• Title/Summary/Keyword: concrete durability.

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Development and Application of Low Permeable Concrete for Underground Structures (지하구조물을 위한 수밀콘크리트의 개발 및 실용화)

  • Paik, S.H.;Park, S.S.;Park, J.Y.;Paik, W.J.;Um, T.S.;Choi, L.
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.10a
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    • pp.259-262
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    • 1999
  • In underground reinforced concrete structures, such as drainage structure, water and chloride ion penetrated into concrete through the cracks of concrete and its permeable property, cause the corrosion of reinforcing steel bar, which accelerates the expansive cracks and deterioration of concrete. It is necessary to control those deterioration of underground structure by improving its permeability and durability through the reasonable solutions in design, construction and materials. In the present study, fly ash concrete, which has good material properties in long-term period, was compared and studied with plain concrete using ordinary portland cement in terms of fundamental mechanical properties, permeability, drying shrinkage and durability. Also, the mix design and field test of low permeable concrete using fly ash were performed. From this study, fly ash concrete can control the penetration of water and chloride ion effectively by forming dense micro-structure of concrete. Therefore, fly ash concrete may increase the long-term function, performance and serviceability of underground structures.

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The Evaluation of Durability and Bond of Resin Concrete (레진 콘크리트의 부착성 및 내구성 평가)

  • Yoo Sung Won;Suh Jeong In;Jeon Sung Hwan;Hwang Sun Bok
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.11a
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    • pp.715-718
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    • 2004
  • The evaluation of durability of resin concrete was examined through various tests, i.e., compressive strength, absorption, abrasion, chemical attack resistance and bond between general and resin concrete. 2 types of concrete were used such as 40 MPa of general concrete and 90 MPa of resin concrete. The characteristics of resin concrete was more improved than that of general concrete, and especially, resin concrete was most effective on compressive strength, the resistance to $H_2SO_4$ solution attack and absorption. However, abrasion. is almost same between general concrete and resin concrete.

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Chloride Penetration Resistance of Ternary Blended Concrete and Discussion for Durability (삼성분계 혼합콘크리트의 염화물 침투 저항성 및 내구성에 대한 고찰)

  • Song, Ha-Won;Lee, Chang-Hong;Lee, Kewn-Chu;Kim, Jae-Hwan;Ann, Ki-Yong
    • Journal of the Korea Concrete Institute
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    • v.20 no.4
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    • pp.439-449
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    • 2008
  • Mineral admixtures are used to improve the quality of concrete and to develop sustainability of concrete structures. Supplementary cementitious materials (SCM), such as silica fume (SF), granulated blast furnace slag (GGBS) and pulverized fly ash (PFA), are gradually recognized as useful mineral admixture for producing high performance concrete. The study on ternary blended concrete utilizing mainly three major mineral admixtures is limited and the study on durability and chloride induced corrosion resistance of ternary blended concrete is very few. This study examines the durability characteristics of the ternary blended concrete composed of different amount of the SCM with ordinary Portland concrete and the study experimentally focuses on corrosion resistance evaluation of ternary blended concrete subjected to chloride attack. In this study, 50% replacement ratio of mineral admixture to OPC was used, while series of combination of $20{\sim}40%$ GGBS, $5{\sim}15%$ SF and $10{\sim}45%$ PFA binder were used for chloride corrosion resistance test. This study concerned the durability properties of the ternary blended concrete including the corrosion resistance, chloride binding, chloride transport and acid neutralization capacity. It was found that the ternary blended concrete utilizing the SCM densified the pore structures to lower the rate of chloride transport. Also, increased chloride binding and buffering to acid were observed for the ternary blended concrete with chlorides in cast.

Development of Using Technique of Impregnating Alkalization Agent to Recover Durability of Carbonated Reinforcement Concrete Structures by Fire Damages (화재로 인해 중성화된 철근콘크리트구조물의 내구성 회복을 위한 침투성 알칼리성부여제의 이용기술개발)

  • Moo-Han, Kim;Yong-Ro, Kim;Jea-Bong, Jang
    • Fire Science and Engineering
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    • v.18 no.3
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    • pp.18-24
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    • 2004
  • Fire breaking out in carbonated reinforcement concrete structures considerably deteriorates the durability of them by propelling carbonation. However, the research and technical development to recover the durability is still in an underdeveloping stage in Korea. Therefore, this research aims to understanding the deteriorated durability of a carbonated structure, evaluating the performance of an impregnating alkalization agent to recover the durability and developing a way of using it.

A Study on Mechanical Properties of Porous Concrete Using Cementless Binder

  • Lee, Jong-Won;Jang, Young-Il;Park, Wan-Shin;Kim, Sun-Woo
    • International Journal of Concrete Structures and Materials
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    • v.10 no.4
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    • pp.527-537
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    • 2016
  • This study evaluated the mechanical characteristics and durability of porous concrete produced with a cementless binder based on ground granulated blast furnace slag (BFS), fly ash (FA) and flue gas desulfurization gypsum (CP). As a result, the void ratio was increased slightly from the target void ratio, by 1.12-1.42 %. Through evaluating the compressive strength, it was found that the compressive strength of porous concrete with cementless binder decreased in comparison to the compressive strength of porous concrete with ordinary Portland cement (OPC), but the difference was insignificant, at 0.6-1.4 MPa. Through the freeze-thawing test to evaluate the durability, it was found that the relative dynamic elastic modulus of porous concrete with cementless binder decreased to 60 % or less at 80 cycles. The result of the chemical resistance test showed that the mass reduction rate was 12.3 % at 5 % HCl solution, and 12.7 % at 12.3 and 5 % $H_2SO_4$ solutions.

Concrete structures under combined mechanical and environmental actions: Modelling of durability and reliability

  • Vorechovska, Dita;Somodikova, Martina;Podrouzek, Jan;Lehky, David;Teply, Bretislav
    • Computers and Concrete
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    • v.20 no.1
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    • pp.99-110
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    • 2017
  • Service life assessments which do not include the synergy between mechanical and environmental loading are neglecting a factor that can have a significant impact on structural safety and durability assessment. The degradation of concrete structure is a result of the combined effect of environmental and mechanical factors. In order to make service life design realistic it is necessary to consider both of these factors acting simultaneously. This paper deals with the advanced modelling of concrete carbonation and chloride ingress into concrete using stochastic 1D and 2D models. Widely accepted models incorporated into the new fib Model Code 2010 are extended to include factors that reflect the coupled effects of mechanical and environmental loads on the durability and reliability of reinforced concrete structures. An example of cooling tower degradation by carbonation and an example of a bended reinforced concrete beam kept for several years in salt fog are numerically studied to show the capability of the stochastic approach. The modelled degradation measures are compared with experimental results, leading to good agreement.

An Experimental Study on Durability of Concrete Covered with Antibiotics (항균제를 도포한 콘크리트의 내구특성에 관한 실험적 연구)

  • Lee Eui-Bae;Lee Dong-Heck;Moon Hyung-Jae;Kim Jae-Hwan;Kim Gyu-Yong;Kim Moo-Han
    • 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.

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Evaluation of Mechanical Properties and Durability of Fabric Concrete Binder for Emergency Repair (기상재해 대응 긴급보수용 패브릭 콘크리트 혼합물의 역학적 특성 및 내구성능 평가)

  • Jeon, Sang-Min;Jo, Sung-Mun;Oh, Ri-On;Kim, Hwang-Hee;Cha, Sang-Sun;Park, Chan-Gi
    • Journal of The Korean Society of Agricultural Engineers
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    • v.62 no.4
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    • pp.23-31
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    • 2020
  • Recently, meteorological disasters have been increasing by climate change, excessive rainfall, and landslide. The purpose is to develop new fabric concrete that can prevent and recover from damages because some of areas are vulnerable to meteorological disaster. Specifically, this technology can minimize time and space constraint when repairing the concrete structure and installing a formwork. The structure of fabric concrete is a mixture of fabric concrete and a high-speed hardened cement, Silica sand, wollastonite mineral fiber, fabric material and waterproof PVC fabric. In this study, the ratio of mechanical properties and durability of the fabric concrete mixture was evaluated by deriving the binder: silica sand mix ratio of the fabric concrete mixture and substituting part of the cement amount with wollastonite mineral fiber. Best binder in performance evaluation: Silica sand mix ratio is 6: 4 and the target mechanical performance and durability are the best when over 15% wollastonite binder is replaced by silicate mineral fiber.

Copper or ferrous slag as substitutes for fine aggregates in concrete

  • Thomas, Job;Thaickavil, Nassif N.;Abraham, Mathews P.
    • Advances in concrete construction
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    • v.6 no.5
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    • pp.545-560
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    • 2018
  • The ever-increasing cost of natural sand and the environmental impacts of extracting manufactured sand (quarry sand) calls for exploring the potential to use alternative materials as fine aggregates in concrete. Copper slag and ferrous slag are industrial by products obtained from the smelting process of copper and iron respectively. A large quantity of copper slag and ferrous slag end up being disposed as waste in landfills and this poses a serious threat to the environment. Copper slag and ferrous slag have similar physical and chemical properties as natural sand and also exhibit pozzolanic activity. This paper studies the technical feasibility of industrial by-products such as copper slag and ferrous slag to replace the fine aggregate in concrete by evaluating the workability, strength and durability characteristics of concrete. The test results indicate that the strength properties are not affected by 40% or 100% replacement of quarry sand with iron slag or copper slag. However, 40% replacement of quarry sand with iron slag or copper slag in concrete is recommended considering the durability aspects of concrete.

An experimental study on the durability evaluation of concrete applied functional nano composite inorganic activated carbon based coatings (기능성 나노복합 무기질 활성탄계 표면 처리제를 적용한 콘크리트의 내구성능 평가에 관한 실험적 연구)

  • Yang, Gi-Young;Jang, Seog-Jae;Baek, Jong-Myeong
    • Proceedings of the KSR Conference
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    • 2006.11b
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    • pp.1385-1390
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    • 2006
  • Concrete structure can be deteriorated by ingress of moisture and aggressive agents. To maintain the sound performance of concrete structure during the service life, it needs to protect concrete from ingress of moisture and aggressive agents before arising deterioration of concrete. Protection of concrete is possible by surface treatment. In this study, durability of the functional nano composite inorganic activated carbon based coatings which can provide a barrier against the ingress of moisture or aggressive ions to concrete is discussed. For the durability evaluation of the coatings, fine void structure evaluation test, chloride penetration acceleration test, accelerated carbonation test, freezing and thawing test, and the accelerated test of chemical erosion are conducted. As the result of this study, the functional nano composite inorganic activated carbon based coatings which became one formed complex compound with adsorption and porosity on concrete surface, had an effect on the function of far infrared radiation, antimicrobial action, air cleaning, airing assurance, and the interception of moisture of deterioration factor, chloride ion, carbon dioxide, sulfate, and so on.

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