• Title/Summary/Keyword: forming agent

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Optimized mix design of rapid-set lightweight-formed mortar for backfill (굴착복구용 속경성 경량기포 시멘트 모르타르의 최적 배합 도출을 위한 기초 물성 연구)

  • An, Ji-Hwan;Jeon, Sung-il
    • International Journal of Highway Engineering
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    • v.19 no.1
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    • pp.1-9
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    • 2017
  • PURPOSES : The objective of this study is to develop an optimized method of mix design for rapid-set lightweight-formed mortar mix. To achieve this objective, the workability, setting time, and compressive strength of mixes under various conditions of mix design were evaluated. METHODS : The water-bonder ratio, fly-ash substitution ratio, and forming agent injection amount were selected as design variables in the study. The fluidity, setting time, density, and strength of the mortar mix were considered as major evaluation criteria of the mixture, and were subsequently utilized to evaluate the characteristics of the mortar mix under various conditions. RESULTS : The observations made from the mix design process are as follows: 1) the air content and fluidity increase as the forming agent ratio and forming agent ratio increase, respectively; 2) the maximum air content is approximately 20%; 3) the accelerating agent decreases the fluidity of the mortar mix by 15% on average; 4) the forming agent injection ratio and fly-ash substitution ratio yield significant effects on the initial and final set times of the mortar mix; 5) as the forming agent injection ratio and fly-ash substitution ratio increase, the compressive strength of the mortar mix decreases; and 6) the 28-day compressive strengths of the forming agent injection ratio and fly-ash substitution ratio yield the most significant effects. CONCLUSIONS : It is concluded that the governing design variables for the rapid-set lightweight-formed mortar mix are the forming agent injection ratio and fly-ash substitution ratio.

Influence of Membrane Forming Compounds for Concrete on Water Retention Properties of Concrete Mortar (콘크리트용 피막 양생제가 시멘트 모르타르의 보습특성에 미치는 영향)

  • Lee, Gun-Cheol;Noh, Sang-Kyun;Cho, Byoung-Young;Kim, Young-Geun
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2009.11a
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    • pp.117-120
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    • 2009
  • It has been gradually increased with the use of resin based membrane forming agent for curing method, which plays a role in protecting moisture evaporation by forming resin membrane at the surface of concrete. In this paper, tests were carried out to examine moisture retention capability of cement mortar applying membrane forming agent. Dosages and types of the membrane forming agent were varied. It is found that sheet curing sealed with the surface of concrete closely has favorable moisture retention capability. However, the application of membrane forming curing method had superiority in moisture retention capability at early stage but at later age, its capability is deteriorated. Hence, further study regarding altering application method was necessary to secure enhanced moisture retention capability.

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Synthesis and Carbonization of Crosslinked Spherical Styrene-Divinylbenzene Copolymer Bead (스티렌-디비닐벤젠 가교결합을 갖는 구형 공중합수지의 합성 및 탄화)

  • Hongkyeong Kim
    • Journal of Institute of Convergence Technology
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    • v.13 no.1
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    • pp.23-28
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    • 2023
  • Crosslinked spherical polystyrene particles with a particle diameter of 200-500 ㎛ were synthesized by using suspension copolymerization of styrene and divinylbenzene, and the effect of divinylbenzene content, poreforming agent on their spherical formation, thermal stability, specific surface area, and carbonization characteristics were examined. The spherical copolymer beads were collapsed during carbonization up to 45% of divinylbenzene content. Toluene was used as pore-forming agent since it is more soluble in monomer phase rather than dispersion media during suspension polymerization, and the specific surface area and total pore volume increased with content of pore-forming agent.

Fabrication of Porous Alumina Ceramics Using Hollow Microspheres as the Pore-forming Agent

  • Nie, Zhengwei;Lin, Yuyi
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.24 no.4
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    • pp.368-373
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    • 2015
  • Porous alumina ceramics with two different pore sizes were fabricated using hollow microspheres as the pore-forming agent. The relative density, total porosity, and microstructure of the obtained alumina ceramics were studied. It was found that the total porosity of sintered samples with different amounts of hollow microsphere content, from 2.0 to 4.0 wt%, was 69.3-75.6%. The interconnected and spherical cell morphology was obtained with 3.0 wt% hollow microsphere content. The resulting ceramics consist of a hierarchical structure with large-sized cells, and small-sized pores in the cell walls. Moreover, the compressive strength of the sintered samples varied from 8.3-11.5 MPa, corresponding to hollow microsphere contents of 2.0-4.0 wt%.

MCPs Product and Process Design of Mixed Materials Using Axiomatic Design (공리적 설계를 이용한 발포제 혼합재료의 MCPs 제품 및 공정 설계)

  • 이경수;차성운
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1414-1417
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    • 2003
  • In chemical forming process, mixed materials of LDPE, EVA and forming agent are used. However mechanical properties has been dropping remarkably through this forming process. In this study, Above materials(LDPE, EVA) were used in microcellular foaming injection process. And various effective factors in this process were selected by Axiomatic approach and systematically estimated by DOE(Design of Experiments). As a results, injection type and rate of mixing resins have more influence on forming rate than other factors.

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A Study on Semi Abrasive Free Slurry including Acid Colloidal Silica for Copper Chemical Mechanical Planarization (구리 CMP 적용을 위한 산성 콜로이드 실리카를 포함한 준무연마제 슬러리 연구)

  • 김남훈;김상용;서용진;김태형;장의구
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.3
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    • pp.272-277
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    • 2004
  • The primary aim of this study is to investigate new semi-abrasive free slurry including acid colloidal silica and hydrogen peroxide for copper chemical-mechanical planarization (CMP). In general, slurry for copper CMP consists of colloidal silica as an abrasive, organic acid as a complex-forming agent, hydrogen peroxide as an oxidizing agent, a film forming agent, a pH control agent and several additives. We developed new semi-abrasive free slurry (SAFS) including below 0.5% acid colloidal silica. We evaluated additives as stabilizers for hydrogen peroxide as well as accelerators in tantalum nitride CMP process. We also estimated dispersion stability and Zeta potential of the acid colloidal silica with additives. The extent of enhancement in tantalum nitride CMP was verified through anelectrochemical test. This approach may be useful for the application of single and first step copper CMP slurry with one package system.

Fabrication and Characterization of Porous Non-Woven Carbon Based Highly Sensitive Gas Sensors Derived by Magnesium Oxide

  • Kim, Yesol;Cho, Seho;Lee, Sungho;Lee, Young-Seak
    • Carbon letters
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    • v.13 no.4
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    • pp.254-259
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    • 2012
  • Nanoporous non-woven carbon fibers for a gas sensor were prepared from a pitch/polyacrylonitrile (PAN) mixed solution through an electrospinning process and their gas-sensing properties were investigated. In order to create nanoscale pores, magnesium oxide (MgO) powders were added as a pore-forming agent during the mixing of these carbon precursors. The prepared nanoporous carbon fibers derived from the MgO pore-forming agent were characterized by scanning electron microscopy (SEM), $N_2$-adsorption isotherms, and a gas-sensing analysis. The SEM images showed that the MgO powders affected the viscosity of the pitch/PAN solution, which led to the production of beaded fibers. The specific surface area of carbon fibers increased from 2.0 to $763.2m^2/g$ when using this method. The template method therefore improved the porous structure, which allows for more efficient gas adsorption. The sensing ability and the response time for the NO gas adsorption were improved by the increased surface area and micropore fraction. In conclusion, the carbon fibers with high micropore fractions created through the use of MgO as a pore-forming agent exhibited improved NO gas sensitivity.

Application of the Color concrete with Red mud to the Floor Construction (레드머드를 이용한 바닥컬러콘크리트의 현장적용)

  • Kim, Tae-Cheong;Kim, Jong;Jeon, Chung-Keun;Yeon, Kyu-Won;Yoon, Gi-Woon;Shin, Dong-An
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2008.11a
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    • pp.27-30
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    • 2008
  • This study investigated the application of red muds, which were industrial wastes fired at 800℃, with a coloring agents. The results were summarized as following. The slumpflow, air content and unit weight volume were satisfied with each target values. The setting time was shortened on the case that 3 % of the red coloring agent and fired red mud were simultaneously replaced about 1 hour compared with the previous study which was 6 % of the red coloring agent was individually used. For the length change ratio caused by drying shrinkage and depth of neutralization on hardened concrete, they were declined when 3 % of the red coloring agent and fired red mud were simultaneously replaced compared with the previous study. On the measurement of forming colors, the case that 3 % of the red coloring agent and fired red mud were simultaneously replaced was similar to the previous study.

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Preparation and Characterization of Chemically Stable PVDF-HFP Asymmetric Microfiltration (MF) Membranes

  • Lee, Yeon-Ee;JeGal, Jong-Geon
    • Membrane Journal
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    • v.22 no.2
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    • pp.104-112
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    • 2012
  • Chemically stable Polyvinylidene fluoride-hexa-fluoropropane (PVDF-HFP) copolymer asymmetric membranes were prepared by the conventional phase inversion process, using Dimethyacetamide (DMAc) as a solvent and water as a non-solvent. To control the pore size and porosity of the PVDF-HFP membranes, tetra-ethoxysilane (TEOS) was used as a pore-forming agent. The prepared membranes were characterized, using several analytical methods such as Fourier Transform Infrared spectroscopy (FTIR), Thermo-gravimetric analyzer (TGA), Field Emission Scanning Electronic Microscopy (FESEM). TEOS turned out to increase porosity and make homogeneous pores on the membranes. Depending on the composition of the dope solutions, the pore size was ranged from 0.1 to 1.0 ${\mu}m$. The flux of the PVDF-HFP membranes prepared by using TEOS as a pore forming agent was increased substantially without much decrease in the rejection. When 15 wt% PVDF-HFP solution was blended with 13 wt% TEOS solution at composition ratio of 70/30 in wt%, the water flux at 2 bars was about 2 $m^3/m^2day$.

Electrochemical Properties of Carbonized Phenol Resin (탄화된 페놀레진의 전기화학적 성질)

  • 김한주;박종은;홍지숙;류부형;박수길
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1999.11a
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    • pp.629-632
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    • 1999
  • For replacing Li metal ai Lithium ton Bakery(LIB) system. we used carbon powder material which prepared by pyrolysis of phenol resin as starting material. It became amorphous carbon by pyrolysis through it\`s self condensation by thermal treatment. Amorphous carbon can be doped with Li intercalation and deintercalation because it has wide interlayer. however it has a problem with structural destroy causing weak carbon-carbon bond. So. we used ZnCl$_2$ as the pore-forming agent. This inorganic salt used together with the resin serves not only as the pore-forming agent to form open pores, which grow Into a three-dimensional network structure in the cured material, foul also as the microstructure-controlling agent to form a loose structure dope with bulky dopants. We analyzed SEM in order to find to different of structure. and can calculate distance of interlayer. CV test showed oxidation and reduction

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