• 제목/요약/키워드: cement production

검색결과 393건 처리시간 0.027초

무기계 건설폐기물을 이용한 재생시멘트 배합설계에 관한 이론적 제안 (Theoretical Proposal for the Mix Design of Recycled Cement Utilizing Inorganic Construction Wastes)

  • 김지훈;태성호;송훈;신현욱
    • 한국건설순환자원학회논문집
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    • 제4권3호
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    • pp.250-258
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    • 2016
  • 오늘날 시멘트 산업은 시멘트 제조시 발생되는 이산화탄소($CO_2$)의 배출량을 줄이기 위해 각종 산업부산물을 연료의 대체재로 사용하거나 건설폐기물을 재활용한 콘크리트 제 2차 제품을 개발하는 등 환경부하 저감 산업으로 변모하기 위해 노력하고 있다. 이에 본 연구에서는 국내 발생되는 건설폐기물의 종류와 발생추이를 고찰함과 건설폐기물을 활용한 재생시멘트 개발에 관련된 선행연구를 분석함으로서 재활용 가능한 무기계 건설폐기물에 선정하고 수집하여 분석하였다. 수집된 무기계 건설폐기물의 각 화학성분은 XRF장비를 이용하여 분석하였으며, 국내 시판되는 시멘트의 화학성분을 기준으로 무기계 건설폐기물을 조합하여 보그(Bogue)식을 활용한 소성이후 생성되는 클링커(clinker)의 광물성분을 예측 분석하였다. 그 결과, 폐석고보드와 폐천장재가 다량의 산화칼슘(CaO)을 함유하고 있어 시멘트 제조시 중요하게 사용되는 석회석의 대체재로서 활용 가능한 것을 확인하였으며, 이러한 무기계 건설폐기물을 적절히 조합한다면 1종 이외에 다양한 포틀랜드 시멘트 개발도 가능할 것으로 사료된다. 본 연구는 실험적 연구에 앞서 이론적 배합에 관한 연구로 무기계 건설폐기물을 이용한 환경부하 저감형 재생시멘트 개발의 가능여부를 분석하고자 하였다.

심층혼합공법용 지반개량재로서 순환자원을 재활용한 CMD-SOIL의 적용성 평가 (Evaluation of Applicability of CMD-SOIL Recycled Resources as Ground Improvement Material for Deep Mixing Method)

  • 함태규;서세관;조대성
    • 한국지반신소재학회논문집
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    • 제20권4호
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    • pp.43-52
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    • 2021
  • 국제 물류수송을 위해 연약지반에서의 항만개발이 활발하게 추진됨에 따라 항만구조물의 안정성 확보를 위해 시멘트를 원지반 흙과 혼합하여 연약지반에 직접 개량체를 형성하는 심층혼합공법의 적용도 지속적으로 이루어지고 있다. 그러나 시멘트의 경우 제품의 생산과정에서 많은 온실가스를 배출하는 문제가 있어 탄소중립이라는 국가적 목표 달성을 위해 새로운 대체재료의 개발 및 사용이 사회적으로 요구되고 있다. 이에 따라 본 연구에서는 순환자원을 재활용하여 시멘트와 유사한 경화반응을 유도할 수 있도록 개발된 CMD-SOIL을 심층혼합공법용 지반개량재로 사용하여 현장에 적용하고, 적용성을 평가함으로써 시멘트의 대체 가능성을 판단하고자 하였다. 연구결과, 설계기준강도 대비 CMD-SOIL의 압축강도는 현장 배합시험에서 1.46 ~ 2.64배, 확인보링에서 대비 1.2 ~ 5.03배 높은 수준을 나타내어 항만구조물의 안정성 확보에 요구되는 충분한 압축강도의 발현이 이루어지는 것으로 분석되었다. 또한 설계기준강도에 대한 현장에서의 압축강도의 비(λ)도 0.63 ~ 1.14로 기존의 연구결과와 유사한 결과를 나타내어 포틀랜드 시멘트, 고로슬래그 시멘트 등의 기존의 재료와 비교할 때 적용성의 차이는 없어 시멘트를 대체하여 심층혼합공법용 지반개량재로서의 사용이 가능할 것으로 분석되었다.

염기성 pH에서의 고점도 커들란에 의한 콘크리트의 재료분리 억제 효과 증진 (A High Viscosity of Curdlan at Alkaline pH Increases Segregational Resistance of Concrete)

  • 이인영;김선원;이중헌;김미경;조인성;박영훈
    • KSBB Journal
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    • 제14권1호
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    • pp.114-118
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    • 1999
  • 본 연구에서는 미생물 담당의 일종인 커들린을 콘크리트 혼화제로 사용하기 위하여 시험공장 수준에서의 커들란 대량생산 공정을 확립하고, 생산한 다당의 물성과 특성을 조사하고 콘크리트와의 혼합에 의한 콘크리트 재료분리 억제제로서의 새로운 용도를 평가하였다. 커들란을 300 리터 발효조에서 고농도로 대량 생산하기 위하여 커다란 규모로 대량 생산 시 종종 제한요인이 되는 산소 전달속도를 높게 유지할 수 있는 최적 교반속도와 세포성장 단계와 커들란 생산 단계에서의 배양액 pH를 전이하는 방법을 적용 하였다 교반속도를 200 rpm으로 유지하여 pH를 7.0으로 조절하여 20시간 배양 후, 배양액 내 암모니움은 고갈되었고. 이때 세포농도는 9.8g/L에 달하였다. 질소원이 고갈되고 커들란이 생산되는 단계에서 발효액의 pH를 5.5로 전이하여 최종 65g/L의 커들란을 120 시간 안에 생산할 수 있었다. 커들란의 용해도는 pH 11.0 이하에서는 거의 불용임을 알 수 있었으며, pH가 증가함에 따라 점차로 증가하여 pH 13에서는 거의 다 녹았다. 커들란의 점도는 pH 12에서 가장 높았고 pH 13에서도 높은 점도를 나타내었다. 시멘트 현탁액의 pH가 약 13 정도임을 생각할 때 커들란을 혼화제로 콘크리트에 첨가할 경우 잘 용해되고 또한 콘크리트의 점도를 증진시킬 수 있을 것으로 판단된다. 커들란을 소량 첨가하였을 때에도 물이 slurry로부터 분리되었으나 커들란을 소량 첨가하였을 때에도 시멘트 slurry로부터 물이 분리되지 않고 균일한 흐름 경향을 보았다. 결론적으로, 본 연구자들은 조업이 간편한 회분식발효를 통하여 고능도로 거들란을 대량생산할 수 있었으며, 효율적이고 저렴한 분리공정을 개발하였다. 이렇게 제조한 커들란을 소량 콘크리트에 첨가하여 재료 분리 억제 효과가 우수하였는 바, 커들란의 산업적 생산에 커다란 가능성을 부여한다.

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Optimal Electric Energy Subscription Policy for Multiple Plants with Uncertain Demand

  • Nilrangsee, Puvarin;Bohez, Erik L.J.
    • Industrial Engineering and Management Systems
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    • 제6권2호
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    • pp.106-118
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    • 2007
  • This paper present a new optimization model to generate aggregate production planning by considering electric cost. The new Time Of Switching (TOS) electric type is introduced by switching over Time Of Day (TOD) and Time Of Use (TOU) electric types to minimize the electric cost. The fuzzy demand and Dynamic inventory tracking with multiple plant capacity are modeled to cover the uncertain demand of customer. The constraint for minimum hour limitation of plant running per one start up event is introduced to minimize plants idle time. Furthermore; the Optimal Weight Moving Average Factor for customer demand forecasting is introduced by monthly factors to reduce forecasting error. Application is illustrated for multiple cement mill plants. The mathematical model was formulated in spreadsheet format. Then the spreadsheet-solver technique was used as a tool to solve the model. A simulation running on part of the system in a test for six months shows the optimal solution could save 60% of the actual cost.

Corrosion initiation time models in RC coastal structures based on reliability approach

  • Djeddi, Lamine;Amirat, Abdelaziz
    • Advances in concrete construction
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    • 제9권2호
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    • pp.149-159
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    • 2020
  • The present work proposes new engineering models for determining corrosion initiation time in concrete reinforcing steels in marine environment. The models are based on Fick's second law that is commonly used for chloride diffusion. The latter is based on deterministic analyses involving the most influencing parameters such as distance of the concrete structure from the seaside, depth of steel concrete cover, ambient temperature, relative humidity and the water-cement ratio. However, a realistic corrosion initiation time cannot be estimated because of the uncertainties associated to the different parameters of the models. Therefore a reliability approach using FORM/SORM method has been applied to develop the proposed engineering models integrating a limit state function and a reliability index β. As a result, the corrosion initiation time is expressed by new exponential engineering models where the uncertainties are associated to the model parameters. The main emerging result is a realistic decision tool for corrosion planning inspection.

초유동 콘크리트의 제조 및 역학적 특성에 관한 실험적 연구 (An Experimental Study on the Production and Mechanical Properties of Super-Workable Concrete)

  • 배수호;윤상대;이대형
    • 한국농공학회지
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    • 제40권6호
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    • pp.104-113
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    • 1998
  • The purpose of this experimental research is to produce the super-workable concrete using ordinary portland cement, blast-furnace slag lowder, and fly ash respectively, and investigate mechanical properties of super-workable concrete. For this purpose, after production of super-workable concrete for different unit weights of binder and percentages of fine aggregate, optimum mixing proportion of them was determined, and then mechanical properties of super-workable concrete such as static modulud of elasticity as well as compressive, tensile and flexural strength were tested and analyzed. Also, the mechanical performances of super-workable concrete were compared with those of high-strength concrete has an excellent mobility, compactability and segregation-resistance, but the strength of super-workable concrete is somewhat lower than that of high-strength concrete with equal mixing proportions of concrete.

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한국공업화과정(韓國工業化過程)에서의 광물자원(鑛物資源)의 수급구조변화(需給構造變化)와 경제성장(經濟成長)에 있어서의 역할(役割) (The Changing Patterns of Demand-Supply and Role of Mineral Resources in Economic Growth during Industrialization of the Republic of Korea)

  • 윤석규
    • 자원환경지질
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    • 제18권1호
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    • pp.65-92
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    • 1985
  • A total of 12 mineral commodities significant in domestic output, economy and/or strategy of the Republic of Korea are chosen to examine the structural changes in production and demand-supply of these minerals during the last two decades of her industrialization. These include iron and manganese ores as the raw materials for iron and steel making, copper, zinc and tungsten ores among other non-ferrous metallic minerals, limestone (cement), kaolin, talc, pyrophyllite and graphite among other non-metallic minerals, and anthracite coal as the only domestic source of fossil energy. These are reviewed historically in time-series based on the statistical data which are tabulated and graphed in terms of domestic output, export, import, apparent demand-supply, its increasing rate, and self-sufficiency rate of each commodity. The increasing rates of demand-supply (IRDS) of some more important commodities are compared with those of Gross Domestic Production (GDP) and Economic Growth Rate (EGR) to evaluate how the IRDS contributed to the GDP and EGR. The major results revealed are as follows: Among the 12 commodities, the domestic output of 8 commodities appeared to have grown with steady upward trends: they are ores of lead, zinc and tungsten, limestone (cement), kaolin, talc, pyrophyllite and anthracite coal. Two commodities, ores of iron and copper, continued with unchanging or slightly declining trends and varied fluctuations, in spite of their cardinal importance to the heavy industry and strategy of Korea. The remaining two, graphite and manganese ore, have gradualy declined in domestic output in which the former has still enough resource potential but the latter has not and virtually ceased its domestic output. Trade patterns for mineral commodities in the Republic of Korea during the last two decades have changed greatly, being marked by a shift from mineral-exporting to mineral importing, mainly because of increasing consumption of mineral raw materials for industrialization rather than beceuse of decreasing output of domestic mineral commodities in quantity. In terms of trade patterns, the 12 commodities concerned in this study can be classified into the following four groups. The 1st group - ores of lead and tungsten have only been exported without imports. The 2nd group - amorphous graphite, and pyrophyllite have mainly been exported but partly been imported. The 3rd group - kaolin, talc and crystalline graphite have equally been exported and imported, but quantity of imports have rapidly been increased with time. The 4th group - ores of iron, manganese and zinc have shifted from exports to imports during the industrialization, particularly owing to the initiation of iron and steel making by the Pohang Iron and Steel Company in the middle 1970' s and the new establishment of the Onsan Zinc Refinery in the late 1970' s. All of the 12 commodities under considerations were far above 100% in self-sufficiency rate before or in the early 1960' s. Recently, however, most of them have been declined to below 100% except for those of limestone (cement) and pyrophyllite. It is particularly serious to identify that the self-sufficiency rates of the three important metallic minerals, iron, copper and manganese ores in 1982 appeared to be 5.1%, 0.5%, and 0.01%, respectively. The average self-sufficiency rate of the total domestic minerals produced in 1982 was 14.4% (in value) for that year. Mining industry appeared to be extremely high in its intermediate demand rate whereas its intermediate input rate to be quite low indicating that mineral raw materials have been exerted strong forward linkage effects upon the other industries rather than backward linkage effects. In comparing the curves of increasing rates of demand-supply of several major minerals - iron ore, manganese ore, copper ore, limestone (cement), kaolin, and anthracite coal - with those of Gross Domestic Production and Economic Growth Rate drawn on every graph, it is clearly shown that the curves of increasing rates of demand-supply comprise around 6 to 7 periods of cycles which roughly harmonious with those of the curves of GDP and EGR, except for the curve of anthracite coal of which the configuration seems to have resulted from the (artificial) government's mineral policy rather than from economic free market mechanism. The harmonic feature of these curves well suggests that the increasing rates of demand-supply of major minerals have been significantly contributed to the GDP and EGR. In addition, the wider amplitudes of the iron, manganese and copper curves than those of the limestone (cement) and kaolin curves indicate that the contribution of the former, metallic commodities, has been greater than that of the latter, non-metallic commodities.

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플라이애쉬 시멘트 모르터를 사용한 비탈형 영구거푸집 개발에 관한 실험적연구 (An Experimental Study on The Development of fly-ash Cement Mortal Permanent)

  • 김형남;김우재;김성식;김영희;정상진
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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    • pp.481-486
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    • 1999
  • According to results of this research Fly-ash Cement permanent-form production was found to be possible by fly-ash mortal. The compress strength 350kg/$\textrm{cm}^2$, banding strength 120kg/$\textrm{cm}^2$ were possible material separting and bleeding by excessive W/C rate was decreased permanent-form made by polymer solved high price of polymer by fly-ash. Model material was made by result of first research. There were no minute-crack on beam form and out surface of form was very smooth, So filling degree seemed desirable length of form after steaming curing was maintained as expected. with these results production of form seemed possible. In the banding load test, fly-ash showed increase of maxim load 12% than RC. in the case of minute-crack, comparing with RC, fly-ash showed no crack at connect. at the first stage under continuing loading size of crack increased. These phenomena seemed to be based on contribution of stress of inner bars in permanent-form. in the test of defection, fly-ash shower about 10% beam load increase than RC. in the case of beam defection, RC showed sudden decrease of tolerance at maxim load and total breaking, but permanent-form showed breaking of bending maintaining defection with contribution of steel stress ($\Phi$6 wire-mash). There phenomenic seemed to be attributed to increase of surface and steel tolerance of form. According to construction explacemaion, it was guessed that each panel was constructed by conner-steels in form edge. so cohesiveness was small. on these bases. keeping width of horizontal band 30cm, form-panel of 20mm width was found to be of use. Permanent-form was found to be efficient in compressibleness, defection, safety and use of Fly-ash mortal.

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고화토차수층에 대한 산성침출수의 영향과 대책방안 - 산업부산물(고로슬래그, 플라이애쉬) 재활용 방안 중심으로 - (Effect of Acidic Leachate on the Cement-based Landfill Soil Liner System)

  • 조재범;현재혁;이종득;박정구
    • 대한환경공학회지
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    • 제28권3호
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    • pp.265-269
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    • 2006
  • 본 연구는 산성상태의 침출수가 차수층에 미치는 영향을 규명하고 년간 산업부산물로 다량 배출되는 고로슬래그, 플라이애쉬를 재활용하기 위한 한 방안으로 매립지 차수층에 첨가시의 역할을 규명하기 위한 기초연구자료이다. 산성침출수가 고화차수층에 미치는 영향을 고찰하기 위해 압축강도와 투수계수 실험결과, 고화재(시멘트)와 준설점토로 성형된 고화차수층의 경우 산성상태의 침출수에 노출됨에 따라 압축강도 감소와 투수계수 증가현상을 나타내었다. 반면 고로슬래그와 플라이애쉬를 첨가한 고화토차수층의 경우는 산성상태의 침출수에 영향을 크게 받지 않는 것으로 나타났다. 이는 고알카리 상태를 나타내는 고로슬래그와 플라이애쉬의 경우 차수층 내부로 침투되어 수화반응에 의해 생성된 칼슘계 수화물을 용해하는 산성물질의 용해작용을 방해하기 때문으로 판단된다.

Carbonation Behavior of Lightweight Foamed Concrete Using Coal Fly Ash

  • Lee, Jae Hoon;Lee, Ki Gang
    • 한국세라믹학회지
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    • 제53권3호
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    • pp.354-361
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    • 2016
  • The purpose of this study was to prepare lightweight foamed concrete by mixing coal fly ash of circulating fluidized bed combustion(CFBC) with cement, and to develop uses for recycling by analyzing carbonation behavior resulting from a change in conditions for pressurized carbonation. For concrete, CFBC coal fly ash was mixed with Portland cement to the water-binder ratio of 0.5, and aging was applied at room temperature after 3 days of curing at $20^{\circ}C$, RH 60%. For carbonation, temperature was fixed at $60^{\circ}C$ and time at 1 h in the use of autoclave. Pressures were controlled to be $5kgf/cm^2$ and the supercritical condition of $80kgf/cm^2$, and gas compositions were employed as $CO_2$ 100% and $CO_2$ 15%+N2 85%. In the characteristics of produced lightweight concrete, the characteristics of lightweight foamed concrete resulting from carbonation reaction were affirmed through rate of weight change, carbonation depth test, air permeability, and processing analysis for the day 28 specimen. Based on these results, it is concluded that the present approach could provide a viable method for mass production of eco-friendly lightweight foamed concrete from CFBC coal fly ash stabilized by carbonation.