterogeneous ion exchange membranes were prepared by mixing cation or anion exchange resins and commercial polyvinylidene fluoride (PVDF) for MCDI process. The mixing ratios of PVDF and ion exchange resins were 1 : 1, 1.4 : 1, 2 : 1, and 3 : 1. We characterized SEM, water content, ion exchange capacity, methanol permeability, and ion conductivity. In the viewpoint of membrane characterization, the blending ratio of 2 : 1 showed the best. For the blending ratio of 2 : 1, heterogeneous cation exchange membrane showed the water content 34%, ion exchange capacity 1.54 meq/g, ion conductivity 0.019 S/cm, and methanol permeability $2.28{\times}10^{-7}{\sim}8.86{\times}10^{-7}cm^2/s$ while In the case of heterogeneous anion exchange membrane, the result showed 37%, 2.18 meq/g, and 0.034 S/cm and $1.46{\times}10^{-7}{\sim}8.66{\times}10^{-7}cm^2/s$.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.355-360
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• 2002

The purpose of this study was to remove the excessive air foaming which was produced in mixing the RSLMC(latex-modified concrete with rapid- setting cement) by choosing the best antifoam agent type and the optimized quantity for performance improved RSLMC. A series of RSLMM(latex-modified mortar with rapid-setting cement) experiments were carried out as the basic for RSLMC with the main experimental variables such as antifiamer types(A, B, C, D), antifoamer contents(0, 1, 2, 3%). Air content test and compressive, flexural tests were carried out to measure the improved properties of RSLMM and RSLMC. Chloride ion permeability test was carried out to estimate water permeability resistance. The results of RSLMM showed that the decrease of 50% air content was obtained by admixturing a antifoam agent by 1%. The compressive strength and flexural strength at 3 hours after RSLMC placement were 235kgf/cm$^2$ and 49kgf/cm$^2$, respectively, which exceeded the flexural strength criterion of 45kgf/cm$^2$ in order to open the RSLMC placed to traffic. The chloride permeability using A and C antifoamer at 28 days were below 100 coulombs, which was the permeability rating of negligible according to ASTM.

• Journal of Ginseng Research
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• v.20 no.3
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• pp.269-273
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• 1996

We investigated the effects of ginseng glycosides and their aglycones on processes of single ion channel formation and channel properties. The glycosides, Rg, and Rb, , and their aglycones, 20-(S)-protopanaxatriol (PT) and 20-(S)-protopanaxadiol (PD) increased the membrane permeability for ions. PT, PD, Rg1, and Rb1; at concentrations of 0.5, 3.0, 10.0 and 30.0 $\mu\textrm{g}$/ml respectively; Induced single ion channel fluctuations with the life times in the range of 0.1~1005 in open states and conductances from 5 to 30 pS in 1 M KCI. At high concentrations of these substances, rapid fluctuations of transmembrane ion current with amplitude from hundred pS to dozen nS were observed. Against other substances, ginsenoside Rbl began to increase the membrane conductance at concentration of about 60 $\mu\textrm{g}$/ml without fluctuation of single ion channel. Membranes treated with PT, PD, Rg1 and Rb1 are more permeable to K+, than to Cl while zero current membrane potentials with 10 gradients of KCI were 12, 16, 8, 25 mV respectively. Key words : Membrane conductance, single ion channel, ginsenosides.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1651-1655
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• 2013

Anion exchange membranes for a vanadium redox flow battery (VRB) were prepared by pore-filling on a PE substrate with the copolymerization of vinylbenzyl chloride (VBC) and glycidyl methacrylate (GMA). The ion exchange capacity, water uptake and weight gain ratio were increased with a similar tendency up to 65% of GMA content, indicating that the monomer improved the pore-filling degree and membrane properties. The vanadium ion permeability and open-circuit voltage were also investigated. The permeability of the VG65 membrane was only $1.23{\times}10^{-7}\;cm^2\;min^{-1}$ compared to $17.9{\times}10^{-7}\;cm^2\;min^{-1}$ for Nafion 117 and $1.8{\times}10^{-7}\;cm^2\;min^{-1}$ for AMV. Consequently, a VRB single cell using the prepared membrane showed higher energy efficiency (over 80%) of up to 100 cycles compared to the commercial membranes, Nafion 117 (ca. 58%) and AMV (ca. 70%).

• Journal of the Korean Applied Science and Technology
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• v.23 no.1
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• pp.45-53
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• 2006

In this study, we prepared porous cation exchange membrane using polystyrene such as, EPS (expanded polystyrene), SAN (styrene acrylonitrile copolymer) and HIPS (high impactive polystyrene). These polystyrenes were sulfonated by acetyl sulfate to make porous cation exchange membrane such as, SEPS, SSAN, SHIPS. SEM was employed to confirm porous structure of membrane, and IR spectroscopy was used to confirm sulfonation rate of ion exchange membrane. Water and methanol content were also increased with amount of sulfuric acid in reactants. SSAN-20 showed the highest value in water and methanol content. Fixed ion concentration and conductivity was also increased with an amount of sulfuric acid in reactants. Methanol permeability for SEPS-20, SSAN-20, SHIPS-20 was found to be $1.326\;{\times}\;10^{-5}\;cm^2/s$, $1.527\;{\times}\;10^{-5}\;cm^2/s$ and $1.096\;{\times}\;10^{-5}\;cm^2/s$ respectively. From the result of electrodialysis experiment in 0.03 M $Pb(NO_3)_2$ aqueous solution, anion exclusion and cation selection effects were confirmed.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.191-196
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• 1999

In underground reinforced concrete structures, such as drainage structure, water and chloride ion penetrated into concrete through the cracks of concrete and its permeable property, cause the corrosion of reinforcing steel bar, which accelerates the expansive cracks and deterioration of concrete. It is necessary to control those deterioration of underground structure by improving its permeability and durability through the reasonable solutions in design, construction and materials. In the present study, fly ash concrete, which has good material properties in long-term period, is compared and studied with plain concrete using ordinary portland cement in terms of fundamental mechanical properties, permeability, drying shrinkage and durability. Also, the mix design and its properties of low permeable concrete using fly ash are reviewed. From this study, fly ash concrete can conctrol the penetration of water and chloride ion effectively by forming dense microstructure of concrete. Therefore, fly ash concrete may increase the long-term function, performance and serviceability of underground structures.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.435-442
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• 2000

Batch test and column test were performed to develop the design factors for permeable reactive barriers(PRBs) against ammonium and heavy metals, Clinoptilolite, a kind of natural zeolites having excellent cation exchange capacity(CEC), was choosen for the reacting materials through the ion-exchange mechanism. In the batch test, the reactivity of clinoptilolite for ammonium, lead, and copper was examined varying the initial concentration of contaminants(ammonium: 20, 40, 80 ppm, heavy metals: 10, 20, 40 ppm) and the particle size of clinoptilolites(0-0.15, 0.42-0.85, 1-1.25 mm). The reactivity is increasing as the initial concentration decrease and particle size decrease. In the column test, the permeability and the reactivity of the specimens were examined using flexible-wall permeameter. Specimens were made of clinoptilolite and Jumunjin-sand with 20 : 80 weight ratio varying particle size of clinoptilolite. The maximum permeability(1${\times}$10$\^$-4/-5${\times}$10$\^$-5/cm/s) was achieved in the specimen made of 0.42-0.85 mm clinoptilolite and sand.