• Title/Summary/Keyword: mass concrete

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An Experimental Study on the Properties of Ultra Low Heat Mass Concrete Containing Limestone Powder (석회석미분말을 혼입한 초저발열 매스콘크리트의 특성에 관한 연구)

  • 하재담;김동석;김태홍;이종열;권영호
    • Proceedings of the Korea Concrete Institute Conference
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    • 2000.10b
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    • pp.1175-1180
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    • 2000
  • Recently, the crack of concrete induced by the heat of hydration of cement is a serious problem for more greater, special and higher strength of concrete structures. The increasing concrete's temperature is mainly caused by the heat of hydration of cement and so, to control the thermal stress of concrete structure is desirable to use low heater material of hydration. There are many methods to diminish the increasing of concrete temperature such as using of low heat cement, addition of fly-ash, application of pre-cooling, etc., and in this study, we evaluate the heating and mechanical properties of ultra low heat mass concrete using Low Heat Portland(KS Type IV) cement with 30% of limestone powder. The results of this study will be applied to side wall and bottom of No. 15 and 16 of underground LNG tank in Inchon.

The Analysis of Cracks in PSC Girder Using High Flowing Concrete (고유동 콘크리트를 사용한 PSC 거더 균열 분석)

  • Lho, Byeong Cheol;Ahn, Gwang Su;Kwak, Kil Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.3
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    • pp.126-135
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    • 2013
  • Recently, mass concrete with high flowability are widely used to improve the quality and constructability in the longer span construction of prestressed concrete bridges, but it may induce nonstructural cracks due to the hydration heat and autogenous shrinkage etc. The stresses in concrete were evaluated by various experiments and numerical analysis. The tensile stress in mass concrete was increased in connection with the accumulation of hydration heat. Moreover, large amount of autogenous shrinkage from powder type admixture could add the tensile stress to mass concrete near anchorage zone. The tensile stresses in anchorage zone by heat and autogenous shrinkage exceeded the tensile strength of early stage of concrete, and small amounts of stress increasement were shown in other parts of PSC girder.

Control of Thermal Crack in Mass Concrete Using Automated Curing System (양생자동화 시스템을 이용한 매스 콘크리트 온도균열 제어)

  • Ha, Ju-Hyung;Cho, Yun-Gu;Hyun, Tae-Yang;Lim, Chang-Keun;Seo, Tae-Seok
    • Journal of the Korea Concrete Institute
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    • v.25 no.2
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    • pp.195-200
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    • 2013
  • New thermal crack control system for mass concrete was developed to increase quality and to save construction period and cost. The principle of this system is that the curing water having proper temperature is supplied automatically to the surface of mass concrete member to keep the temperature difference between center and surface of concrete less than generally recommended temperature difference ($20^{\circ}C$). Mock-up test was conducted to investigate the validity of newly developed curing system. As a result, no crack was founded in the specimen using automated curing system developed in this study, while many cracks occurred in another specimen without automated curing system. It was also confirmed that the strength and the durability of the concrete cured by automated curing system were improved.