• Title/Summary/Keyword: 고온강도특성

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Manufacture of melting temperature controllable modified sulfur (MS) and its application to MS concrete (융점 제어형 개질유황의 개발 및 이를 활용한 콘크리트의 특성 연구)

  • Kim, Jin-Hee;Choi, Jin Sub;Park, No Hyung
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.24 no.6
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    • pp.261-267
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    • 2014
  • In this study, we manufactured melting temperature controllable modified surfur (MS) and studied the properties of sulfur modified cement concrete (SMC). We investigated the effects of sulfur and pyridine content on melting temperature of MS. The reaction is confirmed by measuring Raman spectrophotoscopy. The SMC was produced at Water (W)/Cement (C) = 45 wt%, Sand (S)/Aggregate (A) = 45 wt% and 5, 10, 15 and 20 % of MS on the basis of conventional portland cement, respectively. And then physical properties such as compressive strength, splitting tensile strength and permeability of SMC were measured. As MS added, permeability was decreased, while strength and spalling properties were improved. To confirm the safety of MS and SMC, pyrolyzed gas chromatography (P-GC) and gas hazard test were conducted. The results showed that MS and SMC were relatively safe at an elevated temperature.

An Experimental Study on the Thermal Property of Concrete under the Load Ratio Condition in Fire (고온화재조건 콘크리트 라이닝의 하중비에 따른 폭렬영향성 및 화재손상특성에 관한 실험적 연구)

  • Kim, Hyung-Jun;Kim, Heung-Youl;Park, Kyung-Hun;Ahn, Chan-Sol;Kwon, Ki-Hyuk
    • Fire Science and Engineering
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    • v.24 no.3
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    • pp.145-151
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    • 2010
  • The fire in tunnel, when failed to extinguish at early stage, tends to easily develop to high temperature and spread to entire area of the tunnel because of considerable level of fire load and smoke control facility within the tunnel, resulting in severe damage to the people and tunnel structure. This study was intended to carry out the fire test with MHC fire curve, a scenario, which has the most rapid fire rise, on assumption of load ratio of 1, 20, 40, 60 and 70%, so as to identify the thermal characteristics of the concrete against spalling and the range of fire damage. The specimen was small scale sample as defined by EFNARC and the mixing ratio was based on 24 MPa, which is considered to be the normal strength. As a result of test, 16mm spalling was occurred on the lining under the non-load condition, while no spalling was occurred with 20% and 40% of load ratio. In case of 60% of load ratio, 24 mm of spalling was occurred and it failed in 10 minutes after heating in case of 70% load condition.

A Study on the Hydration and Strength of Accelerated Curing Concrete (가열양생(加熱養生) 콘크리트의 수화(水和) 및 강도(强度)에 관한 연구(研究))

  • Shin, Hyun Mook;Jeon, Chan Ki;Nam, In
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.7 no.3
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    • pp.203-212
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    • 1987
  • The hydration and strength of concrete are affected by curing conditions, especially curing temperature. In this paper, the hydration temperature of heated curing concrete specimen are measured by thermo-couples instead of conduction calorimeter, and strengths of concrete are tested. The results of this study show that the compressive strengths of concrete are especially dependent on the curing temperature. And the strength results of concrete agree approximately with the results of approach to the hydration process of cement concrete.

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Evaluation on Thermal Strain Behavior Properties of Ultra High Strength Concrete considering Load (하중재하조건을 고려한 초고강도 콘크리트의 열변형거동특성 평가)

  • Lee, Young-Wook;Kim, Gyu-Yong;Choe, Gyeong-Cheol;Kim, Hong-Seop;Lee, Bo-Kyeong;Yoon, Min-Ho
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2015.11a
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    • pp.162-163
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    • 2015
  • Thermal deformation behavior of high-strength concrete (HSC) exposed to fire is different from that of normal strength concrete (NSC). In case of ultra-high-strength concrete (UHSC), it is well known that thermal deformation behavior is greater than HSC. With increasing research of UHSC in buildings, it is necessary to understand the performance of UHSC at elevated temperatures considering loading condition. Therefore, evaluation on properties of thermal strain behavior properties of ultra high strength concrete by loading and high temperature was conducted.

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SA106 Gr.C 모재와 용접재의 파괴인성에 미치는 온도와 하중속도의 영향

  • 김진원;박치용;김범년;김인섭
    • Proceedings of the Korean Nuclear Society Conference
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    • 1998.05b
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    • pp.324-329
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    • 1998
  • 본 연구는 주증기배관으로 사용되고 있는 SA106. Gr.C의 모재와 용접계에 대해서 파괴인성에 미치는 온도와 하중속도의 영향을 살펴보기 위해서 다양한 온도와 하중속도에서 J-R 시험 및 인장시험을 수행하였다. 두 재료 모두 동적변형시효의 영향을 받고 있는 온도영역에서 약 40% 정도의 파괴인성 감소가 관찰되었으며, 하중속도에 따른 파괴인성 감소영역은 serration과 인장강도 증가 영역의 하중속도 의존성과 일치하였다. 원자력발전소 운전온도에서 모재와 용접재 모두 하중선변위속도가 4.0mm/min 일 때 파괴인성치의 최저를 보였으며, 하중속도가 증가함에 따라 증가하여 동적하중속도(800, 40mm/min)일 때 최대를 보였다. 모재와 용접재를 비교하면 용접재에서 serration이 뚜렸했고, 보다 넓은 온도영역에서 관찰되었다. 또한 인장강도의 증가가 보다 고온에서 형성되었다. 이러한 특성은 용접재가 모재에 비해 냉각률이 크고 미세한 결정입으로 이루어져있으며, 망간의 함량이 높기 때문으로 판단된다.

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High Temperature Deformation Behavior of Fe-base High Strength Alloys (고강도 Fe계 합금의 고온 변형 특성)

  • Kwon, Woon-Hyun;Choi, Il-Dong
    • Journal of Advanced Marine Engineering and Technology
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    • v.32 no.6
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    • pp.938-946
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    • 2008
  • Fe-base amorphous alloy and two crystalline phases composite were fabricated. The effect of temperature and strain rate on mechanical properties was evaluated utilizing compression test. Mixture of non-crystalline and crystalline phases were found using X-ray diffraction (XRD) and differential thermal analysis (DTA) tests. Based on glass transition temperature and crystallization temperature. compression tests were performed in the temperature ranging from $560^{\circ}C$ to $700^{\circ}C$ with $20^{\circ}C$ interval. Relationship between microstructure, including fracture surface morphology, and mechanical behavior was studied. The peak stress of Fe-base amorphous alloy was over 2GPa and expected to have a good wear resistance, but it is expected hard to deform because of low ductility. The peak stress and elongation of two crystalline phases composite was over 1GPa and about 20%, therefore it is possible to deform high strength wear resistant materials such as engine valve.

A Experimental Study on the Two Sides Heating of High Strength Concrete Flexural Member Exposed to High Temperature (고온에 노출된 고강도콘크리트 휨부재의 2면가열에 관한 실험적 연구)

  • Kim, Dong-Jun;Kang, Seung-Goo;Lee, Jae-Young;Harada, Kazunori;Kwon, Young-Jin
    • Proceedings of the Korea Institute of Fire Science and Engineering Conference
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    • 2012.04a
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    • pp.290-293
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    • 2012
  • 화재는 콘크리트 구조물의 역학적 특성에 치명적 손상을 일으켜 건축물의 안전성을 급격하게 감소시킬 수 있다. 특히 고강도콘크리트는 폭렬이 발생하여 심각한 단면 손실과 노출된 철근으로 인하여 건축물의 안전성에 치명적인 영향을 미친다. 이러한 폭렬에 대하여 다양한 연구가 진행되고 있지만, 폭렬의 발생원인은 명백하게 밝혀지진 않았다. 이에 본 연구는 콘크리트의 함수율과 열응력이 폭렬에 미치는 영향을 분석하여 폭렬로부터 구조물의 안전성을 확보하기 위한 기초 자료를 제시하였다.

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Evaluation on Thermal Strain Behavior Properties of Ultra High Strength Concrete considering Load (하중재하조건을 고려한 초고강도 콘크리트의 열변형거동특성 평가)

  • Lee, Young-Wook;Kim, Gyu-Yong;Choe, Gyeong-Cheol;Kim, Hong-Seop;Lee, Bo-Kyeong;Yoon, Min-Ho
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2015.05a
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    • pp.80-81
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    • 2015
  • Thermal deformation behavior of high-strength concrete (HSC) exposed to fire is different from that of normal strength concrete (NSC). In case of ultra-high-strength concrete (UHSC), it is well known that thermal deformation behavior is greater than HSC. With increasing research of UHSC in buildings, it is necessary to understand the performance of UHSC at elevated temperatures considering loading condition. Therefore, evaluation on properties of thermal strain behavior properties of ultra high strength concrete by loading and high temperature was conducted.

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Evaluation of Laboratory Performance Characteristics of Fiber-Reinforced Asphalt Concrete (섬유활용 아스팔트 콘크리트의 실험적 공용특성평가)

  • Kim, Nak-Seok
    • Journal of the Korean Society of Hazard Mitigation
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    • v.2 no.2 s.5
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    • pp.61-72
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    • 2002
  • The optimum fiber and asphalt binder contents were decided on the base of the Mashall mix design method. To compare the mechanical characteristics between the conventional(dense-graded 20) and the fiber-reinforced mixtures, indirect tension tests were conducted under three temperatures(5, 20, 60$^{\circ}C$). In particular, the wheel tracking tests were performed to evaluate the rutting resistances of the mixtures. Test results showed that the indirect tensile strength of fiber-reinforced asphalt concrete was higher than that of conventional one. The toughness of fiber-reinforced mixture was 1.27 to 1.97 times higher than that of conventional one, depending upon the temperature. In addition, the results of wheel tracking tests and the retained indirect splitting tension tests conducted at $60^{\circ}C$ revealed that the resistance to permanent deformation of fiber-reinforced mixture was stronger than that of the conventional one.

An Experimental Study on the Mechanical Properties of Concrete with High Temperatures and Cooling Conditions (고온 및 냉각조건에 따른 콘크리트의 역학적특성에 관한 실험적 연구)

  • Kim, Gyu-Yong;Kang, Yeoun-Woo;Lee, Tae-Gyu;Choe, Gyeong-Cheol;Yoon, Min-Ho
    • Journal of the Korea Institute of Building Construction
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    • v.12 no.3
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    • pp.323-331
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    • 2012
  • Since the 1970s, the mechanical properties of concrete at high temperature, such as compressive strength, elastic modulus, thermal strain, etc. have been investigated. Internal and external factors should be effect to concrete elevated temperature. In particular, the thermal properties of aggregate and cooling conditions are most important to estimate residual mechanical properties. This study evaluates the mechanical properties of concrete with aggregate type and cooling methods. We use normal and light aggregate for different thermal properties, and also test mechanical properties to use ${\O}100{\times}200$ mm cylinder specimen according to target temperature, slow cooling and water cooling. We found that normal aggregate concrete that uses is more highly influenced by cooling conditions than concrete that uses light aggregate concrete. In addition, the residual mechanical properties of concrete increase as cooling velocity lowers.