• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.473-476
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• 2008

The use of the recycled fine aggregate to the material of structural concrete is not easy currently because there are some problems, such as the difficulty of quality control and the badness of chemical and physical property other than river sand, crushed fine aggregate. To use of recycled fine aggregate, many researches on the recycling of recycled fine aggregate have been studying until today. However, the result of the research is little except for some results. Therefore, the purpose of this study is to confirm the possibility of use of recycled fine aggregate for raw material of plaster mortar. In this study, various tests were performed such as flow, air content, unit weight, bond strength, and compressive strength test to evaluate the effect according to the substitution of recycled concrete aggregate. The results of strength test showed that the concrete strength improved with the increase of replacement ratio of recycled fine aggregate. In the other side, flow and air content are decreased according to replacement ratio of recycled fine aggregate. The result of this study could be used as the basic data for the recycling of recycled fine aggregate.

• Resources Recycling
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• v.30 no.5
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• pp.17-24
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• 2021

Natural aggregate regular exploitation has led to environmental and resource depletion issues; consequently, construction waste has become an important raw material in the supply of aggregate smoothly. The recycled aggregate produced in the most of recycled aggregate processing company in Korea has a high adhesion ratio of cement paste and mortar, which affects the water absorption ratio and density. Therefore, the quality of recycled aggregate needs to be improved. In this study, we improved the quality of recycled aggregate through the use of a multistage separation ball mill. This ball mill has a sieve which protects the ball mix and improves the motion. Products produced by using multistage separation ball mill were compared with various quality standard for utilization as recycle aggregate. Finally, we confirmed that the multistage separation ball mill can efficiently separate cement paste and mortar from natural aggregate and that it is suitable for the production of recycled aggregates.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.643-648
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• 2002

A research for recycling the demolished-concrete as concrete aggregate has been concerned in all over the world. There, however, are some problems that qualities of recycled aggregates are not only largely different, but also mechanical properties of recycled aggregate concrete decrease a little in comparison with that of natural aggregate concrete. In this study, the resistance of freezing and thawing of concrete using source-concrete recycled aggregate(SRN) and demolished-concrete recycled aggregate(DRA) was investigated. Futhermore a research for improvement of freeze and thaw durability of recycled aggregate concrete was performed. Relative dynamic modulus of elasticity of SRN and DRA recycled aggregate concrete was dropped 60% before 150 of freezing and thawing cycle, and was much lower than that of control concrete. Relative dynamic modulus of elasticity of recycled aggregate concrete was increased to decrease water-cement ratio, but the freeze and thaw durability of recycled aggregate concrete was not enough improved. Futhermore, when metakaolin and silica fume were repalced, the freeze and thaw durability of recycled aggregate concrete containg metakaolin was more improved than that of silica fume.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.3
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• pp.33-37
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• 2018

In order to recycle sewage dredging soil, we analyzed particle size distribution and organic content of dredged sewage sediments. Based on this, it was determined that particles with relatively low organic content of 1.0 mm or more could be recycled as fine aggregate. Although it was inorganic at the size of 5 mm or more, it contained a number of foreign substances other than fine aggregate, which were needed to be removed with a sieve. Since there are volatile suspended solids between 1.0 and 5.0 mm size, they were removed by means of flotation. Fine aggregate was obtained from dredging soil by screening followed with flotation method, and the proportion of fine aggregate obtained in this study was around 38 %.

• Journal of the Korea Institute of Building Construction
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• v.5 no.1 s.15
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• pp.123-129
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• 2005

This study is as a part of the new disposal and recycling plans of heat-resource waste of Daegu dyeing industrial center we tried to examine applicable possibility of crushed thing(waste aggregate) as aggregates for mortar and concrete. To examine applicable possibility of waste aggregate as a lightweight-aggregate for concrete and mortar, we carried this study by mainly property examination of concrete according to replacement ratio of waste aggregate. We carried slump, unit weight, compressive strength and bending strength test according to replacement ratio of waste aggregate. As the result of that, if we use waste aggregate, lightweight of concrete and mortar will be possible. Specially it shows a strength improvement effect of cement hardening according to using this so it is judged that applicable possibility as aggregate for concrete and mortar is very excellent.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.05a
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• pp.99-104
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• 2005

This study is as a part of the new disposal and recycling plans of heat-resource waste of Daegu dyeing, industrial center we tried to examine applicable possibility of crushed thing(waste aggregate) as aggregates for mortar and concrete. To examine applicable possibility of waste aggregate as a lightweight-aggregate for concrete and mortar, we carried this study by mainly property examination of concrete according to replacement ratio of waste aggregate. We carried slump, unit weight, compressive strength and bending strength test according to replacement ratio of waste aggregate. As the result of that, if we use waste aggregate, lightweight of concrete and mortar will be possible. Specially it shows a strength improvement effect of cement hardening according to using this so it is judged that applicable possibility as aggregate for concrete and mortar is very excellent.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.105-108
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• 2005

This study investigated fundamental properties of the recycled aggregate which was produced through recent hi-techniques of recycling. In addition, the mechanical properties of the concrete that used the recycled aggregate were compared to the concrete used the natural aggregate. From the results of the mechanical property tests, as the recycled aggregate replacement ratio increased, the compressive strength and elastic modulus decreased. When the recycled aggregate completely replaced the natural aggregate, the compressive strength and elastic modulus was about 15$\%$ and 35$\%$ lower than the natural aggregate concrete, respectively. Based on the test results, equations for prediction of compressive strength and elastic modulus were suggested in the consideration of the amount of the replaced recycled aggregate. Based on the test results and study, the equation predicting the required development length of the recycled aggregate concrete is proposed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.226-227
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• 2021

Various attempts are being made to reduce carbon emissions through recycling of industrial by-products in the construction materials industry to reduce carbon emissions, and cement substitutes such as blast furnace slag and fly ash are widely used. Although it is suggested that the use of industrial by-product aggregate is possible in 'Aggregate', the use case of industrial by-product aggregate is very rare in the actual field. In this study, as an industrial by-product, fine slag aggregate is used as fine aggregate among aggregates that can be used as aggregate for concrete, and coarse aggregate is used as a substitute for natural aggregate. WWe tried to suggest various ways to expand the use of industrial by-product aggregates.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.339-342
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• 2000

Recently, the importance of the conutermeasures for waste materials has pointed out. Waste glass is also one to waste materials used for the recycling in construction sites. The crushed waste glass has been used to make a glass polymer composite that can be applied for sewer, storm drain pipe and interlocking block, etc. In this study, the crushed waste glass is explored with the possibility of recycling it, as a substitute for fine aggregates. The prepose of this investigation is to improve the strengths and acid resistance of the UP mortars using crushed waste glass. The UP mortars are prepare with blast furnace slag fly ash filler. the UP-fine aggregate ratios the crushed waste glass replacements for fine aggregate are tested strengths before and after immersion(H (아래첨자2)SO(아래첨자4) 10%), weight change and acid resistance are also tested. From the test results, the relative strength or UP mortars using fly ash as filler are found to be somewhat superior to that of the UP mortars using blast furnace as filler, And a UP mortar with fly ash as a filler, a UP-fine aggregate ratio of 15% and a waste glass replacement if 50% for fine aggregate is recommended as optimal mix proportion of UP mortar using crushed waste glass. Accordingly, it is enough to assure the use of the crushed waare glass as an aggregate for the production of UP mortar.

• Journal of the Korea Institute of Building Construction
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• v.4 no.2
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• pp.143-149
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• 2004

The recycle of domestic waste concrete is, however, still in an early stage, and it has been only partially being used for the road fillers. As a counter-plan of activating recycled concrete, we have confirmed the hydration possibility of the waste concrete powder from the experiment on recycling the aggregate powder since 2000. Though that study, we have known that the strength is increasing when the baking time is longer, and baking temperature maintain in $700^{\circ}C$. Also, the quality is lowered because of the fine aggregate powder which has a bad influence on flowability & compression strength by adhesion of mortar on the aggregate face. Therefore, mortar and interfacial separation of aggregate are large in proper quality for concrete recycling is expected that affect. The purpose of this study is to investigate effective aggregate separation and to determine the most suitable production method controlling the duration of baking time for recycled cement from the compressive strength, X-ray diffraction and ingredient analysis test.