• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.11a
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• pp.97-100
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• 2005

Recently sewage facilities mainly consisted of concrete structures are being deteriorated seriously by biodeterioration originated from sulfur-oxidizing bacteria. In this study, to prevent biochemical corrosion of the sewer concrete, antibiotics which prevent the growth of sulfur-oxidizing bacteria were developed and antimicrobial performance of it was investigated. After that, to consider applicability of antibiotics to concrete, durability such as resistance to carbonation, salt damage and chemical attack of concrete covered with inorganic and complex antibiotics were investigated. As a result of this study, it was proved that the antimicrobial performance of antibiotics was available. Also resistance to carbonation, salt damage and chemical attack of concrete covered with inorganic antibiotics was little improved but, in case of complex antibiotics, was remarkably improved. Moisture content of concrete, as a application condition of antibiotics in whole case, have little effect on performance but covering times of antibiotics have effect on performance only in case of complex antibiotics.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.148-149
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• 2016

In this paper, the increase in chloride resistance of footing concrete at coastal area was evaluated by replacement of Mineral Admixture. In KBC 2009, the footing concrete's minimum specific concrete strength at coastal area is determined to 35MPa. However, this is criteria only based on the strength aspect. Thus, it is not considered to increase the chloride resistance by replacement of Mineral Admixture. According to the test results of chloride ions penetration resistance, 35MPa class concrete with OPC 100% shown inaccessible state. Low-strength (24~30MPa class) concretes with Mineral Admixture, however, presented better performances. In addition, chloride diffusion coefficient tests showed identical appearance. Therefore, the current KBC's chloride resistance criteria based on only concrete strength has to review for the reason it can cause many problems (ex. cost increases by growing concrete strength and the environmental issues by a lot of cement use).

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.91-91
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• 2011

The quality of the surface layer in concrete structures plays an important role in the durability of the concrete. The concrete factory products are made as they improve the appearance of the surface and compressive strength in need. A common criterion to judge the quality of concrete products frequently seen in our daily life appears to be "beauty" in terms of consistent shaping. However, as for most concrete curb in such areas where a large amount of anti-freezing agents(NaCl) and ice and snow melting agents(CaCl2) are spread over roads to ensure road safety during the winter season, since deterioration advances from the surface, scaling is seen on the surface concrete due to deterioration which combined freezing damage and salt damage. Especially, In cold northern districts, the spreading amount of deicing salts increases by regulation of studded tire use, and the scaling of the concrete products, the various parts of concrete structures for roads is increasing in recent years. In this study, L-shape concrete curb were targeted, the permeable form method with the commercial permeable sheet was applied to it and the improvements of the quality were examined. By the permeable form method, surface layers got strengthened, which prevented permeation of the deterioration factor from the outside, and the scaling resistance of the upper surface where the permeable sheet was applied improved exceedingly. It will be expected by applying the permeable form method to various concrete products that frost resistance improves and scaling damage decreases.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.5
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• pp.112-118
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• 2022

In this study, the diffusion characteristics were evaluated using the concrete mix design of nuclear safety-related structures. Among the concrete structures related to nuclear power safety, we selected the composition of intake and drainage structures that are immersed in seawater or located on the tidal platform and evaluated the chloride ion permeation resistance by compressive strength and electrical conductivity and the diffusion characteristics by immersion in salt water. analyzed. Compressive strength was measured on the 1st, 7th, 14th, 28th, 56th, and 91st days until the 91st day, which is the design standard strength of the nuclear power plant concrete structure, and chloride ion permeation resistance was evaluated on the 28th and 91st. After immersing the 28-day concrete specimens in salt water for 28 days, the diffusion coefficient was derived by collecting samples at different depths and analyzing the amount of chloride. As a result, it was found that after 28 days, the long-term strength enhancement effect of the nuclear power plant concrete mix with 20% fly ash replacement was higher than that of concrete using 100% ordinary Portland cement. It was also found that the nuclear power plant concrete mix has higher chloride ion permeation resistance, lower diffusion coefficient, and higher resistance to salt damage than the concrete mix using 100% ordinary Portland cement.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.227-233
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• 2008

Porous concrete has large continuous voids of 20-30 % by volume, and this concrete is attractive as environmental material in Japan i.e. permeable road pavement, river bank protection with vegetation and green roof system which influence thermal environment. It is necessary to confirm the frost resistance when constructing porous concrete structure in cold region. However applicable test method and evaluation criterion of porous concrete has not defined yet. Therefore, the object of this study is to investigate the frost resistance of porous concrete and this investigation attempts to address this concern by comparing 4 kinds of specified freezing and thawing tests methods (JIS A1148 procedure A/B and RILEM CIF/CDF test) in consideration of actual environment. RILEM freeze-thaw tests are different from JIS A1148 freeze-thaw tests, which are widely adopted for evaluating the frost resistance of conventional concrete in Japan, in water absorption, cooling rate, length of freezing and thawing period, and number of freezing and thawing cycles. RILEM CIF test measures internal damage and is primarily applicable for pure frost attack. CDF test is appropriate for freeze-thaw and de-icing salt attack. JIS A1148 procedure A/B showed extremely low frost resistance of porous concrete if the large continuous voids were filled with water and the ice expansion in the large continuous voids set in during cooling. Frost resistance of porous concrete was improved by mixing coarse aggregate (G7) which particle size is smaller and fine aggregate in JIS freezing and thawing tests. RILEM CIF/CDF test showed that freeze-thaw and de-icing resistance of porous concrete was seems to be superior in that of conventional concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.991-996
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• 2001

The long-term durability characteristics of high-early-strength concrete were assessed. The effect of long-term durability characteristics of high-early-strength concrete were investigated. In experiment, two different types of fiber were adopted for improvement of durability. High-early-strength fiber reinforced concretes using regulated-set cements are compared with high-early-strength concrete without fiber. The durability performance of the laboratory-cured high-early-strength concrete specimens was determined by conducting an accelerated chloride permeability, abrasion resistance, freeze-thaw, surface deicer salt scaling and wet-dry repetition test. The results indicated that incorporation of fibers enhance durability performance.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.207-212
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• 1996

Recently, massive concrete structures exposed to salt from ocean marine environments, or from winter deicing. The corrosion caused by chloride-penetration may affect severey the durability and service life of such a concretestructures. Thus, it is necessary to develop durable concrete to enhance the corrosion resistance. In this study, we investigate the usage of adequate corrosion-protection materials in order to reduce permability-coefficient of concrete and method of enhancing the durability of concrete structures using by penetrating corrosion-protection materials.

• Corrosion Science and Technology
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• v.15 no.1
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• pp.28-37
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• 2016

Due to the increased construction of offshore concrete structures and the use of de-icing salts for the purpose of snow removal, the needs for the development of anti-corrosive concrete are increasing. To solve these problems, an evaluation of the mechanical and durability properties for concrete were conducted by mixing modified-sulfur as 0 %, 5 %, 10 %, 15 % cement weight ratio. Both strengths and the properties affecting durability such as water absorption coefficient, chloride ion permeability, accelerated carbonation resistance, rapid freezing and thawing, and chemical resistance were evaluated. All evaluations performed were according to the test specifications associated KS. The results indicate that mixing of modified-sulfur lowed chloride ion permeability and improved chemical resistance.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.577-580
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• 2006

This paper presents the experimental results of frost durability characteristics including freezing-thawing and de-icing salt scaling of the concrete used for gutter of the road. Mixtures were proportioned with the three level of water-binder ratio (W/B), 0.58, 0.53, and 0.48, and two binder compositions corresponding to Type I cement without any supplementary cementitious materials (OPC) and Type I cement with 30% blast-furnace slag replacement (Slag30). Also, two different solutions of calcium chloride and water that contains 0 and 8g of anhydrous calcium chloride in each 100 mL of solution, respectively, were used to evaluate their effect on the frost durability resistance. Test results showed that the Slag30 mixture exhibited higher durability factor and lower mass loss values than those made with OPC. Among the mixture tested in this work, the mixtures (OPC and Slag30) made with a relatively higher W/B of 0.58 exhibited large amount of the de-icing salt scaling regardless of calcium chloride concentration. Finally, the use of slag can be used effectively in terms of economy and frost durability of the concrete designated for gutter.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.169-172
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• 2006

The IIA structures exposed to marine environment is subject to many different types of potential attack. The physical attack due to drying and wetting would increase the internal stress of concrete. The chemical attack resulting from the diffusion of ions$(Cl^-,SO_4^{2-},Mg^+)$ from seawater through the pores in concrete. Therefore the sea water resistance of concrete must be considered when it is used for structure in the ocean. The objective of this study is to evaluate chloride diffusion and corrosion characteristics of concrete when using the various concrete materials under marine environment. After 5 years of exposure, concrete incorporating 40% blast-furnace slag as replacement for type I cement with low w/c ratio of 0.42 and using the inhibitor shows excellent performance.