• KCI Concrete Journal
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• 제14권1호
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• pp.1-7
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• 2002

This paper reports the experimental and analytical investigations for evaluating the flexural strength of a RC slab strengthened with carbon fiber sheet (CFS). The evaluation of the ultimate flexural strength of a slab is tried under the assumption that the failure occurs when the shear stress mobilized at the interface between the concrete bottom and the glued CFS reaches its bond strength. The shear stress is evaluated theoretically and the bond strength is obtained by a laboratory test. The ultimate flexural strength is obtained by flexural static test of the slab specimen, which corresponds to the part of a real slab. From the results, the new approach based on the bond strength between concrete and CFS looks feasible to evaluate the flexural strength of the CFS and RC composite slab.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.387-392
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• 1999

The bond performance of prestressing strands is still not well understood and is still in controversy on the validity of the test results up to today, although it is a basic information to desing the prestressed pretensioned concrete beams. Different transfer length has been found for a product of the same company, but of the different production methods and factories in the United States. It is necessary to determine optimum transfer bond length of the domestic stands because the ultimate flexural and shear capacity in a section of prestressed concrete beams are evaluated under the assumption that the anchorage bond failure shall not happen. The transfer lenght of low-relaxation, Gr 270, and 1/2" seven-wire prestressing strands from four domestic companies will be evaluated by the concrete strain method. The recent concept of the 95% Maximum Average Strain Method suggested by Russel et al. will be considered to obtain the transfer length of domestic strands. It will be also evaluated if the domestic strands are conform to ACI 318-95.8-95.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.122-125
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• 2006

This paper presents the comparison of the bond behavior of various FRP rebars. A total of 9 specimens including steel reinforcement were tested through direct pull-out test procedure. The test results have revealed that the bond behavior was affected by the deformation shapes and surface treatments. The newly proposed FRP rebar by KICT showed good bond strength and ductile behavior after failure.

• 산업기술연구
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• 제33권A호
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• pp.101-107
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• 2013

The purpose of this study was to investigate bond strength between substrate and HES-LMS mortar, durability of HES-LMS mortar with latex content(0%, 5%, 10%). To measure the bond strength, the direct tensile test based on uniaxial tensile test was used, which was proposed by Kuhlman(1990). Also, Resistance for water permeability, water absorption and image analysis for air void system were conducted to estimating durability of HES-LMS mortar.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.327-330
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• 2005

Bond failure of reinforcing bar generally take place by splitting of the concrete cover as bond force between concrete and reinforcing bars exceeds the confinement of the concrete cover and reinforcement. However, the confinement force in practice has a limitation. Thus, the only variable is the bearing area corresponding to the change of bond force. In this study, to the evaluate anchorage strength of high relative rib area bars, hook bond test specimens are tested and the results are discussed. Higher rib height bars when bars are confined showed higher anchorage strength than lower rib higher bars.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.190-191
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• 2020

The bonding of steel bar to concrete is closely related to the roughness and corrosion degree of steel bar surface. The accelerated corrosion of concrete specimens with different reinforcement diameters was carried out in this test. Through the pullout test of the corroded concrete specimens, the relationship between the bond stress and the displacement of the corroded concrete specimens under the corresponding corrosion degree was obtained. The bond stress of reinforced concrete with different size and corrosion degree are compared and analyzed to find out the influence of corrosion on the bonding property of reinforced concrete.

• 대한치과보철학회지
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• 제51권2호
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• pp.73-81
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• 2013

연구 목적: 이 연구의 목적은 지르코니아 표면처리에 따른 3종의 레진시멘트와 지르코니아의 전단결합강도를 평가하기 위함이다. 연구 재료 및 방법: 총 143개의 디스크 모양의 지르코니아 블록(HASS Co., Gangneung, Korea) 시편을 제작하고 총 13개군(n=11)으로 나누었다. 그중9개군은 표면처리 방식(1. 알루미나 분사, 2. 알루미나 분사와 지르코니아 라이너의 도포, 3.알루미나 분사와 Rocatec (3M ESPE, Seefeld, Germany) 처리) 및 사용한 3종류의 레진시멘트(Bistite II (Tokuyama Dental Co., Japan), Panavia F2.0 (Kuraray Medical, Japan), Super-bond C&B (Sun Medical, Japan))에 따라 나누어 열순환처리 전 접착강도 실험을 시행하였다. 열순환처리 전 접착강도 실험은 위 3종류의 레진시멘트를 3가지 방법으로 표면처리한 지르코니아 시편에 접착하고, 상온의 증류수에 24시간 동안 보관한 후, 전단결합강도를 측정하였다. 열순환처리 후 접착강도 실험은, 열순환처리 전 접착강도 실험에서 우수한 전단결합강도를 보인 지르코니아 표면처리군(알루미나 분사와 Rocatec 처리를 하고 3종류의 레진시멘트를 접착한 3개의 군)과 대조군으로 알루미나만으로 표면처리 후 Super-bond C&B를 접착한 1개의 군을 대상으로 $5^{\circ}C$와 $55^{\circ}C$사이에서 5,000회 열순환처리를 시행하고 전단결합강도를 측정하였다. 결과: 열순환처리 전 접착강도 실험에서는 알루미나 분사와 Rocatec 처리를 한 지르코니아 표면에 Super-bond C&B를 접착한 군이 가장 높은 전단결합강도를 보였다. Super-bond C&B를 사용한 군이 다른 시멘트 군보다 유의성 있게 높은 전단결합강도를 보였으며, 지르코니아 표면에 Rocatec 처리를 한 군이 다른 표면처리를 한 군보다 유의성 있게 높은 전단결합강도를 보였다. 열순환처리를 한 후에는, Rocatec 처리를 한 지르코니아 표면에 Super-bond C&B를 접착한 군만이 유일하게 전단결합강도가 증가하였으며, 다른 모든 군에서는 전단결합강도가 감소하였다. 결론: 본 실험에서는 Super-bond C&B 시멘트가 가장 높은 전단결합강도를 보였으며, Rocatec 시스템은 레진시멘트와 지르코니아의 전단결합강도를 향상시키는 방법이 될 것이라고 사료된다.

• 대한치과기공학회지
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• 제9권1호
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• pp.39-49
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• 1987

This study done to evaluate some surface treatment methods in metal coping which can increase the bond strength between porcelain and metal. Therefore this experiment was performed according to the Mc Lean's Theory of bond strength between porcelain and strength between porcelain and metal. In the experiment the author measured respective thermal expansion coefficents in three types of metal(Tallasium, Vera Bond and Rexillium) and Vita Porcelain to get the differences in the coefficents between porcelain and metals. And using insteron testing machine, the author also performed Planar interface shear bond tests on the 45 specimens(15 specimens in oxide surface, rough surface and fine surface treatment methods respectively) to measure bond strength between metal and porcelain. The results Were as follows, 1. The differences in thermal expansion coefficients between three types of metal and Vita procelain: Talladium - $1.2\;10^{-6/0}\;C$, Vera Bond - $1.6\;10^{-6/0}\;C$, Rexillium - $1.9\;10^{-6/0}\;C$. 2. The bond strength in oxide surface on the Shear bond test was the lowest among the treatment methods. 3. There was no significant differences in treatment methods of rough surface of fine surface. 4. In the oxide surface treatment method, there were significant differences(P<0.05)between Vera bond and Rexillium, and between Talladium and Rexillium. 5. In the fine surface treatment, there was a significant difference(P<0.05)between Talladium and Rexillium.

• 대한소아치과학회지
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• 제23권2호
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• pp.347-355
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• 1996

The purpose of this study was to compare the bond strengths of different kinds of glass ionomer cements (GIC), which is recently increasing the clinical application in the field of pediatric dentistry and measure the repaired bond strengths in order to examine the clinical applicabilty of partial repaired cases. By using one kind of the light cured type GIC and three kinds of the chemical cured type GIC, the bond strengths of the followings were compared : unrepaired group as control, repaired conditioning group, which was treated the repaired surface using 25% polyacrylic acid and repaired non-conditioning group without surface treatment. Three point bending test was performed under Universal Testing Machine in order to measure the compressive bond strengths. The results were as follows : 1. Light cured GIC had higher bond strength than chemical cured type GIC in both of repaired and unrepaired groups. 2. In repaired cases, all of the materials decreased the bond strength when compared to the control group. In the light cured type, the bond strength of repaired conditioning group decreased 31.6%, repaired non-conditioning group decreased 40.8%. In chemical cured types, the bond strength of repaired conditining group decreased 11.8%, repaired non-conditioning group decreased 20.9%. 3. All the materials, in the case of the chemical treatment on the repaired surface using 25% polyacrylic acid had higher bond strength than untreated but, lower than control group.

• Structural Engineering and Mechanics
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• 제56권2호
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• pp.275-291
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• 2015

Adherence between reinforcement and the surrounding concrete is usually ignored in finite element analysis (FEA) of reinforced concrete (RC) members. However, load transition between the reinforcement and surrounding concrete effects RC members' behavior a great deal. In this study, the effects of bond-slip on the FEA of RC members are examined. In the analyses, three types of bond-slip modeling methods (perfect bond, contact elements and spring elements) and three types of reinforcement modeling methods (smeared, one dimensional line and three dimensional solid elements) were used. Bond-slip behavior between the reinforcement and surrounding concrete was simulated with cohesive zone materials (CZM) for the first time. The bond-slip relationship was identified experimentally using a beam bending test as suggested by RILEM. The results obtained from FEA were compared with the results of four RC beams that were tested experimentally. Results showed that, in FE analyses, because of the perfect bond occurrence between the reinforcement and surrounding concrete, unrealistic strains occurred in the longitudinal reinforcement. This situation greatly affected the load deflection relationship because the longitudinal reinforcements dominated the failure mode. In addition to the spring elements, the combination of a bonded contact option with CZM also gave closer results to the experimental models. However, modeling of the bond-slip relationship with a contact element was quite difficult and time consuming. Therefore bond-slip modeling is more suitable with spring elements.