• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.4
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• pp.195-202
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• 2004

In this study, it was founded to make the optimal mixture for producing concrete which is self-compacting, yet, and generates low heat of hydration by using flyash, blast furnace slags and limestone powders as binders in addition to cement while using super-plasticizers and viscosity agents as admixture agents. The structural behaviors of the concrete produced with the selected mixture were compared with those of the concrete currently using for construction of nuclear power plants. The study shows that the blended high fluidity concrete including limestone is better in workability and durability than the concrete currently in use for nuclear power plants.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.161-166
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• 1998

The main object of this study is to examine the basic properties of fresh concrete as well as hardened concrete using several types of cement such as ordinary portland cement, sulphate resisting portland cement, blast furnace slag cement, ternary blended cement. In addition, effects of each cement on the durability including drying shrinkage, freeze-thawing resistance, resistance of chloride ion penetration, carbonation of concrete were investigated. As the results of this study, it was proved that most of the properties of concrete using each cement were similar, but there were some differences in bleeding, setting time, resistance of chloride ion penetration and carbonation.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.501-506
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• 2001

An experimental study was carried out to investigate recycling of an oyster shell, which is disposed in open-dumped way at coastal oyster factory area. For this purpose, the chemical component and reaction of oyster shell with cement paste was examined. And, the characteristics of hardened concrete was quantitatively investigated in terms of fineness modulus and blending rate of the crushed oyster shell. Test results show that interaction between oyster shell and cement paste was not occurred and the crushed oyster shell can be used as the fine aggregate of concrete. And it is found that blending of an oyster shell caused not to reduce the 28 day compressive strength of concrete. Elastic modulus of the concrete blended with crushed oyster shells decreases with increases the blending rate which the modulus reduced about 10% when oyster shells is blended up to the 20% of the sand substitution.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.236-239
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• 2004

The ternary blended cement(TBC) which the ability of resistance for seawater, the effect of decreation of hydration heat of concrete and long-age strength are known to be superior to other types was used to derive the estimation function of 91-age strength, 28-age strength with 28-age strength, 7-age strength respectively by analyzing the characteristics of statistics of compressive strength. The sample specimens was made after testing the variations of slump, air-contents during 30 minutes for consideration of transportation period. The functions might be expected to be useful for construction smoothness and reasonable quality control of concrete with TBC.

• Magazine of the Korea Concrete Institute
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• v.10 no.5
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• pp.177-187
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• 1998

최근 국내에서 해양 구조물, 장대 교량의 하부구조물, LNG저장탱크 등 매스콘크리트의 증가추세에 따라 구조물의 고내구성과 관련하여 시멘트의수화열에 의한 온도균열의 발생을 최소화 시킬 수 있는 3성분계 혼합형 저발열시멘트가 개발되어 실 구조물의 적용단계에 있으나, 저발열시멘트가 개발되어 실 구조물의 적용단계에 있으나 저발열시멘트의 특성에 대한 전반적인 연구보고가 국내에서는 미진한 실정이다. 따라서 본 연구에서는 3성분계 혼합형 저발열시멘트의 특성 및 코\ulcorner리트의기초물성을 1종 보통포틀랜트 시멘트, 5종 내황산염시멘트, 슬래그시멘트와 비교하였다. 글 결과 저발열 콘크리트의 찹축강도는 초기재령에서 강도발현률이 적은 반면 장기강도발현률은 상당히 큰 경향을 보였다. 또한 수화열은 1종시멘트를 사용한 콘크리트에 비하여 1/3~1/2정도로 매스콘크리트의 수화열을 대폭적으로 저감시킬 수 있을 뿐만 아니라 염소이온에 대한 저항성이 상대적으로 높게 나타나 거대 해양 구조물의 적용에 매우 유리한 시멘트로 판단되었다.

• Journal of the Korean Ceramic Society
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• v.35 no.11
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• pp.1227-1232
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• 1998

In order to prohibit the delay of early stage hydration activator Na2SO4 was added to Fly Ash blended ce-ment and its effects were investigated. Various measurements such as Compressive strength Heat of hy-dration Pore size distribution Hydration products Microstructure were evaluated and the results show that specimens of Fly Ash(50wt%) with 5% Na2SO4 dramatically improved the compressive strength because pozzolanic reaction of Fly Ash and the formation of ettringite make th microstructure denser than OPC and flyash cement paste.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.589-592
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• 2006

The growth in concrete structure repair has prompted major efforts to develop high early strength concrete. So, we were examined fundamental properties of cement mortar using the ordinary portland cement with rapid-setting cement. The experiments were carried out to investigate the characteristics of rapid-setting cement according to the blended ratio. The containing ratio of rapid-setting cement were changed five steps (20, 30, 50, 70, 100%) and then the flow value, setting time, compressive and bond strength test of cement mortar with RSC were investigated in this study.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.293-298
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• 1997

Corrosion of steel reinforcing in concrete deteriorated by freezing/thawing and carbonation was characterized. Concrete specimens were prepared using various kinds of cements such as ordinary portland cement (type I), low heat portland cement (type IV, belite rich cement), sulphate resistance portland cement (type V), blast furnace slag portland cement and ternary blended cement. Of various cements, type V and type IV with lower $C_3A$ content revealed better steel corrosion resistance after freezing/thawing and carbonation. $C_3A$ content in cement might affect freezing/thawing resistance in sea water.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.6
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• pp.97-108
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• 2008

The use of fly ash to replace a portion of cement has resulted significant savings in the cost of cement production. Fly ash blended cement concretes require a longer curing time and their early strength is low when compared to ordinary Portland cement(OPC) concrete. By adopting various activation techniques such as physical, thermal and chemical method, hydration of fly ash blended cement concrete was accelerated and thereby improved the corrosion-resistance of concrete. Concrete specimens prepared with 10-40% of activated fly ash replacement were evaluated for their open circuit potential measurements, weight loss measurements, impedance measurements, linear polarization measurements, water absorption test, rapid chloride ion penetration test and scanning electron microscopy (SEM) test and the results were compared with those for OPC concrete without fly ash. All the studies confirmed that up to a critical level of 20-30% replacement; activated fly ash cement improved the corrosion-resistance properties of concrete. It was also confirmed that the chemical activation of fly ash better results than the other methods of activation investigated in this study.

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.82.1-82
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• 2002