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

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
• /
• pp.618-621
• /
• 2006

This paper is to investigate temperature history of cold weather concrete depending on insulation curing sheet kinds. Insulating effect according to curing sheet is shown in order of 5 layer bubble sheet, combination of PE form and 3 layer bubble sheet and 3 layer bubble sheet. It maintained above $10^{\circ}C$ of minimum temperature until the completion of initial curing period when bubble curing sheet was supplied regardless of curing sheet kinds. Five layer bubble curing sheet secure higher curing temperature than any other curing sheet applied in this experiment by as much as $2{\sim}3^{\circ}C$, which performed remarkable insulation effect. Concrete applied with curing sheet secured above $65^{\circ}D{\cdot}D$ of maturity, at which concrete had 5MPa of compressive strength at 3 days.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
• /
• pp.11-12
• /
• 2017

This study aims to analyze the properties of the temperature change in vertical reinforcements in outdoor wall structures in winter in relation to the different methods of bubble sheet installation, and to subsequently determine the possibility of initial frost damage to the concrete as a result of low temperature. As for the experimental variables, double bubble sheets were used as curing materials, and the curing method was to model the part where the slab and the wall intersect and the rebar is exposed, and to measure the change of temperature around the exposed rebar in accordance with the change of the coating curing. It was found that by employing curing method B, which is to install the bubble sheet between the vertical reinforcements, the most vulnerable area, which is 50mm below(④) the surface of the concrete, would be lowered to sub-zero temperature 20 hours later than when using curing method A, and that therefore it is more effective to install the bubble sheet between the vertical reinforcements for the prevention of initial frost damage.

• International Journal of Concrete Structures and Materials
• /
• 제19권1E호
• /
• pp.33-39
• /
• 2007

The magnitude and distribution of hydration heat of concrete structures are related to the thermal properties of each component of the concrete, the initial temperature, the type of formwork, and the ambient temperature of exposed surfaces. Even though the reinforcing steel bar has completely different thermal properties, it has been excluded in the thermal analysis of the concrete structures for uncertain reasons. In this study, finite element analysis was performed on the concrete structures reinforced with steel bars in order to investigate the effect of reinforcing steel bars on the temperature and stress distribution due to the heat of hydration. As the steel content increased, the maximum temperature and the difference in the internal-external temperature decreased by 32.5% and 10.0%, respectively. It is clearly shown that the consideration of the influence of reinforcing steel bars in the heat of hydration analysis is necessary to obtain realistic solutions for the prediction of the maximum temperature and stresses of concrete structures.

• 대한토목학회논문집
• /
• 제35권1호
• /
• pp.129-139
• /
• 2015

차수기능을 점토 코아 대신 상류사면의 콘크리트 슬래브로 수행하는 콘크리트 표면차수벽형 석괴댐의 설계는 이론보다는 사례와 경험에 크게 의존한다. 본 연구에서는 두 개의 CFRDs에서 준공 후 초기 담수기간에 계측된 데이터를 근거로 콘크리트 슬래브와 누수량 거동을 분석하였다. 분석결과 슬래브의 변형률과 수직이음부의 수평변위는 미미하게 계절적인 온도 변화와 저수위면 증가에 의한 담수하중의 영향을 받고, 주변이음부의 변형은 온도 변화의 영향은 미미하고 담수하중의 영향을 크게 받는 것으로 나타났다. 그리고 누수량은 담수하중에 따른 주변이음부의 변형에 의한 영향을 크게 받는 것으로 나타났다.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2008년도 추계 학술논문 발표대회
• /
• pp.21-25
• /
• 2008

In this paper, the temperature history and the strength development of concrete corresponded to various bubble sheets layer and curing temperature. Based on the results, In case of the test temperature of -5℃, concrete subject in the exposure condition, result in a frost damage at initial stage by a fall of below zero temperature. In case of the combination of PE film and non woven fabric was after 36 hour, and combination of bubble sheet over double, a tremendous insulating effect of bubble sheet over double is confirmed due to the temperature of concrete fall of below zero temperature after 60 hours. Meanwhile, regarding the -15℃ of temperature, special measure for insulation curing is necessary to secure stability against early frost damage because frost damage was not affected by the lapping thickness of bubble sheet subjected to severe cold weather condition.

• 콘크리트학회지
• /
• 제2권1호
• /
• pp.109-119
• /
• 1990

이 연구는 충진재의 유무에 따른 철근 콘리크트의 경화수축과 초기 크리이프 특성을 실험적으로 구명한 것이다. 그 결과, 경화수축은 보관온도가 높아질수록 커졌고, 충진재를 사용한 경우가 온도의 영향을 더 크게 받는 것으로 나타났다. 또한, 초기 크리이프는 재하시간과 응력일강도화가 증가함에 따라 증가했고, 강성변형이 클수록 컸는데, 이는 충진재를 첨가한 경우가 더 크게 나타났다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2006년도 추계학술대회 논문집
• /
• pp.1326-1331
• /
• 2006

The precast concrete deck is one of suitable solutions for replacement and new construction in urban area. However, the precast concrete deck could be a weak point of the steel plate girder bridges structurally due to the connections between precast panels in the longitudinal direction. Thereafter, it is necessary for improvement of durability and load carrying capacity to introduce the prestress force in the longitudinal direction Some cracks of connections at the precast concrete deck may be occurred due to live loads, the difference of temperature and long-term effects. The shrinkage and creep of concrete may significantly affect long-term behaviors which occur tensile stresses at the precast concrete deck of steel plate girder bridges. In this study, the time-dependant analysis program has been developed to determine the initial prestress force in the longitudinal direction considering loss of stress at the precast concrete deck. Also it has been estimated the initial prestress force by construction stages and shapes of girder.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2022년도 가을 학술논문 발표대회
• /
• pp.175-176
• /
• 2022

By studying the characteristics of matrix insulated through heat generated through oxidation of iron powder, the basic research results on the possibility of buffering and applicability of Cold weather concrete as a curing method are presented. In order to prevent freezing due to a sharp decrease in temperature in the initial stage of curing, iron powder (Fe), powder activated carbon, which is a small amount of porous carbonaceous adsorbent, and salt (NaCl) as an oxidizing agent are replaced with iron powder admixture. As the curing temperature increases, the strength tends to increase, and when replacing the admixture at the same curing temperature, the strength slightly decreases. This is determined as a result of generating iron oxide through an oxidation reaction of iron powder, activated carbon, and NaCl generating a large amount of pores in the matrix. In addition, the internal temperature tends to increase as the mixing substitution rate increases, and it is judged that the oxidation heat of the iron powder mixture affects the increase of the internal temperature during curing. The higher the replacement rate of the iron powder mixture, the slightly lower the strength, but it is determined that freezing and melting that may occur in the early stage of curing can be prevented due to an increase in the initial internal temperature.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
• /
• pp.517-520
• /
• 2005

This study is basic experiment for estimating influence of strength by curing temperature of concrete's heat of hydration and estimate relationship of compressive strength development by initial curing temperature factor, and then asume temperature factor which influence compressive strength development and for showing basic document of quality control. According to the result of cement mortar by the curing temperature factor high-curing temperature shows high strength on 3 day compare with low curing-temperature, shows higher strength than the piece of high curing temperature.