• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.111-120
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• 2000

In case of constructing concrete structure under water, generally concrete mixed with antiwashout admixture, high range water reducer, or AE-water reducing agent etc has been manufactured to ensure the quality of antiwashout underwater concrete because of being difficulty in ascertaining construction situation by the naked eye. The properties of high quality antiwashout underwater concrete that were aimed at affluent fluidity, workability and the compressive strength of 450 kgf/$\textrm{cm}^2$ at 28 ages using two types of blended cements are following as;(1) Setting time of antiwashout underwater concretes using blended cements was more greatly delayed than that of control concrete, however, was satisfied with criteria value of "Quality standard specification of antiwashout admixture for concrete".(2) As a test results of slump flow, efflux time and box elevation of head, it was found that workability of high quality antiwashout underwater concrete was improved. (3) Heat evolution amount of OPC was 1.5 times as high as that of two types of bended cements in 72 hours. (4) Suspended solids of antiwashout underwater concrete using blended cements was more than that of control concrete, also compressive strength of high quality antiwashout underwater concrete was very low in early age, but was better than that of control concrete as to increasing ages.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.21-22
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• 2022

High fluidity concrete has excellent workability, and if the cross-section of the building is complicated, it is possible to place good quality concrete and increase the construction speed, so its utility value is very high. However, it is premised on the accuracy of concrete formwork assembly. Concrete leakage through formwork gaps is an important consideration when applying high flow concrete. In order to quickly solve the leak of high fluidity concrete caused by formwork gap occurring at the site by accelerator injection, we proceeded with research to confirm the possibility of reducing the amount of formwork leakage of high fluidity mortar. It was confirmed that the injection of the accelerator could reduce the amount of mortar leakage.

• 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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• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.48-53
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• 1998

The purpose of this study to fine the mixture of concrete for Top-Down method. As a result, In fresh concrete, slump value and slump-flow value were increased as fly ash concrete(10% ratio). When plasticizer was added 1.5% by weigh of binder in concrete, no fly ash concrete and fly ash concrete(10% ratio) all occurred segregation. And, no fly ash concrete and fly concrete(10% ratio) all showed compressive strength development close plain concrete as increasing plasticizer quantity. Especially, in case of 1.5% plasticizer of binder showed high compressive strength development.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.1-7
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• 2018

This study examined the effect of binder-to-soil ratio(B/S) and water-to-binder ratio(W/B) on the flow and compressive strength development of soil concrete using high-volume supplementary cementitious materials. As a partial replacement of ordinary portland cement, 10% by-pass dust, 40% ground granulated blast-furnace slag, and 25% circulating fluidized bed combustion fly ash were determined in the preliminary tests. Using the low-cement binder incorporated with clay soil or sandy soil, a total of 18 soil concrete mixtures was prepared. The flow of the soil concrete tended to increase with the increase in W/B and B/S, regardless of the type of soils. The compressive strength was commonly higher in sandy soil concrete than in clay soil concrete with the same mixture condition. Considering the high-workability and compressive strength development, it could be recommended for low-cement soil concrete to be mixed under the following condition: B/S of 0.35 and W/B of 175%.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.42-47
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• 1996

Due to high increase of labor charge and necessarity of better quality control on concrete, various studies have been carried out to improve a flowability of concrete without the use of mechanical vibrator. As a result of enthusiastic study, one can closely access to the development of high flowable concrete in a laboratorial view. Application to practical field, however, is still far as long as a regulation for construction is not properly specified. Based on the idea that lateral pressure measured from high flowable concrete will be larger than those from general typed concrete, we read a series of lateral pressure from mechanical pressure plate and compared those with the values calculated form specified formula.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.21-24
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• 2005

A computational analysis of hygro-thermal and mechanical behaviour of concrete column at high temperature is presented. The objective of this study is to develop a finite difference model that simulates coupled heat and transport phenomena in reinforced concrete structures exposed to rapid heating conditions such as fires. The theoretical basis for the integrated finite difference method is presented to describe a powerful numerical technique for solving of fluid flow in porous media. The numerical results predict the phenomena of 'moisture clog' and the explosive spalling of concrete under fire. The investigations show that high-strength concrete(HSC) and normal-strength concrete(NSC) exposed to high temperature have different pore pressure buildup dependent on porosity, permeability and moisture contents. HSC has more possibility than NSC on spalling.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2001.11a
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• pp.28-33
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• 2001

This paper presents the results of mock up test on the manufacturing of high fluidity concrete by applying flowing methods with segregation reducing type superplasticizer(SRS). Three kinds of mock up structure are made such as. conventional concrete(A), high fluidity concrete(B) and high fluidity concrete incorporating 20% of fly ash(C). Physical and mechanical properties, temperature history of structure and nondestructive test are performed. Segregation reducing type superplasticizer is put into base concrete at field, and base concrete is also flowed at field. C mock up structure which requires 0.85% of SRS to flow base concrete shows most desirable performance at fresh state. The highest rising temperature shows the lowest at C structure among the tested structures. Strength variations before and after flowing also show the lowest values at C structures.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.472-477
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• 2006

This study aims at investigating the failure cases of the pre-cast block system in river environments which widely used nowadays and reviewing the effect and flow resistance for grass concrete structure through the physical experiments by hydraulic model test and developing application method in river slope or levee which has rigid flood resistance. Grass concrete structure has been independently tested under high velocity flow under the super critical condition, it survived the 8 m/sec maximum flow velocity. This results shows grass concrete system is also suited to use in aggressive river environments such as repairing a flood damaged embankment that had placed at risk the adjacent drainage channel with vegetation.