• Title, Summary, Keyword: fly ash

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Experimental study on creep behavior of fly ash concrete filled steel tube circular arches

  • Yan, Wu T.;Han, Bing;Zhang, Jin Q.;Xie, Hui B.;Zhu, Li;Xue, Zhong J.
    • Steel and Composite Structures
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    • v.27 no.2
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    • pp.185-192
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    • 2018
  • Fly ash can significantly improve concrete workability and performance, and recycling fly ash in concrete can contribute to a cleaner environment. Since fly ash influences pozzolanic reactions in concrete, mechanical behaviors of concrete containing fly ash differ from traditional concrete. Creep behaviors of fly ash concrete filled steel tube arch were experimentally investigated for 10% and 30% fly ash replacement. The axes of two arches are designed as circular arc with 2.1 m computed span, 0.24 m arch rise, and their cross-sections are all in circular section. Time dependent deflection and strain of loading and mid-span steel tube were measured, and long term deflection of the model arch with 10% fly ash replacement was significantly larger than with 30% replacement. Considering the steel tube strain, compressive zone height, cross section curvature, and internal force borne by the steel tube, the compressive zone height and structural internal forces increased gradually over time due to concrete creep. Increased fly ash content resulted in more significant neutral axis shift. Mechanisms for internal force effects on neutral axis height were analyzed and verified experimentally.

The Strength of the Portland-Cement Mortar Use of Fly-ash (플라이애쉬를 사용한 시멘트 모르터의 강도에 관한 연구)

  • 서기원;서치호
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.19-22
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    • 1991
  • In order to the Utilization of Fly ash, The Properties of cement Mortar use of Fly ash based on Mixing rate, strength of mortar, W/C+F and quantity of Fly ash, Flow value, and unit weight are investigated. So follow result are unit weight of mortar of Fly ash is about 2014 Kg/㎥, Compressive strength of mortar is 50-404 Kg/$\textrm{cm}^2$ and beneficial reference to the utility of domestic Fly ash were obtained.

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Drying Shrinkage of High-Volume Fly Ash Concrete (High-Volume 플라이애쉬 콘크리트의 건조수축특성)

  • 최석균;이광명;이진용
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.195-198
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    • 1999
  • Fly ash is the most common artificial pozzolan, which is a material precipitated electrostatically from the exhaust gases of coal-fired power stations. Fly ash can be used as the supplementary material as well as the material for high performance concrete and hence, the development of high-volume fly ash concrete is imperative. In this study, the characteristics of drying shrinkage of high volume fly ash concrete is investigated. It is found from test results that as the replaced amount of fly ash in concrete is increased, drying shrinkage of concrete is reduced.

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Self-Cementitious Hydration of Circulating Fluidized Bed Combustion Fly Ash

  • Lee, Seung-Heun;Kim, Guen-Su
    • Journal of the Korean Ceramic Society
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    • v.54 no.2
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    • pp.128-136
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    • 2017
  • Fly ash from a circulating fluidized bed combustion boiler (CFBC fly ash) is very different in mineralogical composition, chemical composition, and morphology from coal ash from traditional pulverized fuel firing because of many differences in their combustion processes. The main minerals of CFBC fly ash are lime and anhydrous gypsum; however, due to the fuel type, the strength development of CFBC fly ash is affected by minor components of active $SiO_2$ and $Al_2O_3$. The initial hydration product of the circulating fluidized bed combustion fly ash (B CFBC ash) using petro coke as a fuel is Portlandite which becomes gypsum after 7 days. Due to the structural features of the portlandite and gypsum, the self-cementitious strength of B CFBC ash was low. While the hydration products of the circulating fluidized bed combustion fly ash (A CFBC ash) using bituminous coal as a fuel were initially portlandite and ettringite, after 7 days the hydration products were gypsum and C-S-H. Due to the structural features of ettringite and C-S-H, A CFBC ash showed a certain degree of self-cementitious strength.

Strength and Workability Characteristics of High-Strength Fly Ash Concrete (고강도 플라이애쉬 콘크리트의 강도 및 작업성 특성)

  • 김진근;박연동;성근열
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.125-130
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    • 1990
  • Fly Ash in concrete is known to be effective in improving workability, the reduction of heat of hydration, increasing the long-term compressive strength, and improving durability. Recently, fly ash is consedered an essential material for the high-strength concrete. In this paper, investigations for the strength and workability characteristics was carried out when fly ash was used in the high-strength concrete. As the result, fly ash was effective in increasing the long-term compressive strength, but the short-term compressive strength was gradually decreased with increating fly ash contents. And also the use of superplasticzers was required for providing the proper workability when fly ash contents were increased. The optimum content of fly ash was about 10%.

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An experimental study on quality change of concrete according to fly ash using (플라이애쉬 사용에 따른 콘크리트 품질변화에 관한 실험적 연구)

  • Park, Il-Yong;Paik, Min-Su;Shon, Jong-Kyu;Choi, Soo;Jung, Sang-Jin
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.147-152
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    • 1999
  • The purpose of this study is to offer foundmental information of fly ash concrete for field application. Through before study of fly ash concrete, various properties were checked. but when fly ash was added In concrete, entrained air quantity was decreased as fly ash substitution is increased in fresh concrete. so entrained air(below AE) quantity and a kind of AE according to fly ash substitution was tested basic properties. Also water-reducing efficiency was tested. And hydration heat according to fly ash substitution was tested by KR-100. As result of test, according to fly ash substitution increase, entrained air quantity is increase for target entrained air quantity, water-reducing efficiency and hydration heat are positive.

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An Experimental Study on Application of Fly Ash in Concrete (플라이애쉬 혼입 콘크리트의 적용성에 관한 실험적 연구)

  • Park, Il-Yong;Paik, Min-Su;Shon, Jong-Kyu;Choi, Soo;Jung, Sang-Jin
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.133-138
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    • 1998
  • The purpose of this study is to offer basic information of fly ash concrete for field application. Through before study and fly ash in mortar, various properties as fly ash ratio in concrete were checked according to the experimental result, slump was increased and entrained air quantity was decreased as fly ash ratio is increased in fresh concrete. In hardened concrete, strength development of plain concrete(W/B 50%) was slower than water-reduced concrete(W/B 40%) at early age. Especially water-reduced concrete was remarkabily faster than no fly ash in concrete. Moduls of stastic elasticity and stress-strain relationship of fly ash in concrete nearly were effect on no fly ash concrete.

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A Study on Strength of Cement Mortar with Micro Grinding High Volume Fly-Ash (플라이애쉬를 다량 사용한 시멘트 경화체의 강도증진에 관한 실험적연구)

  • 정재동
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.82-87
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    • 2001
  • The purpose of this study is for the active use of the fly ash, which is a by-product of the combustion pulverizes coal thermal power plants, to compensate for the lack of landfill and for conservation of energy, by using fly ash as the supplementary cementitious material, and to prove its possibility as the related products of the cement. First of all, the ordinary fly ash is grinded in a special method and its fineness is controlled from 6000$\textrm{cm}^2$/g to 8000$\textrm{cm}^2$/g, then replaced it with the 10% to 80% of the cement mortar in order to test physics characteristics. The first experiment conducts on the strength development in fly ash replacing content and fineness. and the changes of the flow values, incorporating fly ash into cement. The second one is about the slow development of the strength of the fly ash mortar in early ages, and improves its strength with the activator $Na_{2}SO_{4}$, using high volume fly ash.

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An Experimental Study on the Mix Properties of Concrete Pavement Incorporating Fly-Ash (플라이애쉬를 혼입한 콘크리트포장의 배합특성에 관한 실험적 연구)

  • Lee, Joo-Hyung;Choi, Seong-Yung;Yun, Kyong-Ku;Jung, Young-Hwa
    • Journal of Industrial Technology
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    • v.17
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    • pp.313-322
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    • 1997
  • As the weight of trucks increases, the need for concrete pavement also increases. Therefore, the addition of fly-ash may improve the properties of pavement concrete as well as recycle fly-ash. A full factorial experiment was performed using the primary variables, such as water-cement ratio, fly-ash substitution ratio, and maximum size of coarse aggregate, as a preliminary study for optimum mixture design for pavement concrete. The results of preliminary study indicates that the addition of fly-ash is the most important factor determining concrete strength, followed by the maximum size of coarse aggregate and water-cement ratio. It, also, shows the relative importance of fly-ash substitution ratio, compared to the water-cement ratio, and the interaction effects between the primary variables. Optimum mixture designs for pavement concrete incorporating fly-ash, that satisfied the target responses, were proposed in terms of fly-ash substitution ratio, water cement ratio and maximum size of coarse aggregate.

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Fundamental Properties of Concrete Using Casting Foundry Fly Ash as an Admixture (주물공장 플라이애쉬를 혼화재로 사용한 콘크리트의 기초적 성질)

  • 김희성;진치섭
    • Journal of the Korea Concrete Institute
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    • v.12 no.3
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    • pp.87-94
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    • 2000
  • Disposal of casting foundry fly ash generally depends on reclamation up to the present. This is the great loss from a standpoint of saving resources and utilizing industrial wastes. Therefore, a study on the reuse of fly ash as a substitute material for construction is necessary in order to utilize industrial wastes, to reduce cost and improve quality in producing concrete products, and to protect environment from pollution. In this study, methods for the reuse of the casting foundry fly ash, industrial wastes products, as an admixture for concrete are discussed. For this purpose, fly ash was extracted from casting foundry and tests of physical and chemical properties are executed. Also, various characteristics of concrete using fly ash as an admixture are experimented. Finally, the reuse methods for casting foundry fly ash are presented.