• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.189-190
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• 2023

In this study, the compressive strength and hydration heat of cement paste mixed with cellulose nanocrystal(CNC) and graphene oxide (GO) were evaluated. The difference was compared by mixing 0.1 vol.% ~0.4 vol.% of CNC and 0.05 wt.% ~ 0.1 wt.% of GO in a cement paste with a water cement ratio of 0.3. As a result, it was confirmed that the compressive strength increased as CNC and GO were mixed respectively, and then the compressive strength decreased when the appropriate mixing rate was exceeded. In the hydration heat measurement, there was no significant difference when only CNC was mixed, but it was confirmed that the hydration heat decreased as the amount of CNC mixing increased when used in combination with GO.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.469-474
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• 2001

Mass concrete is placed considering placing lifts in order to reduce thermal cracks by hydration heat. But they results in cold joint between placing lifts, which bring about the loss of strength, water tightness and undesirable appearance. Therefore, in this paper, mechanical and hydration heat of mass concrete using super retarding agent developed through previous study are investigated in order to reduce the hydration heat and place it without place lift. According to test results, placing lifts combined with normal concrete and concrete containing super retarding agent have positive effects on reducing hydration heat. Especially, the crack index by thermal stress of the concrete containing super retarding agent less than a quarter, compared to that of plain concrete without placing lifts, and less than a half, compared to that of plain concrete with placing lifts.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.515-520
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• 2001

Mass concrete is placed considering placing lifts in order to reduce thermal cracks by hydration heat. But they results in cold joint between placing lifts, which bring about the loss of strength, water tightness and undesirable appearance. Therefore, in this paper, mechanical and hydration heat of mass concrete using super retarding agent developed through previous study are investigated in order to reduce the hydration heat and place it without place lift. According to test results, placing lifts combined with normal concrete and concrete containing super retarding agent have positive effects on reducing hydration heat. Especially, the crack index by thermal stress of the concrete containing super retarding agent less than a quarter, compared to that of plain concrete without placing lifts, and less than a half, compared to that of plain concrete with placing lifts.

• Journal of the Korea Institute of Building Construction
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• v.3 no.3
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• pp.135-142
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• 2003

This study is for the great quantity use of fly-ash. For the producing of high volume concrete from the use of fly-ash, the method of replacement between bonding agents and fine aggregate by fly-ash was used at the same time. It was used that the adiabatic temperature rise of concrete about the mass member which had been produced by the method that was mentioned before, and the hydration heat of the core test pieces in concrete was measured. Also the core test pieces which were replaced with fly-ash was studied by the compressive strength's comparison between standard care test pieces and core test pieces. In the case of mass test pieces, hydration heat and the time to reach the highest temperature were decreased by an increase in replaced fly-ash's amounts of concrete. In addition, among the test pieces having the same amounts of concrete, the test pieces having more replaced amounts of fly-ash's fine aggregate showed higher hydration heat and the increased time to reach the highest temperature. Compressive strength was also increased by hydration heat's decrease according to fly-ash replacement. Replacement of fly-ash was more effective in high temperature environment.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.67-71
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• 2003

This study is for the great quantity use of fly-ash. For the producing of high volume concrete from the use of fly-ash, the method of replacement between bonding agents and fine aggregate by fly-ash at the same time was used. It was used that the adiabatic temperature rise of concrete about the mass member which bad been produced by the method that was mentioned before, and the hydration heat of the core test pieces in concrete was measured. Also the core test pieces which were replaced with fly-ash was studied by the compressive streneth's comparison between standard care test pieces and core test pieces. In the case of mass test pieces, hydration heat and the tine to reach the highest temperature were decreased by an increase in replaced fly-ash's amounts of concrete. In addition, among the test pieces having the same amounts of concrete, the test pieces having more replaced amounts of fly-ash's fine aggregate showed higher hydration heat and the increased time to reach the highest temperature. Compressive strength was also increased by hydration heat's decrease according to fly-ash replacement. Replacement of fly-ash was more effective in high temperature environment.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.128-131
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• 2004

This paper is to investigate the mock up test results of mass concrete for transfer girder using setting time difference with super retarding agent(SRA) to reduce hydration heat. According to test results, the temperature history of plain concrete without placing lift had a steep rising curvature, and plain concrete had a big temperature difference between surface and middle section of mass concrete, which may result in occurrence of temperature crack. However, considering placing method B, because setting time of middle section concrete was retarded with an increase in SRA contents, higher hydration heat temperature was observed at surface section concrete compared with that at middle section concrete at early age, which can lower the possibility of hydration heat crack. In case of placing method C, although peak temperature of hydration heat was much lower, at early age, high crack occurrence possibility of the hydration heat attributable to the big temperature difference between middle section and bottom section of concrete was expected at bottom section concrete. Therefore, the structure above the ground like transfer girder is not applicable to consider the placing method C.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.235-236
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• 2021

This study evaluated temperature distribution through adiabatic temperature rising test and hydration heat Analysis as a performance verification to utilize CGS as a hydration heat reduction material for mass concrete when replacing it with fine aggregate. According to the analysis, the temperature difference between the center and the surface was the highest at about 30℃, followed by the CGS 50% at 26℃ and the low heat combiner FA 30% at 23℃.

• Journal of the Korea Concrete Institute
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• v.20 no.2
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• pp.157-164
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• 2008

In order to raise efficiency in construction, construction period, construction costs etc. that have been problematic in the methods of hydration heat reduction thus far, this study has developed a new method. The principle of the developed construction method involves the laying of a heat conducting medium such as the heat pipe in the concrete, and through the fast conduction of heat by the heat pipe, the hydration heat occurring within the mass concrete is transferred to the exterior by which the internal hydration heat is reduced. If the study results of the onsite test are summarized, on application of existing hydration heat reduction methods, the highest temperature was reached in about 2$\sim$4 days, but when the heat pipe of this study was used, the period was reduced to within 24 hours. Moreover, when the thermal crack index was calculated with the method using the heat pipe as developed in this study, a value of 1.2 or higher was revealed, which is a level that can restrict the occurrence of cracks. Therefore, when the hydration heat control method using the heat pipe as developed in this study is applied, not only the effects of construction efficiency and reduction in construction period, but also outstanding economical effects can be expected.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5A
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• pp.531-541
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• 2009

The research analyzes and investigates conventional concrete, hydration heat, set, and mechanical properties by making high flowing self-compacting concretes of binary blend and ternary blend as one of evaluations about the properties of the hydration heat of high flowing self-compacting concrete with a strength of 30, 50, and 70 MPa. In addition, it estimates concrete adiabatic temperatures by calculating a thermal property value of powder obtained by measuring a heat evolution amount for powder used in concrete, a thermal property value of concrete obtained by conducting a simple adiabatic temperature test, and a normal thermal property value of material used in concrete, using a simple equation. Moreover, it analyzes and investigates the hydration heat property of high flowing self-compacting concrete and the thermal stress caused by hydration heat by conducting a 3D temperature stress analysis for the hydration heat and the adiabatic temperature obtained by temperature analysis, using MIDAS CIVIL 06 program.

• Magazine of the Korea Concrete Institute
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• v.7 no.1
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• pp.97-108
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• 1995