• Title/Summary/Keyword: high strength cement

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An Experinetal Study on the Influence of Cement Content to Engineering Properties of High Strength Concrete (고강도콘크리트의 공학적 특성에 미치는 단위시멘트량의 영향에 관한 실험적 연구)

  • 남상일;김무한
    • Proceedings of the Korea Concrete Institute Conference
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    • 1992.04a
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    • pp.41-46
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    • 1992
  • A potential use of superplasticizing admixture is to produce structural concrete of High-strength concrete,. By using a superplasticizer, more workable mixes can be achieved while permitting a high cement content and a low water/cement ratio both of which are necessary to obtain high strength by conventional manufacturing technique. In this study, therefore, high strength concrete having a 28-day strength in excess of 650kg/$\textrm{cm}^2$ can be obtained using a superplasticzer. However, before such a high strength concrete is recommended for use, engineering properties have to be assessed. This study is aimed to analyze and investigate the engineering properties, such as strength, elasticity, ultrasonic pulse velocity, rebound value of superplasticized concrete having a various cement content.

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An Experimental Study on the Early Strength Estimation of Belite Cement Concrete by Microwave Method (마이크로파 가열기법에 의한 저열 포틀랜드시멘트 콘크리트의 조기강도 추정에 관한 실험적 연구)

  • 이민경;황병준;전판근;박병근;김성식;정상진
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.05a
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    • pp.1041-1046
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    • 2003
  • 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, Belite cement is suitable for mass structure which is needed high strength, high fluidity and low heat property. This study is to examine the possibility of 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.

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A Study on the Effects of Curing Temperature for Compressive Strength of High Performance Concrete (양생온도 변화가 고성능 콘크리트의 압축강도에 미치는 영향에 관한 연구)

  • Ro, In-Cheul
    • Journal of the Korea Institute of Building Construction
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    • v.2 no.4
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    • pp.163-168
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    • 2002
  • The object of this study is to define the characteristics of high performance concrete with varing compressive strength of concrete and curing temperature. The major test variables are 1) high strength concrete(500kg/$cm^2$) and ordinary strength concrete(240kg/$cm^2$) compressive strength, 2) curing temperature and condition, 3) concrete curing age, 4) three types of cement. From the test results were shown that curing temperature and curing conditions were also very effective for high strength concrete and ordinary strength concrete, and concrete were largely effected by cement type and temperature during the hydration reaction process. This paper describes the effect of curing temperature for strength and characteristics of high performance concrete.

A Study on the Effect of Admixture Types and Replacement Ratio on Hydration Heat Reduction of High-Strength Concrete (고강도 콘크리트의 수화열 저감에 미치는 혼화재 종류 및 대체율의 영향에 관한 연구)

  • Kim, Moo-Han;Choi, Se-Jin;Oh, Si-Duk;Kim, Yong-Ro;Lee, Jong-Ho
    • Journal of the Korea Institute of Building Construction
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    • v.2 no.2
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    • pp.145-150
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    • 2002
  • The hydration of cement paste occurs when the cement is miked with water. During the hydration, hydration heat causes the thermal stress depending on the site of concrete and the cement content. Especially in the high-strength concrete, we must give care to the concrete due to its large cement content. In this study conduction calorimeter and concrete insulation hydration heat meter were used to investigation the hydration heat characteristics of cement and concrete. To reduce hydration heat of high-strength concrete, several types of replacement of fly-ash and blast-furnace slag powder were used in this experiment. As a result of this study, it was found that hydration heat of high-strength concrete was reduced by replacement of fly-ash and blast-furnace slag powder. In case of high-strength concrete using blast-furnace slag powder, the max-heat arrival time was delayed but an effect of heat reduction was lower than a case of high-strength concrete using fly-ash, because it was considered that the heat-dependence property of blast-furnace slag powder was higher than that of fly-ash.

A Study and Evaluation of Super High Early Strength Concrete as Pavement Overlay Materials for Early Traffic Opening(3) (신속개방형 콘크리트 도로포장재의 설계를 위한 평가 연구(3))

  • 임채용;엄태선;유재상;이종열;엄주용;조윤호
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.05a
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    • pp.607-612
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    • 2002
  • In road pavements, it is known that cement concrete pavement has superior durability, safety compared. But in repairing pavement, cement concrete pavement is not usually applied because of the length of time while the road is interrupted when using Ordinary and Rapid-hardening Portland Cement. And Super High Early Strength Cement and Ultra Super High Early Strength Cement are not favorable for ready mixed concrete because of rapid setting time, high slump loss and other restrictions. We developed special cement developing 1 day strength of over 30.0N/mm$^2$ to open the road within 1 day and workable time is maintained over 1 hour so that it can be used as ready mixed concrete. We performed experimental overlay construction with the cement and evaluated the mechanical property and the durability. At curing temperature of 8-l8$^{\circ}C$,the flexural strength was 6.4N/mm$^2$at 1 day, so that the road can be open to traffic within 1 day. In durability test, the hardened concrete showed higher durability than Portland cement concrete.

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A Study on the Adhesive Performance of High-early Strengthening Polymer Cement Composites for Crack Repair of RC Structures (RC 구조물의 균열보수용 조강성 폴리머 시멘트 복합체의 접착성능에 관한 연구)

  • Park, Dong-Yeop;Kim, Sang-Hyeon;Jo, Young-Kug
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2023.11a
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    • pp.179-180
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    • 2023
  • The adhesion performance of PCCs for crack repair of RC structures was greater in the case of using ultra high-early strength cement than in the case of using ordinary Portland cement, and the effect of mixing silica fume was higher in the case of ordinary Portland cement than that of ultra high-early strength cement. On the other hand, 130% of W/C was more fluid than 80% of W/C in the same P/C 80%, which increased the fillability and improved the strength, but the strength improvement effect was the greatest in adhesion in flexure. Through this study, the basic characteristics of the adhesion performance of PCCs were identified, and based on this, it is necessary to induce an optimal mixing design that can increase adhesion performance through various mixing designs.

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Properties of High-strength and Carbonation of Concrete with Overseas Cement (해외시멘트를 사용한 콘크리트의 고강도 및 중성화 특성)

  • 이성복;하부도언;이도헌;지남용
    • Proceedings of the Korea Concrete Institute Conference
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    • 2000.04a
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    • pp.237-242
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    • 2000
  • Recently, the importation of overseas cement has been increasing and the spot materials of different quality from Japan have to be treated in overseas construction work for technical cooperation with neighboring countries. However, a study on the quality of those oversea materials has not yet been carried out systematically, especially cement among those materials. Accordingly, in this study the properties of high-strength concrete with oversea cement imported from four countries in East Asia and South-east Asia were investigated under normal and high temperature condition, including the carbonation of normal-strength concrete under normal temperature. As a result, it is found that the required of normal-strength concrete will be expected regardless of temperature condition when the flowability is ensured by selecting the appropriate superplaticizer and dosage of it, and the carbonation rate of normal-strength concrete with overseas cement is approximately the same as that with Japanese one under the condition of the same compressive strength.

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Development of High Performance Shotcrete for Permanent Shotcrete Tunnel Linings II(II: Application of high-early strength cement in sump water condition) (Permanent Shotcrete Tunnel Linings 구축을 위한 고성능 숏크리트 개발 II (II: 용수부에서의 조강시멘트 적용))

  • 박해균;이명섭;김재권;안병제
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.10a
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    • pp.695-702
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    • 2002
  • Shotcrete (or Sprayed concrete) has been used as an important support material in New Austrian Tunnelling Method (NATM). Since the mid of 1990, permanent shotcrete tunnel linings such as Single-shell, NMT (Norwegian Method of Tunnelling) has 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 shotcrcte linings, high performance shotcrete providing high strength, high durability, better pumpability has to be developed in advance as an integral component. This paper presents the Ideas and first experimental attempts to increase early strength and bond strength of wet-mixed Steel Fiber Reinforced Shotcrete(SFRS) in sump water condition. In order to increase early strength, a new approach using high-early strength cement with liquid alkali-free accelerator has been investigated From the results, wet-mix SFRS with high-early strength cement and alkali-free accelerator exhibited excellent early strength improvement compared to the ordinary portland content and good bond strength even under sump water condition.

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Prediction of the Compressive Strength of High Flowing Concrete by Maturity (적산온도에 의한 고유동콘크리트의 압축강도 예측)

  • 길배수;한장현;김규용;권영진;남재현;김무한
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.10a
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    • pp.281-286
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    • 1998
  • The aim of this study is to compare the development of compressive strength of high-Flowing concrete with maturity and to investigate the applicability of strength prediction models of concrete. An experiment was attempted on the high-flowing concrete mixes using Ordinary portland cement, High belite cement, Blast furance slage cement and replaced Fly-ash of 30% by weight of Ordinary portland cement, the water-binder ratios of mixes being 0.35 and the curing temperatures being 30, 20, 10, 5$^{\circ}C$. Test results of mixes are statistically analyzed to infer the correlation coefficient between the maturity and the compressive strength of high-flowing concrete.

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Development of Pre-Mix Cement for 150 MPa Ultra High Strength Concrete (설계강도 150 MPa 초고강도 콘크리트용 시멘트 결합재의 개발)

  • Hwang, Yin-Soong;Kim, Seong-Su;Cha, Wan-Ho;Kwon, O-Bong;Sohn, Yu-Shin;Lee, Seung-Hoon
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05b
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    • pp.25-28
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    • 2006
  • This study investigated pre-mixed cement combined with ordinary portland cement, BF and SF, in order to manufacture cement binder, which is possible to produce 150MPa ultra high strength concrete. The BF used in this study reduces and control hydration heat. It can also improve concrete fluidity, while AP increases hydration product and accelerates reaction of BF. SF has micro filler effect and makes pozzolanic reaction. It also fabricates high density internal organization. This developed pre-mixed cement can reduce hydration heat and increase hydration product. It is possible to fabricate high density organization and to secure homogeneity. The mock-up test of ultra high strength concrete showed excellent dispersibility and workability and indicated compressive strength more than 150MPa at 28 days.

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