• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.433-436
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• 1999

Long-term durability of the reinforced concrete structures exposed to marine environment deteriorates seriously by the attack of the chloride ion from see water results in corrosion of steel reinforcement in concrete. Their coating effect is aluminum oxide-isocyanate-based coating material, resistance of chloride penetration, carbonation and freezing and thawing resistance were compared to acryl-based coating material and sealer type o waterproofing material. Aluminum oxide-isocyante-based and acryl-based coating material show higher resistance to chloride penetration and carbonation than the sealer type do waterproofing material and aluminum oxide-isocyanate-based coating resist about 99% of chloride penetration. Resultants to the accelerated test for freezing and thawing, coating concrete show higher resistance than non-coating concrete, respectively.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.1
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• pp.215-225
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• 2011

Metakaolin is a dehydroxylated form of the clay mineral kaolinite. Rocks that are rich in kaolinite are known as china clay or kaolin, traditionally used in the manufacture of porcelain. The particle size of metakaolin is smaller than cement particles, but not as fine as silica fume. This paper investigates the effect of the concrete containing metakaolin as a mineral admixture on the compressive strength and resistance properties to chloride ion penetration. In this study, the experiment was carried out to investigate and analyze the influence of replacement ratio of metakaolin and micro silica fume on the compressive strength and chlorine ion penetration resistance of concrete. All levels were water/binder ratio 30%, replacement ratio of metakaolin and silica fume were 0, 5, 10, 15, 20% respectively. The compressive strength of concrete using metakaolin tends to increase, as the replacement ratio increases but the chlorine ion penetration resistance was not so as lager as silica fume concrete. Therefore, the optimum mixing ratio of metakaoline to satisfy a properties of compressive strength and chlorine ion penetration resistance was was approximately10%.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.715-720
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• 2003

The chief factors for the penetration and diffusion of chloride ions in concrete are water-cement ratio(W/C), aging, curing conditions, chloride ions concentration of given environment., wet and dry conditions and etc. In this study, of these factors effect of curing conditions such as standard and outdoor curing on the characteristics of chloride ions diffusion in concrete were researched when environmental factors for the penetration and diffusion of chloride ions were constant. For this purpose, the voltages passing through the diffusion cell were measured by using accelerated test method using potential difference, and then diffusion coefficients of chloride ions by using Andrade's method were estimated for 44%, 49.5% and 60% of w/c, respectively. As a result., according to curing conditions correlation among diffusion coefficients of chloride ions, W/C and aging were concluded through multiple regression model.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.1
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• pp.15-22
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• 2010

Chloride-induced corrosion of steel bars in concrete exposed to marine environments has become one of the major causes of deterioration in many important facilities made of reinforced concrete. A study on chloride penetration in concrete has developed through long period exposure test along seawater, assesment of chloride ion diffusion by electrochemical techniques and so on. However, reasonable and exclusive chloride penetration model considering concrete material properties with mixture, degree of hydration, binding capacity has not been established. Therefore, in this paper, chloride penetration analysis of non-steady state is accomplished with material properties of concrete. Comparing with the results of analysis and chloride ponding test, we could accept the effect of binding capacity on chloride penetration in concrete and these results could be applied to a service life prediction of R.C. structures submerged in seawater. Therefore, there are 20~40% differences of service life to SHRP prediction.

• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.173-182
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• 2003

Recently, the durability of concrete structures has received great attention as the number of sea-side structures, such as new airport, bridges, and nuclear power plants, increases continuously. In this regards, many studies have been done on the chloride attack in concrete structures. However, those studies were confined mostly to the single deterioration due to chloride only, although actual environment is rather of combined type. The purpose of the present study is, therefore, to explore the effects of combined deterioration due to chlorides and sulfates in concrete structures. To this end, comprehensive experimental program has been set up to observe the chloride penetration behavior for various test series. The test results indicate that the chloride penetration is more pronounced for the case of combined attack than the case of single chloride attack. The surface chloride content is found to increase with time and the diffusion coefficient for chloride is found to decrease with time. The prediction equations for surface chloride content and diffusion coefficient were proposed according to test results. The equations for chloride penetration considering the time-dependent diffusion coefficients and surface chlorides were also suggested. The present study allows more realistic assessment of durability for such concrete structures which are subjected to combined attacks of chlorides and high concentration sulfates but the future studies for combined environment will assure the precise assessment.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.31-32
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• 2011

The purpose of this study is to investigate the amount of chloride penetration into concrete finishing materials. Chloride ion migration test was used rapid infiltration method proposed by 'NT-Build 492'. The kind of coated finishing material is 'None-finished(N)', 'Cement Mortal(M)', 'Water based paint(P)', 'Bone-Tile(B)', 'Repair Mortal(R1)' in this paper.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.1
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• pp.34-39
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• 2014

The purpose of this experimental research is to evaluate the resistance of reinforcement corrosion and chloride ion penetration of high volume fly ash (HVFA) concrete. For this purpose, concrete test specimens were made for various strength level and replacement ratio of fly ash, and then compressive strength and diffusion coefficient for chloride ion of them were measured for 28, 91 and 182 days, respectively. Also, corrosion monitoring by half cell potential method was carried out for the made lollypop concrete test specimens to detect the time of corrosion initiation for reinforcement in concrete. As a result, it was observed from the test results that compressive strength of HVFA concrete was decreased with increasing replacement ratio of fly ash but long-term resistance against reinforcement corrosion and chloride ion penetration of that was increased.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.6
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• pp.1-7
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• 2015

Most of chloride diffusion models based on finite difference method (FDM) could not express the diffusion in horizontal direction at each elevation. To overcome these weakness, two dimensional chloride ion penetration model based on finite element method (FEM) to be able to combine various multi-physics simultaneously was suggested by introducing moving mesh technique. To avoid the generation of mesh being able to be distorted depending on the relative movement of water level to static concrete, a rectangular type of mesh was intentionally adopted and the total number of meshes was empirically selected. The simulated results showed that the contents of surface chloride decreased following to the increase of elevation in the top part of low sea level, whereas there were no changes in the bottom part of low level. In the DuraCrete model, the diffusion coefficient of splashed zone is generally smaller than submerged zone, whereas the trend of Life365 model is reverse. Therefore, it could be understood that the developed model using moving mesh technique effectively reflects $DuraCrete^{TM}$ model rather than $Life365^{TM}$ model. In the future, the model will be easily expanded to be combined with various multi-physics models considering water evaporation, heat of hydration, irradiation effect of sun and so on because it is based on FEM.

• Journal of the Korea Institute of Building Construction
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• v.23 no.3
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• pp.221-229
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• 2023

This research aimed to conduct an empirical assessment of the penetration of chloride and sulfate ions into mortar sections using an anion exchange membrane(AEM) and laser-induced breakdown spectroscopy(LIBS). The study involved a simultaneous ion chromatography(IC) analysis and LIBS analysis performed on mortars immersed in varying concentrations of chloride and sulfate. The findings revealed that at the wavelengths specific to Chloride(837.59nm) and Sulfur(921.30nm), the LIBS intensity achieved using AEM surpassed that obtained with a paper substrate at equivalent penetration concentrations. A robust correlation was confirmed between LIBS intensity and chloride ion concentration. Furthermore, when juxtaposed with IC analysis concentration outcomes at identical depths, the AEM displayed a higher intensity. The research noted an enhancement in LIBS intensity and a diminution in errors within the low-concentration section when deploying AEM. However, for the Sulfur wavelength of 921.3nm, there remains a need to augment the sensitivity of the LIBS signal within the low-concentration section in future studies. The findings underscore the potential of employing AEM and LIBS for precise analysis of chloride and sulfate ion penetration into mortar sections. This strategy can aid in bolstering assessment precision and mitigating errors, particularly in regions with low concentrations. It is recommended to further research and develop methods to amplify the sensitivity of the LIBS signal for sulfur detection in low-concentration sections. In sum, the study accentuates the significance of employing advanced techniques like AEM and LIBS for efficacious and precise analysis in the domain of mortar section assessment.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.329-331
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• 2013

The salt damage resistance of waterproofing membrane was evaluated on the cracked mortar substrate. The types of specimens are urethane, acrylic waterproofing membrane, and no coating mortar substrate. After these specimens were cured by water curing for 4 weeks, they were cured by atmospheric curing at 20±2Co for 8 weeks. The salt water immersion test was carried out by following KS F 2737, and the penetration depth of chloride ion into substrate was measured in 1, 4, 8, and 13 weeks. As a result, in the case of non coating specimen, the chloride ion penetrated within one week. In the coated specimens, a regardless of the membrane type, the chloride ion did not penetrate during 13 weeks-tests on condition that the cracked width of substrate is less than 0.3mm. Also, the penetration speeds of the coated specimens were lower than that of non coating specimen. Therefore, our results reached a conclusion that waterproofing membrane has high salt damage resistance.