• Advances in concrete construction
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• 제13권4호
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• pp.291-305
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• 2022

The present investigation deals with the production of the innovative lightweight fly ash angular aggregates (FAA) first time in India using local class 'F' fly ash, its characterization, and exploring the potential for its utilization as alternative coarse aggregates in structural concrete applications. Two types of aggregates are manufactured using two different kinds of binders. The manufacturing process involves mixing fly ash, binder, and water, followed by the briquetting process, sintering and crushing them into suitable size aggregates. Tests are conducted on fly ash angular aggregates to measure their physical properties such as crushing value, impact value, specific gravity, water absorption, bulk density, and percentage of voids. Study shows that the physical parameters are significantly enhanced as compared to commercially available fly ash pellets (FAP). The developed FAA are used in concrete vis-à-vis conventional granite aggregates and FAP to determine their compressive, split tensile and flexural strengths. Although being lightweight, the strength parameters for concrete containing FAA are well compared with conventional concrete. This might be due to the high pozzolanic reaction between fly ash angular aggregates and cement paste. Also, RCC beams are cast and the load-deflection behaviour and ultimate load carrying capacity signify that FAA can be suitably used for RCC construction. Hence, the utilization of fly ash as angular aggregates can reduce the dead load of the structure and at the same time serves as a solution for fly ash disposal and mineral depletion problem.

• Carbon letters
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• 제7권1호
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• pp.27-33
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• 2006

Carbon-ceramic composites were fabricated by using fly ash and PANOX fibers as reinforcement. Fly ash, because of its small size particles e.g. submicron to micron level can be effectively dispersed along with fibrous reinforcements. Phenolic resin was used as carbon precursor. Both dry as well as wet methods were used for forming composites. The resulting composites were characterized for their microstructure, thermal and mechanical properties. The microstructure and mechanical properties of composites are found to be dependent on type of the fly ash, fibrous reinforcements as well as processing parameters. The addition of fly ash improves hardness and the fibers, which get co-carbonized on heat treatment, increase the flexural strength of the carbon-ceramic composites. Composites with dual reinforcement exhibit about 30-40% higher strength as compared to the composites made with single reinforcement, either with fly ash as filler or with chopped fibers.

• 콘크리트학회논문집
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• 제12권3호
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• pp.87-94
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• 2000

Disposal of casting foundry fly ash generally depends on reclamation up to the present. This is the great loss from a standpoint of saving resources and utilizing industrial wastes. Therefore, a study on the reuse of fly ash as a substitute material for construction is necessary in order to utilize industrial wastes, to reduce cost and improve quality in producing concrete products, and to protect environment from pollution. In this study, methods for the reuse of the casting foundry fly ash, industrial wastes products, as an admixture for concrete are discussed. For this purpose, fly ash was extracted from casting foundry and tests of physical and chemical properties are executed. Also, various characteristics of concrete using fly ash as an admixture are experimented. Finally, the reuse methods for casting foundry fly ash are presented.

• 화약ㆍ발파
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• 제21권2호
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• pp.21-30
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• 2003

현재 터널 굴착시 기초 지보수단으로 활용되고 있는 숏크리트는 암반의 굴착 특성상 조기에 얇은 두께로 타설하여도 높은 강도를 유지할 수 있다는 장점 때문에 그동안 우수한 장비와 재료가 개발되어 비약적인 발전을 거듭해 오고 있다. 또한, 계측기술의 발달로 지하암반 거동상태도 조기에 자세히 파악되어 강도와 두께 등 거의 정확한 설계가 이루어지고 있으며, 신소재의 보강재료도 지속적으로 개발되고 있다. 국내 석탄 화력발전소에서 발생되는 석탄회에는 fly ash와 bottom ash가 있으며, 이러한 석탄회는 시멘트, 골재, 건축, 토목 및 농수산 분야에 이르기까지 많은 분야에 기술개발이 되었으며, 연구가 활발히 진행 중에 있다. 따라서, 본 연구에서는 fly ash를 혼합한 콘크리트를 숏크리트 재료로서 활용하기 위해 기존의 숏크리트 배합설계에서 fly ash를 시멘트의 대체재로서 사용할 때, 압축강도의 향상 및 굴착면의 타설 리바운드 율을 저하시키는 최적의 함량에 대하여 실험을 실시하였다. 그 결과, fly ash를 시멘트에 15% 중량 치환했을 때, 약 10%의 압축강도의 향상과 리바운드 율이 6%감소되었다.

• International Journal of Concrete Structures and Materials
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• 제4권1호
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• pp.51-54
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• 2010

Fly ash is used in concrete to improve the fresh and hardened properties of concrete, including workability, initial hydration temperature, ultimate strength and durability. A primary limitation on the use of large quantities of fly ash in blended cement concrete is its slow rate of strength gain. Prior studies investigated the effects of grinding fly ash and fly ash fineness on the performance of concrete containing fly ash. This study aims to discover the sources of those effects, to verify the compressive strength behavior of concrete made with raw and processed Class C fly ash, and to investigate the properties of fly ash particles at the microscopic level. Concrete cylinder test results indicate that grinding fly ash can significantly benefit the early age strength as well as the ultimate strength of concrete with ground fly ash. Therefore, it is demonstrated that grinding fly ash increases its reactivity. Scanning Electron Microscopy was then used to investigate the physical effects of the grinding process on the fly ash particles in order to identify the mechanism by which grinding leads to improved concrete properties.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1994년도 가을 학술발표회 논문집
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• pp.211-216
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• 1994

This study dealt with the properties for fly ash of conbined heat power plant and application for concrete industry. For this purpose, fly ash sampled Ulsan conbined heat power plant and analyzed for physical and chemical properties. As analyzed results of fly ash, contents of $SiO_ and Al_O_ $in the fly ash of Ulsan were less than those of Thermo-electric power plant(Boryuing), but contents of CaO were tem times as much as those of Boryung, because of these differences, it is expected that pozzolanic activity of concrete using fly ash of Ulsan will be different from another fly ash. Concrete specimens were tested to evaluate concrete preformance when 10 to 50 percent of the portland cement by weight in the concrete mix was replaced with fly ash of conbined heat power plant. As test results, workability and consideration in the fresh concrete were increased and concrete strength was showed more than 400kg/$\textrm{cm}^2$ for the required age. This study would be provided valuable data for the practical utilization of fly ash(conbined heat power plant). In the future, properties of fly ash concrete including long term strength, elapsed time, pozzolanic activity, modulus of elasticity, sulfate resistance, shrinkage, freeze-thaw durability and so on will be studied.

• 환경영향평가
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• 제8권4호
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• pp.25-35
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• 1999

Fly ash, by-product from coal fired power station, has long been regarded as a potential contamination source for heavy metals and inorganics due to their enriched concentrations and associations with particle surface. Feed coal and fly ash samples were collected from two power stations; Yongdong deliang with domestic anthracite coals and Boryong with imported bituminous coals. The coal and fly ash samples were analyzed for chemical composition and mineral components, using XRF and XRD. Batch leaching experiments were conducted by agitating samples with deionised water for 24 hours. Anthracite coals are generally higher in Al and Si contents than bituminous coals. This is due to the higher ash contents of the anthracite coal than bituminous coal. The chemistry of the two fly ash samples shows broadly similar compositions each other, except for the characteristically high contents of Cr in anthracite coal fly ash. Leaching experiments revealed that concentrations of metals gradually decreased with leachings in general. However, measurable amounts of metals were present in the effluent from weathered ash and the samples subjected to the leaching procedure. These metals are likely to indicate that the metals in fly ash were incorporated into glass fraction as well as associated with particle surface of samples. Dissolution of aluminosilicate glass would control releasing heavy metals from fly ash as weathering progresses during landfill with implication of possible groundwater contamination through fly ash landfill.

• 한국재료학회지
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• 제32권1호
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• pp.23-29
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• 2022

Fly ash is a by-product of coal fired electrical power plants and used as a material for cement and concrete; particularly, imported fly ash is mainly applied for cement production. Main objectives of this article are to replace domestic fly ash with an imported source. To verify the possibility of domestic fly ash as a material for cement from the aspect of chemical composition and physical properties, we manufactured various kinds of cement, such as using only natural raw material, shale, and partial replacement with domestic and imported fly ash. When we used the domestic and imported fly ash, there were no specific problems in terms of clinker synthesis or cement manufacturing in relation to the natural material, shale. In conclusion, domestic fly ash has been confirmed as an alternative raw material for cement because 7 days and 28 days compressive strength values were better than those of reference cement using natural raw material, on top of the process issue.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.196-202
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• 1997

The objective of this study is characterize of Mortar and Concrete mae with Cement made with Cement containing Fly ash as an additive. Cement samples were prepared using tow kinds of Fly ash, which containing unburnt Carbon content 3.5% and 4.5%. Fly ash content in cement was in range 3wt% to 13wt%. In consequence of various experiments, these cement samples satisfied specification of Type I cement, and it is possible to use Fly ash as an additive to Type I cement in this content.

• 천문학회보
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• 제38권2호
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• pp.51.2-51.2
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• 2013

Galactic fly-by interactions are believed to be far more frequent than direct mergers, acting as hidden drivers of galaxy evolution. We perform a tree-particle-mesh code GOTPM, and investigate the statistical properties of the fly-by interactions as functions of halo masses and ambient environments. Based on the total energy of the two halos of interest, impulsive fly-by pairs are identified from eventual merger candidates. We find three obvious results as follows: (1) Halos in the high-dense environment experience more frequent mergers and fly-by encounters than those in the low-dense region; (2) In the massive halos, both merger and fly-by fractions evolve more dramatically with time than those in dwarfs; and (3) The fly-by fraction decreases as approaching the present epoch, in contrast to the increase of the merger fraction.