• 제목/요약/키워드: durability of concrete

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고강도 콘크리트의 동해저항에 관한 기포조직의 영향 (Effect of Air Void Organization to Frost-Resistance in High-Strength Concrete)

  • 김생빈;홍찬홈
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 1991년도 가을 학술발표회 논문집
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    • pp.5-10
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    • 1991
  • This study was performed to find out the effect about the spacing factor and durability factor to evaluate the durability of concrete in high-strength concrete with freezing and thawing as following each condition, 1) unit cement content : 500kg/$\textrm{m}^3$, 550kg/$\textrm{m}^3$ 2) water/cement ratio : 25%, 30%, 35% 3) air content : below 1.5%, 1.6~3.5%, 4~6%, over 7% From the results tested, a variation of air content was more effective to the durability of concrete than that of water/cement ratio and unit cement content.

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석회석 미분말과 슬래그 미분말을 혼합한 콘크리트의 내구성 (Durability in Concrete Containing Limestone Powder and Slag Powder)

  • 구봉근;이재범;이현석;박주원
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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    • pp.82-85
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    • 2003
  • This study is to investigate durability in concrete containing slag powder and limestone power. The variables are the substitution ratio of slag powder and limestone powder. In order to study the effect of slag powder and limestone powder, all mixtures were prepared at a fixed water/cement ratio, slump, and entrained air quantity. When concrete containing slag powder is mixing rate 40%, durability appeared the highest in general. When concrete containing limestone powder is mixing rate 10% in all experiments, the most suitable result appeared.

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콘크리트 종류에 따른 강도 및 내구성 특성 (Strength and Durability Properties by Concrete Type)

  • 이병덕;심대원;양우석;안태송
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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    • pp.189-194
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    • 2000
  • The optimum mix proportioning of concrete is to produce a concrete which satisfies the strength, workability and durability required with minimum component of materials. However in practice the cement content of mix proportioning in construction field is normally higher then required. In this study, the existing mix proportioning of concrete currently used in Korea Highway Corporation has been reviewed by reducing 10kg of cement content by 3~5 strength in strength and workability during the first year of this project. The optimum mix design is established based on the results of the above review and durability were examined during the second year. The experimental results though 2 year show that 103~0% of the reduction of cement content still satisfies the specified strength of concrete and produces higher durability concrete.

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Strength and durability of concrete in hot spring environments

  • Chen, How-Ji;Yang, Tsung-Yueh;Tang, Chao-Wei
    • Computers and Concrete
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    • 제6권4호
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    • pp.269-280
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    • 2009
  • In this paper an experimental study of the influence of hot springs curing upon concrete properties was carried out. The primary variables of the investigation include water-to-binder ratio (W/B), pozzolanic material content and curing condition. Three types of hot springs, in the range $40-90^{\circ}C$, derived from different regions in Taiwan were adopted for laboratory testing of concrete curing. In addition, to compare with the laboratory results, compressive strength and durability of practical concrete were conducted in a tunnel construction site. The experimental results indicate that when concrete comprising pozzolanic materials was cured by a hot spring with high temperature, its compressive strength increased rapidly in the early ages due to high temperature and chloride ions. In the later ages, the trend of strength development decreased obviously and the strength was even lower than that of the standard cured one. The results of durability test show that concrete containing 30-40% Portland cement replacement by pozzolanic materials and with W/B lower than 0.5 was cured in a hot spring environment, then it had sufficient durability to prevent steel corrosion. Similar to the laboratory results, the cast-inplace concrete in a hot spring had a compressive strength growing rapidly at the earlier age and slowly at the later age. The results of electric resistance and permeability tests also show that concrete in a hot spring had higher durability than those cured in air. In addition, there was no neutralization reaction being observed after the 360-day neutralization test. This study demonstrates that the concrete with enough compressive strength and durability is suitable for the cast-in-place structure being used in hot spring areas.

The Effects of Superplasticizers on the Engineering Properties of Plain Concrete

  • Park, Seung-Bum
    • KCI Concrete Journal
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    • 제11권3호
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    • pp.29-43
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    • 1999
  • The effects of superplasticizers on fresh and hardened concrete were investigated. The experimental program included tests on the workability and slump loss, bleeding, setting time, air content, compressive, tensile and flexural strength, permeability, shrinkage, freeze-thaw durability and creep deformation. Properties of superplasticized concrete were compared with those of conventional and base concretes. Superplasticizers were observed to have an appreciable fluidifying action in fresh concrete. They permitted a significant water reduction while maintaining the same workability. Bleeding of superplasticized concrete was much lower than that of conventional concrete of the same consistency. This indicates that the use of superplasticizers did not affect the tendency of segregation of fresh concrete. The compressive, tensile, and flexural strengths of superplasticized concrete were significantly higher than those of conventional concrete. The permeability and drying shrinkage and creep of superplasticized concrete were less than those of conventional concrete, but there were no significant differences between base and superplasticized concrete. Compared with base concrete, non-air-entrained superplasticized concrete had slightly higher freeze-thaw durability. and superplasticized concrete with an appropriate amount of entrained air Eave even better resistance to freezing and thawing.

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Self-cleaning 침투성 함침제의 적용에 따른 타일 및 콘크리트 표층부의 개질특성 (Reforming Property of Tile and Concrete Surface layer Using Self-cleaning Concrete Impregnant)

  • 송훈;전찬수;김영호
    • 한국디지털건축인테리어학회논문집
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    • 제13권4호
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    • pp.61-68
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    • 2013
  • Concrete structure is not the only material vulnerable to physical and chemical processes of deterioration associates with severe conditions. Deterioration of the concrete structure, however, occurs more progressively from the outside of the concrete exposed to severe conditions. Especially, Carbonation, chloride ion attack is more important factor of concrete durability. This study is interested in manufacturing the self-cleaning concrete surface impregnant including TEOS, lithium silicate for the repair of the exposed concrete surface and the color concrete requiring the advanced function in view of the concrete appearance. Form the results, TEOS and lithium silicate are very effective that increasing the concrete durability using self-cleaning concrete impregnant. Self-cleaning concrete impregnant specimens is satisfied with performance requirement of KS standard in adhesion test in tension but the reinforcement of concrete substrate is slight. So, the self-cleaning concrete impregnant of this study is more desirable for the improvement of durability rather than the reinforcement.

고강도콘크리트의 내구성진단을 위한 영향인자 파악을 위한 연구 (A Study on the Effect of Experimental Factors for the Durability Inspection of High Strength Concrete)

  • 권영진;김무한
    • 한국구조물진단유지관리공학회 논문집
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    • 제1권2호
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    • pp.123-130
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    • 1997
  • The effect of experimental factors on the Freeze-Thaw durability in the High Strength Concrete has been analyzed and investigated with [DESIGN of EXPERIMENT: L16). The Experimental parameters included the type of aggregate and mixer, the conditions of aggregates, and the difference of mixing temperature, procedure and placing, etc. It is aim of this study to provide the fundamental data on the effect of various factors on the frost resistance of high strength concrete for the practical use and research data accumulation of durability inspection. The results of this experiment indicate that the freeze-thaw durability of high strength concrete is markedly affected by the coarse aggregate source, mixing temperature and curing conditions.

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ASSESSMENT OF PROPERTIES AND DURABILITY OF FLY ASH CONCRETE USED IN KOREAN NUCLEAR POWER PLANTS

  • Cho, Myung-Sug;Noh, Jae-Myoung
    • Nuclear Engineering and Technology
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    • 제44권3호
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    • pp.331-342
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    • 2012
  • Since the opening of the Shin-Kori #1,2 in 2005, fly ash mixed concrete has been used for NPP concrete structures under construction in Korea with the aim of preventing aging and improving durability. In this paper, the quality suitability of fly ash manufactured in Korea is assessed and the basic physical properties of fly ash mixed concrete and its durability against primary causes of aging are verified through experimental methods. Because of the internal structure filling effect from the pozzolanic reaction of fly ash and the resulting improvements in mechanical performance in such areas as strength and salt damage resistance, the durability of fly ash mixed concrete is shown to be superior. It is judged that this result can be applied in measures not only for improving the safety of NPP structures in operation in Korea but also for implementing effective structure life management should extending the life of structures be needed in the future.

Mechanical and Durability Performance of Roller-Compacted Concrete with Fly Ash for Dam Applications

  • Park, Chan-Gi;Yoon, Jong-Whan;Kim, Wan-Young;Won, Jong-Pil
    • International Journal of Concrete Structures and Materials
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    • 제1권1호
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    • pp.57-61
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    • 2007
  • This study investigated the mechanical and durability performance of roller-compacted concrete (RCC) with fly ash for dam applications. A test program studied the effects on the properties of fresh and hardened RCC with fly ash replacement ratio, as well as the long-term durability of the resulting mixture. Fly ash replaced 20, 30, 40, and 50% by mass of the cement. Laboratory tests of the compressive strength, splitting tensile strength, shear strength, chloride ion permeability, abrasion, and drying shrinkage were conducted. The test results demonstrated that 30% fly ash replacement is an optimum level, and that this mixture has excellent mechanical and durability properties.

초고층 콘크리트 매트 기초용 콘크리트 내구성에 관한 연구 (A Study on the Durability of Concrete for High-rise Concrete Mat Foundation)

  • 박동천;김영봉
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2022년도 가을 학술논문 발표대회
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    • pp.115-116
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    • 2022
  • Large concrete mass members are commonly used as matte bases for skyscrapers. In general, Integral casting is preferred to secure construction convenience and durability quality rather than separate casting. However, there is a possibility that cracks may occur in the early stages due to the generation of a lot of hydration heat, and thus durability will decrease, so it is necessary to determine an appropriate mixture and verify it through experiments. The purpose of the study was to conduct a review on the durability of the optimal high-performance low-heating concrete combination derived through the experiment and to conduct a review analysis on the performance satisfaction and performance expression mechanism.

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