• Title/Summary/Keyword: Low Heat Cement

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Effects of Mineral Admixture on the Paste Fluidity and Mortar Strength Development of High Chloride Cement (염소 고함유시멘트의 페이스트 유동성과 모르타르 강도발현성에 미치는 무기질 혼화재의 영향)

  • Jeong, Chan-Il;Park, Soo-Kyung;Lee, Eui-Hak;Lee, Kyung-Hee
    • Journal of the Korean Ceramic Society
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    • v.44 no.1 s.296
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    • pp.43-51
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    • 2007
  • Fluidity, setting time, hydration heat, bond water ratio, compressive strength, SEM and BET of OPC were measured by adding 1.0 wt% KCl and replacing 20 wt% mineral admixture in order to examine effects of blast furnace slag (BFS), limestone powder (LSP), and fly ash (FA) on fluidity and strength development of the cement contained much chloride. In general, the cement contained much chloride was high in heat of hydration, short in its setting time, low in its fluidity and low in its strength at 28 days due to the rapid hydration in its initial stage. As a result of the experiment, it has been demonstrated that fluidity became improved but the compressive strength at 28 days was decreased as replaced LSP to the cement contained much chloride. the fluidity and compressive strength at 28 days was improved as replaced BFS, the initial compressive strength development was improved due to the activation of initial reaction by KCl. Fluidity, initial compressive strength and late compressive strength at 28 days of cement contained much chloride replaced 5 wt% LSP and 15 wt% BFS concurrently was better than OPC, but the hydration heat was lower.

Hydration Characteristics and Synthesis of Hauyne-Belite Cement as Low Temperature Sintering Cementitious Materials

  • Park, Sang-Jin;Jeon, Se-Hoon;Kim, Kyung-Nam;Song, Myong-Shin
    • Journal of the Korean Ceramic Society
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    • v.55 no.3
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    • pp.224-229
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    • 2018
  • OPC production requires high calorific value and emits a large amount of $CO_2$ through decarbonation of limestone, accounting for about 7% of $CO_2$ emissions. To reduce $CO_2$ emissions during the Ordinary Portland Cement (OPC) production process, there is a method of reducing the consumption of cement or lower temperature calcination for OPC product. In this study, for energy consumption reduction, we prepared Hauyne-belite cement by calcination at a low temperature compared to that used for OPC and studied the early hydration properties of the synthesized Hauyne-belite cement. We set the ratios of Hauyne and belite to 8 : 2, 5 : 5 and 3 : 7. For the hydration properties of the synthesized Hauyne-belite cement, we tested heat of hydration of paste and the compressive strength of mortar, using XRD and SEM for analysis of hydrates. As for our results, the temperature for optimum synthesis of Hauyne-belite is $1,250^{\circ}C$. Compressive strength of synthesized Hauyne-belite cement is lower than that of OPC, but it is confirmed that compressive strength of synthesized Hauyne-belite cement with mixing in of some other materials can be similar to that of OPC.

Effect of Fineness of GGBS on the Hydration and Mechanical Properties in HIGH Performance HVGGBS Cement Paste (고성능 하이볼륨 슬래그 시멘트 페이스트의 고로슬래그 미분말 분말도에 따른 수화 및 강도 특성)

  • Choi, Young Cheol;Shin, Dongcheol;Hwang, Chul-Sung
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.5
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    • pp.141-147
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    • 2017
  • Recently, lots of researches on concrete with high volume mineral admixtures such as ground granulated blast-furnace slag(GGBS) have been carried out to reduce greenhouse gas. The high volume GGBS concrete has advantages such as low heat, high durability, but it has a limitation in practical field application, especially low strength development in early ages. This study investigated the compressive strength and hydration characteristics of high performanc and volume GGBS cement pastes with low water to binder ratio. The effects of fineness($4,330cm^2/g$, $5,320cm^2/g$, $6,450cm^2/g$, $7650cm^2/g$) and replacement(35%, 50%, 65%, 80%) of GGBS on the compressive strength, setting and heat of hydration were analyzed. Experimental results show that the combination of high volume slag cement paste with low water to binder ratio and high fineness GGBS powder can improve the compressive strength at early ages.

Hydration Heat Control of Marine Pier Foundation using Low-Heat Cement and Mesh Form (저발열 콘크리트와 Mesh형 거푸집을 이용한 교각기초의 수화열 저감 방안 연구)

  • Cho, Yong-Yeon;Lee, Won-Joon;Won, Jong-Hwa;Kim, Tae-Min;Kim, Moon-Kyum
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2009.04a
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    • pp.315-318
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    • 2009
  • 본 논문에서는 해상 기초 교각 매스 콘크리트의 수화열 저감 방안을 다루었다. 저발열 콘크리트, Mesh형 거푸집 공법 등에 대한 실험을 수행하여 각각의 수화열 저감효과를 평가하였다. 현장 실험은 사용 시멘트와 거푸집의 종류, 거푸집의 사용 면수에 따라 총 4 type으로 구성하였으며, 이에 대한 실험 결과와 유한 요소 해석 결과를 비교, 검증하여 최종적인 수화열 저감 성능을 도출하고자 하였다. 실험을 통해, 저발열 시멘트와 유로폼을 사용하는 것이 수화열 저감을 위해 효과적인 방법으로 판명되었으나 추가 공사비의 발생으로 효율성이 떨어질 것으로 판단된다. 또한 Mesh형 거푸집 적용 면 수와 온도 상승 저감 효과는 비례하는 것을 알 수 있었지만 내 외부 온도차가 다소 크게 나타나 수화열에 의한 균열 발생 확률면에서는 다소 불리하게 나타났다. 그러나 실험 단계에서 생략된 양생과 관리를 통하여 균열의 저감효과를 거둘 수 있을 것으로 판단되며, 추가적으로 거푸집 해체 단계를 생략함으로 공기단축 측면에서 유리할 것으로 판단된다.

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The Effects of Various Cement Type and Compositions on the Material Properties of high Strength Concrete (시멘트 특성의 변화가 고강도콘크리트의 재료특성에 미치는 영향)

  • 백상현;이종열;엄태선;임채용;안광원
    • Proceedings of the Korea Concrete Institute Conference
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    • 2000.04a
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    • pp.47-52
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    • 2000
  • Recently, it is very necessary the development of the manufacturing techniques for high strength concrete(HSC) for the large-scale size and good quality of civil structure. But, the manufacture and quality control of HSC of which shrinkage, heat of hydration and workability at construction filed are considered, is very difficult due to its low water-cement ratio and high quantity of unit cement content. In the present study, we tried to know and assess the influences of chemical and physical properties of cement on the material properties of HSC. We analyzed basic properties of 4 kinds of cement whose chemical and physical properties are different each other through various tests such as chemical analysis and mortal test. Also, we performed the assessment of the material properties of HSC for each dement by the test for the conditions of same mix design and similar compressive strength. From the results in the study, the assessment of the important quality factors of cement influencing the properties of HSC may be utilized to quality control of applied cement to manufacture the HSC of high quality.

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Corrosion of Steel in Concrete Deteriorated by Freezing/Thawing and Carbonation (동결융해 및 중성화를 받은 콘크리트의 철근 부식 특성)

  • 정해문;김종우;이대근;최광일
    • Proceedings of the Korea Concrete Institute Conference
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    • 1997.10a
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    • pp.293-298
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    • 1997
  • Corrosion of steel reinforcing in concrete deteriorated by freezing/thawing and carbonation was characterized. Concrete specimens were prepared using various kinds of cements such as ordinary portland cement (type I), low heat portland cement (type IV, belite rich cement), sulphate resistance portland cement (type V), blast furnace slag portland cement and ternary blended cement. Of various cements, type V and type IV with lower $C_3A$ content revealed better steel corrosion resistance after freezing/thawing and carbonation. $C_3A$ content in cement might affect freezing/thawing resistance in sea water.

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The Mechanical Characteristics and Hydration Heat on the Cold Weather Concrete using High Early Strength Portland Cement (조강시멘트를 사용한 한중콘크리트의 수화발열 및 역학적 특성)

  • Lee Won Am;Um Tae Sun;Ryu Jae Sang;Lee Jong Ryul
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.11a
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    • pp.305-308
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    • 2004
  • Cold weather concrete is the concrete which is used during construction under low-temperature' environment, and this kind of concrete has to be taken care not to be frozen in early ages of setting-hardening, It is specified in the Concrete Standard Specification(2003) as 'the cold weather concrete must be used on the weather condition under the average daily outdoor temperature below $4^{\circ}C$.' In this research, the mechanical characteristics and hydration heat on the cold weather concrete using high early strength portland cement were studied. As a result, the excellent quality was obtained and high early strength portland cement is expected to be used widely as the cold weather concrete.

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An Experimental Study For Basic Property of Ultra High Strength Concrete using Belite Cement (저열 포틀랜드 시멘트를 사용한 초고강도 콘크리트의 특성에 관한 연구)

  • Min, Hong-Jun;Kim, Ji-Man;Gong, Min-Hoi;Yang, Dong-Il;Lee, Han-Souk;Jung, Sang-Jin
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.457-460
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    • 2006
  • Recently ultra high strength concrete is actively being developed and studied, and this trend is explained with the following effects. Technological effects expected from the application of ultra high strength concrete include the reduction of section, the decrease of structure mass and the improvement of workability. Belite cement has properities like low heat of hydration, excellent long term strength, and durablity without admixture. so, Belite cement is suitable for mass structure which is needed high strenghth, high fluidity and heat property. The objective of this study is to examine the suitability of mixture ratio through experiment of basic physical properties and provide materials for the field application of ultra high strength concrete.

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Chloride binding isotherms of various cements basing on binding capacity of hydrates

  • Tran, Van Mien;Nawa, Toyoharu;Stitmannaithum, Boonchai
    • Computers and Concrete
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    • v.13 no.6
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    • pp.695-707
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    • 2014
  • This study investigated the chloride binding isotherms of various cement types, especially the contributions of C-S-H and AFm hydrates to the chloride binding isotherms were determined. Ordinary Portland cement (OPC), Modified cement (MC), Rapid-hardening Portland cement (RHC) and Low-heat Portland cement (LHC) were used. The total chloride contents and free chloride contents were analyzed by ASTM. The contents of C-S-H, AFm hydrates and Friedel's salt were determined by X-ray diffraction Rietveld (XRD Rietveld) analysis. The results showed that OPC had the highest chloride binding capacity, and, LHC had the lowest binding capacity of chloride ions. MC and RHC had very similar capacities to bind chloride ions. Experimental equations which distinguish the chemically bound chloride and physically bound chloride were formulated to determine amounts of the bound chloride basing on chloride binding capacity of hydrates.

Effects of Cement Fineness Modulus (CFM) on the Fundamental Properties of Concrete (시멘트 입도계수(CFM)가 콘크리트의 기초적 특성에 미치는 영향)

  • Noh, Sang-Kyun;Han, Cheon-Goo
    • Journal of the Korea Institute of Building Construction
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    • v.12 no.3
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    • pp.284-290
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    • 2012
  • Cement Fineness Modulus (CFM) is a method of expressing the distribution of particle sizes of cement in numeric form. If CFM is controlled through crush process of cement without modifying the chemical components or mineral composition of cement, it is judged to be able to produce a cement satisfying various requirements because it is estimated to enable various approaches to cement such as high early strength, moderate heat, low heat cement and so on. Therefore, in this study, as basic research for manufacturing special cement utilizing the controls of CFM, the intention was to review the impacts of CFM on the fundamental properties of concrete. To summarize the result, as mixture characteristics of fresh concrete, ratio of small aggregate and unit quantity were gradually increased, securing greater fluidity, with an increase in CFM, while the amount of AE and SP were reduced gradually. In addition, setting time was delayed as CFM increased. Furthermore, compression strength was relatively high during initial aging as CFM became smaller, but as time passed, compression strength became smaller, and it showed the same level of strength as aging time passed about three years.