• Title/Summary/Keyword: Fluidity of concrete under high temperature

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Effects of Portland Cement Characters and Working Temperature on the Physical Properties of Cement Mortars (시멘트의 특성과 사용 온도가 모르터의 물성에 미치는 영향)

  • 김원기;김창은
    • Journal of the Korean Ceramic Society
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    • v.37 no.5
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    • pp.410-417
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    • 2000
  • In this study the effects of specifics surface area of cement, addition amount of gypsum and substitution ratio of gypsum anhydrite ont he physical properties of cement mortars were investigated by measruements of setting time, flow, compressive strength and hydration heat evolution rate. The results showed that fluidity of mortars was increased by 40 wt.% of maximum flow change with the decreasing specific surface area of cement from 3,500$\textrm{cm}^2$/g to 3,300${\pm}$50$\textrm{cm}^2$/g and affected by the relationship between the cement and balancing between the chemical activityof cement and solubility of calcium sulfate are desirable to prevent the fluidity of concrete from decreasing by high temperature in summer season.

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An Experimental Study on the fluidity properties of Polymer Concrete According to Replacement Ratio of Rapidly-Chilled Steel Slag and polymer resin (급냉 제강 슬래그 대체율과 폴리머 수지에 따른 폴리머 콘크리트의 유동특성에 관한 실험적 연구)

  • Choi, Duck-Jin;Kim, Jae-Won;Sun, Joung-Soo;Kim, Ha-Suk;Hwang, Eui-Hwan;Kim, Jin-Man
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2007.11a
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    • pp.75-78
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    • 2007
  • The steel slag, a by-product which is produced by refining pig iron during the manufacture of steel, is mainly used as road materials after aging. It is necessary to age steel slag for long time in air because the reaction with water and free-CaO in steel slag could make the expansion of volume. This problem prevents steel slag from being used as aggregate for concrete. However, steel slag used in this study was controled by a air-jet method which rapidly cools substance melted at a high temperature. The rapidly-chilled method would prevent from generation of free-CaO in steel slag. Also, Molten steel slag rapidly-chilled by air in high speed becomes a fine aggregate of nearly spherical shape. This study dealt with the influence of the using rate of rapidly-chilled steel slag and polymer resin on fluidity of polymer concrete, as a results Since RCSS has spherical shape and high density, up to replacement ratio of 100%, increases concrete fluidity under same polymer content and decrease polymer content in order to secure the same fluidity

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Recovering Hydration Performance of Cementitious Powder by Concret Waste according to Burning Temperature (폐콘크리트계 미분말의 소성조건에따른 수화성 회복)

  • 강태훈;정민수;안재철;강병희
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2003.05a
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    • pp.81-87
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    • 2003
  • The purpose of this study is the development of a recycling process to recover the hydrated ability of cement hydrate which accounts for a large proportion of cementitious powder by concrete waste in order to recycle cementitious powder by concrete waste as recycle cement. Therefore, after having theoretical consideration based on the properties of high-heated concrete, we consider the properties of hydration of cementitious powder in hardened mortar under various temperature conditions. As a result of experiment, it is revealed that an effective development of recycling cement is possible since the cementitious powder by concrete waste recovers a hydraulic property during burning at $600^{\circ}C$ or $700^{\circ}C$. And it is shown that the fluidity of mortar decreases rapidly as the burning temperature of recycle cement increases. however, the improved effect of fluidity is predominant if adding the additive such as fly-ash or blast furnace slag.

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A Study on Constructability Estimation of Multi-component High Fluidity Concrete based on Mock-up Test (모의실험체에 의한 다성분계 고유동 콘크리트의 시공성능 평가에 관한 연구)

  • Kwon, Ki-Joo;Noh, Jea-Myoung
    • Journal of the Korea Institute of Building Construction
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    • v.10 no.4
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    • pp.75-82
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    • 2010
  • As structures become larger, taller, and more diverse, a high degree of technology and expertise are required in the construction industry. However, it has been becoming difficult to construct under severe conditions and to fulfill the high performance needs of structures due to a lack of skilled construction engineers. To compensate for these weak points, high-performance concrete and performance specifications have been developed. The application of reliable high-fluidity concrete, which is one of these efforts, is expected to be effective in terms of overcoming severe conditions, reducing the number of workers required, and shortening the construction period. In order to apply high fluidity concrete in the field, practical mock-up tests were carried out to estimate whether self-compaction concrete could satisfy constructability needs. From the results, it was verified that the multi-component high fluidity concrete has excellent flowability in practical structures. In addition, it was shown that the temperature distribution in the concrete due to hydration heat is satisfactory. As a result, it is judged that multi-component high fluidity concrete can be utilized as an effective building material for various structures, including structures related to the electric power industry.

A Fundamental Study on the Quality Improvement of Lightweight Foamed Concrete with Admixture Types (혼화재료에 의한 경량기포 콘크리트의 품질향상에 관한 기초적 연구)

  • Shin Jae-Kyung;Jeong Kwang-Bok;Lee Youl-Koo;Lee Gun-Cheol;Yoon Gi-Won;Han Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2006.05a
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    • pp.35-38
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    • 2006
  • This study investigated fundamental properties of lightweight foamed concrete using cement kiln dust (CKD) and both fly ash(FA) and stability agent. Test results showed that concrete incorporating more amounts of admixture decreased slump flow and it caused increase of superplasiticizer in order to secure the fluidity performance. In addition concrete adding stability agent showed stable flow state, resisting segregation of materials and decreasing bleeding capacity. Sinking depth of concrete incorporating 20% of CKD and adding 0.002% of stability agent was indicated at 0mm. For the properties of hardened concrete. compressive strength of concrete incorporating CKD declined due to a lower appearance density, compared with other specimens. The difference of that was not very significant and the value of ail specimen was higher than KS range. Moreover strength of concrete incorporating CKD was even higher at curing temperature $5^{\circ}C$. Tensile strength ratio of concrete incorporating CKD was indicated between 0.50 to 0.59, which is higher value than control concrete. Heat conductivity of concrete incorporating FA was under the KS range while concrete incorporating 20% of CKD was satisfied in KS. Concrete adding stability agent improved insulation performance due to the lower heat conductivity. In conclusion, it is possible that concrete incorporating 20% of CKD and adding 0.002% of stability agent can secure high quality of lightweight foamed concrete.

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Setting Analysis of Super Retarding Agent according to Curing Temperatur (양생온도 변화에 따른 초지연제의 응결지연 성능 변화 분석)

  • Hyun, Seung-Yong;Lim, Gun-Su;Han, Soo-Hwan;Kim, Jong;Han, Min-Choel;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2020.11a
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    • pp.10-11
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    • 2020
  • This research is part of the research for unifying the mass concrete and utilizing the rate of super retarding agent. We analyzed the performance of super retarding agent under low temperature conditions. It was found that there was no deterioration in fluidity and air quality due to the change in the super retarding agent mixing rate. It was found that when super retarding agent was mixed up to 0.5 %, it was delayed for 22.3 hours at 20℃, 48.2 hours at 10℃, and 48.5 hours at 5℃. Therefore in order to ensure the performance required at the site, the super retarding agent mixing rate must be determined by fully considering the situation at the site. In addition it will be analyzed that super retarding agent performance analysis at high temperature will be required in subsequent studies.

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