• Title/Summary/Keyword: Accelerating Agents

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Setting Time and Strength Characteristics of Cement Mixtures with Set Accelerating Agent for Shotcrete (숏크리트용 급결제를 첨가한 시멘트 모르타르의 응결 및 강도특성)

  • Kim Jin-Cheol;Ryu Jong-Hyun
    • Journal of the Korea Concrete Institute
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    • v.16 no.1 s.79
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    • pp.70-78
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    • 2004
  • Although set accelerating agents are used generally in New Austrian Tunneling Method, the standards for test methods and quality of set accelerating agents are not prescribed domestically. In this study, the proprieties of the various standards and the characteristics of set accelerating agents for shotcrete were evaluated. The alkali contents of set accelerating agents based on silicate, aluminate and cement were higher than those of alkali-free ones. From the result, it is thought that the quality control of aggregate should be enhanced and that the number of test cycle of alkali-aggregate reaction should be increased. The setting times of cement paste with set accelerating agents based on silicate and alkali-free ones were different largely with mixing methods. Compressive strength of mortar with set accelerating agents based on silicate, aluminate and cement at one day satisfied the specifications of Korea Concrete Institute. However, the strength ratio compared to control mix at 28 days showed as $50{\~}65\%$ except for the alkali-free set accelerating agents. As a results of setting time and strength test, the establishment of domestic standards that can reflect the characteristics of materials and construction methods of tunnels and that can increase quality of set accelerating agents is required immediately.

Sytheses of Quaternary Ammonium Salts Containing Dodecyl Group and Theirs Applications as Weight Loss Accelerating Agents (도데실기를 함유한 제4급 암모늄염의 합성과 감량촉진제로서의 응용)

  • Park, Jin-Woo;Hahm, Hyun-Sik;Park, Hong-Soo
    • Journal of the Korean Applied Science and Technology
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    • v.12 no.1
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    • pp.81-86
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    • 1995
  • Some weight loss accelerating agents, dodecyltrimethylammonium chloride(DTAC), dodecyltrimethylammonium bromide(DTAB), dodecyldimethylammonium chloride(DDBAC), polyoxyethylene(2) dodecylbenzylammonium chloride(PDBAC), and 1-(2-hydroxyethyl)-1-benzyl-2-undecylimidazolinium chloride(AEUIC), were synthesized. As a result of weight loss treatment of the weight loss accelerating agents with NaOH to PET fiber, the increase of weight loss was the order of PDBAC > DDBAC > DTAC > DTAB > AEUIC. Among the weight loss accelerating agents, AEUIC hardly showed weight loss effect, and it was separated into two layer in the NaOH solution at the treatment concentration above 6g/L, but POBAC showed good weight loss effect of 21% that approach almost to a theoretical weight loss, 21.6%, at the concentration above 8g/L.

Setting Time and Compressive Strength Gains of Glycocalix Coating Materials with Silica-based Accelerating Agents (실리케이트계 급결제를 혼입한 글라이코 캘릭스 코팅재의 응결시간 및 압축강도 발현 특성)

  • Jeong, Yun-Ji;Yoon, Hyun-Sub;Yang, Keun-Hyeok
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.8 no.1
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    • pp.105-111
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    • 2020
  • The present study examined the effect of the silica-based accelerating agents on the setting time and compressive strength gain of biomimetic glycocalix coating materials that has been developed for protecting the substrate of concrete exposed to chemical and microbiological attacks. The accelerating agent contents varied from 10mL/L to 40mL/L in the mixtures of glycocalix coating materials determined for shotcrete and lining techniques. Test results showed that the setting time of coating materials containing accelerating agents was affected by the contents of the bacteria carrier. When the accelerating agent content was 40mL/L, the final setting time was 80 minutes for shotcrete mixtures and 318 minutes for lining mixtures. Meanwhile, the compressive strength gain of coating materials with accelerating agents tended to be lower than that of counterpart materials without accelerating agents.

Alkali-Silica Reaction of Accelerating Agents in Shotcrete (숏크리트용 급결제의 알칼리-실리카 반응성 검토)

  • Choi, Bo-Ra;Hong, Byung-Tak;Lee, Jae-Wan;Lee, Su-Jin;Park, Hae-Kyun;Won, Jong-Pil
    • Proceedings of the Korea Concrete Institute Conference
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    • 2010.05a
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    • pp.323-324
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    • 2010
  • The purpose of this study was to investigate alkali-silica reaction of accelerating agents in shotcrete. The test was performed with accelerating agents (aluminate, alkali-free, cement based mineral admixture) in the Type I cement. As a test result, using the nonreactive aggregates, detrimental expansion due to alkali-silica reaction doesn't occurred regardless of equivalent alkali contents of accelerating agent.

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Strength Characteristics of 3D Printing Concrete for Exterior materials using Accelerating agent (급결제를 사용한 외장재용 3D 프린팅 콘크리트의 강도 특성)

  • Seo, Dae-Seuk
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.2
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    • pp.267-272
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    • 2021
  • In this study, the output results of 3D printed exterior materials for application to buildings of various shapes are output tests using test specimens, in which 3D printing concrete is cast in a mold and accelerating agents are used to ensure stackability. The unit weight and strength characteristics of the body were analyzed. Compared to the unit weight of concrete placed in the mold, the unit weight of 3D printing concrete using accelerating agents tends to decrease by approximately 3.5% to 5.0%, and the compressive strength is the compressive strength of the concrete placed in the mold. In comparison, the compression strength of the output by 3D printing tended to decrease by approximately 36% to 46%. In the flexural strength, the compressive strength of the output through 3D printing decreased by approximately 36% to 46% compared to the compressive strength of concrete placed in the mold. The impact on the strength characteristics of 3D printed concrete using accelerating agents tended to decrease by approximately 2.0 to 5.8%. Therefore, 3D printing output accelerating agents can be used.

Fast-Curing of Phenol·Formaldehyde Resin Adhesives for Plywood (합판용 페놀수지 접착제의 속경화)

  • Roh, Jeang-Kwan
    • Journal of the Korean Wood Science and Technology
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    • v.23 no.3
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    • pp.33-39
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    • 1995
  • To accelerate the cure of phenolic resin adhesives for plywood, the complexation with melamine resin and the addition of cure-accelerating agents were discussed. The hot-pressing temperature and time of phenol resin could be decreased by complexation with melamine resin. but the wet glue-joints strength of phenol melamine resin was lower than that of ordinary phenol resin in case of plywood using spruce veneer at core layer. Among the tested cure-accelerating agents. the sodium carbonate showed the greatest effect on shortening gelation time of phenolic resin. In addition, in the manufacturing scale test, the hot-pressing time of phenol resin with the addition of 5 parts sodium carbonate could be shortened about 20% compared with ordinary phenol resin which had same glue-joints properties.

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The Chemical and Microbial Characteristics of Northern Sand Lance, Ammodytes personatus, Sauce Manufactured with Fermentation Accelerating Agents (발효촉진제로 속성 발효한 까나리 어간장의 화학 및 미생물적 특성)

  • Kim, Woo-Jae;Kim, Sang-Moo
    • Korean Journal of Food Science and Technology
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    • v.35 no.3
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    • pp.447-454
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    • 2003
  • Chemical and microbial properties of Northern sand lance, Ammodytes personatus, sauce fermented at $15^{\circ}C$ with fermentation accelerating agents, koji, enzyme, and squid viscera, were analyzed. Total creatine content of Northern sand lance sauce with squid viscera increased up to 2 months of ripening and decreased gradually thereafter, while that with koji or enzyme, and control, increased up to 3 months of ripening and then decreased slowly. TBA values of all samples increased sharply during early ripening, followed by slight decrease. Free amino acid content with all agents increased continuously as fermentation progressed. Major free amino acids of Northern sand lance sauce were glutamic acid, alanine, valine, leucine, and lysine. Total viable cell counts with all agents also increased during early ripening and then decreased. Total viable cell count of Northern sand lance sauce with squid viscera was the highest followed that with koji, enzyme, and control. Northern sand land sauce manufactured with koji showed the most acceptable sensory evaluation result, followed by that with squid viscera.

Effects of the Structure of Weight Loss Accelerating Agents on the Weight Loss in Alkaline Hydrolysis of PET Fibers (감량촉진제의 구조에 따른 PET섬유의 감량가공효과)

  • Chun, Dong-Woo;Kim, Seung-Jin;Keun, Jang-Hyoun;Park, Hong-Soo
    • Applied Chemistry for Engineering
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    • v.5 no.1
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    • pp.63-73
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    • 1994
  • Weight loss accelerating agents, TDACW and TTAMW were prepared by adding water to n-tetradecyldimethylbenzylammonium chloride(TDAC) and n-tetradecyltrimethylammonium methyl sulfate(TTAM) synthesized in our lab. On weight loss finishing of PET fiber with NaOH and TDACW or TTAMW, TDACW showed much more weight loss than TTAMW. Optimum concentration was about $8g/{\ell}$, treatment time 60~90min and treatment bath ratio 1:40~1:50. Density and crystallinity increased with weight loss and tensile strength decreased with weight loss. From the reaction mechanism of weight loss accelerating agent and PET fiber, weight loss accelerating agent was proved to function as a catalyst and the surface structures of PET fibers treated with weight loss accelerating agent were characterized with SEM.

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The Properties of Early Strength of Concrete Containing Slag and Fly-ash for In-situ Application (현장 적용을 위한 3성분계 콘크리트의 조기강도 특성)

  • Jung Chul-Hee;Kim Kyoung-Min;Lee Jin-Woo;Bae Yeon Ki;Lee Jae-Sam
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05b
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    • pp.497-500
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    • 2005
  • This study was performed to evaluate the characteristics which are slump, air content and time of set in fresh concrete and compressive strength of hardened concrete containing slag powder and fly-ash. Replacement rate of FA is fixed on 10$\%$ and replacement rate of slag powder are 0$\%$, 20$\%$ and 30$\%$. Also AE water-reducing agents(standard type, accelerating type) are used. The results were as follows. (1)Slump flow of concrete using AE water-reducing agents is similar. Flowability is incresed when replacement rate of slag powder is increased due to slag powder's ball bearing reaction.(2)Time of set of concrete using accelerating type agent is more faster than that of concrete using standard type agent because of ettringite generation that promote setting.(3)Early strength of three-component concrete using accelerating type agent is higher than that using standard type agent. Therefore cumulative pore is reduced due to ettringite

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A Study on Early-strength Development of Concrete Using Accelerating AE Water Reducing Agents for the Estimation of Optimum Duration (촉진형 AE감수제를 사용한 콘크리트의 최적공기산정을 위한 조기강도 발현 특성 연구)

  • Lee, Joo-Hun;Sa, Soon-Heon;Ji, Suk-Won;Jeon, Hyun-Gyu;Seo, Chee-Ho
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2006.11a
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    • pp.91-94
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    • 2006
  • The way to shorten a construction period is considered to an very important technology development element as reducing the formwork removal periods with promoting strength revelation own concrete. This study executed experiment to review usability of early strength revelation chemical admixture which is judged in ways effective with premature removal of form about concrete. Use of early strength revelation AE water reducin admixture is apperaing so that strength revelation by early hydration promotions is excellent. The results of being applied proposed work process are that compressive strength are appeared more than 5MPa within 16 hours so that removal of vertical form was possible. the concrete compressive strength satisfied with a more than 2/3 of specified concrete strength for removal of horizontal form are appeared in 42 hours of 27 MPa proportioning strength, in 36 hours of 30, 35 MPa proportioning strength so that the 6 days cycle time of concrete structural frame work is cut by 2 days as shortening delayed period in works of removing slab forms. So construction cost reductions and a construction period shortening are judged so that it is possible.

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