• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.43-48
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• 2003

This paper investigate that the effect of the concrete containing mineral admixtures(pozzaolanic materials such as fly-ash, ground granulated blast-furnace slag, silica fume and meta kaolin) on the resistance properties to chloride ion invasion. The purposed testing procedure was applied to the concrete added mineral admixtures for 3∼4 replacement ratios under W/B ratios ranged from 0.40 to 0.55. For the electrical migration test, Tang and Nilsson's method was used to estimate the migration coefficient of chloride ion. As a results, the W/B ratios, kinds of admixture and replacement ratios, water curing periods had a great effect on the migration coefficient of chloride ion, and the optimal replacement ratios of admixture had a limitation for each admixtures. Also, the addition of mineral admixtures by mass(replacement of OPC) enhanced the resistance of the mixture to chloride penetration compared with the plain concrete. The amount of acid soluble chloride ions and water soluble chloride ions were varied with the kinds of mineral admixtures. The compressive strength was shown related to the migration coefficient of chloride ion, the compressive strength increased with the decreasing migration coefficient of chloride ion. Below the 50MPa, the variation of migration coefficient of concrete added mineral admixtures was bigger than plain concrete.

• Journal of the Korean institute of surface engineering
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• v.26 no.2
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• pp.55-62
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• 1993

The effect of interlayer coating thickness of Ni and Ti on corrosion behavior was studied for TiN ion plat-ed steel plate. Interlayer coating was carried out in a single and bi-layer to a various thickness combination prior to final TiN coating. Corrosion behavior was evaluated by anodic polarization test in 1N H2SO4 as well as salt spray test. Ni interlayer coating was effectived in reducing corrosion current density of active region and Ti interlayer coating over Ni coating reduced the anodic corrosion current density by an order of 4 with increasing the thickness of Ti up to$ 3\mu\textrm{m}$. The improvement of corrosion resistance by Ni/Ti interlayer coating was attributed to the effective prevention of penetration of active corrosion agent resulting from the inherent corrosion resistance of Ni and Ti. Putting corrosion behavior was observed from salt spray test result for all specimens and corrosion resistance at salt atmosphere was enhanced with increasing Ni and Ti thickness, Cor-lay TiN coating was spalled out by the generation of corrosion products.

• Geotechnical Engineering
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• v.8 no.3
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• pp.13-22
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• 1992

Model pile tests using calibration chamber are performed in !his paper in order to clarify the effect of the fundamental differences between the newly developed SPLT(Simple Pile Loading Test)and the conventional pile loading test on the pile bearing capacity. They are : (1) the direction of the applied load to mobilize the skin friction ; and (2) the use of reduced sifted sliding core. The conclusions obtained from the model pile tests are as follows : (1) The skin friction in tension loading is found to be somewhat smaller than that in compression loading. The average ration is 0.73 with the coefficient of variation (COV) of 0.18. (2) The ratio of the tip resistance rosin연 the reduced sized sliding core to that using the whole shoe shows wide scattering ; its average is 0.99 and the COV is 0.28. The aver - age of 0.99 means that there is no considerable difference in the tip resistance whether the reduced sized sliding core or the whole shoe is used, on condition that penetration depth ratio is larger than 4 : if the boundary effect of the chamber test is considered, the resistance of the whole shoe might be even larger.

• Elastomers and Composites
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• v.57 no.4
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• pp.197-204
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• 2022

Recently, the demand has increased for protective clothing materials capable of shielding the wearer from bullets, fragment bullets, knives, and swords. It is therefore necessary to develop light and soft protective clothing materials with excellent wearability and mobility. To this end, research is being conducted on hybrid design methods for various highly functional materials, such as carbon nanotube (CNT) sheets, which are well known for their low weight and excellent strength. In this study, a hybrid protective material using CNT sheets was developed and its performance was evaluated. The material design incorporated a bonding method that used a binder for interlayer combination between the CNT sheets. Four types of binders were selected according to their characteristics and impregnated within CNT sheets, followed by further combination with aramid fabric to produce the hybrid protective material. After applying the binder, the tensile strength increased significantly, especially with the phenoxy binder, which has rigid characteristics. However, as the molecular weight of the phenoxy binder increased, the adhesive force and strength decreased. On the other hand, when a 25% lightweight-design and high-molecular-weight phenoxy binder were applied, the backface signature (BFS) decreased by 6.2 mm. When the CNT sheet was placed in the middle of the aramid fabric, the BFS was the lowest. In a stab resistance test, the penetration depth was the largest when the CNT sheet was in the middle layer. As the binder was applied, the stab resistance improvement against the P1 blade was most effective.

• Journal of the Korea Institute of Building Construction
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• v.3 no.4
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• pp.103-109
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• 2003

Reinforced concrete structures under sever conditions such as marine structures, bridges and structural constructed with aggregated(dredged front sea). can be deteriorated from corrosion of the reinforcing bars. The purpose of this study is to evaluate the corrosion reflectance of coated steel using polymer dispersion and polymer cement slurry. Polymer dispersion and polymer cement slurry with various polymer types were coated to the surface of bars and steel plate, and tested for accelerated corrosion tests. Tests include adhesion in tension, bending test, chloride ion spray, penetration of NaCl 10％ solution and carbonation. From the test results, the corrosive resistance of steel is considerably improved by using polymer dispersion and polymer cement flurry at surface of steel. The difference of the corrosive resistance is hardly recognized according to types of polymer dispersion. The coated steel using polymer dispersion and polymer foment slurry will be improved to a great extent compared to those of plain steel when increasing content of chloride ion in cement concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.1
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• pp.56-63
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• 2016

This experiment was compared and analyzed between the original surface paint through chloride penetration, neutralization, freeze-thaw and chemical corrosion resistance measuring internal structure and volume of voids in order to evaluate the effect of increase in durability of the newly modeled nano synthesized polymer paint painted on concrete surface which results improvement on air permeability to increase the durability of concrete structures. The test result of measuring volume of void and inner structure, concrete, spreaded with nano synthesized polymer paint, showed decreasing trend of pore volume in the range of less than $0.1{\mu}m$ and more than $0.3{\mu}m$. Also, using an electron microscope inside showed tightness of hydration texture. Chloride penetration depth of concrete, painted with nano synthesized polymer paint, was decreased more than 92% compared to non-painted concrete and 70% with water-based epoxy painted concrete. Especially, chemical corrosion resistance test set with aqueous solution of 5% sulfuric acid, non-painted concrete and water-based epoxy painted concrete showed weight loss of 4% after dipping for 12 days. On the other hand, concrete painted with nano synthesized polymer paint showed 1.7% weight loss under the same condition. Also, it showed great result of appearance under the criteria of Tsivilis et al.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.4
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• pp.21-28
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• 2014

In this study, evaluated ware the strength and durability of the vegetated water purification channel concrete to which recycled aggregates, hawang-toh and jute were applied. Box-Behnken method of response surface analysis in statistics was applied to the experimental design. Experimental variables are as follows, recycled coarse aggregates, hawang-toh, blast-furnace slag and jute fiber. In the experiment, conducted were the tests of compressive strength, chloride ion penetration, abrasion resistance and impact resistance the replacement rate effects of the recycled aggregates, blast-furnace slag and hwang-toh on the performance of vegetated water purification channel concrete were analyzed by using the response surface analysis method on the basis of the experimental results. In addition, an optimum mixing ratio of vegetated water purification channel concrete was determined by using the experimental results. The optimum mixing ratio was determined to be in 10.0% recycled coarse aggregates, 60.0% blast-furnace slag, 10.1% hwang-toh and 0.16% jute fiber. The compressive strength, chloride ion penetration, abrasion rate, and impact number of fracture test results of the optimum mixing ratio were 24.1 MPa, 999 coulombs, 10.30 g/mm3, and 20 number, respectively.

• Journal of the Korea Institute of Building Construction
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• v.12 no.6
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• pp.607-614
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• 2012

In this study, the evolution of the electro-mechanical impedance (EMI) of a piezoelectric (PZT) patch embedded in fresh cement paste was investigated to discuss the possibility of monitoring the setting process of cement-based materials using an EMI sensing technique. A tailored thin square PZT patch was embedded in cement paste before casting, and EMI signatures of the embedded patch were continuously measured from casting up to 12 hours. A standard penetration resistance test was performed to compare and correlate the evolution of EMI during the setting process. The results showed that EMI responses differ according to the age of the cement paste, and that the behavior of the EMI resonance peak has a clear correlation with the penetration resistance of the cement paste. Based on the results, it is concluded that an EMI sensing technique using embedded PZT patch can be effectively applied to monitor the setting process of cement-based materials.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.213-214
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• 2010

An objective of this experimental research is to investigate the diffusion characteristics for chloride ion of concrete subjected to sulfate attack. For this purpose, concretes with three types of cement such as ordinary portland cement(OPC), binary blended cement(BBC), and ternary blended cement(TBC) containing mineral admixtures were made for water-binder ratios of 32% and 43%. The concrete specimens were immersed in sulfate solution for 365 days, and then the resistance against chloride ion penetration of them were estimated by using NT BUILD 492. It was observed from the test results that the resistance to chloride ion penetration of concrete subjected to sulfate attack was greatly decreased than that of standard curing concrete under the same age.

• Journal of Industrial Technology
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• v.37 no.1
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• pp.32-36
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• 2017

In this study, as part of a research on the development of economical high-performance concrete with high strength and high quality, the physical properties of high-performance concrete were analyzed by substituting a certain amount of low-cost domestic silica fume exempted from the re-importation type distribution structure of the domestic production and the existing high-priced silica fume distribution structure. Performing tests to identify the physical properties of the fresh and hardened concrete and durability analogy of the concrete which use low-cost domestic silica fume and imported silica fume, the chloride ion penetration resistance test result showed that the strength difference between the low-cost silica fume and the imported silica fume is not big but the strength of the low-cost silica fume was measured higher than the imported silica fume. The chloride ion penetration resistance of all variables was measured as "very low". Since the low-cost domestic silica fume can be used as a high-performance admixture of concrete, the results suggest that it is possible to produce a more economical high-performance concrete.