• 한국농공학회지
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• 제38권6호
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• pp.83-95
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• 1996

The normal cement concrete is widely used material to build the construction recently, but it has a fault to increase the dead load on account of its unit weight is large compared with strength. So, main purpose of this study was to establish the physical and mechanical properties of lightweight concrete using expanded polystyrene bead on fine aggregate and natural gravel, expanded clay and pumice stone on coarse aggregate. The test rusults of this study are summarized as follows; 1. The water-cement ratio of concrete using pumice stone was larger than that of the concrete using natural gravel and expanded clay. 2. The unit weights of concrete using pumice stone and expanded caly were shown less than 1,000g/$m^3$. 3. The compressive strengths of all types were shown less than 60kg/$cm^2$, tensile and bending strengths were shown less than l3kg/$cm^2$ and 3lkg/$cm^2$$^2$, respectively. 4. The pulse velocity of concrete was shown similar with using natural gravel and pumice stone, and shown the lowest using pumice stone. 5. The dynamic modulus of elasticity of concrete was shown considerably smaller, and shown the lowest using pumice stone. 6. The static modulus of elasticity of concrete using expanded clay and pumice stone were shown considerably smaller, and shown 22% ~29% as compared with the dynamic modulus of elasticity. 7. The stress-strain curves of concrete were shown similar, generally. And the curves were repeated at short intervals increase and decreased irregularly.

• 콘크리트학회지
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• 제28권3호
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• pp.74-78
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• 2016

• Advances in concrete construction
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• 제10권6호
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• pp.489-498
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• 2020

This paper investigates mechanical properties of roller compacted concrete (RCC) involving reclaimed asphalt pavement (RAP). In this way, a set of 276 cylindrical RCC specimens were prepared with different RAP sizes (i.e., fine, coarse & total) at various ratios (i.e., 10%, 20%, and 40%). Results reveal that incorporation of RAP decreases unconfined compressive strength (UCS), modulus of elasticity (E), and indirect tensile (IDT) strength of RCC. For each RAP size, a regression model was used to maximize RAP content while satisfying the UCS lower limit (27.6 Mpa) mentioned by ACI as a minimum requirement for RCC used in pavement construction. Moreover, UCS of RAP incorporated mixes, dissimilar to that of control mixes, was found to be sensitive and insensitive to the testing temperature and curing time after 7 days, respectively. The results also demonstrate that the higher amounts of RAP, the more flexibility in RCC is. This issue was also proved by the results of modulus of elasticity test. In addition, the toughness index (TI) shows that increase in RAP content leads to up to 43% increase in energy absorbance capacity of RCC.

• 한국건축시공학회지
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• 제9권1호
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• pp.43-47
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• 2009

The most of waste foundry sands(WFS) have been discarded. It is very urgent for our country to make a study on recycling of WFS. The one of recycling method of WFS is using them as fine aggregate for concrete. This study provided the optimum amount of WFS and flyash when WFS and flyash were used together in concrete. The concrete made with 60% WFS fine aggregate replacement showed higher compressive strength, splitting tensile strength and modulus of elasticity than normal concrete. In the case that the flyash and WFS are replaced together, the compressive strength and splitting tensile strength were improved at flyash replacement ratio $10%{\sim}20%$ and WFS replacement ratio $40%{\sim}60%$. The increase of WFS and flyash replacement led lower air content. While the increase of WFS replacement led lower slump, the increase of flyash replacement led higher slump.

• 한국농공학회지
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• 제45권6호
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• pp.128-135
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• 2003

This study is performed to examine the physical and mechanical properties of concrete using recycled aggregate and industrial by-products. The test results show that the unit weight, compressive and flexural strength, ultrasonic pulse velocity and dynamic modulus of elasticity are decreased with increasing the content of recycled aggregate. But, the absorption ratio is increased with increasing the content of recycled aggregate. The unit weight is 2,237∼2,307 kg/$\textrm{m}^3$, the absorption ratio is 2.96∼4.12%, the compressive strength is 415∼532 kgf/$\textrm{cm}^2$, the flexural strength is 75∼96 kgf/$\textrm{cm}^2$, the ultrasonic pulse velocity is 4,350∼4,949 m/s and the dynamic modulus of elasticity is $390\times10^3\;∼\;465\times10^3$ kg f/$\textrm{cm}^2$, respectively These recycled aggregate concrete can be used for high strength concrete.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2005년도 추계 학술논문 발표대회
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• pp.183-186
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• 2005

This study investigates material properties of epoxy resins and reinforced materials for adhesion repairing-reinforced of RC construction. According to the test. elasticity modulus of mortar indicated 16-26(GPa) and that of concrete was 18-27(GPa). It became decreased as mixture proportion, W/C and fluidity of both mortar and concrete increased In addition the elasticity modulus of epoxy resins exhibited around 45.3-220(GPa), while that of steel plate and Carbon Bar indicated 338(GPa) and 34.1 (GPa), respectively. It is obvious that individual materials had big different value of elasticity modulus. Meanwhile, thermal expansion coefficients of mortar was 10-13 ${\mu}\varepsilon$ /$^{\circ}C$ and that of concrete was 9-11 $\mu \varepsilon$ /$^{\circ}C$ The increase of mixture Voportion and W/C resulted in lower value of thermal expansion coefficients and the increase of flow and slump exhibited slightly higher value. The epoxy resin indicated 41-54 ${\mu}\varepsilon$ /$^{\circ}C$ which is 4-5 times larger value than concrete and steel plate and Carbon Bar was 11.93 ${\mu}\varepsilon$ /$^{\circ}C$ and -1.68 ${\mu}\varepsilon$ /$^{\circ}C$ respectively. Hence, the adhesion strength of the epoxy resins should be considered before it is used in field condition, due to different thermal expansion coefficient of each material.

• 콘크리트학회지
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• 제6권3호
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• pp.131-141
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• 1994

이 연구는 불포화 폴리에스터 수지를 이용한 고강도 폴리머 콘크리트를 제조하여 구성재료와 첨가제의 변화에 따른 역학적 특성을 실험적으로 구명한 것이다. 그 결과 제조된 폴리머 콘크리트는 재령7일에서 압축강도$1,291~1,445kg/cm^2$, 할열인장강도 $106~145kg/cm^2$, 휨강도 $182~235kg/cm^2$를 발현하였으며, 이들에 대한 탄성계수 및 포아슨비를 구해 보았던 바 $2.8~3.8{\times}10^5\;kg/cm^2$, 0.21~0.32였고, 최대압축변형도는 0.005~0.0065로서 시멘트 콘크리트에 비해 매우 크게 나타났다.

• 콘크리트학회논문집
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• 제28권2호
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• pp.213-221
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• 2016

이 연구에서는 강섬유 혼입률에 따른 초고성능 강섬유 보강 콘크리트(UHPC)의 압축거동에 관한 연구를 수행하였으며, 실험결과를 바탕으로 강섬유 보강 콘크리트의 압축강도와 탄성계수를 제안하였다. 지름 100 mm, 높이 200 mm의 원주형 공시체에는 0, 0.5, 1.0, 1.5, 그리고 2%의 강섬유가 혼입되었다. 실험에 사용된 UHPC는 굵은골재를 사용하지 않았으며, 16 mm와 19 mm의 강섬유가 일정비율로 혼입된 하이브리드 강섬유가 사용되었다. 실험결과, UHPC의 압축강도와 탄성계수는 강섬유 혼입률에 따라 증가하는 경향을 보였다. 실험결과를 바탕으로 강섬유 보강 콘크리트의 압축강도와 탄성계수가 제안되었다. 강섬유 보강 콘크리트의 압축강도는 무보강 콘크리트의 압축강도의 함수로 제안되었으며, 탄성계수는 강섬유 보강 콘크리트의 압축강도의 함수로 제안하였다. 기존 실험값과 비교한 결과 제안된 압축강도와 탄성계수는 실험값을 비교적 잘 예측하는 것으로 나타났으며, 압축강도가 35~235 MPa인 강섬유 보강 콘크리트에 적용가능 할 것으로 판단된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.37-42
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• 2001

This paper presents the improved elastic modulus equation more appropriate to predict the modulus of elasticity of structural elements designed and made by high-strength concrete. To propose the elastic modulus equation, more than 300 laboratory specimen tests having the range of 5n to 800kgf/$cm^{2}$ in concrete compressive strength were conducted and analyzed statistically. The equation derived in terms of empirical constant, the elastic moduli of coarse aggregate and mix proportions. Comparison of the proposed elastic modulus equation with the previously suggested equations in the ACI363R, and New-RC were also presented to demonstrate the applicability to practice.

• 한국농공학회논문집
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• 제56권5호
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• pp.45-54
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• 2014

This study was performed to evaluate compressive strength, flexural strength, static modulus of elasticity, stress-strain ratio and durability of abrasion on EVA concrete reinforced steel fiber (SF) in order to use hydraulic structures, underground utilities, offshore structures and structures being applied soil contaminated area. It is used ordinary portland cement, crushed coarse aggregate, nature fine aggregate, EVA redispersible polymer powder, superplasticizer and deforming agent to find optimum mix design of EVA concrete reinforced steel fiber. EVA concrete reinforced SF was effected on the improvement of mechanical properties and durability of abrasion.