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A Study on the Fluidity of Antiwashout Underwater Concrete Containing Fly Ash (Fly Ash를 사용한 수중불분리 콘크리트의 유동성에 관한 연구)

  • 권중현;배기성
    • Journal of Ocean Engineering and Technology
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    • v.12 no.1
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    • pp.153-161
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    • 1998
  • This paper is to investigate the Fluidity of Antiwashout Underwater Concrete containing Fly Ash. The results of study are concluded as follows: the increase in Slump Flow value did not happen in the plain concrete which was replaced cement by Fly Ash; however, the maximum value could reach in the replacement of 30% of Fly Ash by weight of cement in the Fly Ash replaced concrete. On the condition of Fly Ash-Antiwashout Underwater Concrete in expecting 50 cm of the Slump Flow, it was necessary that the usage amount of Superplasticizer be around 1% of unit Binder, and 1.5% in 60 cm of the Slump Flow, respoectively.

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An Experimental Study on Freezing and Thawing Resistance of Fly Ash Concrete (플라이애쉬 콘크리트의 동경융해저항성에 관한 연구)

  • 배성용
    • Journal of Ocean Engineering and Technology
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    • v.15 no.3
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    • pp.128-133
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    • 2001
  • It is generally known that the concrete structure subjected to severe environment is much affected by the corrosion of reinforcement, the freezing and thawing action of concrete structure. The main objective of this study is to investigate the freezing and thawing resistance of concrete including fly ash. The effect of the air content in concrete using fly ash is investigated. The experimental study is conducted for 10 mix-ratio cases of concrete of which variables are content of fly ash, concrete compressive strength and containment of air-entrained admixtures. Test results show that the freezing and thawing resistance improves as the amounts of fly ash increase, and concrete with air-entrained admixtures has good freezing and thawing resistance. The concrete with fly ash is to be included air-entrained admixture according to content of fly ash in order to increase the freezing and thawing resistance.

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An Experimental Study on Strength Development of Concrete Including Fly Ash (석탄재가 혼입된 콘크리트 강도발현에 관한 연구)

  • 배성용
    • Journal of Ocean Engineering and Technology
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    • v.14 no.3
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    • pp.66-71
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    • 2000
  • The main objectives of this study are to carried out in order to evaluate strength development of Fly Ash concrete containing various amounts of Fly Ash such as 0%, 10%, 20% and 30%. The experimental variables included in this test program consist of content of Fly Ash, concrete strength and chemical activation. As Fly Ash increases, air content, strength development of concrete and slump loss of normal strength concrete were gradually decreased. The inclusion of Na$_2$SO$_4$increased the short-term strength of concrete that contains Fly Ash. In addition, the strength development of concrete that contains Fly Ash and Na$_2$SO$_4$were improved.

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Bond behavior between high volume fly ash concrete and steel rebars

  • Liang, Jiong-Feng;Hu, Ming-Hua;Gu, Lian-Sheng;Xue, Kai-Xi
    • Computers and Concrete
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    • v.19 no.6
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    • pp.625-630
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    • 2017
  • In this paper, 54 pull-out specimens and 36 cubic specimens with different replacement ratios of fly ash in the concrete (i.e., 0%, 20%, 30%, 40%, 50%, 60%) were fabricated to evaluate the bond at the interface between fly ash concrete and steel rebar. The results showed that the general shape of the bond-slip curve between fly ash concrete and steel rebar was similar to that for the normal concrete and steel rebar. The bond strength between fly ash concrete and the steel rebar was closer to each other at the same rebar diameter, irrespective of the fly ash replacement percentage. On the basis of a regression analysis of the experimental data, a revised bond strength mode and bond-slip relationship model were proposed to predict the bond-slip behaviour of high volume fly ash concrete and steel rebar.

Research for geotechnical properties of Fly ash-Lime-Sludge mixture (플라이 애시-생석회-하수처리 슬러지 혼합물의 지반공학적 특성 연구)

  • 구정민;권무남;이상호
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.44 no.3
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    • pp.122-135
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    • 2002
  • Although fly ash possesses viable engineering properties, an overwhelming majority of fly ash from coal combustion is still placed in storage or disposal sites. Similarly, sludges generated from various water treatment operations are predominantly subjected to the fate of land disposal. To prepare sludges fur land disposal typically requires time consuming dewatering schemes, which can become extremely difficult to execute depending upon the composition of the sludge and its affinity for water. This study was undertaken to reuse fly ash and sludge as construction materials. This paper includes geotechnical properties of fly ash and fly ash-lime-sludge mixture and results of compaction test, UU-test, falling head test, leaching test and CBR test. The effect on mixing fly ash with sludge and lime and the effect of curing period and the results are obtained from this test.

A Study on the Formation Mechanism of the Fly Ash from Coal Particles in the Coal Burning Boiler (석탄연소 보일러에서 생성된 석탄회의 분석과 형성 메커니즘 해석에 대한 연구)

  • Lee, Jung Eun;Lee, Jae Keun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.22 no.12
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    • pp.1691-1701
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    • 1998
  • Fly ash produced in coal combustion is a fine-grained material consisting mostly of spherical, glassy, and porous particles. A study on the formation mechanism of the fly ash from coal particles in the pulverized coal power plant is investigated with a physical, morphological, and chemical characteristic analysis of fly ash collected from the Samchonpo power plant. This study may contribute to the data base of domestic fly ash, the improvement of combustion efficiency, fouling phenomena and ash collection in the electrostatic precipitator. The physical property of fly ash is determined using a particle counter for the measurement of ash size distribution. Morphological characteristic of fly ash is performed using a scanning electron micrograph. The chemical components of fly ash are determined using an inductively coupled plasma emission spectrometry(ICP). The distribution of fly ash size was bi-modal and ranged from 12 to $19{\mu}m$ in mass median diameter. Exposure conditions of flue gas temperature and duration within the combustion zone of the boiler played an important role on the morphological properties of the fly ash such as shape, particle size and chemical components. The evolution of ash formation during pulverized coal combustion has revealed three major mechanisms by large particle formation due to break-up process, gas to particle conversion and growth by coagulation and agglomeration.

A Characteristic Analysis of Physical, Chemical and Electrical Property for Bunker C Fly Ash (Bunkder C유 회분의 물리적, 화학적, 전기적 특성분석)

  • 이재근;이정언;안영철
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • pp.88-96
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    • 1996
  • The characteristic analysis of fly ash generated from a fired power plant using bunker-C oil has been investigated. Ash size distribution by an optical microscopy with image processing technique, morphological shape by a scanning electron microscope(SEM) and microscope, chemical composition by the inductively coupled plasma emission spectrometry(ICP), and resistivity measurement as a function of temperature and moisture content by the resistivity meter are performed. A study of physical, chemical and electrical characteristics of bunker-C fly ash plays an important role of improving the performance of an electrostatic precipitator and protecting air pollution. The samples of bunker-C fly ash for analysis were collected from the electrostatic precipitator hopper of Ulsan Power Plant Unit 1 and Pusan Power Plant Unit 1. Mass median diameter(MMD) of bunker-C fly ash was measured 12.7${\mu}{\textrm}{m}$, while MMD of fly ash generated from the mixture of bunker-C oil(40%) and domestic anthracitic coal(60%) was 25.7${\mu}{\textrm}{m}$. The morphological structure of bunker-C fly ash consisted of fine particles of non-spherical shape. The primary chemical components of bunker-C fly ash were composed of SiO2(2.36%), Al2O3(4.91%), Fe2O3(14.33%) and C(11.84%). Resistivity of bunker-C fly ash was found to be increased with increasing temperature at the range of 100~15$0^{\circ}C$ and was measured 103~104 ohm-cm.

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A Study on the Compressive Strength Property of Mortar with Fly Ash Using Water Eluted from Recycled Coarse Aggregates (용출수를 사용한 플라이애쉬 혼입 모르타르의 강도특성에 관한 연구)

  • Shin, Sang-Yeop;Jeong, Euy-Chang;Kim, Young-Soo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.31-32
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    • 2013
  • ThThe purpose of this study is to investigate the compressive strength properties of fly ash using water eluted from recycled coarse aggregate. When fly ash come into contact with water, they have not a autonomously chemical reaction. But fly ash is a pozzolan reaction when fly ash come into contact with water and calcium hydroxide(Ca(OH)2) in alkaline environment. For that reason, if water eluted from recycled coarse aggregate use mixture water, fly ash is expected to reaction of pozzolan reaction property in early stage. According to the experimentation result, ICP-MS analysis showed water eluted from recycled coarse aggregate has a high alkali-ash value of pH of 12 and over. And mixing ratio 30% fly ash mortar using water eluted from recycled coarse aggregate showed a similar strength of plain mortar due to the pozzolan reaction. Also, poor strength in initial age, disadvantage of mortar using fly ash, can be improved as hydration in early age is expedited due to calcium hydroxide(Ca(OH)2) and unhydrated cement component eluted from recycled aggregate mortar.

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Effects of Fly Ash Application to Soil on Growth of Sorghum (토양중 석탄회(石炭灰) 시용이 수수의 생육에 미치는 영향)

  • Kim, Jai-Joung
    • Korean Journal of Soil Science and Fertilizer
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    • v.28 no.4
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    • pp.334-339
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    • 1995
  • To investigate the utilization of fly ash in agriculture, sorghum [Sorghum bicolor(L.) Moench] was used as the test crop. Soil was treated in pot experiments with anthracite and bituminous fly ash at 5 levels of 0, 6, 12, 18, and 24%, respectively. Growth status in terms of plant height and the number of nodes was improved in the order of bituminous treatment > anthracite treatment > control. The increment of fly ash had a positive effects on plant growth in both anthracite and bituminous treatment. The ratio of the senescent leaves to the all leaves during the maturing period was higher in fly ash treatments than in the control. As increasing the fly ash treatment, the ratio of senescent leaves was increased. Total yield was higher in the order of bituminous treatment > anthracite treatment > control. Grain yield also was higher in fly ash treatment than in the control. Bituminous fly ash treatments were more favourable in grain yield than anthracite. The increment of up to 12% fly ash to soil increased grain yield in both anthracite and bituminous. Application of bituminous fly ash could be recommended due to the fact that high pH of soil is favorable for growth of sorghum.

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A Study on the Properties of the Concrete Containing Fly-ash of Class F According to the 3 Different Mixture Design (F급 플라이애쉬의 혼입방법을 달리한 콘크리트 특성에 관한 실험적 연구)

  • Moon, Jong-Wook;Yoo, Taek-Dong;Seo, Chee-Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.3 no.2
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    • pp.191-198
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    • 1999
  • The purpose of this study is investigating characteristics of the concrete containing Fly-ash according to different 4 mix design, that is, the first mix design is partial replace Fly-ash of cement, second is partial replace Fly-ash of cement and fine aggregate, third is partial replace Fly-ash of fine aggregate, fourth partial replacement of fine and coarse aggregate. For this purpose, selected test variables were water-binder ratio with two levels of 45%, 50%, and Fly-ash contents with four levels 0%, 10%, 20%, 30%, As the result of this study are as follow. 1) The result of mix design of a partial replacement of cement, the slump-flow value was appeared a promotive effect of viscosity. But in case of the over with Fly-ash 10% and the other mix design was not changed slump value. 2) The unit weight of the mixing rate with Fly-ash 0% was $1.875{\sim}1.884t/m^3$, the other mix design 10% over with Fly-ash was $1.846{\sim}1.615t/m^3$, the difference was appeared less about 15% than that. 3) In design, partial replace Fly-ash of fine aggregate, this compressive strength was appeared that the concrete age after 7 days was higher than in partial replacement of cement, therefore, the default of a concrete with Fly-ash, that is the earlier compressive strength was to lessen, was improved. 4) The thermal conductivity of the all mix design was $0.447{\sim}1.144kcal/mh^{\circ}C$, this value was as good as a lightweight aggregate concrete.

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