• Title/Summary/Keyword: 응결제

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The Effect of Additives on Formation Structure of Polyetherimide Hollow Fiber Membrane (폴리이미드계 중공사막의 생성구조에 미치는 첨가제의 효과)

  • 정용재;최성부;김수용;윤현희;김병식
    • Proceedings of the Membrane Society of Korea Conference
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    • 1998.10a
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    • pp.91-92
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    • 1998
  • 1. 서론 : 고분자를 소재로 하는 중공사막의 제막은 일반적으로 상전환법(phase inversion method)에 의하여 제조된다. 이 방법에 의한 비대칭막의 생성은 용매가 고분자용액을 빠져나가는 속도와 응결액이 고분자쪽으로 침투되는 속도의 차이에 의해서 막의 1차구조가 형성된다. 그러므로 이 속도를 첨가제 등을 사용하여 조절하므로서 막의 특성을 변화시킬 수 있다. 본 연구에서는 polyetherimide(PEI) 중공사막의 첨가제로서 dioxane 등 9종류를 사용하여 중공사막의 생성 구조에 미치는 영향을 검토하였다.

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Durability of Ultrarapid-Hardening Polymer-Modified Mortar Using Redispersible Polymer Powder (재유화형 분말수지 혼입 초속경 폴리머 시멘트 모르타르의 내구성)

  • 이윤수;주명기;연규석;정인수
    • Journal of the Korea Concrete Institute
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    • v.14 no.5
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    • pp.660-667
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    • 2002
  • The effects of polymer-cement ratio and antifoamer content on the durability of ultrarapid-hardening polymer-modified mortars using redispersible polymer powder are examined. As a result, regardless of the antifoamer content, the setting time of the ultrarapid-hardening polymer-modified mortars using redispersible polymer powder tend to delay with increasing polymer-cement ratio. The water absorption and chloride ion penetration depth of the ultrarapid-hardening polymer-modified mortars using redispersible polymer powder decrease with increasing polymer-cement ratio and antifoamer content. The resistance of freezing and thawing and chemicals improvement is attributed to the improved bond between cement hydrates and aggregates because of the incorporation of redispersible polymer powder

A Study for Application of Polycarboxilic Type Admixture to Precast High-Strength Concrete Piles (프리캐스트 고강도 콘크리트(PHC) 파일에 조강형 폴리카본산(PC)계 혼화제의 적용에 관한 연구)

  • Yi, Seong Tae;Noh, Jae Ho;Park, Chul Ju;Heo, Hyung Seok
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.1
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    • pp.263-270
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    • 2011
  • In this study, the performance of Poly-Naphthalene Sulfonate (PNS) type-admixture used widely in South Korea and Polycarboxilic type-admixture(i.e., WF2000) developed in the J company of the domestic, for precast concrete products produced in the factories, was evaluated. With the 20% reduced usage of WF2000 compared to PNS type-admixture, workability was considerably improved due to high water-reducing ratio, accelerating effect of concrete setting and accelerant dispersant action, which the product has, under the high temperature. In addition, the development of initial and long-term strengths of PHC plies was predominant. For WF2000, it is also possible to correspond with the change of original materials and environmental conditions since the control of water-reducing and supporting forces is feasible. Accordingly, it was noted that WF2000 is superior for deterioration of production & workability and bad casting problems in summer and the solution of initial strength reduction problem due to the delay of setting in winter.

Durability of High-fluidity Polymer-Modified Mortar Using Redispersible Polymer Powder (재유화형 분말수지 혼입 고유동 폴리머 시멘트 모르타르의 내구성)

  • Joo Myung-Ki;Lee Youn-Su;Youn Do-Yong;Jung In-Su
    • Journal of the Korea Concrete Institute
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    • v.17 no.5 s.89
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    • pp.703-708
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    • 2005
  • The effects of polymer-cement ratio and antifoamer content on the setting time and durability of high-fluidity polymer-modified mortars using redispersible polymer powder are examined. As the result, the setting time of the polymer-modified mortars using redispersible polymer powder tends to be delayed with increasing polymer-cement ratio, regardless of the antifoamer content. The water absorption, chloride ion penetration depth and carbonation depth of the high-fluidity polymer-modified mortars using redispersible polymer powder decrease with increasing polymer-cement ratio and antifoamer content. The resistance of freezing and thawing and chemicals improvement is attributed to the improved bond between cement hydrates and aggregates because of the incorporation of redispersible polymer powder

The Hardening Characteristics of Underwater Concrete According to the Cellulose Underwater Non-segregation Admixture and Its Preparation (Cellulose계 수중재료분리 방지제의 제조 및 첨가에 따른 수중콘크리트의 경화특성)

  • Shin, Dong-Gil;Song, Yon-Ho;Lee, Chul-Tae
    • Applied Chemistry for Engineering
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    • v.16 no.2
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    • pp.267-274
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    • 2005
  • Preparation of cellulose type underwater non-segregation admixture was attempted and the hardening characteristics of underwater concrete according to the addition of this admixture was investigated in order to make underwater concrete with the compressive strength ratio of 0.8 to that of concrete manufactured in common atmosphere. The proposed underwater non-segregation admixture consisted of methyl cellulose of 0.4% by weight, silicon type antifoaming agent of 20% by weight, and sodium aluminate of 0.1% by weight to the amount of cement as setting accelerant, respectively. As the proposed non-segregation admixture was increased, the amount of suspended solid decreased, air content in concrete was increased but the flow loses by elapsed time did not change. The proper amount added of the proposed non-segregation adimixture was 0.8 wt% to the amount of cement. The compressive strength of the test sample underwater concrete manufactured by the addition of the proposed admixture was $325Kg/cm^3$, and the ratio of compressive strength of this sample concrete to that of a concrete manufactured in air was 0.94.

Effects of Animal Additives on the Fundamental Properties of Mortar and Concrete (동물성 첨가제가 모르타르 및 콘크리트의 기초 물성에 미치는 영향)

  • Song, Jin-Woo;Moon, Seung-Kwon
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.7 no.1
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    • pp.69-75
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    • 2012
  • The study was conducted to determine the effects of adding pig blood as an admixture to both mortar and concrete. The mortar tests included the determination of its unit weight, flow and its compressive strength. Moreover, the concrete test includes the determination of air content, slump, bleeding, setting time compressive strength and freeze-thaw resistance of the material. As the test result, the utilization of pig blood, as an additive to both mortar and concrete mixtures causes air entrainment. The mortar flow increased and both the unit weight and the compressive strength of mortar decreased. As the blood replacement rate increases, the air content decreases over time, the setting and amount of bleeding showed a tendency to decline and reduced compressive strength, and the freeze-thaw resistance of the concrete increased.

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Properties of Shrinkage Reducing Agent used C12A7-Based Slag according to Content of Admixtures (C12A7계(系) 슬래그를 사용(使用)한 수축저감제(收縮低減劑)의 혼합재(混合材) 함량(含量)에 따른 특성(特性))

  • Park, Soo Hyun;Chu, Yong Sik;Seo, Sung Kwan;Park, Jae Wan
    • Resources Recycling
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    • v.22 no.6
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    • pp.12-18
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    • 2013
  • In this Study, it was fabricated that shrinkage reducing agent and mortar used $C_{12}A_7$-based slag enhanced the shrinkage reduction and compressive strength. To reduce cement content, setting time, flow and compressive strength of mortar with varying content of fly ash and blast furnace slag were experimented. The flow increased and setting time delayed as the increase of fly ash and blast furnace slag content. And early strength was lower and long age strength was higher than that of mortar with low content of admixture.

Experimental Study on the Application of Concrete Admixture using the EAF Reduction Slag (전기로 환원 슬래그 미분말의 콘크리트용 혼화재 적용성에 관한 실험적 연구)

  • Choi, Jae-Seok;Jang, Pil-Sung;Jo, Young-Jin
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.11
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    • pp.6890-6897
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    • 2014
  • EAF reduction slag has unstable properties of expansion and destruction. Therefore, it cannot be used as a construction material. The purpose of this study was to use EAF reduction slag as a concrete admixture. EAF reduction slag contains $11CaO{\cdot}7Al_2O_3{\cdot}CaF_2$ and ${\beta}-C_2S$ (calcium aluminate compounds). To confirm the properties of EAF reduction slag as a concrete admixture, the condensation, compressive strength and activity factor due to substitution rate of EAF reduction slag were measured. Originally, EAF reduction slag was cured rapidly because of its chemical composition ($11CaO{\cdot}7Al_2O_3{\cdot}CaF_2$). On the other hand, when 8% gypsum was added, its properties of condensation and compressive strength were similar to the plain specimen. When 6% gypsum was added, the quality of the KS F 2536 standards (quality standard number 3) were met in terms of activity factor. Overall, 8% gypsum addition is the most appropriate by considering the activity factor in the long-term compressive strength.

Effects on the Properties of Cement Mortar with Various Molecular Structures of Polycarboxylate-Type Superplasticizers (폴리카복실레이트계 고유동화제의 분자구조가 시멘트 모르타르의 물성에 미치는 영향)

  • Song, Jong-Taek;Ryu, Ho-Seok
    • Journal of the Korean Ceramic Society
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    • v.41 no.4
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    • pp.302-312
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    • 2004
  • This paper presents the experimental results on the properties of the cement mortar with polycarboxylate-type superplasticizers PCA) which were synthesized by different mole ratio of methoxypoly(ethyleneglycol)monomethacrylate (MPEGMAA) and methacrylic acid (MAA) and by different length of polyethyleneoxide (PEO). As the PEO chain was longer and mole ratio of [MPEGMAA]/[MAA] was lower, the fluidity of cement mortar was better. The setting time of mortar with PCA was retarded, and as PEO chain was shorter and [MPEGMAA]/[MAA] was lower, it was more retared. Espeacially, when the molecular weight of MPEGMAA was 475(repeat unit of ethylene oxide=l0), the degree of retardation was the highest of them. The surface tensions of PCA solutions were lower than that of water due to the effect of PEO chain, and also the pore size distribution of cement mortar was influenced by it. The pores in cement mortar with PCA at 28 days were macropores in the range of 7 to 370$\mu\textrm{m}$, and accordingly, the densities and compressive strengths of mortar were lower than those of OPC mortar.

An Experimental Study on the Carbonation and Drying Shrinkage of Concrete Using High Volumes of Ground Granulated Blast-furnace Slag (고로슬래그 미분말을 대량 사용한 콘크리트의 건조수축 및 중성화에 관한 실험적 연구)

  • Ryu, Dong-Woo;Kim, Woo-Jae;Yang, Wan-Hee;Park, Dong-Cheol
    • Journal of the Korea Institute of Building Construction
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    • v.12 no.4
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    • pp.393-400
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    • 2012
  • The effect of ground granulated blast-furnace slag (GGBS) and alkaline activator on the properties of setting, compressive strength, drying shrinkage and resistance of carbonation was assessed to develop high volume slag concrete, the GGBS replacement rate of which was more than 80 percent. The changes in the concrete as the replacement rate of GGBS increases were as follows. Initial and final setting time was delayed by two and a half hours, and the compressive strength development properties of concrete in early and long term age were decreased. Drying shrinkage was satisfactory as below $6{\times}10^{-4}$ in every mixture, and yet showed a tangible trend by replacement rate. Carbonation was materially increased. Setting time and early strength development property, however, were extremely advanced by the addition of the alkaline activator. While drying shrinkage was improved by the alkaline activator, resistance to carbonation was not.