• Title/Summary/Keyword: ash dispersion

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Characteristics of sintered fly ash-clay body prepared by slip processing and its applicability for foundation soils (슬립 공정으로 제조된 비산재-점토 계 소결체의 물성 및 기반재로의 적용특성)

  • Kang, Seung-Gu;Lee, Yeong-Saeng
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.18 no.6
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    • pp.271-276
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    • 2008
  • The civil engineering properties for the coal fly ash produced from a power plant mixed with sintered powders made from the fly ash-clay slip system were measured and its applicability for the foundation soils was investigated. The F-slip whose dispersion state is 'not good' and C-slip which is re-flocculated by adding a flocculant to a well-dispersed slip were fabricated and then sintered. The sintered body made from C-slip had more uniform microstructure than that of F-slip, therefore, the bulk density and compressive strength were improved. The civil engineering properties such as compression index, compressive strength, permeability coefficient of fly ash were improved by mixing $0.84{\sim}2\;mm$ powders obtained by crushing a sintered body made from C-slip. Therefore, the applicability of mixed powders composing of fly ash and sintered body made from C-slip was confirmed to foundation soils due to its improved civil engineering properties.

Physical Properties of Sintered Body for Coal Fly Ash-clay Slip of Varying Dispersion State (석탄회-점토계 슬립의 분산상태에 따른 소결체의 물리적 특성)

  • 강승구;이기강;김유택;김정환
    • Journal of the Korean Ceramic Society
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    • v.40 no.7
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    • pp.677-682
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    • 2003
  • The physical properties of sintered body made from 3 kinds of slip, F (Flocculated), M (Moderate), and D (Dispersed) for coal fly ash 70-clay 30 (wt%) were studied in terms of slip states and pore size distribution of sintered bodies. The floc particle size distribution for slip F was wider than slip D and the slip F contained flocs larger than 11 $\mu\textrm{m}$. The pore size distribution of the green body of all slips ranged over 1∼4 $\mu\textrm{m}$. The pores smaller than 1 $\mu\textrm{m}$ almost disappeared during the sintering process, while the larger pore of 2.5∼3 $\mu\textrm{m}$ growed by 1 $\mu\textrm{m}$. The pore distribution for the green body of slip F became a narrow in width and high in height after sintering and the large pore limit in a slip F sintered body was 5.1 $\mu\textrm{m}$ which is smaller than that of other slip. The slip F rather flocculated was favorable over slip D well dispersed, in offering a higher compressive strength. From these results, the mechanical strength of sintered body is dependent on the pore distribution which could be controlled by dispersion state of the slips.

Developing Interactive Simulator for Predicting Volcanic Ash (실시간 대화형 화산재 확산 예측 시스템 개발)

  • Kim, Hae-Dong;Lee, Ho-Man
    • Journal of Environmental Science International
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    • v.23 no.3
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    • pp.527-532
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    • 2014
  • According to the analysis of volcanic observation data around Korean peninsula, the activities of volcano increase continuously. For example, the volcanic eruption of Mt. Sakurajima is an example, and Mt. Baekdu can be another example potentially. In these regards, developing unified system including realtime prediction and 3D visualization of volcano ash are important to prepare the volcanic disaster systematically. In this technical report, an interactive simulator embedding dispersion algorithm and 3D visualization engine is developed. This system can contribute to the realtime prediction of volcanic disaster scientifically.

The Study on the Comparison of the ISCST3 Model and Receptor Model by Dispersion Tracing of Particulate Matter from Large Scale Pollution Sources (대단위배출원에서 기인한 입자상오염물질의 확산ㆍ추적을 통한 ISCST3모델과 수용모델의 비교연구)

  • 전상기;이성철;박경선
    • Journal of Korean Society for Atmospheric Environment
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    • v.19 no.6
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    • pp.789-803
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    • 2003
  • The purpose of this study is to compare the usefulness between Gaussian dispersion model and receptor model with the experimental result of the dispersion tracing of the particulate pollutants from Taean coal-fired power plants. For this purpose, the component analysis of the collected PM 10 samples was performed. In order to trace the pollution sources, factor analysis was done with the result of the component analysis. As a result of the correlativity analysis of the fifteen power plants' profiles offered by US EPA, the correlativity of No.11202 source profile showed highest rate up to 84.5%. Thus it was adopted as proper one and the contribution rate by each pollution source was calculated by Chemical Mass Balance (CMB)-8 model. The contribution rate, which was the effect rate of the power plants on each measuring point, were calculated with a range of 24∼52% and the standard error was below 0.9 $\mu\textrm{g}$/㎥. This indicates the selection of the source profile was appropriate. Also, the concentrations of each point were calculated by the ISCST3 which is suggested by US EPA as one of the regulatory Gaussian dispersion model. The calculation result showed that the predicted concentration was 50∼58 $\mu\textrm{g}$/㎥, comparing with the measured result of 9∼65 $\mu\textrm{g}$/㎥. It was found that the concentration calculated by ISCST3 was underpredicted. It was thought that the receptor model was more favorable than the Gaussian dispersion model in estimating the effect of the particulate matter on a certain receptive point.

Experimental Study on Fundamental Quality Characteristics of Non-cement Repair Mortar Using High-volume Fly Ash Based on Potassium Magnesia Phosphate (마그네시아-인산칼륨 기반 하이볼륨 플라이애시 활용 무시멘트 보수 모르타르의 기초 품질 특성에 대한 실험적 연구)

  • Doo-Won Lee;Il-Young Jang
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.12 no.2
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    • pp.152-161
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    • 2024
  • This paper investigates the manufacturing and fundamental quality characteristics of potassium magnesia phosphate-based non-cement high-volume fly ash repair mortar. To derive the optimal mix for non-cement mortar, the manufacturing characteristics were evaluated based on the magnesia ratio, and the mortar manufacturing characteristics were assessed with the fly ash mixture. Additionally, the non-cement magnesia repair mortar was produced considering the effects of fly ash mixture and basalt fiber. The evaluation results determined the optimal mix of non-cement magnesia repair mortar, and the feasibility was examined through workability and fundamental quality assessments. The optimal magnesia ratio was found to be P:M 1:0.5, with W/B at 30 %. It was also confirmed that mixing FA and basalt fiber improves fiber dispersion and workability. Even with over 50 % FA mixture, the target strength was achieved within six hours, with a flow increase of up to 18 % and a flexural strength decrease of about 1-2 MPa.

Basic Properties of Polymer Cement Mortar with EVA Emulsion and Admixtures (EVA 에멀젼과 혼화재를 사용한 폴리머 시멘트 모르타르의 기초적 성질)

  • Jo, Young-Kug
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.6
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    • pp.53-60
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    • 2019
  • The purpose of this study is to evaluate the degree of improvement in strengths by mixing blast-furnace slag and fly ash in polymer cement mortar(PCM). The test specimens are prepared with EVA polymer dispersion, two types of Admixtures (blast-furnace slag and fly ash), five kinds of polymer-cement ratios (0, 5, 10, 15 and 20%), and six kinds of admixtures (0, 3, 5, 10, 15 and 20%). Plain cement mortar is also made for comparison. From the test results, the flowing of PCM is greatly improved with the mixing of the admixtures, and strengths of PCM compared to ordinary cement mortar are also improved due to a decrease in water cement ratio. In addition, the strength characteristics of PCM by admixtures are greatly improved in flexural strength with fly ash compared to other strengths. It is apparent that the optimum mix proportions with polymer-cement ratio of 10% or more, admixture contents 5 to 10% of flay ash for flexural strength improvement of EVA-cement mortar are recommended in this study.

Mix Design of Polymer Grouting Mortar for Prepacked Concrete Using Polymer Dispersions (폴리머 디스퍼션을 이용한 프리팩트 콘크리트용 주입 모르타르의 배합에 관한 연구)

  • Jo, Young-Kug;Kim, Wan-Ki
    • Journal of the Korea Institute of Building Construction
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    • v.8 no.5
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    • pp.85-91
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    • 2008
  • Prepacked concrete has recently been used in the special constructions fields such as underwater concrete work, heavy-weight concrete work, underground structure work, partial repair works for damaged reinforced concrete structures. and polymer-modified mortars have been employed as grouting mortars for the prepacked concrete. The purpose of this study is to recommend the optimum mix design of polymer-modified grouting mortars for prepacked concrete. Polymer-modified mortars using SBR and EVA emulsions as admixture of grouting mortars for prepacked concrete are prepared with various mix proportions such as sand-binder ratio, fly ash replacement ratio, polymer-binder ratio. and tested for flowability, viscosity of grouting mortars, bleeding ratio, expansion ratio, flexural and compressive strengths of grouting mortars and compressive and tensile strengths of prepacked concretes. From the test results, it is apparent that polymer-modified mortars can be produced as grouting mortars when proper mix design is chosen. We can design the mix proportions of high strength mortars for prepacked concrete according to the control of mix design factors such as type of polymer, polymer-binder ratio, sand-binder ratio and fly ash replacement ratio. Water-binder ratio of plain mortars for a constant flowability value are in the ranges of 43% to 50%. SBR-modified mortar has a little water-binder ratios compared to those of plain mortar, however, EVA-modified mortar needs a high water-binder ratio due to a high viscosity of polymer dispersion. The expansion and bleeding ratios of grouting mortars are also controlled in the proper value ranges. Polymer-modified grouting mortars have good flexural. compressive and tensile strengths, are not affected with various properties with increasing fly ash replacement to cement and binder-sand ratio. In this study, SBR-modified grouting mortar with a polymer-binder ratio of 10% or less, a fly ash replacement of 10% to cement and a sand-binder ratio of 1.5 is recommended as a grouting mortar for prepacked concrete.

Effect of the Various Combinations of the Binders and the Silica Fume Types to the Physical Properties of the Pre-Mix Cement (프리믹스 시멘트의 물리적 특성에 미치는 결합재조합 및 실리카퓸 종류의 영향)

  • Jin, Cheng-Ri;Kim, Ki-Hoon;Pei, Chang-Chun;Lee, Hai-III;Kim, Sung-Su;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2007.11a
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    • pp.37-40
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    • 2007
  • This study investigates the effect of the pre-mix cement to the physical properties of the concrete according to the various combinations of the binders and the silica fume types. The results are summarized as following. For the properties of the fresh, the fluidity in the case that OPC+cilica fume-blast-furnace slag is appropriate compared to OPC+cilica fume+fly ash. Expecially, it is favorable when pre-mix is used. The fluidity time of the A, B depending on silica fume types is favorable, but it is decreased on C. The air content depending on silica fume types is low when the fly ash is used. Specially, the air content in the case that pre-mix is used is low caused by the dispersion of the silica fume. For the properties of the hardened concrete, the compressive and flexible strength when the blast-furnace slag is pre-mixed are high, and they exceed OPC. The strength depending on the silica fume types is high on B, and the strength of the others is similar.

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Impact of Meteorological Wind Fields Average on Predicting Volcanic Tephra Dispersion of Mt. Baekdu (백두산 화산 분출물 확산 예측에 대기흐름장 평균화가 미치는 영향)

  • Lee, Soon-Hwan;Yun, Sung-Hyo
    • Journal of the Korean earth science society
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    • v.32 no.4
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    • pp.360-372
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    • 2011
  • In order to clarify the advection and dispersion characteristics of volcanic tephra to be emitted from the Mt. Baekdu, several numerical experiments were carried out using three-dimensional atmospheric dynamic model, Weather and Research Forecast (WRF) and Laglangian particles dispersion model FLEXPART. Four different temporally averaged meteorological values including wind speed and direction were used, and their averaged intervals of meteorological values are 1 month, 10 days, and 3days, respectively. Real time simulation without temporal averaging is also established in this study. As averaging time of meteorological elements is longer, wind along the principle direction is stronger. On the other hands, the tangential direction wind tends to be clearer when the time become shorten. Similar tendency was shown in the distribution of volcanic tephra because the dispersion of particles floating in the atmosphere is strongly associated with wind pattern. Wind transporting the volcanic tephra is divided clearly into upper and lower region and almost ash arriving the Korean Peninsula is released under 2 km high above the ground. Since setting up the temporal averaging of meteorological values is one of the critical factors to determine the density of tephra in the air and their surface deposition, reasonable time for averaging meteorological values should be established before the numerical dispersion assessment of volcanic tephra.