• Title/Summary/Keyword: structural recycling

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A Study on the Recycling of Coal Ash as Fill Materials (석탄회 자원의 채움재로서의 활용에 관한 연구)

  • 천병식;고용일;송경율;이준기
    • Proceedings of the Korean Geotechical Society Conference
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    • 1999.03a
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    • pp.513-520
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    • 1999
  • 20 million tons of coal ash has been produced in Korea annually. This causes the environmental problems and the cost of land for ash pond. However the amount of coal ash for recycling is small because of the low level of recycling technology and the ignorance. As the coal ash has the significant engineering properties, it can be utilized as soft ground stabilizer, backfill materials and so forth. The purpose of this paper is to summarize some of the recycling methods of coal ash. One is structural backfill materials, the other is flowable fill. Optimal mixture ratio(fly ash : bottom ash) is determined for structural backfill materials and the model test is performed. The model test accompanied with physical tests were executed for identifying that the flowable fly ash can be used as fill materials such as trench back filling.

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Investigation of Current Practice on Hot In Place Recycling (HIR) in USA: Literature Review (현장가열재생 아스팔트 포장의 현재 미국 내의 적용 현황 연구: 문헌조사)

  • Im, Jeong Hyuk;Cho, Seong-Hwan;Hwang, Sung-Do
    • International Journal of Highway Engineering
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    • v.16 no.2
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    • pp.73-89
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    • 2014
  • PURPOSES : The objective of this study is to investigate the current state of the practice, examining the steps in the process recommended by various agencies and the Asphalt Recycling and Reclaiming Association (ARRA)-namely mix design, structural design, structural capacity evaluation, and material characterization-in order to better understand the implications of hot in-place recycling (HIR). METHODS : In addition, the current practice of state departments of transportation (DOTs) is here reviewed with the purpose of learning from successful past experiences so as to forestall any difficulties that may emerge under similar circumstances. Also, HIR benefits, including reduced costs, improved construction processes, and environmental friendliness are presented, as well as advantages and disadvantages of HIR application. RESULTS : Most of the United States highway system is now deteriorating so that rehabilitation or reconstruction techniques are required for the most distressed roads, taking into account ways to increase the effectiveness of existing budgets. Several options are available in rehabilitating distressed roads, and the choice among these depends on many factors, including pavement distress condition, funding, and design life. Among these techniques, Hot In-Place Recycling (HIR) has emerged as a cost-effective treatment for deteriorated pavements, and has been proven an effective long-term strategy for pavement rehabilitation.

Investigation on the Significance and Necessity for Recycling of Wood Wastes (목재 폐기물 재활용의 의의 및 필요성에 대한 고찰)

  • Kim, Gwang-Chul;Park, Hee-June;Jung, In-Soo
    • Journal of the Korea Furniture Society
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    • v.20 no.1
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    • pp.31-41
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    • 2009
  • In our country, most of the wood resources are imported. We faced a continuous rising of wood price by export country's some conditions and excess rising of transport charge, also a shortage of structural size members. In these situation, recycling or reuse of wood residues and wastes under wood processing industry, building construction and demolition is not a option but a prerequisite. In our country, there is a dearth of data on recycling or reuse of wood residues and wastes, so the investigation on the necessity of recycling or reuse of wood residues and wastes was conducted by using the foreign data and documents. First of all, fields and actual conditions for the domestic wood processing industry were surveyed. Then, kinds and signification of wood residues and wastes were organized. Later, the necessity and the signification of recycling or reuse of wood residues were investigated, and postulations for effective recycling and reuse were suggested. Above all, the necessity of grading standards for reuse or recycling and some important consideration for developing grading standards were emphasized. At last, foreign research tendencies and some applications on recycling or reuse of wood residues and wastes were supplemented.

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A Study on the Recycling of Coal Ash as Structural Backfill materials (구조물 뒷채움재로서의 석탄회 활용에 관한 연구)

  • 여유현
    • Journal of Ocean Engineering and Technology
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    • v.14 no.1
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    • pp.74-79
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    • 2000
  • The purpose of this paper is to recycle coal ash as structural backfill materials from electric power plants. Two million tons of coal ash are produced annually. The laboratory test was executed for the basic compatibility as substitution for structural backfill materials and the optimal mixture ratio(fly ash : bottom ash) was decided. In addition the model test was performed using medium scale earth pressure model with small size earth pressure cells model box data logger and some other apparatuses. Mixed coal ash and excellent backfill materials(coheisonless soil SW) were compared in the view of lateral earth pressure variation depending on wall displacement. The reduction of earth pressure when coal ash was used as a bockfill material was monitored comparing to that of cohesionless soil. the cost and environmental pollutants by treating coal ash can be reduced through developing the recycling technology.

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Morphological Change of Crosslinked ${\beta}$-Cyclodextrin after Recycling

  • Han, Eun-Mi;Kim, Song-Hee;Kim, Ki-Woo;Kwak, Hae-Soo
    • Journal of Dairy Science and Biotechnology
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    • v.25 no.1
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    • pp.9-13
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    • 2007
  • The present study was carried out to examine the effect of crosslinked ${\beta}$-cyclodextrin(${\beta}$-CD) made by adipic acid on cholesterol removal rate and find the structural change after recycling on SEM observation. The size reduction and morphological changes were found during the recycling process and the profound changes were observed at 8th time reuse. After cholesterol removal in milk, the used crosslinked ${\beta}$-CD was washed for cholesterol dissociation and reused. In recycling study, the cholesterol removal rate at first trial was 92.5% in milk, which was mostly same as that using new crosslinked ${\beta}$-CD(92.4%). With repeated 10th reuse of crosslinked ${\beta}$-CD resulted in 81.4% of cholesterol removal in milk. Similar trend was found in cream and cholesterol removal was 91.5% at 1st trial and 83.4% at 10th trial. In both milk and cream samples, the removal rate at 1st reuse was not significantly different from that at 6th reuse(p>0.05). The present study indicated that crosslinked ${\beta}$-CD made by adipic acid resulted in the effective recycling efficiency, especially up to 6th reuse and morphological modifications were not distinguishable up to 8th reuse.

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Current Status of Magnesium Smelting and Recycling Technology (마그네슘의 제련 및 리사이클링 기술 현황)

  • Sohn, Ho-Sang
    • Resources Recycling
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    • v.29 no.5
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    • pp.3-14
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    • 2020
  • Magnesium is the third most abundant structural metal after aluminum and iron. Magnesium is the lightest metal in the common metals. It has a density 33 % less than aluminum and 77% lower than steel. However, the primary magnesium production process is highly energy intensive. The recycling of magnesium scrap reduces the energy consumption and environmental burden, comparing to the primary metal production. However, the amount of recovered metal from scrap is limited because of the difficulties to remove the impurities in the scrap. This work provides an overview of the magnesium production and recycling process.

Current Status of Titanium Recycling Technology (타이타늄의 리사이클링 기술 현황)

  • Sohn, Ho-Sang
    • Resources Recycling
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    • v.30 no.1
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    • pp.26-34
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    • 2021
  • Titanium is the fourth most abundant structural metal, after aluminum, iron, and magnesium. However, it is classified as a 'rare metals', because it is difficult to smelt. In particular, the primary titanium production process is highly energy-intensive. Recycling titanium scraps to produce ingots can reduce energy consumption and CO2 emissions by approximately 95 %. However, the amount of metal recycled from scrap remains limited of the difficulty in removing impurities such as iron and oxygen from the scrap. Generally, high-grade titanium and its alloy scraps are recycled by dilution with a virgin titanium sponge during the remelting process. Low-grade titanium scrap is recycled to ferrotitanium (cascade recycling). This paper provides an overview of titanium production and recycling processes.

Systematization of Module Design Principle for Recycling (자원 재활용을 위한 모듈 설계 원칙의 체계화)

  • 목학수;양태일
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.11a
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    • pp.969-971
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    • 2000
  • In this paper, shortening of product life cycle and wide disposal of consumer product have given rise to many environmental problems, it needs to propose module design principle for saving of disassembly cost and reusing of used part and subassembly. To analyze characteristics of module for recycling, materials and function of part and subassembly must be classified. In disassembly process, a unit operation can be grasped for disassembly function, worker, tool and sorting process. As a result of applying module design principle, simpler structure and reduced structural interference can be realized for product structure. For disassembly, simpler disassembly and quicker disassembly can be obtained for recycling.

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Experimental Research for Flexural and Shea Behavior of Recycling Concrete Beam (재생 콘크리트보의 휨 및 전단 거동에 대한 실험연구)

  • 윤진수;류금성;정영수
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.04a
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    • pp.561-566
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    • 1999
  • Due to recent demolition works of aged concrete bridges and buildings, a considerable amount of waste concrete material have been reclaimed without crushing works. It is well believed that waste concrete could be used for recycling good coarse aggregate, which could contribute to partly reduce environmental pollutions due to noise and dust by demolition works, and also to solve the shortage of natural aggregate for new concrete works. This experimental study is to investigate the flexural and shear behaviour of recycling RC beams with pertinent amount of recycling coarse aggregate, such as 30%, 50% and 100% of total aggregate volume. It is concluded from the test that structural behaviour of recycled concrete is determined to have similar behaviour of normal concrete.

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