• 제목/요약/키워드: fine aggregate/aggregate ratio

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순환골재콘크리트의 수축특성에 관한 연구 (Study on the Shrinkage Properties of Concrete using Recycled Fine Aggregate)

  • 나철성;이형준;남정수;권수길;김규용;김무한
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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    • pp.681-684
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    • 2008
  • 순환잔골재는 천연잔골재에 비해 밀도 및 흡수율 등이 열악하여 저부가가치용으로 활용되고 있고, 사용이 한정되어 있으며, 순환잔골재를 순환골재 콘크리트는 압축강도, 인장강도 등의 강도특성이 저하하고 특히, 높은 흡수율로 인하여 수축특성이 매우 저하하는 것으로 보고되고 있다. 따라서 본 연구에서는 고속회전충격식 비중분리장치 및 원심력 미분말 집진장치 등으로 구성된 건식생산시스템을 개발하고 이를 통해 생산된 순환잔골재를 사용한 순환골재 콘크리트의 수축특성을 평가함으로서 향후 순환잔골재의 활용을 위한 기초자료를 제시하고자 한다.

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석탄 가스화 용융 슬래그를 잔골재로 사용하는 플라이애시 치환 콘크리트의 기초적 특성 및 수화열에 관한 연구 (A Study on the Fundamental and Heat of Hydration Properties of Fly Ash Replacement Concrete Mixed with Coal Gasification Slag for Fine Aggregate)

  • 한민철;최일경
    • 대한건축학회논문집:구조계
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    • 제36권1호
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    • pp.155-162
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    • 2020
  • The aim of the research is to investigate the fundamental properties and heat of hydration reducing performance of the fly ash incorporated concrete mixture when the coal gas slag (CGS) from integrated gasification combined cycle (IGCC) is used as fine aggregate. From the results of the experiment, the workability was generally increased and the air content was decreased up to one to four percent with increasing the replacing ratio of CGS to fine aggregate. The compressive strength was similar or increased within five percent to the Plain mixture when the CGS was used as a fine aggregate. When the CGS and fly ash were used same time, the heat of hydration reducing performance was improved than single using cases either CGS or fly ash. Based on the results, for the concrete mixture using CSG as a portion of the combined fine aggregate, the general properties were improved and heat of hydration was decreased approximately 16 % when the fly ash was replaced 30 % to cement and the CGS was replaced less than 50 % to fine aggregate.

경량콘크리트의 개발에 관한 실험적 연구 (An Experimental Study on the Development of Lightweight Concrete)

  • 김성완;성찬용;민정기;정현정
    • 한국농공학회지
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    • 제37권5호
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    • pp.90-100
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    • 1995
  • This study was performed to develop the lightweight concrete using synthetic lightweight aggregate and natural coarse aggregate. Mixing ratios were three types, the first type was mixed cement and synthetic lightweight fine aggregate (Type CP), the second type was mixed cement, synthetic lightweight fine aggregate and synthetic lightweight coarse aggregate (Type CPE), the third type was mixed cement, synthetic lightweight fine aggregate and natural coarse aggregate (Type CPN). The results of this study are summarized as follows ; 1. The W/C of each mixing ratio was increased with increase of the amount of cement used, and it was shown higher in order of Type CP, CPN, CPE. 2. The unit weight of Type CP, CPE and CPN was 1.473~1.647g/cm$^3$, 1.467~1.622g/cm$^3$ and 1.658~1 .838g/cm$^3$, respectively. And the absorption ratio was approximately 20%, which was higher than that of the normal cement concrete. 3. The compressive strength of Type CP was shown 178 ~249kg/cm2, Type CPE was shown 149~241kg/cm$^2$ and Type CPN was shown 196~297kg/cm$^2$, respectively. Each strength ratio was smaller than that of the normal cement concrete. 4. The pulse velocity of Type CP, CPE and CPN was 2, 688~3, 240m/sec, 2, 981~3, 324m/sec and 2, 989 ~ 3, 545m/sec, respectively. And it was increased with increase of strength and unit weight. 5. The length change ratio at 28 days was in the range of 0.057~0.077%, and earlier length change ratio was higher than that of the later.

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초고강도 콘크리트에서 전기로 산화 슬래그 잔골재 사용에 의한 강도 증진 기구 (Mechanism of Strength Development in Ultra High Strength Concrete Using the Electric Arc Furnace Oxidizing Slag as Fine Aggregate)

  • 이승헌;임두섭;이승훈;이주하
    • 콘크리트학회논문집
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    • 제25권1호
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    • pp.3-9
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    • 2013
  • 초고강도 콘크리트에서 잔골재로 세척사 대신에 전기로 산화 슬래그를 사용했을 경우, 재령 91일 압축강도가 약 15 MPa 정도 향상되었다. 압축강도가 향상된 원인을 규명하기 위해 잔골재의 Ca 성분 용출 특성을 고찰하였고, 잔골재와 페이스트 계면에서의 미세조직, 기공율, 미소경도 및 Ca/Si 몰비를 검토하였다. 그리고 잔골재 형상에 의한 강도 증진 효과를 알아보기 위해 잔골재의 표면 거칠기를 AFM으로 측정하였다. 실험 결과, 초고강도 콘크리트에서 전기로 산화 슬래그 잔골재 사용에 의한 강도 증진 기구는 화학적 기구와 물리적 기구로 구분할 수 있다. 화학적 기구로는, 전기로 산화 슬래그에서 함유되어 있는 가용성 Ca 성분이 용출되어 잔골재와 페이스트 사이에 반응생성물을 형성시켜 조직을 치밀화 시킴으로 잔골재-페이스트간의 부착력을 증진 시키는 것으로 나타났다. 그리고 물리적 기구로는, 전기로 산화 슬래그 잔골재는 세척사에 비해 표면의 굴곡도가 2배 정도 커서, 잔골재와 페이스트 간의 interlocking strength를 증가시킴으로서 압축강도 발현에 기여하는 것으로 판단했다.

펠레타이저 공정변수와 인공경량골재의 성형체와 소성체 물성과의 상관관계 (Correlation to the Physical Properties of Green and Sintered Body of Artificial Lightweight Aggregate with the Pelletizing Variables)

  • 위영민;이기강
    • 한국세라믹학회지
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    • 제44권10호
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    • pp.568-573
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    • 2007
  • For the manufacturing lightweight fine aggregate, clay and waste material was formed by pelletizer. The fine aggregate of 1-5 mm diameter was formed by diameter 76 cm pelletizer disc. Pelletization variables were : (1) pelletizer disc angle, (2) speed of revolution of pelletizer, (3) added pelletization time. Green and sintered aggregate were measured specific gravity, absorption rate and average size. The optimum condition were found that the pelletization variables were angle at $70^{\circ}$, speed of revolution of pelletizer at 23.2 rpm, and water/solid ratio at 1/5. At these conditions, it was formed that fine aggregate green whose average size was $2.0{\sim}3.35mm$. Specific gravity and average size are increased with low angle of disc and fast revolution speed of disc. Specific gravity and average size were not distinctly influenced by added pelletization time. Sintered aggregate was distinctly influenced by properties of green.

잔골재의 종류에 따른 초속경콘크리트의 특성에 관한 연구 (A Study on the Characteristics of Rapid-set concrete as to Fine aggregate Kinds)

  • 정해동;강의주;이환우;장희석;김명식
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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    • pp.417-422
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    • 2001
  • The purpose of this study is to investigate experimentally the workability, compressive and flexural strength properties of rapid-set concrete with various mixture. The kinds of fine aggregate(river sand, sea sand, crushed sand), water-cement ratio(40%, 45%, 50%), sand-aggrega to ratio(33%, 36%, 39%) were chosen as the experimental parameters. Test variables are temperature of concrete, slump, air contents, compressive and flexural strength. The compressive and flexural strength for 3 hours and 6 hours were tested. As result, it was shown that temperature of concrete involved 45$^{\circ}C$, some time later decreased. The workability were decreasing in steps as the sand-aggregate ratio increased and crushed sand was the highest value. Higher compressive and flexural strength was shown following the order of river sand, sea sand, crushed sand regardless of sand-aggregate ratio. But the values of gap was just a little.

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부순모래 치환율별 목표슬럼프 값 고정에 따른 화학혼화제의 특성에 관한 연구 (A Study on the Chemical Admixture According to Target Slump Value by Crushed Sand Replacement Rate)

  • 류현기;조명근
    • 한국건축시공학회지
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    • 제8권4호
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    • pp.87-93
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    • 2008
  • With an increased use of alternative aggregate due to exhaustion of quality aggregate resources, the amount of used crushed aggregates have been increased and as a result, development of admixture materials has also been improved and its amount of use is increasing from day to day in order to secure quality in concrete. Accordingly, the purpose of this study is to make concrete of good quality by using chemical admixture developed in this study by replacement rate of fine aggregate. At first, susceptibility, compressive strength ratio and length change ratio in both fresh and hardened concrete were evaluated according to corresponding regulation. As for high performance related regulation, APC NO.3 and PC series were going to rule, and as for AE agent regulation, replacement ratio of fine aggregate of high performance chemical admixture was 10:0 and other chemical admixture met quality regulation for AE agent.

Porous concrete with optimum fine aggregate and fibre for improved strength

  • Karanth, Savithri S.;Kumar, U. Lohith;Danigond, Naveen
    • Advances in concrete construction
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    • 제8권4호
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    • pp.305-309
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    • 2019
  • Pervious concrete pavements are the need of the day to avoid urban flooding and to facilitate ground water recharge. However, the strength of pervious or porous concrete is considerably less compared to conventional concrete. In this experimental investigation, an effort is made to improve the strength of pervious concrete by adopting fibres and a small amount of fine aggregate. A porous concrete with cement to aggregate ratio of 1:5 and a water-powder ratio of 0.4 is adopted. 30% of the cement is replaced by cementitious material ground granulated blast furnace slag (GGBS) for better strength and workability. Recron fibres at a dosage of 0.5, 1.0 and 1.5% by weight of cement were included to improve the impact strength. Since concrete pavements are subjected to impact loads, the impact strength was also calculated by "Drop ball method" in addition to compressive strength. The effect of fine aggregate and recron fibres on workability, porosity, compressive and impact strength was studied. The investigations have shown that 20% inclusion of fine aggregate and 1.5% recron fibres by weight of cement give better strength with an acceptable range of porosity.

순환잔골재 혼입 콘크리트의 강도 특성 및 전과정 환경영향 평가 연구 (A Study on the Strength Properties and Life Cycle Assessment of Recycled Fine Aggregate Concrete)

  • 최원영;김상헌;이세현;전찬수
    • 한국건설순환자원학회논문집
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    • 제7권2호
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    • pp.123-130
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    • 2019
  • 본 연구에서는 순환잔골재의 혼입률에 따른 콘크리트의 강도 특성을 실험을 통해 확인하고, 전과정평가(LCA, Life Cycle Assessmet) 기법을 이용하여 순환잔골재의 전과정 환경영향을 평가하여, 콘크리트를 제조함에 있어서 순환잔골재 사용의 유효성을 확인하여 순환골재 콘크리트 활용을 위한 기초적 자료로 사용하는 것을 목적으로 한다. 이를 위해, 목표설계기준압축강도는 27MPa로 하였으며, 순환골재 실용화를 고려하여 순환잔골재의 혼입률을 0, 30, 60, 100%로 설정하여 굳지 않은 콘크리트 및 굳은 콘크리트에 대한 실험을 통해 슬럼프, 공기량, 압축강도 등을 확인하였고, 순환잔골재의 전과정 환경영향을 평가하고 타 골재와 환경영향을 비교 분석 하였다.

나노실리카 혼입률이 실리카퓸 및 고로슬래그 미분말을 혼입한 4성분계 고강도 순환잔골재 모르타르의 역학적 성능에 미치는 영향 (Investigation on the Mechanical Properties of High-Strength Recycled Fine Aggregate Mortar Made of Nanosilica Dispersed by Sonication)

  • 김성우;문래교;조은비;정철우
    • 한국건설순환자원학회논문집
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    • 제11권2호
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    • pp.97-104
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    • 2023
  • 본 연구에서는 순환잔골재 사용량 증대를 목적으로 순환잔골재만 혼입한 고강도 모르타르를 제조하고 이의 물성을 분석하여, 순환잔골재의 구조용 골재로서의 활용가능성을 파악하고자 하였다. 시멘트, 실리카퓸 및 고로슬래그 미분말을 함유한 물결합 재비 0.2 시멘트 모르타르에, 나노실리카를 추가로 혼입하고 이의 치환율을 변화시켜, 나노실리카 혼입량 변화가 순환잔골재 모르타르의 물성 변화에 미치는 영향을 분석하였다. 시험체 제작 시 결합재 내부에서의 나노실리카 분산도 향상을 위해, 초음파 처리한 수분산된 나노실리카 수용액을 활용하였고, 나노실리카의 혼입률은 1 %까지 변화시켜 모르타르 플로우, 공극률 및 압축강도의 변화를 평가하였다. 실험 결과에 따르면, 나노실리카의 혼입률이 증가할수록 모르타르 플로우는 감소하였으며, 나노실리카 혼입률 0.75 %까지는 혼입율을 높일수록 공극률은 감소하고 압축강도는 증가하였으나, 치환율 1 %에서는 공극률의 상승 및 압축강도의 저하가 관찰되어, 나노실리카 혼입률 0.75 %가 성능 최적화를 위해 가장 적절한 혼입 비율인 것을 확인할 수 있었다.