• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 추계 학술논문 발표대회
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• pp.68-71
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• 2013

Reactive Powder Concrete (RPC) is an ultra high strength and high ductility cement-based composite material and has shown some promise as a new generation concrete in construction field. It is characterized by a silica fume-cement mixture with very low water-binder (w/b) ratio and very dense microstructure, which is formed using various powders such as cement, silica fume and very fine quartz sand (0.15~0.4mm) instead of ordinary coarse aggregate. However, the unit weight of cement in RPC is as high as 900~1,000 kg/㎥ due to the use of very fine sand instead of coarse aggregate, and a large volume of relatively expensive silica fume as a high reactivity pozzolan is also used, which is not produced in Korea and thus must be imported. Since the density of RPC has a heavy weight at 2.5~3.0 g/㎤. In this study, the modified RPC was made by the combination of ternary pozzolanic materials such as blast furnace slag and fly ash, silica fume in order to economically and practically feasible for Korea's situation. The fire resistance and structural behavior of the modified RPC exposed to high temperature were investigated.

• Advances in concrete construction
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• 제5권6호
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• pp.587-611
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• 2017

This study focused on the influences regarding the use of polyepoxide-based polymer and silica fume (SF) on the fresh and hardened state properties of self-compacting lightweight concrete (SCLC) along with their impacts on electrical resistance and ultrasonic pulse velocity (UPV). To do so, two series of compositions each of which consists of twelve mixes, with water to binder (W/B) ratios of 0.35 and 0.4 were cast. Three different silica fume/binder ratios of 0, 5%, and 10% were considered along with four different polymer/binder ratios of 0, 5%, 10%, and 15%. Afterwards, the rupture modulus, tensile strength, 14-day, 28-day, and 90-day compressive strength, the UPV and the electrical resistance of the mixes were tested. The results indicated that although the use of polymer could enhance the passing and filling abilities, it could lead to a decrease of segregation resistance. In addition, the interaction of the SF and the polymeric contents enhanced the workability. However, the impacts regarding the use of polymeric contents on fresh state properties of SCLC were more prevalent than those regarding the use of SF. Besides the fresh state properties, the durability and mechanical properties of the mixes were affected due to the use of polymeric and SF contents. In other words, the use of the SF and the polymer enhanced the durability and mechanical properties of SCLC specimens.

• Smart Structures and Systems
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• 제23권2호
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• pp.207-214
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• 2019

Achieving a pervious concrete (PC) with appropriate physical and mechanical properties used in pavement have been strongly investigated through the use of different materials specifically from the global waste materials of the populated areas. Discarded tires and the rubber tire particles have been currently manufactured as the recycled waste materials. In the current study, the combination of polymer, silica fume and rubber aggregates from rubber tire particles have been used to obtain an optimized PC resulting that the PC with silica fume, polymer and rubber aggregate replacement to mineral aggregate has greater compressive and flexural strength. The related flexural and compressive strength of the produced PC has been increased 31% and 18% compared to the mineral PC concrete, also, the impact resistance has been progressed 8% compared to the mineral aggregate PC and the permeability with Open Graded Fraction Course standard (OGFC). While the manufactured PC has significantly reduced the elasticity modulus of usual pervious concrete, the impact resistance has been remarkably improved.

• 융복합기술연구소 논문집
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• 제8권1호
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• pp.27-31
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• 2018

The age of electric vehicle is coming. One of the most important problems to be solved for popularization of electric vehicle is fuel economy. To increase fuel economy of electric vehicles, it is necessary to improve the performance of the battery or the car body should be lighter than now. To solve the problem of the car body, change the car body's material to carbon fiber reinforced composites can be an excellent answer. However, the part made from carbon fiber reinforced composites is vulnerable to accidents due to their high brittleness. In this study, ductile silica fume was added into the carbon fiber composites to enhance toughness. To examine this, various amounts and sizes of silica fume were considered and the toughness enhancement was examined by performing tensile tests.

• Advances in concrete construction
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• 제12권5호
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• pp.419-427
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• 2021

The overuse level of cement for civil industry has several undesirable social and ecological consequences. Substitution of cement with industrial wastes, called by-products, such as fly ash, ground granulated blast furnace slag, silica fume, metakaoline, rice husk ash, etc. as the mineral admixtures offers various advantages such as technical, economical and environmental which are very important in the era of sustainability in construction industry. The paper presents the experimental investigations for assessing the mechanical properties of the concrete made using the Pozzolanic waste materials (supplementary cementitious materials) such as fly ash and silica fume as the cement replacing materials. These materials were used in eight trial mixes with varying amount of ordinary Portland cement. These SCMs were kept in equal proportions in all the eight trial mixes. The chemical admixture (High Range Water Reducing Admixture) was also added to improve the workability of concrete. The compressive strengths for 7, 28, 40 and 90 days curing were evaluated whereas the flexural and tensile strengths corresponding to 7, 28 and 40 days curing were evaluated. The study corroborates that the Pozzolanic materials used in the present investigation as partial replacement for cement can render the sustainable concrete which can be used in the rigid pavement construction.

• 한국구조물진단유지관리공학회 논문집
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• 제9권2호
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• pp.173-180
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• 2005

메타카올린은 고성능 콘크리트를 제조하기 위해 콘크리트에 혼합재로서 사용되는 결합재의 일종이다. 이 재료는 일반적으로 국내에서는 내화벽돌의 재료로 많이 사용되었으나, 현재는 이러한 고성능 콘크리트를 제조하기 위하여 필요한 실리카흄의 대용으로 사용되어지고 있다. 본 연구는 실리카흄 및 메타카올린 두 결합재를 콘크리트 중에 일정량 치환하여 몰르타르 및 콘크리트의 압축강도, 인장강도, 휨강도와 같은 역학적 시험뿐만 아니라, 염소이온확산시험, 화학침식에 대한 저항성 시험, 동결융해저항성 시험과 같은 내구성시험을 병행 실시하였다. 역학적 시험결과 메타카올린을 결합재전체 대비 10에서 15%정도 치환 사용했을 때 가장 적당한 강도결과를 보였다. 그리고, 메타카올린 및 실리카흄 두 결합재의 치환율이 증가할수록 염소이온확산이 훨씬 줄어드는 것을 확인할 수 있었다. 그리고, 두 결합재의 미세분말에 의한 충전효과에 의해 일반 콘크리트에 비해 화학적침식저항성이 훨씬 뛰어남을 보였다. 다른 내구성 시험에서도 메타카올린을 사용한 콘크리트가 실리카흄을 사용한 콘크리트에 상응하는 상당한 역학적, 내구특성을 가지고 있음을 확인할 수 있었다. 따라서, 이들 시험을 통해 우리는 메타카올린이라는 재료가 충분히 고가의 실리카흄을 대체가능할 수 있을 것이라고 판단할 수 있었다.

• 자원리싸이클링
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• 제19권4호
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• pp.35-40
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• 2010

최근에 들어 투수콘크리트의 동결융해에 대한 저항성이 저하되는 것과 줄눈부에서의 골재박리 등의 많은 문제점들이 대두되고 있다. 따라서 본 연구에서는 기존의 투수콘크리트의 내구성을 향상시키기 위한 방안으로 잔골재와 실리카흄, 고성능감수제를 사용하여 강도 및 내구성 증진 방안을 연구하였다. 주요실험인자로 실리카흄 혼입률 10%와 잔골재 혼입률(0%, 7%, 15%)을 선정하고, 압축강도와 휨강도, 투수계수 및 공극률, 동결융해시험을 수행하였다. 실험결과 강도측면에서는 잔골재 혼입률이 증가함에 따라 압축 및 휨강도는 증가하는 경향을 보였으나, 상대적으로 공극률 감소로 인한 투수성은 저하되고, 동결융해 저항성도 크게 감소하는 것으로 나타났다. 따라서 투수콘크리트에 있어서 강도증진을 위해 사용되는 잔골재는 혼입률 제한이 필요하며, 실리카흄 10%이상을 사용하는 것이 강도 및 내구성 측면에서 효율적인 대안이 될 수 있을 것으로 판단된다.

• 콘크리트학회논문집
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• 제17권5호
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• pp.743-750
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• 2005

교량 교면에 적용되는 실리카퓸을 혼합한 고성능 콘크리트는 경제성이 향상된 교면 포장 방법이다. 실리카퓸 콘크리트는 기존의 LMC와 비교하여 경제성 향상으로 미국, 유럽, 캐나다 지역에서 비교적 짧은 기간에 널리 사용하고 있다. 본 연구에서는 실리카퓸을 혼합한 고성능 콘크리트의 교면 포장에 대한 적용성을 알아보기 위하여 실내 실험을 실시하였다. 실내 실험은 물리, 역학적 및 내구성능을 평가하였는데 실험 결과 실리카퓸을 혼합한 고성능 콘크리트는 우수한 성능을 발휘하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.644-647
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• 2004

Modulus of rupture (MOR) and flexural toughness in hybrid fiber reinforced cement pastes mixed with micro-fiber (carbon fiber) and macro-fiber (steel fiber) and replaced with silica fume according to the fixed ratio were researched. Reinforcing efficiency in specimens were estimated by two factors, such as strengthening factor $(F_s)$ and toughening factor $(F_t)$, which were calculated from the analysis of variance (ANOVA) of the response values, such as MOR and absorbtion energy $(W_0)$. According to the experimental design by the fractional orthogonal array, nine hybrid fibrous reinforced paste series and one non-reinforced control paste were manufactured. Specimens of each series were tested by the INSTRON Inc. 8502(model) equipment in three-points bending and then measured the load-deflection response relationships. Considerable strengthening of cement pastes resulted in' the case of other factors without carbon fiber and toughening of cement pastes about all factors showed high. Based on the significance of factors related to response values from ANOVA, following assessments were available; $F_s$ or MOR: silica fume $\gg$ steel fiber $\gg$ carbon fiber; $F_t\;or\;W_0$: steel fiber > carbon fiber > silica fume. Optimized composition condition was estimated by steel fiber of $1.5\%$, carbon fiber of $0.5\%$ and silica fume $7.5\%$ in side of strengthening and steel fiber of $1.5\%$, carbon fiber of $0.75\%$ and silica fume $7.5\%$ in side of toughening.

• 한국산업보건학회지
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• 제11권1호
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• pp.1-8
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• 2001

This study was performed to evaluate a local exhaust ventilation system capability and welding fume concentration in welding laboratory at 5 technical high schools. Results of the study are as follows; 1. The personal exposure of welding fume in welding laboratory was measured. The geometric mean of 73 personal samples was $6.27mg/m^3$($3.85{\sim}9.88mg/m^3$), and 68.5% of these exceeded TLV of the Korea Ministry of Labor. 2. The geometric mean of welding fume at outside of booth was $2.27mg/m^3$($1.57{\sim}2.58mg/m^3$). All of measured concentrations were lower than TLV of the Korea Ministry of Labor. 3. Local exhaust ventilation system in welding laboratory could not remove hazardous substance effectively because of inappropriate canopy hood and absurd design. 4. The possibility of exposure risk was estimated to be high because of working point under breathing zone, misplacement of working table and insufficient supply of respiratory protector. 5. The mean values of capture velocity and transportation velocity of local exhaust ventilation system in welding laboratory were 0.38m/sec, 4.27m/sec respectively. These values were satisfied the guideline of the Korea Ministry of Labor. 6. The efficiency of performance of local ventilation system was anticipated to be decreased because of accumulated dust and alien substance on fan and duct.