• 한국도로학회논문집
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• 제19권2호
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• pp.17-24
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• 2017

PURPOSES : This study aims to develop a sealant for use in the installation of Weigh-In-Motion (WIM) sensor for asphalt concrete or cement concrete pavements. METHODS : In order to investigate the properties of various sealants that were mixed with latex and carbon fiber, various test methods were adopted, such as bituminous bond strength test, softening point test, and cone penetration test. To evaluate moisture susceptibility, the BBS test was conducted under moist condition. The bond strength ratio (BSR) was calculated based on tensile strength ratio method. RESULTS : The sealant's properties significantly varied according to the amount of latex or carbon fiber. The usage of latex marginally enhanced the cone penetration test result, notwithstanding reduced asphalt content. This implies that the sealant will be proper cold temperature reason. Moreover, the addition of latex and carbon fiber evidently increased the softening point. This indicates that the tendency of the material to flow at elevated temperatures is encountered during service. With the addition of latex and carbon fiber, the moisture susceptibility measured with BSR improved marginally, while the bond strength under dry condition decreased marginally. Sealant F displays the highest bond strength and BSR under limited test conditions. CONCLUSIONS : According to the proportion of latex and carbon fiber mixed, properties of sealant, such as softening point, cone penetration, and BSR varied marginally. This indicates that the sealant has to be applied considering the environmental condition, to improve service life.

• Restorative Dentistry and Endodontics
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• 제29권3호
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• pp.273-280
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• 2004

The purpose of this study was to evaluate the etching effects and bond strength of total etching and self-etching adhesive system on unground enamel using scanning electron microscopy and microtensile bond strength test. The buccal coronal unground enamel from human extracted molars were prepared using low-speed diamond saw. Scotchbond Multi-Purpose (group SM). Clearfil SE Bond (group SE), or Adper Prompt L-Pop (group LP) were applied to the prepared teeth. and the blocks of resin composite (Filtek Z250) were built up incrementally. Resin tag formation was evaluated by scanning electron microscopy. after removal of enamel surface by acid dissolution and dehydration. For microtensile bond strength test. resin-bonded teeth were sectioned to give a bonded surface area of $1\textrm{mm}^2$. Microtensile bond strength test was perfomed. The results of this study were as follows. 1. A definite etching pattern was observed in Scotchbond Multi-Purpose group. 2. Self-etching groups were characterized as shallow and irregular etching patterns. 3. The results (mean) of microtensile bond strength were SM: 26.55 MPa, SE: 18.15 MPa, LP: 15.57 MPa. SM had significantly higher microtensile bond strength than 8E and PL (p < 0.05). but there was no significant differance between SE and PL.

• 콘크리트학회논문집
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• 제24권1호
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• pp.79-86
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• 2012

이 연구에서는 콘크리트에 보강된 섬유의 종류 및 함유량이 FRP 보강근 부착강도에 미치는 효과를 조사하였다. 실험체는 3종류의 보강근과 구조용 강섬유, 절곡형 PP섬유와 친수성 PVA섬유를 사용하여 제작하였으며 직접부착 강도시험을 실시하여 부착강도를 평가하였다. 실험 결과 섬유의 종류 및 함유량에 따라 섬유보강 콘크리트와 보강근 사이의 부착강도에 영향을 미침을 알 수 있었다. 섬유의 가교효과로 인해 할렬균열을 제어함으로써 함유량이 증가함에 따라 부착강도가 증가하였으며, 연성 또한 증가하였다. 부착강도 및 연성증가 효과는 강섬유 > PVA섬유 > PP섬유 순으로 나타났다.

• 대한치과기공학회지
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• 제24권1호
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• pp.33-41
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• 2002

In dental prosthetics, the application of metal-ceramic restorations has steadily increased since their introduction. This is due to excellent esthetics in combination with high mechanical stability. In order to optimum bond strength between metal and ceramics, controlled oxidation of metal substructure is essential factor. Beryllium containing and beryllium free Ni-Cr alloys for metal-ceramic restorations were evaluated for the metal-ceramic bond strength by changing heat treatment for oxide formation. A mechanical three-point bending test was employed to evaluate the interfacial bond strength of metal-ceramic. In each metal, plate type specimens were used for mechanical three-point bending test. With Ni-Cr alloys for metal ceramics, mechanical three-point bending test showed that double degassing was more available preheat treatment method than another. It was found that beryllium containing Ni-Cr alloys are more effective than beryllium-free for metal-ceramic bond strength.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회논문집(II)
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• pp.621-626
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• 1998

An experimental investigation on the reinforcing bar corrosion and relationshid of reinforcing bar and concrete bond strength has been conducted to establish the allowable limit of rust in the construction field. The reinforcing bars used in this study were rusted before embedding in concrete. The first component of this experiment is to make rust of reinforcing bar rust artificially based on Faraday's theory at certain rates such as 2, 4, 6, 8 and 10% of reinforcing bar weight. For estimation of the amount of rust by weight, Clarke's solution and Shot blasting were adopted and compared. Parameters include 240 and 450kg/㎠ of compressive strengths and diameter of reinforcing bar (16, 19 and 25mm) corresponding development length for pull-ort test. And, pull-out tests were carried. out according to KSF 2441 and ASTMC 234 to investigate the effect of the corrosion rate on reinforcing bar-concrete bond behavior. It is found from the test results that the test techniques for corrosion of bar used in this study is relatively effective and correct test method. Results shows that up to 2% of rust increases the bond strength regardless of concrete strength and diameter of reinforcing bar like the existing data. It might be because of the roughness from rust. As expected, the bond strength increases as compressive strength of concrete increases and the diameter of bar decreases.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.443-448
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• 2001

This paper presents a bond characteristics of high strength steel reinforced concrete members. High strength steel is what yield strength is higher than that of normal strength steel. So, the amount of flexural steel needed in R.C. members can be decreased. In result, it is expected that the workability and structure quality can improve and man power can minimize. For this purpose, specimens were made and tested with experimental parameters, such as concrete strength, steel diameter and yield strength. The result showed that under same tensile force of steel, in case of substituting normal strength steel with high strength steel, maximum bond stress increased and development length didn't almost change. In addition, the governing equation of bond and bond stress verse slip relationship were derived and compared with test values such as maximum bond stress, slip and bond stiffness.

• 대한치과기공학회지
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• 제33권1호
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• pp.1-6
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• 2011

Purpose: To examine the shear bond strengths of zirconia and veneering ceramic according to their surface processing. Methods: The test samples were divided into three groups: one without zirconia surface processing, one sandblasted, and one sandblasted then 3% etched. Then veneering ceramic was fired on all test samples, and their shear bond strengths were measured. Results: The test samples of the control group (Z1) showed the lowest shear bond strengths of $21.82{\pm}1.02$ MPa. The shear bond strengths of Z2 and Z3 ($28.25{\pm}0.72$ and $26.23{\pm}0.82$ MPa, respectively) were relatively higher than those of the control group. The fracture surface of the control group showed adhesive fractures while the test groups had relatively large numbers of cohesive fractures. Conclusion: The shear bond strength was high in the test groups with surface processing while the fracture surfaces showed compound fractures of adhesive and cohesive fractures.

• Restorative Dentistry and Endodontics
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• 제21권1호
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• pp.280-288
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• 1996

The purpose of this study was to assess comparatively the shear bond strength on dentin of four dentin bonding agents used in conjunction with light-curing composite resins. Clearfil New Bond, Scotchbond Multipurpose Dentin Adhesive, All-Bond 2 and X-R Bond were applicated on labial dentin surfaces just below dentin - enamel juction of bovine incisor teeth. After shear bond strength testing with the universal testing machine, the bonding interface of the specimens were observed under light stereomicroscope. Following results were obtained. 1. The shear bond strength was high in the order of B,C,D,A and group B Scotchbond Multipurpose Dentine Adhesive revealed greater bond strength than Clearfil New Bond and X-R Bond. (p<.001) 2. When using ANOVA and Duncan's multiple range test, there were statistical differences among the four groups, except between group Band C,group D and A. 3. There was no relationship between mode of failure and shear bond strength.

• Computers and Concrete
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• 제8권4호
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• pp.465-472
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• 2011

This paper investigates bond behavior of structural lightweight concrete (SLWC) and ordinary concrete (OC) comparatively using bending test called Standard Belgium Hinged Beam Test (SBHBT). For this purpose the experiments were carried out as three series on 36 beam specimens (12 specimens of SLWC and OC with $20{\phi}$ development length, 12 specimens of SLWC with $25{\phi}$ development length). For each series bond behavior of steel rebars with 8, 10, 12, 14 mm diameters were tested. The results indicate that bond strength of SLWC is considerable lower than OC and $20{\phi}$ development length is insufficient for steel rebars with 12 mm and 14 mm diameters. Therefore development length of SLWC was extended to $25{\phi}$, even if 8 and 10 mm steel rebars provided acceptable bond strength. In this way, bond strength between SLWC and 8 and 10 mm steel rebars was developed. In addition, adequate bond behavior was achieved for 12 mm rebar but the beam in which 14 mm rebar used exceeded their bearing capacity by shear forces before yield stress. This result shows that SBHBT is more convenient for small sized steel rebars.

• 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.