• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.281-286
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• 1997

Recent construction activities and maintenance of marine facilities have been accelerating to keep up with rapid economic growth in Korea. Marine concrete structures are exposed to salts an chloride from ocean environments. The corrosion of reinforcement steel caused by chloride-penetration into concrete may severely effect the durability of concrete structures. The objective of this research is to develop a durable concrete by investigating the corrosion resistance of various corrosion protection systems utilizing different water/cement ratio, silica fumes, corrosion inhibitors and etc. A tow-year verification test on various corrosion protection systems has been doing in the laboratory and at the seaside. Corrosion investigations on reinforcement steel are now under progress for more than 180 concrete specimen. Corrosion-related measurements include macrocell corrosion current, instant-off voltage between corroding and noncorroding reinforcement, chloride contents, the corroded surface areas on the reinforcement steel, and etc. A low level of corrosion is investigated on reinforcement steels in concrete specimen made with corrosion inhibitors or applied aqueous impregnating corrosion inhibitors into their surface, even though high chloride contents of concrete specimen.

• 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%.

• Computers and Concrete
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• v.19 no.5
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• pp.489-499
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• 2017

Self-Compacting Concrete (SCC) is a new technology capable to flow without segregation or any addition of energy which leads to efficient construction and cost savings. In this study, the effect of replacing the Ordinary Portland Cement (OPC) with Fly Ash (FA) on the strength, durability of the concrete was investigated experimentally, and carbon footprint and cost were also assessed. Four different replacement FA ratios (0%, 20%, 40% and 60%) were used to create four SCC mixes. Standard test methods were used to determine the workability, strength, and durability of the SCC mixes including resist chloride ion penetration, water permeability, water absorption, and initial surface absorption. The axial cube compressive strength tests were performed on the SCC mixes at 1, 7, 14, 28 and 35 days. Replacing the OPC with FA had a significant positive impact on chloride iron penetration resistance and water absorption but had a considerable negative impact on the compressive strength. The SCC mix with 60% FA had 36.7% and 15.8% enhancement in the resistance to chloride ion penetration and water absorption, respectively. Evaluation of the carbon footprint and the cost of each SCC mixes showed the $CO_2$ emissions mixes 1, 2, 3 and 4 were significantly reduced by increasing the FA content from 0% to 60%. Compared with the control mix, the cost of all mixes increased when the FA content increased, but no significant differences were seen between the estimated costs of all four mixes.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.11a
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• pp.43-48
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• 2003

This paper investigate that the effect of the concrete containing mineral admixtures(pozzolanic 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.

• 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.

• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.357-358
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• 2010

This study was performed an evaluation of chloride attack resistance properties of marine concrete by accelerated deterioration test of artificial seawater. As the results of study, when considering the compressive strength and chloride ion penetration of concrete, the proper type to improvement of chloride attack resistance is thought to marine cement.

• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.727-730
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• 2005

The purpose of this study evaluates possibilities of waste phosphogypsum into concerts by steam curing admixture. The waste phosphogypsum is made use of 4 forms(Dehydrate, $\beta$-Hemihydrate, III-Anhydrite and II-Anhydrite) which were changed to in low temperature of calcination. The penetration depth and compressive strength of cement mortar are investigated to evaluate the chloride ion and carbonation resistance. As a result, chloride ion and carbonation resistance of cement mortar admixed with waste phosphogypsum are more excellent than cement mortar contained OPC alone. The internal pores of cement mortar are decreased by using waste phosphogypsum, because the hydrates of ettringite which is denesified in structure is much formed in early ages at steam curing. These densified effect is concluded with improving the resistance to attack of cement mortar including waste phospogypsum.

• Journal of the Korea Institute of Building Construction
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• v.18 no.6
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• pp.507-515
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• 2018

The purpose of this research is to develop a slurry-type accelerator that contains various beneficial properties such as reduction of dust generation, lower alkalinity, early age strength development, etc., and uses such slurry type accelerator to produce high performance shotcrete that present excellent resistant against chloride ion penetration. In this work, shotcrete mixtures of 0.44 and 0.338 water-to-binder ratio (w/b) were produced at construction site using slurry-type accelerator. The mechanical properties and chloride ion penetration resistance of such shotcrete (including base concrete) were evaluated. According to the experimental results, the slurry-type accelerator was successfully used to produce both w/b 0.44 and 0.338 shotcretes. The 1 day and 28 day compressive strength of shotcrete were found to be closer to or higher than 10MPa and 40MPa, respectively. The w/b 0.338 shotcrete that used 40% replacement of blast furnace slag showed lower compressive strength than w/b 0.44 shotcrete without any mineral admixture at 1 day. However, the compressive strength with 40% blast furnace slag increased significantly at 28 day. Moreover, there was more than 50% increase in chloride ion penetration resistance with blast furnace slag, showing its strong potential for higher performance shotcrete application.