• Structural Engineering and Mechanics
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• 제17권2호
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• pp.141-152
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• 2004

The bonding behaviors of Lightweight Aggregate Concrete (LWAC) and normal weight concrete were investigated experimentally. Pull-out tests were carried out to measure the bond strengths of three groups of specimens with compressive strength levels of 60, 40, and 20 MPa, respectively. Test results showed that the difference in the bond failure pattern between LWAC and normal weight concrete was significant as the concrete compressive strength became lower than 40 MPa. The corresponding bond strengths of LWAC were lower than that for normal weight concrete. As the compressive strength of concrete became relatively high (> 40 MPa), a bond failure pattern in normal weight concrete occurred that was similar to that in LWAC. The bond strength of LWAC is higher than that for normal weight concrete because it possesses higher mortar strength. Stirrup use leads to an increase of approximately 20% in nominal bond strength for both types of concrete at any strength level.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
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• pp.197-198
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• 2010

본 연구는 다공성 인공 경량골재를 사용한 콘크리트와 보통 골재를 사용한 콘크리트의 염해에 대한 저항성을 비교하고, 그 실용성을 확인하는데 목적을 두었다. 그 결과, 인공 경량골재 콘크리트의 염해 저항성은 보통 콘크리트의 염해 저항성 보다 낮음을 알 수 있었다.

• 한국농공학회지
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• 제39권4호
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• pp.75-81
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• 1997

This study was performed to evaluate the engineering properties of surlightweight polymer concrete using synthetic lightweight aggregate. The following conclusions were drawn; 1. The unit weight was in the range of 0.849~0.969t/$m^3$, the unit weights of those concrete were decreased by 58 ~ 63% than that of the normal cement concrete. 2. The highest strength was achieved by $P_1$, and compressive strength was increased by 93% and bending strength by 364% than that of the normal cement concrete, respectively. 3. The ultrasonic pulse velocity was in the range of 2, 346~2, 702m/s, which was low compared to that of the normal cement concrete. 4. The dynamic modulus of elasticity was in the range of $1.561{\times} 10{^5}~1.916{\times} 10{^5}kgf/cm^2$, which was approximately 52~98% of that of the normal cement concrete. 5. The compressive and bending strength were increased with the increase of unit weight. But, the dynamic modulus of elasticity and ultrasonic pulse velocity were decreased with the increase of unit weight.

• Structural Engineering and Mechanics
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• 제62권5호
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• pp.651-661
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• 2017

This paper presents an experimental study of bond-slip behavior of reinforced lightweight aggregate concrete (LC) and normal weight concrete (NC) with embedded steel bar. Tests were conducted on tension-pull specimens that had cross-sectional dimension with a reinforcing bar embedded in the center section. The experimental variables include concrete strength (20, 40, and 60 MPa) and coarse aggregate type (normal-weight aggregate and reservoir sludge lightweight aggregate). The test results show that as concrete compressive strength increased, the magnitudes of the slip of the LC specimens were greater than those of the NC specimens. Moreover, the bond strength and stiffness approaches zero at the loaded end, or close to the central anchored point of the specimen. In addition, the proposed bond stress-slip equation can effectively estimate the behavior of bond stress and steel bar slipping.

• Journal of Ceramic Processing Research
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• 제20권4호
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• pp.363-371
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• 2019

In this study, physical properties of normal concrete, magnetite concrete, EAF concrete, and EAF concrete with added iron powder were evaluated and a feasibility of radiation shielding is also evaluated through irradiation tests against X-rays and gamma-rays. While the unit weight of EAF concrete (3.21 t/㎥) appeared lower than that of magnetite concrete (3.50 t/㎥), the results in compressive strength of EAF concrete were greater than those in magnetite and normal concrete. While the radiation transmission rate of normal concrete reaches 26.0% in the X-ray irradiation test, only 6.0% and 9.0% of transmission rate were observed in magnetite concrete and linear relationship with unit volume weight and radiation shielding. In the gamma-ray irradiation test, the performance of EAF and magnetite concretes appeared to be similar. Through the results on the excellent physical properties and radiation shielding performance a potential applicability of EAF concrete to radiation shielding was verified.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 추계 학술논문 발표대회
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• pp.175-176
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• 2011

Applying previous studies performed in the moisture transportation characteristics and shrinkage of lightweight concrete application of shrinkage reduction is to discuss. Applicability of shrinkage reduction effect of lightweight concrete applies for the analysis of PSC girder bridge beam placed on the construction site. Stress of the concrete bridge deck, rebar quantity is calculated by effective elastic modulus method and crack risk is assessed by moisture transport and differential shrinkage analysis. After approximately 10 days maximum tensile stress occurs 6MPa, similar to the case of normal concrete, a maximum tensile stress occurs 3MPa in lightweight concrete and comparing to normal concrete stress was reduced to approximately 50%. Normal and lightweight concrete crack index, respectively, is reduced 1.6 to 1.2, 1.2 to 0.9 in surface and boundary region. Therefore, reduction in shrinkage of concrete were able to confirm reduction of crack risk.

• 한국농공학회지
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• 제37권3_4호
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• pp.72-81
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• 1995

This study was performed to evaluate the mechanical properties of high performance lightweight polymer concrete using fillers and synthetic lightweight coarse aggregate. The following conclusions were drawn. 1. The unit weight of the G3, G4 and G5 concrete was 1.500t/m$^3$, 1.506t/m$^3$ and 1.535t/m$^3$, respectively. Specially, the unit weights of those concrete were decreased 33~35% than that of the normal cement concrete. 2. The highest strength was achieved by heavy calcium carbonate, it was increased 27% by compressive, 95% by tensile and 195% by bending strength than that of the normal cement concrete, respectively. 3. The elastic modulus was in the range of 8.0 x 104~ 10.4 x lO4kg/cm2, which was approximately 35~42% of that of the normal cement concrete. Normal cement concrete was showed relatively higher elastic modulus. 4. The ultrasonic pulse velocity of fillers was in the range of 2, 900m/sec, which was showed about the same compared to that of the normal cement concrete. Heavy calcium carbonate was showed higher pulse velocity. 5. The compressive, tensile, bending strength and ultrasonic pulse velocity were largely showed with the increase of unit weight.

• 콘크리트학회논문집
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• 제22권2호
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• pp.159-169
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• 2010

경량골재 사전흡수에 의한 콘크리트 내 수분이동 변화와 수축 저감 효과를 파악하기 위하여 일반콘크리트 및 경량콘크리트의 수분이동, 열전달, 변형률의 다중물리모델의 해석과 실험을 수행하였다. 그 결과 동일 물-결합재비일 경우 경량 콘크리트와 일반 콘크리트와의 습도 변화 비교는 모두 경량 콘크리트가 일반 콘크리트보다 초기재령, 장기 재령 모두에서 작은 습도 감소를 나타내어 경량 골재 사전흡수수에 의한 수분 공급이 효과적으로 이루어진 것으로 판단된다. 이에 따라 경량 콘크리트는 일반 콘크리트에 비해 수축변형률 크기 및 분포 모두 감소하였으며, 수축저감효과는 물-시멘트비 0.3에서는 초기재령에서, 물-시멘트비 0.5에서는 초기재령, 장기재령 모두에서 효과적인 것으로 나타났다. 수분이동 및 변형률 해석과 모형실험을 통해 일련된 연구에서 도출한 수분이동 특성값과 습도, 수축 관련식은 적합한 것으로 판단되며, 향후 경량콘크리트의 부등수축해석에 적절히 활용될 수 있을 것으로 생각된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.149-152
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• 2005

To make artificial light-weight aggregate with EAF-dust and estimate ability to apply to concrete, characteristics of the aggregate were considered in density, weight of unit volume, fineness modulus and so on. And then it was executed to experiments of the concrete mixed with the light-weight aggregate. As it was results that artificial light-weight aggregate with EAF-dust was heavier and more watertight than with only clay, concrete weight of unit volume was heavier than with expended clay aggregate. But it was regarded that concrete with EAF-dust artificial aggregate was able to field application as light-weight concrete because concrete of the weight of unit volume was lighter and compress strength and workability were similar to normal concrete.

• 한국농공학회지
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• 제42권2호
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• pp.93-98
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• 2000

This study is performed to evalute experimentally the nondestructive properties on the concrete that is treated with crushed oyster shell powder of 0.15m or smaller in diameter. The ultrsonic pulse velocity of crushed oyster shell concrete(COSC) is in the range of 4.110-4.267m/s, and the dynamic modulus of elasticity of COSC range from 288$\times$10$^3$ to 318 $\times$10$^3$kgf/$\textrm{cm}^2$. The ultrasonic pulse velocity and dynamic modulus of elasticity are similar to those of normal portland cement concrete. The highest ultrasonic pulse velocity and dynamic modulus of COSC are measured at the 2.5% addition rate by weight of crushed oyster shell powder. The acid-resistance in increased of the content of crushed oyster shell powder. The acid-resistance of COSC with 15% addition rate by weight of crushed oyster shell power is 1.6 times greater than that of normal portland cement concrete. It is concluded that the addition of crushed oyster shell powder to normal portland cement concrete contributed to improve the nondestructive properties of concrete.