• 한국도로학회논문집
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• 제11권2호
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• pp.229-238
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• 2009

본 연구에서는 콘크리트지하차도 시공 시 수화열에 의한 열응력 분포 특성을 분석하여 시공 재료와 시공 과정에 따른 균열 발생 여부를 분석하여 설계 시에 균열을 억제할 수 있는 재료 특성과 시공 단계를 제시하는 방법에 대하여 연구하였다. 이러한 분석을 위해 열전달 이론을 도입하여 지하차도의 3차원 유한요소해석 모델을 개발하여 구조해석을 수행하였다. 1회 타설하는 콘크리트 부재의 부피가 지나치게 크면 매스콘크리트가 되기 때문에 수화열에 의한 균열이 발생하기 쉬우며 이러한 균열을 억제할 수 있는 방법으로는 크게 시공 단계를 적절하게 배치하는 것과 또는 이러한 균열을 방지 할 수 있도록 재료 특성을 바꾸어 시공하는 것으로 구분할 수 있다. 따라서 본 연구에서는 이를 위해 콘크리트 재료 성질의 시간에 따른 변화 특성 시멘트 종류 및 첨가제 유무에 따른 수화열 발생 특성, 시공 단계에 따른 구조물의 크기, 외부 환경조건 등을 고려하여 분석을 수행하였다.

• 한국식품영양학회지
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• 제27권2호
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• pp.294-301
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• 2014

Rice (Oryza sativa L.) is one of the most important staple foods in Korea and the consumption of brown rice is increasing annually. The objective of this study is to investigate the physicochemical, hydration and textural properties related to eating quality of cooked brown rice by using glutinous, semi-glutinous, four non-glutinous and four colored varieties. The moisture, protein and total dietary fiber contents of brown rice are shown in the range of 11.1~12.6%, 6.6~8.7% and 6.28~12.40%, respectively. The amount of water uptakes for brown rice during the hydration has shown significant differences. The glutinous variety of Boseogchal indicate the highest water absorption levels by reaching $0.38gH_2O/g$. The hardness of hydration for Seolgaeng is distinctively lower than those of the other brown rice varieties. According to the textural characteristics of cooked brown rice when using the Tensipresser, the hardness of Boseogchal, Baegjinju and Seolgaeng all exhibit the lowest values out of ten varieties and the highest levels of adhesiveness.

• 콘크리트학회논문집
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• 제28권6호
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• pp.665-672
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• 2016

본 연구는 상전이물질이 시멘트 모르타르의 수화특성 및 강도특성에 미치는 영향을 평가하기 위하여 실시되었다. 이를 위하여 바륨 및 스트론튬계 상전이물질을 사용하였으며, 상전이물질 혼입률 1~5%에 대한 실험을 수행하였으며, 시멘트 모르타르 작업성 평가, 간이단열온도상승 실험, 압축 및 휨 강도 평가를 실시하였다. 실험결과 상전이물질의 혼입은 시멘트 모르타르의 수화열 감소에 효과적인 것으로 나타났으며, 바륨 기반 PCM을 사용할 경우 흐름성능이 다소 감소하는 것으로 나타났다. 압축 휨 강도의 경우 상전이물질의 혼입률이 증가함에 따라 감소하는 경향을 나타내었으며, PCM을 사용할 경우 혼입률에 따라 압축강도 발현추이의 변화가 발생하였다. 따라서 본 연구에서는 상전이물질이 혼입률에 따른 압축강도 추정식을 제시하였다.

• 대한건축학회논문집:구조계
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• 제35권10호
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• pp.207-215
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• 2019

The aim of the research is analyzing the simple adiabatic temperature rising properties and the heat of hydration based on different placing timing of the mass concrete depending on various replacing ratios of blast furnace slag to comparative analyze the thermal cracking index and cracking possibility. As a result from the experiment, a suggested adiabatic temperature rising equation based on various blast furnace slag replacing ratios can be provide favorable correlation with over 0.99 of $R^2$ value by applying the initial induction period. With this relationship, more accurate prediction of the amount of the hydration heat rising and heating timing, and it is known that there is an approximately $13.1^{\circ}C$ of gap between plain concrete without blast furnace slag and concrete with 80 % of replacing blast furnace slag. To control the setting time and heat rising gap, the mix designs between top and bottom concrete casts were changed 15 cases, and D, E, H, I, and L models of controlling the heat of hydration showed 41.23 to $46.88^{\circ}C$ of core temperature and 0.98 to 1.27 of thermal cracking index. Therefore the cracking possibility was 15 to 52 % of favorable results of possibly controlling both the cracking due to the internal and external retainment and concrete temperature at early age.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.612-615
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• 2004

The objective of this experimental study was to understand inelastic strain of concrete incorporating hwangtoh or combination of hwangtoh and slag. Main variables were replacement level of admixtures, hwangtoh and slag. We studied the properties of concrete such as heat of hydration, drying shrinkage and creep according to the replacement level of hwangtoh and slag. Test results showed that the heat of hydration of concrete decrease with increasing hwangtoh and slag replacement. Also drying shrinkage and creep of concrete increase with increasing hwangtoh replacement.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.147-152
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• 1999

The purpose of this study is to offer foundmental information of fly ash concrete for field application. Through before study of fly ash concrete, various properties were checked. but when fly ash was added In concrete, entrained air quantity was decreased as fly ash substitution is increased in fresh concrete. so entrained air(below AE) quantity and a kind of AE according to fly ash substitution was tested basic properties. Also water-reducing efficiency was tested. And hydration heat according to fly ash substitution was tested by KR-100. As result of test, according to fly ash substitution increase, entrained air quantity is increase for target entrained air quantity, water-reducing efficiency and hydration heat are positive.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.683-686
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• 2005

This paper is related to investigate adding effect of fluorine-silicate hybrid type crack controlling agent(FS) on initial behavior, dynamic properties, adibatic hydration temp, and plastic crack behavior of concrete(Specification : 25-30-18). It is appeared that adding of FS contributed to strength elevation, lowering of hydration temperature as well as plastic crack reduction without disturbance of initial behaviors of concrete such as slump, air content and setting.

• The Korean Journal of Ceramics
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• 제3권4호
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• pp.235-238
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• 1997

Basic properties of new cement pastes based on the system $CaO-Al_2O_3-P_O_5-H_2O$were studied Phosphoric acid solutions and calcium dialuminate clinkers synthesized by the hydration-burning method were used for liquid and powder components of the paste, respectively Variation in the compositions of the paste was achieved by changing the liquid/powder ratio and the concentration of phosphoric acid solution. The hardening rate of the paste was so largely affected by the amount of phosphoric acid that hardening was inhibited with the low-concentrated solution but was explosively accelerated with the high-concentrated solution. The phosphoric acid solutions of concentration of 45~50% and the liquid/powder ratio of 0.5~1.5 were favoured for the high early-strength cement paste with the reasonable hardening rate and high strength. The binding phase of hardened paste was the dense amorphous gel of the system $CaO-Al_2O_3-P_O_5-H_2O$. in which the unreacted calcium dialuminate grains were embeded.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
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• pp.203-204
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• 2010

수축저감 특성을 갖는 관능 그룹이 도입된 폴리카복실레이트계 고유동화제를 합성하였고, DSC 분석을 통해 시멘트 계 내에서 합성된 수축저감형 고유동화제에 대한 수화반응 거동을 확인하였다. 또한 기존 폴리카복실레이트계 고유동화 및 본 연구에서 합성된 수축저감형 고유동화제의 콘크리트 적용 성능을 평가하였고, 길이변화 시험 및 링테스트(ASTM C 1581-04) 방법을 활용하여 균열의 정량분석을 실시하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
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• pp.259-260
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• 2010

본 연구는 저발열 콘크리트의 적용성 검토를 위한 기초적 시험으로서, 각각의 배합조건 및 규격별 물리적 성질 및 수화열 저감특성을 알아보고자 하였다.