• 제목/요약/키워드: early strength cement

검색결과 563건 처리시간 0.028초

영구 숏크리트 터널 라이닝 구축을 위한 고성능 숏크리트 개발 (용수부에서의 조강시멘트와 alkali-free급결제 적용 검토) (Development of high performance shotcrete for permanent shotcrete tunnel linings (Application of high-early strength cement with alkali-free accelerator in spring water condition))

  • 박혜균;이명섭;김재권
    • 한국터널지하공간학회 논문집
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    • 제5권1호
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    • pp.23-31
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    • 2003
  • 최근 NATM 터널 현장타설 콘크리트 라이닝의 시공성 향상과 균열에 따른 유지관리비 절감을 위해 양질 암반의 배수형 터널 시공에 있어서는 숏크리트만으로 라이닝을 대체하려는 영구지보 개념의 터널시공 (Single-Shell Tunnel, NMT 등)이 세계적으로 증가하고 있는 추세이다. 이러한 영구지보 개념의 터널 시공을 위해서는 고성능 숏크리트의 개발이 선결되어야 하며, 이러한 목적에서 본 논문에서는 조강시멘트와 최근 주목받고 있는 환경친화적인 alkali-free 급결제의 조합을 통해 고성능 숏크리트의 개발 가능성을 확인하였다. 그 결과, 보통시멘트(OPC)를 사용한 숏크리트보다 약 25%의 높은 초기강도를 확보하였으며, 용수부에서도 뛰어난 부착특성을 확인할 수 있었다.

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조강형 고로 슬래그 시멘트 및 보통 포틀랜드 시멘트 대체용 고로 슬래그 시멘트에 관한 연구 (A Study of Blast Furnace Slag Cement of High Early Strength and Replacement Ordinary Portland Cement)

  • 권기동;최현국
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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    • pp.1211-1214
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    • 2000
  • The purpose of this paper was to study of blast furnace slag cement of high early strength and replacement ordinary portland cement. we prepared the specimens of cement and concrete with various mixing proportions of elementary materials. For example, clinker, gypsum(1~10%), fineness $4, 000~6, 000cm^2/g$ of blast furnace slag(30~50%), limestone etc. As a result of this study, fineness $(4, 000cm^2/g)$ blast furnace slag was of used replacement ordinary portland cement and fineness $(6, 000cm^2/g)$ blast furnace slag was of used blast furnace slag cement of high early strength.

내한성 혼화제를 이용한 시멘트 모르타르의 초기양생 온도변화에 따른 강도증진 특성 (Properties of Strength Development Under Various Curing Condition at Early Age of Cement Mortar Using Agent for Enduring Cold Weather)

  • 한천구;홍상희;김현우
    • 한국구조물진단유지관리공학회 논문집
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    • 제5권2호
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    • pp.191-197
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    • 2001
  • In this study, the admixtures for agents for enduring cold weather used widely are collected and applied to cement mortar to analyze the strength development due to variation of curing temperature at early age. The test results show that anti-freezing admixture have some problems due to high chloride content, which may cause the corrosion of reinforcement embedded in concrete. However, the mortar applied by accelerator and another kind of agent for enduring cold weather produced by S company lead to delay of strength development in low temperature. Also, it is clarified that there are no significant problems for cement mortar in strength development due to low temperature if a suitable kind of agent enduring cold weather is used and cement mortar is cured for more than $7.5^{\circ}D.D$ at early age.

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Synthesis and Characterization of Zinc Phosphate Cement Powder and Cement-forming Liquid

  • Park, Choon-Keun
    • The Korean Journal of Ceramics
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    • 제3권4호
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    • pp.269-273
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    • 1997
  • Chemical composition of cement powder influences the setting time and early compressive strength development. The setting time increases as the amounts of zinc oxide and magnesium oxide are increased. For one day compressive strength development, a cement powder with a composition 90% ZnO, 8% MgO and 2% silica resulted in the highest strength (greater than 1, 090 kg/$\textrm{cm}^2$). Cement-forming liquids also need to be buffered, with both aluminum and zinc ions, for a good consistency and a higher strength of the zinc phosphate cement. These liquids control the setting reactions.

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콘크리트의 초기강도 향상을 위한 고로슬래그 미분말의 사용에 관한 실험적 연구 (Improvement of Early age Concrete Strength Using Blast Furnace Slag Powder)

  • 유장원;이주선;박병관;배장춘;한민철;한천구
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2009년도 춘계 학술논문 발표대회 학계
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    • pp.77-80
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    • 2009
  • The purpose of the study was to examine engineering characteristics due to fine particle cement and gypsum contents to improve early strength of concrete substituted blast furnace slag powder. The results were as follows. Above all, For fluidity, generally all mixtures had lower fluidity than Plain mixture and was not satisfied target scope, but for mixture substituted the gypsum showed a little increasing trend. For air content, generally all mixtures compared to Plain mixture had decreasing tendency. However, all mixtures were satisfied target scope. For compressive strength, long-term strength was better than early strength according to ternary blast furnace slag contents was increased. For complex mixture was better than individual use of gypsum and fine particle cement.

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마이크로파를 이용한 저열 포틀랜드(4종)시멘트 모르터의 조기강도 추정에 관한 실험적 연구 (An Experimental Study on the Strength Estimation of Belite Cement Mortar by Microwave Heating)

  • 김민석;정근호;이영도;정재영;정상진
    • 한국건축시공학회지
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    • 제1권2호
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    • pp.179-184
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    • 2001
  • The most recent building trend is going large, high rise, high strength as overlarge project is developing in domestic construction business. Belite cement has properties like low heat, excellent long term strength, and durability without admixture(fly ash, silica fume). so, Beilte cement is suitable for mass structure which is needed high strength, high fluidity and low heat property. This study is to examine the possibility if site adoption microwave-use early strength estimation method. Based on the existed study related the portland cement, the interrelation between Belite cement and microwave-use early strength estimation method is required. In this study, interrelation between mortar and Evaluating strength estimation method is investigated before the concrete experiment.

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한중콘크리트의 초기 동해 방지를 위한 초기 양생기간의 산정 (Determination of the Protecting Periods of Frost Damage at Early Age in Cold Weather Concreting)

  • 한천구;한민철
    • 콘크리트학회논문집
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    • 제12권3호
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    • pp.47-55
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    • 2000
  • Protections from the frost damage at early ages are one of the serious problems to be considered in cold weather concreting. Frost damage at early ages brings about the harmful influences on the concrete structures such as surface cracks and declination of strength development. Therefore, in this paper, protecting periods of frost damage at early ages according to the standard specifications provided in KCI(Korean Concrete Institute) are suggested by appling logistic curve, which evaluates the strength development of concrete with maturity. W/B, kinds of cement and curing temperatures are selected as test parameters. According to the results, the estimation of strength development by logistic curve has a good agreement between calculated values and measured values. As W/B and compressive strength for protecting from frost damages at early ages increase, it is prolonged. It shows that the protecting periods of FAC(Fly Ash Cement) and BSC(Blast-furnace Slag Cement) concrete are longer than those of OPC(Ordinary Portland Cement) concrete. The protecting peridos from frost damage at early age by JASS are somewhat shorter than those by this paper.

고분말도 시멘트와 고로슬래그 미분말을 사용한 콘크리트의 강도발현 성상 (Properties of Strength Development of Concrete Using High Fineness Cement and Blast Furnace Slag)

  • 김한식;하정수;이영도
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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    • pp.197-198
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    • 2018
  • As part of the effort to shorten the construction period, this study examined the strength expression characteristics at the early age of concrete using high fineness cement and blast furnace slag. accordingly to provide a basic data on how to solve the problem that the initial strength is lowered.

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활성제를 사용한 슬래그 미분말 혼합 모르타르의 강도 (Strength of Alkali-Activated GGBF Slag Mortar)

  • 문한영;신화철;권태석
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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    • pp.481-486
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    • 2001
  • Ground granulated blast-furnace slag shows very high strength when proper alkali-activator exists. This paper deals with setting time, heat evolution rate and the strength development of alkali-activated slag cement activated by KOH, Ca(OH$)_{2}$, $Na_{2}$ $So_{4}$ , and alum(potassium aluminum sulfate). Alkali-activated slag mortar is studied by comparison with GGBF slag cement mortar. The experimental results indicate that for moisture curing at $25^{\circ}C$, the addiction of either 4% $Na_{2}$ $So_{4}$ or 4% alum increases the strength of GGBF slag cement mortar consisting of 50% GGBF slag and 50% portland cement at early age. Strength of activated GGBF slag cement mortars at 1, 3 and 7 days exceeded that of GGBF slag cement mortar. A conduction calorimeter was used to monitor early age hydration.

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조기교통개방 콘크리트의 내구성능 향상에 관한 연구 (Enhanced Durability Performance of High Early Strength Concrete for Early Traffic Opening)

  • 원종필;김현호;안태송
    • 콘크리트학회논문집
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    • 제13권4호
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    • pp.362-370
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    • 2001
  • 콘크리트포장 보수공사에서 조기교통개방을 위해 현재 국내에서는 초속경시멘트를 사용하고 있으나 이는 초기의 빠른 수화반응과 내.외부적 구속으로 인한 온도수축 및 건조수축이 발생하여 콘크리트포장에 인장응력을 유발한다. 구속으로 인한 수축은 콘크리트내에 균열을 발생시켜 투수성을 증가시키고 장기적으로는 내구성을 약화시킨다. 콘크리트보강재료로서 섬유는 이러한 균열을 제어하는데 효과적이다. 본 연구에서는 국내에서 사용되고 있는 3종류의 초속경시멘트의 내구성을 평가하였고 내구성을 증진시키기 위하여 콘크리트 보강 섬유를 혼입하였으며 일반 콘크리트와 섬유보강 콘크리트를 비교.분석하였다. 실험결과 조기교통개방콘크리트에서 섬유의 혼입은 일반 콘크리트보다 내구성을 증진시키는데 우수한 효과를 나타내었다.