• Computers and Concrete
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• v.17 no.2
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• pp.271-280
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• 2016

This study examined the mechanical properties and adiabatic temperature rise of low-heat concrete developed based on ternary blended cement using ASTM type IV (LHC) cement, ground fly ash (GFA) and limestone powder (LSP). To enhance reactivity of fly ash, especially at an early age, the grassy membrane was scratched through the additional vibrator milling process. The targeted 28-day strength of concrete was selected to be 42 MPa for application to high-strength mass concrete including nuclear plant structures. The concrete mixes prepared were cured under the isothermal conditions of $5^{\circ}C$, $20^{\circ}C$, and $40^{\circ}C$. Most concrete specimens gained a relatively high strength exceeding 10 MPa at an early age, achieving the targeted 28-day strength. All concrete specimens had higher moduli of elasticity and rupture than the predictions using ACI 318-11 equations, regardless of the curing temperature. The peak temperature rise and the ascending rate of the adiabatic temperature curve measured from the prepared concrete mixes were lower by 12% and 32%, respectively, in average than those of the control specimen made using 80% ordinary Portland cement and 20% conventional fly ash.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.641-644
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• 2006

Considering properties of the low-heat concrete mixed with the blended cements, the influences compared blended cements with ordinary portland cement made experiments on. (1) Blended cements were superior to OPC in the fresh concrete flow that the use of blended cements reduced chemical admixture. (2) The more the use of additive increase, the more bleeding happens. So it is considered to heights, order, and rate of placement, curing methods and so on. (3) The use of blended cements increase long term strength after 28 days, but decrease early strength and durability. So it is considered to the curing methods and early frost damage, and endurance limit.

• Journal of the Korea Concrete Institute
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• v.25 no.4
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• pp.411-418
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• 2013

Recently, in order to reduce a damage of chloride attack and hydration heat in marine concrete structures, blended cement in mixing the marine concrete is widely used. Long term strength development is distinct in concrete with blended cement and it also has excellent resistance to chloride attack and reduction of hydration heat. However, blended cement has a characteristic of relatively low compressive strength in early age of 28 days. On the other hand, a high level of compressive strength is required in the Standard Specification for marine concrete mix design. Such concrete mix design satisfying Standard Specification is effective to chloride attack but disadvantageous for hydration heat reduction due to large quantity of binder. In this study, the material properties of marine concrete considering water-binder ratio and binder type are experimentally investigated. Through the research results, compressive strength in blended cement at the age of 56 days is similar although it has smaller compressive strength at the age of 28 days compared with result of OPC (ordinary portland cement). Even though blended cement has a large water-binder ratio and small unit of binder content, chloride ion diffusion coefficient is still small and hydration heat is also found to be reduced. For meeting the required compressive strength in Standard Specification for marine concrete at 28 days, the increased unit content of binder is needed but the increased hydration heat is also expected.

• 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.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.69-70
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• 2012

This paper is to investigate the engineering properties of the concrete incorporating different types of low heat generating binders subjected to various W/B. As expected, it is found that increase of W/B resulted in a decrease of hydration heat and compressive strength. It also showed that the application of high early strength and low carbon type mixture had favorable strength development at early and later age, while hydration heat showed rather higher than existing low heat mixture.

• Journal of the Korean Ceramic Society
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• v.34 no.10
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• pp.1027-1036
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• 1997

The reology and several physical properties of cements are studied by varying the different mineral composition and particle size distribution(PSD) of cements with closed circuit ball mill for high workability, low heat of hydration, and high strength. In this study, we found that the workability of concretes is related to the viscosity of cement, and affects to strength. Here, this workability is affected by mineral composition (C3A) and the PSD. Especially, rosin-rammer index and 44${\mu}{\textrm}{m}$ residue in the PSD of cements are affected to water demand, casting property, slump loss, strength of cements. From the above results, the conditions of cement for high workability, low heat of hydration and high strength are to use low C3A clinker, 5-10% slag addition, and to grind cement below 0.7 rosin-rammer index, above 3.5-4.5% 44 ${\mu}{\textrm}{m}$ residue, 4000$\pm$100 $\textrm{cm}^2$/g blaine. Such cements are, therefore, supurior to super low heat cement and slag-blended cement in comparing the physical properties of strength, slump, slump-flow, adiabetic temperature, etc.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.556-559
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• 2004

In this Paper, concrete durability, coefficient variation of compressive strength, and hydration heat development characteristics of concrete using different types binder for 2nd Phase Construction in IIA were investigated. The experimental results show that the coefficient variation of compressive strength decreased with the slag cement when compared with the replacement of granulated blast furnace slag powder. And the diffusion coefficient of chloride ion decreased with use of a blended cement when compared with using a only portland cement. Also the type of low heat cement is very suitable to reduce the thermal crack caused by hydration heat development.

• Journal of the Korea Concrete Institute
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• v.23 no.2
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• pp.145-150
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• 2011

Presently, mass concrete structures are being built in federal and private projects of civil infrastructures and building structures. The hydration heat of mass concrete structures is the most important factor in the quality of concrete matrix and construction period. Moreover, internal cracks caused by hydration heat degrades durability, water tightness, and strength of concrete. To reduce hydration heat, it is necessary to blend belite cement (${\beta}-C_2S$) with industrial by-products (i.e. granulated slag and fly ash). In this experiment, 14 levels of binary binders and 4 levels of ternary binders were used to understand the effect of different replacement ratio on hydration heat, strength and microstructure (i.e. SEM and XRD) of mortar. Cumulative hydration heat at 28 days for the binary and ternary binders was affected by replacement ratio of fly ash and/or granulated slag. As fly ash content increased, hydration heat decreased. As granulated slag content increased, reduction rate of the hydration heat was lower than when fly ash was used. Especially, the hydration heat of ternary binder blended with 40% flyash and 30% granulated slag showed about 50% of hydration heat from using belite cement (P). The study results showed that the temperature rise of concrete matrix can be decreased by using blended belite binders producing low hydration heat and reasonable strength.

• Resources Recycling
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• v.23 no.3
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• pp.13-20
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• 2014

Nowadays, due to the development of industrial and civil engineering technology, enlargement and diversification of concrete structures are being tried. At the same time, the hydration heat generated during the construction of large structures lead to thermal crack, which is occurs causing a problem that durability degradation. In this paper, in order to study the durability and reducing hydration heat of concrete according to the types of cement, that is ordinary portland cement, fly ash cement mixed with a two-component, ternary blend cement mixed with fly ash and blast furnace slag and low heat cement concrete are produced, and compare and analyze the results using property, durability and hydration characteristics, ternary blend cement is appeared to be the most excellent in durability and reduction of hydration heat, and it was determined suitable for construction of mass concrete and requiring durability.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.333-336
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• 1999

The crack of concrete induced by the heat of hydration is a serious problem, particularly in concrete structures such as mat-slab of nuclear reactor buildings, dams or large footings, foundations of high rise buildings, etc.. As a result of the temperature rise and restriction condition of foundation, the thermal stress which may induce the cracks can occur. Therefore the various techniques of the thermal stress control in massive concrete have been widely used. One of them is prediction of the thermal stress, besides low-heat cement which mitigates the temperature rise, pre-cooling which lowers the initial temperature of fresh concrete with ice flake, pipe cooling which cools the temperature of concrete with flowing water, design change which considers steel bar reinforcement, operation control and so on. The Aim of this paper is to verify the effect of low heat blended cement in reducing thermal stress in slab type's mass concrete such as container harbor structures.