• Journal of the Korea Concrete Institute
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• v.17 no.1 s.85
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• pp.69-76
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• 2005

In this study, the high qualify recycled fine aggregate manufacturing system by the drying specific gravity separation method was evaluated. For the evaluation of the performance of the recycled aggregate, the engineering properties and durability of recycled aggregate has been tested. From the test results, the quality of recycled fing aggregates was improved by high quality recycled fine aggregate manufacturing system and satisfied with the quality standards of KS and JASS 5. Also, compressive and tensile strengths of recycled concrete show no critical difference caused by recycled fine aggregate replacement ratio. However, durability such as carbonation depth chloride ion penetration depth and drying shrinkage shows more deterioration than the concrete without recycled fine aggregate

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.05a
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• pp.111-114
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• 2006

Recently, it is increased on the concern for the reuse of waste concrete because of the shortage of natural aggregate and the increase of waste concrete. And recycled coarse aggregate is used variously, but the existing wet method producted recycled fine aggregate has problem like the high price facilities, the long time progress of the work and the poor of recycled fine aggregate. The aim of this study is to investigate outline and performance evaluation of the drying specific gravity separation method to product high duality recycled fine aggregate. Finally, this study is shown investigate process flowing of drying separation type with gravity manufacture, producte system and function of detail devices. The performance of the method of drying specific gravity separation is certificated as the qualities of recycled fine aggregate satisfied the KS

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.11a
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• pp.29-32
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• 2005

Recently, for the problem solution of demand and supply imbalance of fine aggregate due to the shortage of natural fine aggregate and the environment regulation on sea sand extraction in the construction field, the studies for the application of recycled fine aggregate using waste concrete are being progressed versatilely. The purpose of this study is to investigate quality of recycled fine aggregate manufactured by drying manufacturing system which is the manufacture method of high duality recycled fine aggregate, and to analyze on thehardened and durability properties of recycled concrete using it. Therefore it is to present the fundamental data for application and utilization of recycled concrete. The results of this study are as follows; Quality of recycled fine aggregate by drying manufacturing system is improved, and compressive strength, carbonation depth and chloride ion penetration depth of recycled concrete using high quality recycled fine aggregate are similar to those of normal concrete using natural and crashed sand. But, resistance to $H_{2}SO_{4}$ show decreased somewhat.

• Mineral and Industry
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• v.28
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• pp.1-13
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• 2015

In this study, it was carried out separation process research and development to be able to produce high-grade tungsten concentrate form tungsten taken form Mongolia. In order to reduce treatment cost and increase separation efficiency the jig separation at first was applied for recovering the concentrate. Which reground would make the degree of liberation increase. Which was treated by shaking table to reject the gangue minerals from the first concentrate. Because the heavier product contains not only ferberite but also cassiterite, the product was treated by further dry magnetic separation to obtain the ferberite concentrate. Finally, the high-grade ferberite concentrate of 67.63% $WO_3$ could be obtained with recovery of 86.07% through the separation process developed in this study.

• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.1
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• pp.89-97
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• 2005

Recently, for the problem solution of demand and supply imbalance of fine aggregate due to the shortage of natural fine aggregate resource and the environment regulation on sea sand extraction in the construction field, the studies for the application of recycled fine aggregate using waste concrete are being progressed versatilely. On the other hand, the treatment of fly-ashes that of industrial by-product originated in the steam power plant is discussed by the continuous increasing of origination quantities. In the ease of using fly-ash, advantages are the improvement of workability, viscosity and long-time strength, and the reduction of hydration heat under the early ages, as the admixtures for concrete, but the studies for the application of fly-ash as recycled concrete admixtures are inadequacy. There fore, in this study, through investigating the properties of fresh, hardened and durability according to the replacement of recycled fine aggregate and fly-ash, it is intended to propose the fundamental data for structural application of recycled concrete using recycled fine aggregate and fly-ash. As the result of this study, they arc shown that the engineering properties and durability, in the case of replacement ratio 100% of recycled fine aggregate, arc similar to those of concrete using natural fine aggregate, so it is considered that recycled fine aggregate could be used as the fine aggregate for concrete. Also, the performances of recycled concrete are improved by replacing fly-ash.