• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.59-68
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• 2000

A series of experiments were performed to investigate the strength characteristics of concrete which contain air cooled blast-furnace slag as coarse aggregate. The slag is a by product of GISC. The experimental conditions are varied with three different W/C(45%, 50%, 55%) and the weight of water and S/a are constant. The strength properties of the concrete at 7days, 28days, 90days are examined. Also the same strength properties are examined for the normal concrete which contain river gravel and crushed stone respectively as coarse aggregate. As the comparison results of the strength properties, it was found that the compressive strength development of concrete containing blast-furnace slag is better than that of concrete using river gravel at early age, however this is adversely at long-term age, and the tensile and flexural strength of the concrete were not nearly affected by water-cement ratio.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.218-219
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• 2018

This study analyzed the unit weight and compressive strength properties of lightweight concrete using high volume blast furnace slag powder by the mixing ratio of lightweight coarse aggregate to investigate the properties of lightweight concrete using domestic artificial lightweight aggregate.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.37-40
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• 2006

In this paper, long term deflection of RC beam with variable substitution ratio of recycled aggregate is investigated. 6 RC beam specimens are designed using concrete made of coarse aggregate of 25mm size, mix strength of 21MPa, slump of 12cm and air content of $5.0{\pm}1.5%$. A few concrete blocks are made and used for long term loading. The loading and deflection instrumentation are conducted following the process codified in ACI 318-05 code. Test result shows that the deflection of specimens depends on the compressive strength of concrete. And it is concluded that the deflection of RC beam can be predicted like normal beam using ACI formula if certain level of compressive strength is acquired even recycled aggregate is used in making the beam.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.1
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• pp.35-40
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• 2004

This study is performed to examine the physical and mechanical properties of eco-concrete using soil, natural coarse aggregate, excellent soil compound and polypropylene fiber. The test result shows that mass loss ratio is decreased with increasing the content of coarse aggregate and excellent soil compound. The compressive and flexural strengths are increased with increasing the content of coarse aggregate, excellent soil compound and polypropylene fiber. The coefficient of permeability is decreased with increasing the content of coarse aggregate and excellent soil compound, but it is increased in 0.2% polypropylene fiber content. The lowest coefficient of permeability is showed in $5.066\times 10^{-9}$cm/s. These eco-concrete can be used for farm road.

• Journal of the Korea Concrete Institute
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• v.13 no.1
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• pp.23-29
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• 2001

This study presented the experimental results on the durability properties of recycled aggregate concrete incorporating fly ash. The main experimental variables were the substitution ratio of recycled aggregate and fly ash, where the substitution ratios of recycled aggregate were 0, 30, and 50%, and those of fly ash were 0, 10, 20, and 30%. The tests for evaluating compressive strength, freezing-thawing resistance, and drying shrinkage were conducted for each specimen. As a result, the compressive strength and the durability of the recycled aggregate concrete were compared from those of ordinary concrete. The followings were conclusion; The compressive strengths of recycled aggregate concrete were less than those of ordinary concrete by 5-10%. However, the durability factor of recycled aggregate concrete remained above 90% at the substitution ratio of 30%. The quality of recycled aggregate concrete were improved by substitution at the range of less that 20% of fly ash and 30% of recycled aggregate.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.3
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• pp.122-129
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• 2016

In this study, we developed a pressing device which can reproduce the pressure of concrete inside the conveying pipe as a part of the basic study to development of high fluidity concrete under high pressure pumping. Using this pressing device, we evaluated a absorption properties of aggregate that are crushed coarse aggregate, river gravel and lightweight coarse aggregate according to pressure of coarse aggregate and aggregate inside a high fluidity concrete, focused on the reduction of unit water quantity by pressure. In addition, it was evaluated the compressive strength of high fluidity concrete about before and after of pressive. Test a result, case of condition under the high pressure of 250 bar, absorption ratio of crushed coarse aggregate and river gravel were not increased above the surface absorption, absorption ratio of lightweight coarse aggregate was increased than the surface absorption.

• Journal of the Korea Concrete Institute
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• v.13 no.2
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• pp.114-122
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• 2001

The purpose of this study was to manufacture sintered lightweight aggregate using paper sludge ash and to evaluate the qualities of the aggregate according to various mix proportions, conditions of pelletization and sintering. The paper sludge ash alone, due to its mineral and chemical compositions could not gain suitable expansion and strength. Hence, it was essential to add mineral additives such as clay, fly ash etc. The optimum muting ratio range determined in this study is as follows , paper sludge ash 30∼50 %, clay 30∼50 %, fay ash 0∼40 %, Paper sludge 0∼10% and hematite 2∼3 %(for manufacturing lightweight aggregate both for non-structural and structural concrete). It was possible to manufacture various lightweight aggregate whose dry specific gravity ranged about from 0.6 to 1.4 by using this optimum mixing ratio. From the test results of the qualities of aggregate, it showed that the 10% granules crushing value test and water absorption percentage ranged about 5∼10 ton and 10∼20%. Thus, it was favorably comparable to those of the imported aggregate. The manufactured lightweight aggregate could be used for structural concrete and non-structural concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.133-136
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• 2005

Compressive strength of recycled aggregate concrete was tested by the core and by the non-destructive testing. A prediction model of compressive strength considering the replacement level of recycled aggregate was suggested by multi-regression analysis and was compared with test results. Also, Test results showed that the ratio of compressive strength by core and non-destructive testing to actual was somewhat affected by the replacement level of recycled aggregate.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.3
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• pp.63-69
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• 2020

The volume of construction waste material from the entire waste material volume in Korea is approximately 47.3% to take the biggest ratio, and from them, the waste concrete takes up approximately 62.8% that recycling is an urgent issue to address. Therefore, the government recommends more diverse and broader facilitation of the recycled aggregate in order to promote recycling the construction waste materials. In addition, when using concrete recycled aggregate in building, building standard such as floor area ratio and building height are being mitigation. The standard is a condition that mitigation the floor area ratio by up to 15% when using up to 25% of concrete recycled aggregate. Therefore, this study reviewed the relaxation of construction of construction standards when using concrete recycled aggregate in order to actively recommend the use of concrete recycled aggregate. And using the recycled coarse aggregate among the recycled aggregate, the appropriate mixing time in the batch plant according to the substitution rate was derived. In addition, using recycled aggregate admixture in order to improve the drying shrinkage, did comparative analysis about physical and mechanical property of concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.677-682
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• 2000

Porous concrete is defined as d type of concrete for which the fine aggregate component the matrix is entirely omitted. Although it had been used as a building material in Europe for over 60 years, low strength and high void ratio limited its application in the past. In recent years, however high void ratio of concrete has been recognized again and can be used as an environmental conscious material, for example, parking lots, draining light-traffic-volume pavements and as sea water purifying material. The result of an experiment on the void ratio of fiber reinforced porous concrete and its influence on the compressive strength and permeability relationship of concrete are reported in this paper. One-sized coarse aggregate of 5-10mm, and three absolute content of fiber(steel fiber, polyprophylen fiber) were used. The result of measured void ratio, permeability coefficient and compressive strength show a small variation. Void ratio, permeability coefficient and compressive strength of fiber reinforced porous concrete depend on contents of fiber and absolute volume ratios of paste to aggregate.