• 콘크리트학회지
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• 제15권5호
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• pp.17-23
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• 2003

• 콘크리트학회지
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• 제15권5호
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• pp.24-32
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• 2003

• 한국구조물진단유지관리공학회 논문집
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• 제10권3호
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• pp.97-105
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• 2006

고성능 콘크리트의 자기수축은 초기균열을 유도할 수 있기 때문에 내구성 측면에서 매우 중요하다. 이에 따라, 본 연구에서는 실험을 통해 혼화재료를 혼입한 고성능 콘크리트의 자기수축 특성을 분석한 후 예측모델을 제안하였다. 이를 위해 다양한 실험변수를 가진 시편에 대해 광범위한 실험을 수행하였다. 주요 실험변수는 혼화재료의 종류 및 혼입률로 설정하였으며 물-시멘트비는 30%로 고정하였다. 실험결과 플라이애시를 치환한 경우에는 자기수축량이 다소 감소하였으며, 고로슬래그를 사용한 경우에는 자기수축이 증가하였다. 또한, 수축저감제 및 팽창재의 혼입량이 클수록 고성능 콘크리트의 자기수축은 감소하는 경향을 보였다. 한편, 본 논문에서는 회귀분석을 통해 혼화재료를 사용한 고성능 콘크리트의 자기수축 예측식을 제안하였으며, 제안된 자기수축 예측식은 실험결과와 비교적 일치하였다

• 한국건축시공학회지
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• 제3권3호
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• pp.127-133
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• 2003

Carbonation and drying shrinkage are very important properties of concrete, that can cause concrete to lower its capacity and spall. But the research on them in high strength concrete is very poor. In this study, to estimate influences of W/B, the kind of admixture, the replacement ratio of admixture, fineness of blast furnace and etc. on drying shrinkage and carbonation, we make experiment with 3 levels(28, 35, 55%) of W/B, 3 kinds(blast-furnace slag, fly-ash, silica-fume) of admixture, 3 levels of the replacement ratio, 3 levels(4000, 6000, 8000cm2/g) of fineness of blast-furnace slag and 2 kinds of curing condition. As the results, compressive strength of concrete was decreased, as W/C was increased and the replacement ratio of admixture was increased. Drying shrinkage was increased, as W/B was higher, the replacement ratio of admixture was increased and fineness of blast-furnace slag was decreased. And carbonation was increased, as W/B ratio was higher, the replacement ratio of admixture was increased.

• 한국건축시공학회지
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• 제12권6호
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• pp.566-574
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• 2012

To address the problem of global warming, consumption of cement, the main material of concrete, should be decreased. Unfortunately, when industrial by-products are used in large quantities as admixture, the early age strength of concrete will be decreased, reducing its viability for use in concrete structures. Therefore, in this study, the application of an ionization accelerator and alkaline activator as addition agent of superplasticizer were investigated to secure a similar early age strength to that of normal concrete, thus increasing the viability of low cement concrete. Through the investigation, it was found that specimens that used a combination of Alkaline-activator (Na2Sio3) and ionization accelerator (Amine) had the highest early and long-age compressive strength. From this, we can determine an appropriate range of application of superplasticizer to improve early-age compressive strength of low cement concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.269-272
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• 2003

This study is intended to investigate the properties of concrete using AE Water Reducing Agent of Early-Strength Type. According to the results, as for the replacing method of mineral admixture, setting time is shortened faster in order of replacement for fine aggregate, combination and replacement for cement, and when AE Water Reducing Agent of Early-Strength Type is used, it is shortened by about 4 hours, compared with normal AE Water Reducing Agent Compressive strength is lower in the case of replacement for fine aggregate, but higher in the other case than that of plain concrete. And When AE Water Reducing Agent of Early-Strength Type is used, early compressive strength is very high in comparison to normal AE Water Reducing Agent. Early strength development is very favorable by the use of AE Water Reducing Agent of Early-Strength Type regardless of the replacing method of mineral admixture at $20^{\circ}C$, but at $l0^{\circ}C$, it is effective for Early strength development that W/B is lowered to below 45%, BS of 20% is replaced for fine aggregate, and AE Water Reducing Agent of Early-Strength Type is used.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.802-805
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• 2004

This study was performed to investigate the effect of mineral admixture' type and replacement ratios on the chloride penetration resistance of concrete which was immersed in the artificial chloride solution. The chloride penetration resistance was evaluated by penetration depth and chloride diffusion coefficient. As a result, all of the mineral admixtures were effective on the chloride penetration resistance of concrete compared to ordinary portland cement only.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.749-754
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• 2002

In this study, it is investigate to influence on tile dispersion of fiber and the flowability of matrix of type and amount of superplasticizer, velocity agent, mineral admixture and steel fiber to improve for construction performance of steel fiber reinforced cementitious composites. As for the test results, it was found that the dispersion of fiber and the flowability of matrix in steel fiber reinforced cementitious composites can improve by using of properly amount and combination of superplasticizer, velocity agent, mineral admixture. Furthermore, It show that the aspect ratio of steel fiber affect the construction performance of fiber reinforced cementitious composites, and the improvement for construction performance is the more effective the smaller aspect ration of steel fiber.

• Computers and Concrete
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• 제21권3호
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• pp.345-353
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• 2018

This paper approaches to improve the mechanical and durability properties of low calcium fly ash geopolymer concrete with the addition of Alccofine as a mineral admixture. The mechanical and durability performance of GPC was assessed by means of compressive strength, flexural strength, permeability, water absorption and permeable voids tests. The correlation between compressive strength and flexural strength, depth of water penetration and percentage permeable voids are also reported. Test results show that addition of Alccofine significantly improves the mechanical as well as permeation properties of low calcium fly ash geopolymer concrete. Very good correlations were noted between the depth of water penetration and compressive strength, percentage permeable voids and compressive strength as well as between compressive strength and flexural strength.

• 콘크리트학회지
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• 제10권2호
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• pp.155-165
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• 1998

굳지 않은 콘크리트의 슬럼프손실을 저감시키기 위한 목적으로 고로슬래그 미분말 및 플라이애쉬의 혼합비율과 혼화제의 첨가방법을 변화시킨 콘크리트의 믹싱후 경과시간에 따른 슬럼프 변화에 대하여 고찰하였다. 연구결과 보통포틀랜드시멘트에 고로슬래그 비분말 또는 플라이애쉬를 혼합한 콘크리트가 혼화재를 혼합하지 않은 콘크리트보다 슬럼프손실을 줄일 수 있었으며, 고로슬래그 미분말과 플라이애쉬를 각각 50 및 5%를 혼합한 3성분계 콘크리트의 경우 슬럼프손실을 저감시키는데 유효하였다. 또한 혼화제의 일부를 15분후 분할하여 후첨가하는 혼합방법이 굳지않은 콘크리트의 슬럼프손실을 저감시키는데 가장 큰 효과가 있다. 한편 혼화재를 혼합한 3성분계 보통강도용 및 고강도용 콘크리트의 재령 28일까지의 압축강도는 혼화재를 혼합하지 않은 콘크리트보다 작았으나 재령 91일 압축강도는 31% 및 15%정도 크게 증가하였다.