• 한국세라믹학회지
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• 제46권1호
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• pp.35-40
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• 2009

Using zirconia and poly (methyl methacrylate-coethylene glycol dimethacrylate) (PMMA) microbeads, macroporous zirconia ceramics were fabricated by a simple pressing method. Effects of template size and content on microstructure, porosity, and flexural and compressive strengths were investigated in the processing of the macroporous zirconia ceramics. Three different sizes of microbeads (8, 20, and $50{\mu}m$) were used as a template for fabricating the macroporous ceramics. The porosity increased with increasing the template size at the same template content. The flexural and compressive strengths were primarily influenced by the porosity rather than the template size. However, the strengths increased with decreasing the template size at the same porosity. By controlling the template size and content, it was possible to produce macroporous zirconia ceramics with porosities ranging from 58% to 75%. Typical flexural and compressive strength values at 60% porosity were ${\sim}30\;MPa$ and ${\sim}75\;MPa$, respectively.

• 한국농공학회논문집
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• 제46권3호
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• pp.65-72
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• 2004

Modern underground and tunnel works that the wet type shotcrete is getting widely designed and applied in a large scale project. Further to its applications, the needs of improving the performance of the shotcrete, such as new and developed additives and accelerators fur increasing the performance of shotcrete, become the most important issue in the field. The main objective of this study evaluated to performance of steel fiber reinforced shotcrete using alkali free based accelerator for the durability and high quality of shotcrete. The major test variables are accelerator type and its dosage. One type silicate based accelerator and one type aluminate based accelerator and one type alkali free based accelerator were used. The dosage of accelerators is determined by the manufactures and laboratory test condition. Compressive strength test results showed that the dosage of silicate and aluminate based accelerators caused reduction of mechanical properties of shotcrete. Compressive strength of alkali free based accelerator is more stable than of silicate and aluminate based accelerators. Also, according to the compressive strength and flexural test results, it was found that steel fiber reinforced shotcrete used alkali free based accelerator could attain significant improvement in the mechanical and flexural performance.

• 한국농공학회논문집
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• 제48권3호
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• pp.85-94
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• 2006

Practially useful method of steel fiber for construction work is presented in this study. The most important purpose of this study is to develop a model which can predict mechanical behavior of the structure according to aspect ratio and volume fraction of steel fiber. Experiments on compressive strength, elastic modulus, and splitting strength were performed with self-made cylindrical specimens of variable aspect ratios and volume fractions. The experiment showed that compressive strength was not in direct proportion to volume fraction which doesn't seem to have great influence over compressive strength. However, splitting strength showed almost direct proportion to aspect ratio and volume fraction. Improvement of optimal efficiency was confirmed when the aspect ratio was 70. Experiments on flexural strength, fracture energy, and characteristic length were carried out with self-manufactured beams with notch. As a result, increases of flexural strength, fracture energy, and characteristic length according to increase of volume fraction tend to be prominent when aspect ratio is 70. The steel fiber improves concrete to be more ductile and tough. Moreover, regression analysis was the performed and predictable model was developed after determining variables. With comparison and analysis of suggested estimated values and measured data, reliance of the model was verified.

• Computers and Concrete
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• 제7권2호
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• pp.169-190
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• 2010

The focus of this research effort was characterization of the flexural and tensile properties of a specific ultra-high-strength, fiber-reinforced concrete material. The material exhibited a mean unconfined compressive strength of approximately 140 MPa and was reinforced with short, randomly distributed alkali resistant glass fibers. As a part of the study, coupled experimental, analytical and numerical investigations were performed. Flexural and direct tension tests were first conducted to experimentally characterize material behavior. Following experimentation, a micromechanically-based analytical model was utilized to calculate the material's tensile failure response, which was compared to the experimental results. Lastly, to investigate the relationship between the tensile failure and flexural response, a numerical analysis of the flexural experiments was performed utilizing the experimentally developed tensile failure function. Results of the experimental, analytical and numerical investigations are presented herein.

• 대한토목학회논문집
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• 제26권2A호
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• pp.401-409
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• 2006

본 연구에서는 고강도 강섬유보강 콘크리트(HSFRC)의 설계 및 시공을 위한 기초 자료를 제공하기 위하여 역학적 특성 및 장기변형 특성에 관한 연구를 수행하였으며, 탄성계수, 압축강도, 인장강도, 휨강도, 건조수축 및 크리프에 미치는 강섬유 혼입의 영향을 검토하고, 휨파괴인성을 평가하였다. 연구결과, HSFRC의 압축강도에 미치는 강섬유의 혼입효과는 그다지 크지 않았고, 탄성계수는 섬유혼입률이 증가함에 따라 증가하는 것으로 나타났으며, 인장강도, 휨강도 및 휨인성에 미치는 섬유혼입률($V_f$) 및 섬유형상비($l_f/d_f$)의 영향은 대단히 큰 것으로 나타났다. 이는 $V_f$ 및 $l_f/d_f$의 증가와 함께 극한하중에 상응하는 처짐량이 증가하고, 강섬유의 균열구속성능에 의해 하중-처짐곡선의 하강곡선이 완만하게 감소하기 때문인 것으로 판단된다. 또한 크리프 및 건조수축에 미치는 섬유혼입률($V_f$)의 영향은 대단히 큰 것으로 나타났으며, 특히 고강도 콘크리트에 강섬유를 혼입하면 크리프 변형에 비해 건조수축 변형의 저감에 더욱 효과가 큰 것으로 나타났다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.189-190
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• 2023

Environmental pollution problems are occurring in Jeju Island due to negative treatment of basalt waste. Measures for various approaches and utilization measures are needed to solve the problem of waste stones that occur during basalt processing. In this study, the Properties of permeable blocks with basalt were identified and the applicability and functionality as building materials were reviewed. This experiment is basic data for evaluating the functionality of the permeable block by manufacturing permeable blocks using basalt waste stones and analyzing flexural strength and compressive strength. The higher the basalt waste stone replacement rate, the lower the flexural strength and compressive strength, but it was judged that 20% of basalt waste stone replacement rate that satisfies the minimum flexural strength (4.0MPa) stipulated in KS F 4419 was appropriate. In addition, additional permeability coefficient and absorption rate experiments tended to increase as the basalt lung stone replacement rate increased. Therefore, it is judged that the permeable block using basalt waste stone is superior to the existing permeable block.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 추계 학술논문 발표대회
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• pp.97-98
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• 2012

This research examined the fundamental property of the MgO as the fundamental study that substituted the MgO in the low melting point modified sulfur mortar to examine the physical properties.In this research, the table floor, flexural strength test, and compressive strength test were performed. And as the replacement ratio increased, the floor showed the tendency to increase. And when being the replacement ratio 3%, the flexural strength and compressive strength made the high strength. In case of being substituted for over 5% they displayed the tendency that the intensity is degraded.

• 한국농공학회논문집
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• 제51권6호
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• pp.97-103
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• 2009

This study was performed to evaluate the strength and durability properties of recycled polymer concrete using unsaturated polyester resin and recycled aggregates. Unsaturated polyester resin, natural and recycled aggregates and fly ash were used. The mix proportions were determined to satisfy the requirement for the workability and slump according to aggregate sizes (5-10 and 5-25 mm) and unit binder contents (10% and 12%). Tests for the compressive and flexural strength, freezing and thawing and durability for 20% sulfuric solution were performed. The compressive and flexural strength of recycled polymer concrete were in the range of 85~97 MPa and 17.9~20.8 MPa, respectively. The strengths of recycled polymer concrete using recycled aggregate have similar or slightly decreased compared to polymer concrete using natural aggregate. After 300 cycles of freezing and thawing, weight decrease ratio and durability factor of recycled polymer concrete were in the range of 0.13~1.42% and 94~99, respectively.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.441-444
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• 2003

Polymer concrete has more useful than cement concrete in the strength and durability. So, it is widely utilizing as panel for wall, manhole for communication, foundation and underground connection box, etc. But polymer concrete is a defect that is disadvantageous in economical aspect because cost of resin is expensive. Polymer concrete (PC) using unsaturated polyester resins based on recycled polyethylene terephthalate(PET) plastic waste were used in our study for grasping its mechanical properties such as compressive strength, tensile strength, flexural strength and chemical resistance was tested by dealing with 20% HCl, 30% NaOH. As a result of it, compressive, tensile and flexural strength of PC indicated 752kgf/$\textrm{cm}^2$, 80kgf/$\textrm{cm}^2$ and 243kgf/$\textrm{cm}^2$ kind of satisfaction successively. Also, properties of chemical resistance are superior to those of cement concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.840-845
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• 2003

Polymer concrete (PC) using unsaturated polyester resins based on recycled polyethylene terephthalate (PET) plastic waste were used in our study for grasping its mechanical properties such as compressive strength, tensile strength and flexural strength, etc. by changing its quantity of resin, filler and dilution(SM) respectively. As a result of it, compressive, tensile and flexural strength of PC indicated 752kgf/$cm^2$, 80kgf/$cm^2$, and 243kgf/$cm^2$, kind of satisfaction successively. Judging from the above results, polymer concrete (PC) using unsaturated polyester resins as a coupling are suitable for construction material both in the aspect of ECO-building materials and in the aspect of superior strength of PC so that it is good possibility of success as a product.