• 한국결정성장학회지
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• 제19권6호
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• pp.318-323
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• 2009

본 실험에서는 로터리 킬른으로 제조되는 인공경량골재의 실험실적 제어 가능성을 찾고자 여러 가지 소성조건에서 석탄 화력발전소에서 발생되는 바닥재와 준설토를 이용하여 인공경량골재를 제조하였다. 인공경량골재 조성은 바닥재 70 wt%와 준설토 30 wt%의 무게비로 성형하였고, 산화 분위기, 불활성 분위기, 환원 분위기에서 각각 $1150^{\circ}C$, $1200^{\circ}C$에서 소성하여 제조된 인공경량골재는 산화 분위기에서 명확한 블랙코어와 껍질(shell)간의 경계를 보이나, 불활성 분위기에서는 질소량이 증가할수록 그리고 소성온도가 증가할수록 경계가 없어지는 경향을 보이며, 환원 분위기에서는 단면 전체가 진회색을 띄게 된다. 로터리 킬른의 분위기와 가장 근접한 소성 분위기는 불활성분위기였으며 밀도나 흡수율 또한 그것과 유사하였다. 이러한 결과로 소형 전기로에서 로터리 킬른의 환경과 유사하게 조건을 제어할 수 있고, 물성을 예측할 수 있는 실험이 가능할 것으로 생각된다.

• 한국구조물진단유지관리공학회 논문집
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• 제28권1호
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• pp.24-31
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• 2024

기존 대부분의 3D 콘크리트 프린팅 연구는 모르타르를 재료로 활용하고 있다. 다만, 굵은 골재를 포함한 콘크리트에 비해 모르타르를 사용할 경우에는 높은 바인더 함량과 잔골재량으로 인하여 경제성이 저하될 수 밖에 없다. 따라서, 3D 프린팅 기술의 건설산업 적용 확대를 위해서는 굵은 골재를 사용한 콘크리트 3D 프린팅에 대한 연구가 요구된다. 본 연구에서는 굵은 골재가 포함된 3D 프린팅 용 콘크리트의 배합설계 프로세스를 제안하고자 하였다. 다양한 문헌연구 및 배합실험을 참고하여 3D 프린팅에 적합한 배합을 도출하였으며, 출력실험을 통하여 압출성을 검증하였다. 콘크리트 배합의 증점제(Viscosity modifying agent, VMA) 함량을 출력실험의 변수로 설정하였으며, 출력된 필라멘트의 치수 적합성, 골재분포도, 표면 품질을 평가하여 압출성능을 검증하였다. 실험결과, VMA의 함량이 높은 배합이 더 우수한 치수 적합성과 표면 품질을 보였으며, VMA 함량이 다름에도 불구하고 모든 배합에서 골재분포가 균등하게 나타났다. 실험결과를 바탕으로 굵은 골재가 포함된 콘크리트의 압출성을 향상 시킬 수 있는 배합설계 프로세스를 도출하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.317-318
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• 2009

In this paper, we observed stretching of carbon nanotube (CNT) aggregates driven by the electric filed in a nematic liquid crystal (LC) medium. The CNT aggregates started to stretch above a threshold filed which is $1.5\;V/{\mu}m$ and the original CNT length which is $1.7{\mu}m$ was stretching up to $19.2\;{\mu}m$ at $3.5\;V/{\mu}m$ electric filed. When the CNT aggregates became to stretching, the width and length of CNT aggregates became narrow and long, respectively. The original morphology of the CNT aggregates was restored upon removal of filed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.969-978
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• 2010

In this study, a laboratory model test on utilization of recycled aggregates and crushed stone as vertical drains to use alternative material of sand in soft ground is performed. The vertical and horizontal coefficient of permeability of the recycled aggregates and crushed stone showed largely 1.2~4.0 times and 3.0~3.3 times greater than sand, respectively. Therefore, it showed enough to be an alternative material to the sand which had been being used as the vertical and horizontal drainage material before. The variations of pore water pressure with time showed constantly regardless of the load in all vertical drainage materials. When water level drops suddenly, the pore water pressure of the recycled aggregate and crushed aggregate is reduced to nearly zero. Therefore, it was applicable to the field because discharge capacity was similarity to that of sand. The settlement in crushed aggregates and recycled aggregate decreases gradually with the load increase. When water level drops suddenly, earth pressure in all drains materials was evaluated the equivalent drainage capacity similarity to sand because it show approaching the nearly zero.

• 농업과학연구
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• 제37권1호
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• pp.97-104
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• 2010

In this study, a laboratory model test on utilization of recycled aggregates and crushed stone as vertical drains to use alternative material of sand in soft ground is performed. The vertical and horizontal coefficient of permeability of the recycled aggregates and crushed stone showed largely 1.2~4.0 times and 3.0~3.3 times greater than sand, respectively. Therefore, it showed enough to be an alternative material to the sand which had been being used as the vertical and horizontal drainage material before. The variations of pore water pressure with time showed constantly regardless of the load in all vertical drainage materials. When water level drops suddenly, the pore water pressure of the recycled aggregate and crushed aggregate is reduced to nearly zero. Therefore, it was applicable to the field because discharge capacity was similarity to that of sand. The settlement in crushed aggregates and recycled aggregate decreases gradually with the load increase. When water level drops suddenly, earth pressure in all drains materials was evaluated the equivalent drainage capacity similarity to sand because it show approaching the nearly zero.

• 공업화학
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• 제20권1호
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• pp.67-74
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• 2009

오늘날 대규모 건설사업에 따른 골재의 고갈과 환경보호 측면에서 폐콘크리트 순환골재의 재활용이 절실히 요구되고있다. 폐콘크리트 순환골재를 재활용한 폴리머 복합재료를 개발하기 위하여 순환골재의 치환율을 5단계로 변화시키고(0, 25, 50, 75, 100%) 또 폴리머-시멘트비도 5단계로 변화시켜(0, 5, 10, 15, 20%) 총 25종류의 공시체를 제조하였다. 공시체의 제 성능을 조사하기 위하여 공시체의 압축 및 휨강도, 흡수시험, 내열수성시험, 총세공량 및 공극률에 대하여 조사하였다. 시험결과, 폴리머 복합재료의 물성은 폴리머 시멘트비의 증가에 따라 현저히 증가되었으나 폐콘크리트 순환골재의 치환율 증가에 따라서는 크게 저하되었다.

• 한국세라믹학회지
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• 제49권2호
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• pp.161-166
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• 2012

The temperature-rasing sintering method was used in this study to fabricate the aggregates of uniform pore size and distribution containing reject ash occurred in the thermal power plant. The spheric green aggregates made of reject ash were put into the box furnace of 800~$1000^{\circ}C$, heated with a heating rate of 5~$15^{\circ}C$/min to 1200~$1275^{\circ}C$, sintered for 10 min and then discharged out of the furnace to the room temperature. The input temperature, heating rate and sintering temperature increased the bloating phenomenon of the specimen, and the sintering temperature among them was the most effective factor. The aggregate manufactured at $1275^{\circ}C$ had the specific gravity of about 1.0 and water absorption of 1~2%, and the pores of 500~1,000 ${\mu}m$ were uniformly distributed across the whole specimen. Especially, the aggregates fabricated using the temperature-rasing sintering method in this study showed an excellent bloating properties and uniform microstructure without black core phenomenon which is typical for the bloated ceramics synthesized by direct sintering method.

• 한국도로학회논문집
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• 제15권2호
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• pp.73-81
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• 2013

PURPOSES : In this study, various laboratory tests were performed to investigate basic physical properties of the asphalt concrete which uses wasted vinyl aggregates. METHODS : The thermal conductivity, ultrasonic velocity, Marshall stability, flow, indirect tensile strength were measured according to binder content and wasted vinyl aggregate content. An experimental construction was performed to verify construct ability of the asphalt pavement using the wasted vinyl aggregates. RESULTS : The thermal conductivity and ultrasonic velocity decreased showing insulation effect by mixing more wasted vinyl aggregate, whereas stability and flow increased. The void ratio shows similar value regardless of the mixing ratio. The highest indirect tensile strength was measured at 2.5% of wasted vinyl aggregate content. The construct ability was verified by observing the process of mixing, placing, and compaction and the state of the pavement surface. CONCLUSIONS : The basic properties and construct ability of the asphalt concrete using the wasted vinyl aggregates were verified. The temperature according to pavement depth will be measured to verify the insulation effect of the wasted vinyl aggregates. In addition, amount of snowfall, snowmelt area, and ice adhesion strength will be analyzed quantitively.

• 상하수도학회지
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• 제18권6호
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• pp.785-793
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• 2004

Coagulation has been investigated for pretreatment of low-pressure membrane systems such as microfiltration and ultrafiltration. Coagulation pretreatment can reduce foulants (particles and organic matter) prior to membrane filtration. However, when in-line coagulation or submerged type of filtration is used, flocculent aggregates could act as a foulant depending on concentrations and specific properties of floc. A natural water and three synthetic waters were used to investigate effects of coagulation pretreatment and presence of flocculent aggregates on membrane fouling. Coagulation pretreatment shows that foul ants were effectively removed during coagulation and the formed cake layer on the membrane surface had less resistances compared to raw natural water. In addition, little difference in membrane fouling was found by flocculent aggregates from the natural water. Interestingly, however, the results by three synthetic waters indicated that flocculent aggregates could have adverse effects on membrane fouling in a specific condition.

• 한국분말재료학회지
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• 제13권2호
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• pp.102-107
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• 2006

Recycling industrial wastes such as fly ash from a coal burning heat power plant and shell from an oyster farming were investigated to prevent environment contamination as well as to enhance the value of recycling materials. In this study, the lightweight aggregates and the red bricks were fabricated from fly ashes with other inorganic materials and wastes. The starting materials of the lightweight aggregate were fly ash powder and water glass, and the compacts of these materials were heat treated at $1100^{\circ}C$. The fabricated lightweight aggregates had low bulk density, $0.9-1.2\;g/cm^3$, hence floated on the water and had the strength of 7.0-11.0 MPa and the modulus of 2900-3300 MPa which indicates it has enough strength as the aggregate. Another type of the light weight aggregate was prepared from fly ashes, shell powders and clays. The bulk density, porosity, and compressive strength of these aggregates were $1.19-1.34\;g/cm^3,\;18.3{\sim}56.1%$ and 5-12 MPa, respectively. The addition of a small amount of fly ash powder prevented hydration of the light weight aggregates. The red brick was also fabricated from the fly ash containing materials. It is suitable for the brick facing of a building as it has moderate strength and low water absorption rate.