• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.121-126
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• 1994

In this study, several rheological properties of binder pastes and concrete are investigated for the development of commercially available fly ash super-flowing concrete. Fly ash contents with 5 leves(0, 10, 20, 30, 40%), slag contents with 6 levels(0, 5, 15, 25, 35, 45%), and water-binder ratios with 4 levels(30, 33, 36, 39%) are selected for test variables to evaluate the super-flowing characteristics of binder pastes. For the estimation of the workability of super-flowing concrete, slump flow, funnel time, box height, and L-flow are measured and compared. As the results, the flow is decreased and the viscosity is increased with increasing fly ash content. Super-flowing concrete is succesfully produced with 30% fly ash replacement.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.1
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• pp.25-32
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• 2005

This study was performed to evaluate strengths and non-destruction properties of super flow concrete using recycled coarse aggregate. At the curing age of 28 days, the compressive strength was 22.7-37.5 MPa, the splitting tensile strength was $2.65\~3.73$ MPa, the flexural strength was $5.78\~6.86$ MPa, the ultrasonic pulse velocity was $3,103\~3,480$ mis, the dynamic modulus of elasticity was $3.401{\times}104\~4.521{\times}104$MPa, respectively. The strengths, ultrasonic pulse velocity and dynamic modulus of elasticity of super flow concrete were decreased with increasing the content of recycled coarse aggregate. The super flow concretes using recycled coarse aggregate were improved by substitution in the range of less than the fly ash content 30010 and recycled coarse aggregate content $75\%$.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.2
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• pp.55-61
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• 2005

This study was performed to evaluate fluidity of super flow concrete using recycled coarse aggregate. The unit weight was $2,246{\sim}2,344\;kg/m^3$, the unit weights of these concrete were decreased with increasing the content of fly ash and recycled coarse aggregate. The slump flow was $58{\sim}63\;cm$, the Box type passing was $3.4{\sim}6.8\;cm$, respectively. The L type compacting was excellent in the fly ash content $10\%\;and\;20\%$, but, it was showed in good in the fly ash content $30\%$. The super flow concretes using recycled coarse aggregate were improved by substitution in the range of less than the fly ash content $20\%$ and recycled coarse aggregate content $75\%$. This recycled coarse aggregate can be used for super flow concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.56-62
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• 1995

In this study, the properties of super flowing cocrete containing gly ash were experimentally investigated and compared with those of ordinary concrete. Tests were carried out on five types of super flowing concrete mixes containing fly ash and three types of ordinary concrete mixes without fly ash. Flow test, O-funnel test, box test, Ltype thest and slump test were carried out to obtain the properties for the workability of fresh concrete. Compressime strength, splitting tensile strength, modulus of elasticity. creep and shrinkage test were also obtained as the mechanical properties of hardened concrete. In fresh concrete, it was found that super flowing concrete had excellent workability and flowability compared with ordinary concrete, and the volume ratio of coarse aggregate to concrete volume greatly influenced flowability. Super flowing concrete also had good mechanical properties at both early and late ages with compressive strengths reaching as high as 40 MPa at 28 days. The creep deformation of super flowing concrete investigated were relatively lower than that of ordinary concrete.

• Magazine of the Korea Concrete Institute
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• v.8 no.3
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• pp.135-146
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• 1996

In this study, the properties of super flowing concrete containing fly ash were experimentally investigated and compared with those of ordinary concrete. Tests were carried out on five types of super flowing concrete mixes containing fly ash and three types of ordinary concrete mixes without fly ash. Flow test, 0-funnel test, box test, L type test and slump test were carried out to obtain the properties for flowability and workability of fresh concrete. The mechanical properties of hardened concrete were also investigated in terms of compressive strength, splitting tensile strength, modulus of elasticity, creep and drying shrinkage. In fresh concrete, it was found that super flowing concrete had excellent workability and flowability compared with ordinary concrete, and had self-compactable performance. Super flowing concrete *also had good mechanical properties at both early and late ages with compressive strength reaching as high as 40 MPa at 28 days. The creep deformation of super flowing concrete investigated was relatively lower than that of ordinary concrete, but drying shrinkage was much higher.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.573-578
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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 30∼35N/㎟ in 1 day, without steam curing and with slump flow about 60-65cm and suggest various concrete products to apply the developed SSCC for practical use in factory and in site place

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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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.

• Structural Engineering and Mechanics
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• v.48 no.3
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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.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.395-398
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• 2005

In recent years, the applications of high-strength concrete have increased, and high-strength concrete has now been used in many parts of the world. The growth has been possible as a. result of recent developments in material technology and a demand for higher-strength concrete in Korea. In this study, we have an object to produce the ultra-high strength concrete(Super-Con) of over 100MPa with low price materials. First, the binders for Super-Con should be selected by the tests; setting time of paste, flow value and strength of mortar. From the test results, the binders are blended with ordinary portland cement, pulverized portland cement and silica fume. Fundamentally the compressive strength, frost resistance and chloride resistance are investigated.

• Journal of the Korea Institute of Building Construction
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• v.9 no.3
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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.