• Title/Summary/Keyword: early strength cement

Search Result 563, Processing Time 0.034 seconds

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

  • Park, Hae Geun;Lee, Myeong Sub;Kim, Jea Kwon
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.5 no.1
    • /
    • pp.23-31
    • /
    • 2003
  • Since the mid of 1990, permanent shotcrete tunnel linings such as Single-shell and NMT have been constructed in many countries for reducing the construction time and lowing construction costs instead of conventional in-situ concrete linings. Among essential technologies for successful application of permanent shotcrete linings, high performance shotcrete having high strength, high durability and better pumpability has to be developed in advance as an integral component. This paper presents the idea and first experimental attempts to increase early strength and bond strength of wet-mixed Steel Fiber Reinforced Shotcrete (SFRS) in spring water condition. In order to increase early behavior of SFRS, a new approach using high-early strength cement with alkali-free liquid accelerator has been investigated. From the test results, wet-mix SFRS with high-early strength cement and alkali-free accelerator exhibited excellent early compressive strength improvement compared to the ordinary portland cement and good bond strength even under spring water condition.

  • PDF

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

  • 권기동;최현국
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 2000.10b
    • /
    • pp.1211-1214
    • /
    • 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.

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

  • Han, Cheon-Goo;Hong, Sang-Hee;Kim, Hyun-Woo
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.5 no.2
    • /
    • pp.191-197
    • /
    • 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.

  • PDF

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

  • Park, Choon-Keun
    • The Korean Journal of Ceramics
    • /
    • v.3 no.4
    • /
    • pp.269-273
    • /
    • 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.

  • PDF

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

  • Yoo, Jang-Won;Lee, Ju-Sun;Park, Byung-Kwan;Pei, Chang-Chun;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
    • /
    • 2009.05b
    • /
    • pp.77-80
    • /
    • 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.

  • PDF

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

  • 김민석;정근호;이영도;정재영;정상진
    • Journal of the Korea Institute of Building Construction
    • /
    • v.1 no.2
    • /
    • pp.179-184
    • /
    • 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.

  • PDF

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

  • 한천구;한민철
    • Journal of the Korea Concrete Institute
    • /
    • v.12 no.3
    • /
    • pp.47-55
    • /
    • 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.

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

  • Kim, Han-Sic;Ha, Jung-Soo;Lee, Young-Do
    • Proceedings of the Korean Institute of Building Construction Conference
    • /
    • 2018.05a
    • /
    • pp.197-198
    • /
    • 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.

  • PDF

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

  • 문한영;신화철;권태석
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 2001.05a
    • /
    • pp.481-486
    • /
    • 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.

  • PDF

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

  • 원종필;김현호;안태송
    • Journal of the Korea Concrete Institute
    • /
    • v.13 no.4
    • /
    • pp.362-370
    • /
    • 2001
  • The internal or external restraint of thermal and dry shrinkage movements could thus generate tensile stresses in concrete pavement for early traffic opening. Restrained shrinkage and thermal stresses could produce microcracks in concrete which increase its permeability and accelerate its long-term deterioration under weathering and load effects. Fiber reinforced concrete is an effective approach to the control of microcrack and crack development under tensile stresses. This study aims at evaluation of the durability of high early strength concrete for early traffic opening and increase of service life. Three different types of regulated-set cement which recently has been used much in Korea were adopted. Fibers were added and their mixtures were compared with plain high early strength concrete mixture. The use of fibers increased durability performance of high early strength concrete using regulated-set cement than the corresponding plain mixtures.