• Title, Summary, Keyword: Porous ratio

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Influence of Paste Fluidity and Vibration Time for Fundamental Properties of Porous Concrete (시멘트체이스트의 유동성 및 진동다짐시간이 포러스콘크리트의 기초물성에 미치는 영향)

  • 이성일;유범재;장종호;김재환;백용관;김무한
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.311-316
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    • 2001
  • This study analyzed the influence of paste fluidity and vibration time for fundamental properties of porous concrete. Results of this study were shown as follows; 1) Even if target void ratio is same, void ratio and compressive strength of porous concrete is different according to w/c, paste flow and vibration time. So, In case of target void ratio, we must consider the influence of w/c, paste flow, and vibration time. 2) Though w/c and vibration time are same, as paste flow increase, all void ratio, continuous void ratio, and compressive strength decrease and difference between upper and lower void ratio increase. 3) Though w/c and paste flow are same, as vibration time increase, all void ratio and continuous void ratio decrease and difference between upper and lower void ratio increase. Also, compressive strength increase by 10 seconds and decease after 10 seconds. 4) As types of superplasticizer is different, all void ratio, continuous void ratio, and compressive strength are different. So, we must give consideration to paste fluidity and vibration time in order that increase of strength of porous concrete and distribution of uniform void.

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Water Droplet Ejection Characteristics of a Wet Porous Point-Plate Airgap (다공성 수침-평판전극간의 수적 방출 특성)

  • Jung, Jae-Seung;Lee, Woo-Seok;Moon, Jae-Duk
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.10
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    • pp.2005-2010
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    • 2009
  • Water droplet ejection characteristics of a point-to-plate airgap, with a wet porous point as a corona electrode, has been investigated. And the water droplet traces, charge, mass and number were measured experimentally. More particles are observed with wet porous point than metal point because the corona-discharging wet porous point can eject a number of water droplets. The water droplets ejected from the positive-corona-discharging wet porous point showed very fine traces as compared with those from the negative-corona-discharging wet porous point. Moreover, the water droplets ejected from the AC-corona-discharging wet porous point showed granular-like larger traces. It was shown that the weak corona discharge can eject smaller water droplets with larger ratio of mass-to-charge than the intense corona discharge.

Effect of Blast Furnace Slag, Hwang-toh and Reinforcing Fibers on The Physical and Mechanical Properties of Porous Concrete Using Blast Furnace Slag Coarse Aggregate (고로슬래그 골재를 사용한 다공성 콘크리트의 물리·역학적 특성에 미치는 고로슬래그 미분말, 황토 및 보강섬유의 효과)

  • Lee, Jin-Hyung;Park, Chan-Gi
    • Journal of The Korean Society of Agricultural Engineers
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    • v.52 no.5
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    • pp.53-60
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    • 2010
  • The effects of blast furnace slag, hwang-toh, and reinforcing fiber on the physical and mechanical properties of porous concrete using blast furnace slag coarse aggregates have been evaluated in this study. The effect of the depending on replacement ratio of blast furnace slag to cement was investigated such that the replacement ratio was varied to 0 %, 25 % and 50 %. Also, the replacement ratios of hwang-toh were 0, 20 and 30 %. The polyvinyl alcohol fiber was used for the reinforcing fiber. A series of pH, unit mass, and void ratio tests have been performed to study the physical properties of the porous concrete using blast furnace slag coarse aggregates with the polyvinyl alcohol fiber and the replacement ratios of blast furnace slag, hwang-toh, while a series of compressive tests have been performed to evaluate the strength property depending on polyvinyl alcohol fiber and the replacement ratios of blast furnace slag, hwang-toh. The test results indicated that the physical and mechanical properties of porous concrete using blast furnace slag coarse aggregates is affected by the replacement ratio of blast furnace slag, and the fiber contents. According to the tests with polyvinyl alcohol fiber contents, the void ratio was decreased and the compressive strength was upgraded.

A Study on the Flame Stability of Porous Ceramic Burner (다공성세라믹버너의 화염안정화에 관한 연구)

  • Lee, Do-Hyung;Yun, Bong-Seok
    • Journal of the Korea Society For Power System Engineering
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    • v.20 no.4
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    • pp.12-18
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    • 2016
  • Typical boiler system consists of combustion chamber and heat exchanger in one housing, therefore the size of boiler system is large and the heat exchanging efficiency becomes low. At these boiler systems, because the combustible mixture fires as free flame in the combustion chamber, consequently the combusted hot gas heats the heat exchanger only as conductive and convective heat transfer. The present Porous Ceramic Burner concept is that combustion process is occurred at the gaps of the porous ceramic materials, and the heat exchanger is placed in the same porous materials. Therefore we can reduce the boiler size, and we can also use radiative heat transfer from ceramic material with conductive and convective heat transfer from combusted gas throwing the porous materials. The purpose of this study is to search the flame stability ranges at different fuel flow rate and excess air ratio burning in the $Al_2O_3$ ceramic balls. We found out the stable excess air ratio range on given combustion intensity. And we can get clean porous ceramic combustion results compared with free flame.

Marine Plant Adhesion Properties of Porous Concrete Using Specially Treated Granular Fertilizer (특수처리 입상비료를 이용한 포러스콘크리트의 해양식물 부착특성에 관한 연구)

  • Lee, Byung-Jae;Park, Seong-Bum;Lee, Jun;Son, Sung-Woo;Cho, Kwang-Yeon
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.893-896
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    • 2006
  • This study examined plant adhesion characteristics of the porous concrete that used specially treated granular fertilizer for field application, which was used for the restoration of the marine ecosystem. The results of the experiment showed that nutrient eruption amount, the destruction and dissolution ratio tended to decrease when the coating thickness was increased. The void ratio and compressive strength tended to decrease when the specially treated granular fertilizer mixing ratio was increased. According to these results, the appropriate thickness of coating for cement coated granular fertilizer was 1.0mm. The adhesion ability of marine plant to porous concrete was superior when the cement coated granular fertilizer was mixed. Therefore, the appropriate cement coated granular fertilizer mixing ratio of 20% with a coating thickness of 1.0mm is thought to be a factor when considering the strength of the porous concrete for marine ecosystem restoration and the adhesion characteristics of marine plant.

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Performance Evaluation of Porous Hwang-toh Concrete Using Blast Furnace Slag Cement (고로슬래그시멘트를 사용한 다공성 황토콘크리트의 성능 평가)

  • Kim, Hwang-Hee;Kang, Su-Man;Park, Jong-Sik;Park, Sang-Woo;Jeon, Ji-Hong;Lee, Jin-Hyung;Cha, Sang-Sun;Park, Chan-Gi
    • Journal of The Korean Society of Agricultural Engineers
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    • v.52 no.3
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    • pp.9-17
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    • 2010
  • This study aims to evaluate a porous concrete using hwang-toh, blast furnace slag and blast furnace slag (BFS) cement instead of type I cement. The tests that were carried out to analysis the properties of porous hwang-toh BFS cement concrete included compressive strength, continuous void ratio, absorption rate, and pH value, repeated freezing and thawing test were conducted. Test results indicated that the performance in porous hwang-toh concrete are effective on the kaoline based binder materials. The pH value were shown in about 9.5 ~ 8.5. The compressive strength was increased and void ratio was decreased with increasing the kaoline based binder materials, respectively. The void ratio and compressive strength were in the range of about 21 ~ 30 %, 8 ~ 13 MPa, respectively. The increased in void ratio of more than 25 % is showed to reduce the resistance of repeated freezing and thawing. Also, the resistance of repeated freezing of thawing and the compressive strength of porous hwang-toh BFS cement concrete are independent with hwang-toh content and BFS cement amount. But, the void ratio was decreased with increasing the high volume hwang-toh contents (more than 15 %).

An Experimental Study on the Properties of Porous Concrete according to the Mix Factors and Compaction Load (배합조건 및 다짐하중에 따른 포러스 콘크리트의 특성에 관한 실험적 연구)

  • Lim, Seo-Hyung
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.19 no.3
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    • pp.83-91
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    • 2015
  • Porous concrete consists of cement, water and coarse aggregate and has been used for the purpose of decreasing the earth environmental load such as air and water permeability, sound absorption, etc. However, the physical and mechanical properties of porous concrete changes due to compaction load during construction. For such a reason, the purpose of this study is to investigate the physical and mechanical properties of porous concrete according to the kinds of binder, the ratio of water to binder and target void ratio. In particular, this study has been carried out to investigate the influence of compaction load on the void ratio, strength and coefficient of permeability. Aggregate used in this study are by-products generated during production of crushed gravel with a maximum size of 13mm. The results of this study showed that the target void ratio, the coefficient of permeability and compressive strength of porous concrete had a close relationship with the void ratio, and it will be possible that the void ratio is suggested by the mix design of porous concrete. The compressive strength of porous concrete was the highest at the content of the expansive admixture of 5% and compared to non-mixture, 10% mixture of silica fume improved compressive strength about 32%. And in the result of the study to change the compaction load, the compressive strength increased from the load of 15kN, the void ratio decreased from the load of 0.8kN, the coefficient of permeability decreased from the load 35kN, respectively.

Microsotructure Designed Porous Apatite Ceramics Prepared by Hydrothermal Method

  • Ioku, Koji;Fukuhara, Michiko;Fujimori, Hirotaka;Goto, Seishi
    • The Korean Journal of Ceramics
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    • v.5 no.2
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    • pp.162-164
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    • 1999
  • Microsotructure designed porous ceramics of calcium hydroxyapatite $(Ca_{10}(PO_4)_6(OH)_2)$ were prepared by hydrothermal method. The particle size, shape, and the micro-pore size of the porous hydroxyapatite ceramics could becontrolled. The hydroxyapatite was non-stoichiometric apatite with calcium deficient compositions (Ca/P ratio < 1.67). The composition of non-stoichiometric hydroxyapatite ceramics could be controlled from 1.50 to 1.63 in Ca/P ratio. The hydroxyapatite ceramics preparedc at $105^{\circ}C$ under the saturated vapor pressure for 20h were composed of rod-shaped crystals with about 10$\mu\textrm{m}$ in length with the mean aspect ratio of 40. The porous ceramics of calcium deficient hydroxyapatite had about 45% porosity with the inter-connecting pore structure. Porous hydroxyapatite ceramics prepared hydrothermally had the compressive strength of about 10 to 30 MPa. In addition, porous ceramics of $\beta$-tricalcium phosphate ($\beta-Ca_3(PO_4)_2$) were prepared from the calcium deficient hydroxyapatite.

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A Study on the Void Ratio and Permeability Coefficient Properties of fiber Reinforced Porous Concrete (섬유보강 포러스 콘크리트의 공극률과 투수계수 특성에 관한 연구)

  • Kim, Jeong-Hwan;Cho, Gwang-Yoen;Lee, Jun;Park, Seung-Bum
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.677-682
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    • 2000
  • Porous concrete is defined as d type of concrete for which the fine aggregate component the matrix is entirely omitted. Although it had been used as a building material in Europe for over 60 years, low strength and high void ratio limited its application in the past. In recent years, however high void ratio of concrete has been recognized again and can be used as an environmental conscious material, for example, parking lots, draining light-traffic-volume pavements and as sea water purifying material. The result of an experiment on the void ratio of fiber reinforced porous concrete and its influence on the compressive strength and permeability relationship of concrete are reported in this paper. One-sized coarse aggregate of 5-10mm, and three absolute content of fiber(steel fiber, polyprophylen fiber) were used. The result of measured void ratio, permeability coefficient and compressive strength show a small variation. Void ratio, permeability coefficient and compressive strength of fiber reinforced porous concrete depend on contents of fiber and absolute volume ratios of paste to aggregate.

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A Study on the Sound Absolution Properties of Porous Concrete by Recycled Aggregate Contents and Target Void Ratio (재생골재의 혼입률과 목표공극률에 따른 포러스콘크리트의 흡음특성에 관한 연구)

  • Park Seung-Bum;Seo Dae-Seuk;Lee Jun
    • Journal of the Korea Concrete Institute
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    • v.16 no.4
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    • pp.541-548
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    • 2004
  • This study peformed an evaluation of the physical and mechanical properties and sound absorption characteristics of porous concrete according to the target void ratio and content of the recycled aggregate in order to reduce the noise generated in roads, railroads, residential areas and downtown areas and effectively utilize the recycled waste concrete aggregate generated as a byproduct of construction. The test results demonstrated that the difference between the target void ratio and the actual measured void ratio was less than 1.7% and that the tendency of the compression strength was to reduce rapidly when the target void ratio and the content of the recycled aggregate exceeded 25% and 50%, respectively. In addition, the sound absorption characteristics of the porous concrete using recycled waste concrete aggregate showed that the NRC was the highest at the target void ratio of 25% and the content of the recycled aggregate had very little influence on the NRC. Therefore, when considering the compression strength and the sound absorption characteristics of porous concrete, the proper target void ratio and the content of the recycled waste concrete aggregate are thought to be 25% and 50%, respectively