• 한국구조물진단유지관리공학회 논문집
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• 제15권5호
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• pp.218-226
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• 2011

본 연구에서는 스트론튬계 잠열재를 사용한 저발열 콘크리트를 레미콘 배처플랜트에서 시험생산한 후 생산된 콘크리트의 기초성능 및 모의부재에 의한 수화온도 특성을 평가하였으며, 그 결과 스트론튬계 잠열재를 사용한 저발열 콘크리트의 현장적용 가능성을 확인하였다. 이후 스트론튬계 잠열재를 사용한 콘크리트를 실제 교각 건설현장에 적용하였으며, 적용부재에 대한 수화열 해석 및 타설 콘크리트의 성능평가 결과 수화열 및 온도균열 저감효과가 우수한 것으로 나타나, 향후 대형 매스콘크리트의 수화열 및 온도균열 저감대책으로서 활용이 기대된다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
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• pp.105-106
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• 2019

In this research, considering the practical conditions at field, thermal cracking method was suggested based on the comparative analysis between predicted value and actual value obtained from the actual structure member with optimum mix design. The optimum mix design was deduced from the various mix designs with various proportions of cementitious binder for upper and lower placement lifts of mat-foundation mass concrete. Therefore, it can be stated that applying low heat mix design and different heating technique between upper and lower placement lifts for mass concrete are efficient to control the thermal cracking. As future issues, based on the interpretation result value, we will select the optimal combination that is applied specifically to the actual site, and deeply analyze the correlation between the measured value and the analysis value through the combination and the test of the actual structure.

• 토지주택연구
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• 제3권1호
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• pp.83-88
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• 2012

In this study, physical characteristics of cement and/or concrete materials that are typically used for energy-foundation (EF) structures have been studied. The thermal conductivity and structural integrity of the cement-based materials were examined, which are commonly encountered in backfilling a vertical ground heat exchangers, cast-in-place concrete piles and concrete lining in tunnel. For this purpose the thermal conductivity and unconfined compression strength of cement-based materials with various curing conditions were experimentally estimated and compared. Hydration heat generated from massive concrete in the cast-in-place concrete energy pile was observed for 4 weeks to estimate its dissipation time in the underground. The hydration heat may mask the in-situ thermal response test (TRT) result performed in the cast-in-place concrete energy pile. It is concluded that at least two weeks are needed to dissipate the hydration heat in this case. In addition, a series of numerical analysis was performed to compare the effect of thermal property of the concrete material on the cast-in-place pile.

• 한국건설순환자원학회논문집
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• 제2권1호
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• pp.10-18
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• 2014

본 연구에서는 시멘트와 광물질혼화재인 고로슬래그미분말과 플라이애쉬를 미리 혼입한 Premixed Cement를 사용한 콘크리트와 수축저감제가 혼입된 3성분계 콘크리트, OPC 100%의 콘크리트에 대하여 기초물성 평가로 공기량, 슬럼프, 압축강도 및 건조수축 시험을 수행하고, 수화열 해석을 수행하여 Premixed Cement를 사용한 콘크리트의 현장 적용성을 검토하였다. 검토결과 Premixed Cement를 사용한 콘크리트는 목표 작업성 및 설계기준압축강도를 충분히 만족하며, 건조수축 측면에서도 수축 저감제를 혼입한 3성분계 콘크리트와 유사한 건조수축 특성을 나타내었다. 또한, 수화열 해석 결과 Premixed Cement를 사용한 콘크리트는 목표 온도균열지수를 충분히 확보할 뿐만 아니라, 수축 저감제를 혼입한 3성분계 콘크리트보다 경제성을 확보할 수 있는 방안으로 도출되었다. 향후 매스콘크리트구조물 시공에 있어 구조물의 내구성능 및 유지관리 편의성 향상을 위해 Premixed Cement를 사용한 콘크리트의 현장적용은 바람직한 것으로 판단된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.789-794
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• 2002

The relationship is investigated between material modeling of concrete and the evaluation procedure of thermal stress by the hydration heat. In this respect, some important points are suggested to which special attention should be paid to reasonably evaluate the thermal stress using the widely-used structural analysis programs. This study indicates that proper material model should be used to draw incremental stress evaluation that takes into account the change of elastic modulus with time. Some correction techniques are also presented when using the program that don't have proper built-in procedure for the calculation of the thermal stress.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
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• pp.36-37
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• 2019

In domestic construction industry progress, construction and quality control of large structures are considered to be important as the superstructure and mass scale of structures. In the case of mass concrete, high hydration heat caused by cement hydration generates temperature stress by generating internal temperature difference with the concrete surface. These temperature stresses cause cracks to penetrate the concrete structure. A method of lowering the heat generation by incorporating Urea in order to reduce the concrete temperature crack has been proposed. In this study, the heat function coefficient for the FEM temperature crack analysis of the mass concrete containing the element was derived and the adiabatic temperature rise test was carried out according to the incorporation of the element. As a result of this experiment, the maximum temperature of 41 ± 1℃ was obtained irrespective of the amount of urea, and the maximum temperature decreased by 16.9℃ in concrete containing 40kg/㎥ of urea.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 추계 학술논문 발표대회
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• pp.31-36
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• 2008

This study aims to examine the effects of thickness of the concrete members and curing temperature on the properties of low heat concrete through heat of hydration analysis. Type of the members that was analyzed in the experiment is ternary mixture of ordinary portland cement, blast-furnace slag incorporating ratio(20%) and fly ash incorporating ratio(30%), which formed a mat foundation. Thicknesses of the concrete members were 1, 2 and 3(m) and three levels of curing temperatures were 10, 20 and 30(℃). They were applied to analyze the effects on the temperature and thermal cracking index. As a result, for temperature history, temperature difference between the central area and the surface tended to decrease as the thickness of the concrete members get thinner. For the temperature cracking index, on the other hand, the risk of cracking tended to decrease as the curing temperature gets higher and as the thickness gets thinner.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 추계 학술논문 발표대회
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• pp.13-14
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• 2014

Ultra high performance concrete (UHPC) consists of cement, silica fume (SF), sand, fibers, water and superplasticizer. Typical water/binder-ratios are 0.15-0.20 with 20-30% of silica fume. The development off properties of hardening UHPC relates with both hydration of cement and pozzolanic reaction of silicafume. In this paper, by considering the production of calcium hydroxide in cement hydration and its consumption in the pozzolanic reaction, a numerical model is proposed to simulate the hydration of UHPC. The degree of hydration of cement and degree of reaction of silica fume are obtained as accompanied results from the proposed hydration model. The properties of hardening UHPC, such as degree of hydration of cement, calcium hydroxide contents, and compressive strength, are predicted from the contribution of cement hydration and pozzolanic reaction. The proposed model is verified through experimental data on concrete with different water-to-binder ratios and silica fume substitution ratios.

• 한국컴퓨터산업학회논문지
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• 제9권3호
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• pp.99-104
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• 2008

매스콘크리트에서 수화열에 의한 응력은 외기온도와 콘크리트의 타설온도에 따라 변하므로 이들의 영향을 고려한 해석이 필요하다. 본 연구에서는 교각의 코핑부를 대상으로 해석을 수행하여 분석하였다. 최대 인장응력은 타설 후 2.75일을 전후하여 표면 모서리부에서 발생하며 균열지수는 계속 증가하여 균열 발생 가능성은 거의 없는 것으로 나타났다. 그리고 계절에 관계없이 콘크리트의 타설온도를 낮추면 수화열에 의한 균열 발생 가능성을 줄일 수 있는 것으로 나타났다. 따라서 콘크리트를 타설하기 전에 타설온도를 낮추기 위한 여러 가지 방안을 강구하면 수화열에 의한 균열을 최소화할 수 있다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.35-40
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• 2002

This paper presents a numerical study on the heat of hydration of reinforced concrete with different steel ratio. And this study intends to determine the effect of the steel on the variation of temperatures during hydration. In order to do this, the thermal analyses of the pier-foundation models were carried out using the finite element analysis program, ADINA. As the steel rate increased, the maximum temperature and the internal-external temperature difference decreased.