• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2004년도 학술.기술논문발표회
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• pp.11-14
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• 2004

In this paper, field application of mass concrete using setting time difference of super retarding agent is reported to reduce hydration heat of concrete placed at newly constructed apartment house in Busan. Horizontal placing lift is applied. According to test results. slump and air content meets the requirement of target values. For compressive strength, it exceeds the nominal strength ordered by the costumer. Compressive strength of concrete cured in place is achieved more than the values of nominal strength at l4days. For temperature history, maximum temperature of center at top section shows 58.5$^{\circ}C$, and at bottom section, 62.6$^{\circ}C$. According to naked eye's investigation, no hydration heat crack is observed at the surface of concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.401-402
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• 2009

본 연구에서는 물-결합재비가 아주 낮은 초고강도 콘크리트를 실험배합을 통하여 제조하고, 콘크리트의 수축억제 대책으로서 활용되고 있는 수축저감제를 사용, 초고강도콘크리트에 미치는 영향에 관하여 기초적인 연구를 실시하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 봄 학술발표회 논문집
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• pp.402-407
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• 1996

In this paper, we described the basic elements(flowability, fillingability, elapsed time, pumpability, no-vibrating effects, and etc.) required for the application and quality control of the super flowing concrete (SFC) in construction site. Also, after investigating characteristics of SFC through various experiments, SFC were placed in the reaction wall of large scale structural laboratory in Deawoo Insititute of Construction Technology. As the result of this project, the developed SFC showed high flowability and self-filingability good enough for the requirement. Furthermore, quality control and assurance of the no-vibrating concrete in actual site was verified by various testing.

• 한국건축시공학회지
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• 제9권3호
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• pp.95-101
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• 2009

Constructing large-scale mat foundation mass concrete is increasing for the stability of building structure, because a lot of high rise building are being built in order to make full use of limited space. However, It is of increasing concerns that because limited placing equipments, available job-site and systems for mass concete placement in construction field do not allow to place great quantity of concrete at the same time in large scale mat foundation, consistency between placement lift can not be secured. And also, it is likely to crack due to stress caused by the difference of hydration heat generation time. To find out the solution against above problems, this study is to reconfirm the performance of normal concrete designed by mix proportion and super retarding concrete. The Fundamental test shows what happens if low heat proportioning and control method of setting time are applied at the job-site of newly constructed high rise building. The test result show that slump flow of concrete has been somewhat increased as the target retarding time gets longer, while the air content has been slightly decreased but this is no great difference from normal concrete. The setting time shows to be retarded as target retarding time gets longer, the range of retarding time increases. It is necessary to increase the amount of mix of super retarding agent in the proportion ration by setting curing temperature high since outdoor curing is about 6 hours faster than standard curing, which means the temperature of the concrete will be higher than the temperature of the surrounding environment, due to its high hydration heat when applying in a construction site. The compressive strength of super retarding concrete appears to be lower than normal concrete due to the retarding action in the early stage. However, as the time goes by, the compressive strength gets higher, and by the 28th day the strength becomes the same or higher than normal concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.79-84
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• 2002

We carried out the feasibility study of super early self compacting concrete having the characteristics of 1 day demoulding without steam curing, high flowable concrete with self compacting, high strength and high durability etc. Here, We test and selected by several methods using high early cement with and without admixtures for the condition of super early strength self compacting concrete's manufacture (SSCC). we sucessed to meet at the goal of SSCC with 20-35N/mm$^2$ at 1 day, without steam curing and with slump flow about 60-65cm. We continue to search the effectual conditions of SSCC's manufacture by changing mix designs, several of admixture (superplasticizer, stabilising agent), slag, fly ash, high early cement and apply the products for practical use.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.439-440
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• 2009

초고강도 콘크리트는 수화 반응에 의한 체적의 감소나 자기건조에 의한 수축이 큰 경향이 있다. 이에 본 연구에서는 석고계 팽창재를 사용하여 초고강도콘크리트의 자기수축 제어에 관한 기초적 연구를 실시하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.3-8
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• 1998

This research is to examine the relationships between viscosity and fluidity according to binders in the super flowing concrete. And this research is described with respect to rheology concept, confined water ratio($\beta_p$) of binders in paste and mortar, also investigated experimentally the relationships between the relative flowing ratio ($\Gamma_m$) and the funneling velocity ratio($R_m$) on the mortar state according to the water binder ratio(W/B) and the dosage of the superplasticizer. From the confined water ratio tests, it is found that $\beta_p$ of the class C fly ash is higher than that of the class F fly and limestone in paste and mortar, therefore class F fly ash and limestone and super flowing concrete. The result of test, the optimum mix condition to the compactibility if satisfied when the replacement ratio is 30% and $K_p$ is 0.8 for the case of fly ash and limestone.

• Structural Engineering and Mechanics
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• 제48권3호
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• pp.395-414
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• 2013

The present study fundamentally investigated the mechanical performance of the rib-stiffened super-wide bridge deck with twin box girders in concrete, which is a very popular application to efficiently widen the bridges with normal span. The shear lag effects of the specific cross-sections were firstly studied. The spatial stress distribution and local stiffness of the bridge deck with twin box girders were then investigated under several typical wheel load conditions. Meanwhile, a comparative study for the bridge deck with and without stiffening ribs was also carried out during the investigation; thereby, a design optimization for the stiffening ribs was further suggested. Finally, aiming at the preliminary design, an approximate methodology to manually calculate the bending moments of the rib-stiffened bridge deck was analytically proposed for engineers to quickly assess its performance. This rib-stiffened bridge deck with twin box girders can be widely applied for concrete (especially concrete cable-stayed) bridges with normal span, however, requiring a super-wide bridge width due to the traffic flow.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.607-612
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• 2002

In road pavements, it is known that cement concrete pavement has superior durability, safety compared. But in repairing pavement, cement concrete pavement is not usually applied because of the length of time while the road is interrupted when using Ordinary and Rapid-hardening Portland Cement. And Super High Early Strength Cement and Ultra Super High Early Strength Cement are not favorable for ready mixed concrete because of rapid setting time, high slump loss and other restrictions. We developed special cement developing 1 day strength of over 30.0N/mm$^2$ to open the road within 1 day and workable time is maintained over 1 hour so that it can be used as ready mixed concrete. We performed experimental overlay construction with the cement and evaluated the mechanical property and the durability. At curing temperature of 8-l8$^{\circ}C$,the flexural strength was 6.4N/mm$^2$at 1 day, so that the road can be open to traffic within 1 day. In durability test, the hardened concrete showed higher durability than Portland cement concrete.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2016년도 춘계학술대회
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• pp.135-136
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• 2016

초고강 콘크리트를 활용한 부잔교는 강재부잔교에 비해 부식의 염려가 없어 내구성과 동적안전성이 우수하고, 일반 콘크리트에 비해 경량구조물로 건현확보가 유리하다. 현재 국내 연구개발 결과 SUPER concrete는 100MPa까지는 강섬유의 배합없이 일반골재만으로 배합이 가능하여 고부식성 환경의 항만구조물의 내구성에 적합한 강도이다. 부잔교는 상부슬래브에 작용하는 차량(DB-18) 또는 군집하중(5kN/m2)과, 외부 벽체 및 하부슬래브에 작용하는 파력의 수평과 양력성분을 견디도록 하여야 한다. 설계 파랑은 인천 연평도지역을 대상으로 50년 빈도 유의파와 주기에 해당하는 파력을 산정하여 X,Y축 위치에 따라 수평 및 양력성분을 재하하였다. 전체계 해석시 부잔교는 연직방향 경계조건이 없는 상태에서 부력 산정이 가능하도록 기하비선형 및 시간이력해석기법을 응용하였다(Strand 7). 부잔교 슬래브에 대해서는 실물모형실험을 통해 DB-18하중 재하에 따른 안전성을 확인하였다.