• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.1041-1046
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• 2003

The most recent building trend is going large, high rise, high strength as overlarge project is developing in domestic construction business. Belite cement has properties like low heat, excellent long term strength, and durability without admixture (fly ash, silica fume). So, Belite cement is suitable for mass structure which is needed high strength, high fluidity and low heat property. This study is to examine the possibility of site adoption microwave-use early strength estimation method. Based on the existed study related the portland cement, the interrelation between Belite cement and microwave-use early strength estimation method is required.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.1
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• pp.10-18
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• 2014

This study carried out to evaluate the hydration heat analysis and fundamental characteristics such as air content, slump, compressive strength and dry shrinkage according to concrete with premixed cement, ternary concrete and OPC concrete for using concrete with premixed cement. The results of experiment are founded that concrete with premixed cement have sufficient performances such as workability, compressive strength and dry shrinkage. Also, the results of hydration heat analysis are founded that concrete with premixed cement have more performance than ternary concrete and OPC concrete at a point of view for the quality control such as thermal crack reducing and economic benefit. Therefore, it is desirable that concrete with premixed cement should be used to rise durability performance and convenience of maintenance.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.85-88
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• 2006

This study describes the optimum mix proportion of the high strength and self-compacting concrete placed in main structures of LNG above tank. This concrete requires high strength level about $60{\sim}80MPa$, low hydration heat, balance between workability and consistency without vibrating in the actual work. For this purpose, low heat portland cement and fly ash are selected and design factors including water-binder ratio, replacement ratio of fly ash are tested. As experimental results, low heat portland cement shows lower the confined water ratio than another cement type and the optimum replacement ratio of fly ash in order to improve properties of the binder-paste shows 10% by cement weight considering test results of the confined water ratio$({\beta}p)$. Also, flowability of the high strength and self-compacting concrete by using fly ash about $10{\sim}20%$ is improved. The replacement ratio of fly ash 10% and water-binder ratio $25{\sim}27%$ are suitable to the design strength 80MPa and cost, In case of the design strength 60MPa, the replacement ratio of fly ash and water-binder ratio show 20% and $25{\sim}30%$ separately. Based on the results of this study, the optimum mix proportions of the high strength and self-compacting concrete will be applied to the construction of LNG above tank as a new type.

• Advances in concrete construction
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• v.6 no.6
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• pp.659-677
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• 2018

The use of some superplasticizers in the production of mortar or concrete influences the hydration kinetic and the amount of total heat. This results in a modification of some properties, namely mortar workability, mechanical strength and durability. Three superplasticizers were used; a polynaphthalenesulfonate (PNS), a melamine resin (PMS) and a polycarboxylate (PC). They have been incorporated into various amount in a standardized mortar based on limestone cement. The aim of this study was to evaluate the rheological, mechanical and Calorimeters properties of this mortar. This will select the most compatible product and more able to be used depending on the climate of the country and the cement used. The PNS is incompatible with this type of cement registering a decrease of strength but the PMS and the PC modify the kinetics of hydration with significant heat generation and improved mechanical strength. The measured heat flow is significantly influenced by the type and dosage of superplasticizer especially for low dosage. Hydration heat and compressive strength of the different mixtures can be evaluated by determining their ultimate values and ages to reach these values where the correlation coefficients are very satisfactory.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.1229-1234
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• 2001

The bottom slab of Inchon LNG in-ground #213 tank is designed as a massive structure witch has a large depth and section. The purpose of this study is to determine the optimum mix design having good workability and low hydration heat for bottom slab concrete and to control the actual concrete quality in site. For this purpose, we select the optimum mix design used ternary blended cement(furnace slag cement＋fly ash) and design factors. As test results of actual application, we have finish placing the bottom slab concrete of 23,180㎥ during 68hours with good success and obtain the good quality of fresh and hardened concrete including slump, air contents, no-segregation, compressive strength and low hydration heat in actual data. All test results are satisfied with our specifications for bottom slab concrete and we cut costs as the use of ternary blended cement and the reduction of placing hours.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.11a
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• pp.45-48
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• 2007

This study investigates mechanical properties of the concrete using coarse particle cement which is manufactured by the classifying process. The variable factors are 3 types of W/C such as 40, 50, and 60% and 5types of the replacement of the coarse particle cement such as 0, 25, 50, 75, and 100%. As the results, amount of SP agent to secure the target fluidity is gradually declined in accordance with increasing CC replacement. There is no special tendency for target air content, but setting time is delayed according to increasing CC content. The peak of the simple adiabatic temperature rise is gradually decreased in accordance with increasing CC content, and approach time to peak is slightly delayed. The compressive strength is comparatively delayed.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.685-688
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• 2008

This study has examined the effect of bottom ash(BA) on the properties of low heat-blended cement(LHC) and concrete. A number of binders were prepared by the replacement of LHC with BA in range of 5$^{\sim}$20wt%. The results showed that the final setting time of cement paste were delayed when the BA replaced part of the cement. However, The heat of hydration increased narrowly with adding BA in a early hydration period. The results also showed the inclusion of BA at replacement levels of 5$^{\sim}$10wt% resulted in an increase in compressive strength of the specimens compared with that of the control concrete and improved a resistance of concrete against the sulfate and chlorine ion.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.165-168
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• 2005

This paper investigated the effect of W/C and the kinds of cement on the chloride invasion resistance of the offshore concrete. W/C set up 0.30, 0.35, 0.40 and The kinds of cement were used four(ordinary portland cement, ground granulated blast-furnace slag cement, belite cement, low heat portland cement). For the electrical migration test, NT BUILD 492's method was used to estimate the migration coefficient of chloride ion. As a result, the migration coefficients of chloride ion of concrete according to w/c were shown reducing with the w/c increasing, and according to kinds of cement were shown discrepancy in chloride invasion resistance. Especially blast-furnace slag cement was most low it. In the each cement, the compressive strength was shown related to the migration coefficient.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1131-1137
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• 2004

With the recent continuous expansion of subways, newly created subways tend to have lower locations and wider sections. Furthermore. since box structures and evacuating tunnels are classified into a category of mass-concrete. the thermal-stress, emitted from the inside. causes cracks to structures from the inception of constructing. In this paper, thermal-stress analysis and durability evaluation of box structure were carried out to investigate relationship between durability and parameter causing the heat of hydration. Through the examination, this paper tries to find out satisfactory solutions to regulated thermal crack and ensure the required duration period. The results of this paper showed that to control thermal crack and guarantee the required duration period it was more effective to use low-heat-portland cement and moderateheat-portland cement. As cement volume due to reduction of water-cement ratio increased, the possibility of thermal cracks occurrence increased but results of durability evaluation was different depending on evaluation method. The results showed that the appropriate water-cement ratio to control the heat of hydration and satisfy the required durability was $45\∼55\%$. And it was showed that during placement of concrete blocks ambient temperature affect the heat of hydration. thermal crack and long-term durability largely and when concrete was placed at low temperature to control thermal crack. it need to try to guarantee the required duration period. Henceforth, by studying not only internal and external conditions, such as the relative humidity and the unit weight. but also methods, to evaluate durability, in accordance with domestic situations, more reasonable design of durability should be achieved.

• 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.