• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.353-356
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• 2006

Hardening of 2 component adhesive such as epoxy resin used in saturating FRP composite is triggered by mixing each component part within a batch. Chemical reactions occur explosively after a certain time after mixing the batch, viscosity and temperature rapidly increase. As a results, bond performance remarkably decreases and workability declines due to increase in viscosity. Therefore, adhesion should be completed before chemical hardening reaction is rapidly going on. This study examined pot life of structural adhesive for FRP composites by means of change in apparent viscosity and means of exothermic reaction temperature proposing in existing test standards. Result of each test method was compared and analyzed, and reasonable test method and evaluation method are suggested.

• Journal of Surface Science and Engineering
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• v.25 no.2
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• pp.97-102
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• 1992

Transimission electron microscope(TEM)/ultramicrotomy were used to characterize the detailed surface morphology of 2024-T3 Al alloy surfaces prepared by various pretreatment process. It was found that, for good and superior initial adhesive strength and durability, chemically pretreated substrates appeared essential. The film morphology developed after CSA etching treatment, ass revealed by TEM, suggested the present of irregular cell pattern with finely separated whisker-like protrusion with was responsible for increase of bond strength.

• Journal of Korean Association for Spatial Structures
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• v.13 no.4
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• pp.41-47
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• 2013

For the artistic column used by Glass Fiber Reinforced Plastic(GFRP), the connection of steel with GFRP were needed. Due to the fabricating characteristics of hand laminating, GFRP surfaces had to be connected. Because there were no existed data of these connection, experimental study has to be followed so that the structural strength and buckling mode could be investigated. In this paper, therefore, the axial tests of steel with GFRP were performed. The connection of GFRP's surfaces could be also tested as well. As a result, it could be figured out that the strength of these connections were determined by the adhesive strength.

• Magazine of the Korea Concrete Institute
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• v.9 no.6
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• pp.157-164
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• 1997

최근 손상된 구조물에 탄소섬유쉬트 보강공법이 많이 사용되고 있다. 탄소섬유쉬트 보강에 따른 휨내력의 증진이 이루어지기 위해서는 보와 탄소섬유쉬트의 일체거동이 이루어져야 하며, 쉬트단부에서 부착파괴가 발생하지 않아야 한다. 따라서 이번 실험에서는 탄소섬유쉬트의 보강매수에 따른 부착파괴의 거동을 살펴보았다. 전시험체에서 부착파괴가 발생하였으며 부착파괴가 발생한 하중의 크기는 보강매수에 관계없이 비슷하였다. 부착파괴의 거동은 순수부착파괴와 피복박리파괴로 구분될 수 있었으며 부착응력은 단부에서 집중현상이 나타났고 집중된 응력의 크기는 15.39~41.42kg/$\textrm{cm}^2$로 나타났다. 정착길이내의 평균부착응력은 6.85~8.99kg/$\textrm{cm}^2$으로서 평균 7.38kg/$\textrm{cm}^2$이고 이 값은 이론치인 6.19kg/$\textrm{cm}^2$보다 약간 높으며 설계부착응력인 6kg/$\textrm{cm}^2$에 부합되는 것으로 나타났다. 따라서 설계부착응력 6kg/$\textrm{cm}^2$은 정착길이의 설계시 합리적 값으로 평가되었다.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.457-460
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• 2008

CFRP plates has been established as an effective method for rehabilitation and strengthening of concrete structures. The CFRP reinforcements are bonded to beams and slabs using structural adhesives. Adhesive strength can be affected by environmental exposure. During freezing-and-thawing cycling, temperature-induced stresses in the adhesive layer, due to differential thermal expansion between the CFRP and the substrate concrete, may lead to bond damage and contribute to or cause premature CFRP composite separation. This paper presents the results of experimental program undertaken to investigate the effects of freeze-thaw cycling (from -18 to $4^{\circ}C$) on the behavior and failure characteristics of RC beams strengthened in shear with CFRP plate using acoustic emission (AE) technique.

• Proceedings of the KACD Conference
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• 2003.11a
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• pp.625-625
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• 2003

I. Objectives Self-etching primer adhesive system is affected to dentin surface conditioning and priming. Especially application time of self-etching primer is very important factor of clinical procedure which has direct influence on smear layer, etching reaction and primer penetration to dentin. This study evaluated the influence of application time of self-etching primers on microtensile bond strength (${\mu}{\;}TBS$) to dentin using three self-etching primer adhesive systems.(omitted)

• Restorative Dentistry and Endodontics
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• v.20 no.1
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• pp.1-16
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• 1995

The purpose of this study was to investigate the effect of dentin bonding agents on the bond strength of composite resin restorations in case of applying the dentin bonding agents to acid etched enamel surfaces. Freshly extracted 364 bovine anterior teeth were selected as a adherents. 320 enamel specimens were divided into two groups(unetched group (1) and etched group (2) for testing the shear bond strength, 40 specimens were used for the hardness testing, and 4 specimens of rest were to observe the resin-tag formation into etched enamel surfaces. All surfaces of enamel specimens were polished with 320~1500 SiC paper under continuous running water. In Group (1), 100 enamel specimens were polished and unetched. 220 polished enamel specimens in Group (2) were etched with 37 % phosphoric acid solution for 60 seconds, washed with water for 20 seconds, and dried with a light air pressure for 60 seconds. Three kinds of dentin bonding agents(Gluma, Prisma, Scotchbond 2) were evaluated the effect on the bond strength to conditioned enamel surfaces. Shear bond strengths were measured on the three cases such as a coating of primer only, a coating of sealer only, and a sequential coating of primer and sealer to acid etched enamel surfaces were compared with the bond strengths measured by the coating of enamel bonding agent followed by the bonding of composite resin (Photo clearfil bright, Kuraray, Japan) to unetched and acid etched enamel surfaces. In addition, the hardness tested on the adhesive fractured surface between composite resin enamel as a mean of evaluation of a factor whether the mechanical bond strengths were affected and the penetration of dentin bonding agents into etched enamel surfaces was also observed. Bond strengths were measured using the method of shear bond strength by a universal testing machine (Instron-4467, USA), statistical test were applied to the results using a one way analysis variance(ANOVA), and hardness was measured by the Vicker's Hardness Tester(MHT-i, Matsuzawa, Japan) and the penetration of the resins were observed by the SEM (Hitachi, S-2300, Japan). The following conclusions were drawn; 1. Enamel bonding agent showed to affect the improvement of bond strength of composite resin to enamel surface both unetched and etched. 2. Dentin bonding agents could be resulted in increase of bond strength to unetched enamel surface, but there were no statistical significances. 3. Bond strengths to etched enamel surface were significantly decreased with a coating of dentin primer only. 4. Coating of sealer only and coating of primer and sealer noticed the similar bond strengths of composite resin to etched enamel using the enamel bonding agents. 5. The applying method proved to be more effective than the kinds of dentin bonding agents on the bond strength of composite resin to etched enamel than the kind of dentin. 6. Vicker's hardness numbers of dentin bonding agents were lower than that of composite resin, but the degree of penetration of dentin bonding agents into etched enamel surfaces was excellent.

• Journal of the Korea Concrete Institute
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• v.23 no.4
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• pp.529-536
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• 2011

Recently, there has been a growing interest in expanded sidewalks for existing bridges. The cantilever beam system applied to expanded sidewalks for existing bridges are connected with the concrete structure by adhesive anchor bolts. However, the extended sidewalks are currently constructed without standardized regulations, which lead to excessive design of the beam spacing and installation and the construction difficulties due to the excessive over-weight. Moreover, there is only limited analysis and experiment data on the post-installed adhesive anchor bolts, so the excessive number of bolts is used for the connection. This paper deals with a method to increase the effectiveness of beam sections and anchor bolts geometry for expanded sidewalk of existing bridge. The study results showed that the failure of cantilever beam connected by adhesive anchor bolts was dominated by bond failure of interface between concrete and bolt. Also, the results indicated the possibilities of improving serviceability as well as safety of the sidewalks by changing of beam section and prestressing the bolts.

• Journal of the Korea Institute of Building Construction
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• v.18 no.4
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• pp.329-335
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• 2018

The objective of this study is to develop a mortar mixture with high workability and adhesive strength for section jacketing in seismic strengthening technology of existing concrete structures. To achieve targeted requirements of the mortars (initial flow exceeding 200 mm, compressive strength of 30MPa, and adhesive strength exceeding 1MPa), step-by-step tests were conducted under the variation of the following mixture parameters: water-to-binder ratio, sand-to-binder ratio, polymer-to-binder ratio, dosage of viscosity agent, and content of ultra-rapid-hardening cement. The adhesive strength of the mortars was also estimated with respect to the various surface treatment states of existing concrete. Based on the test results, the mortar mixture with the polymer-to-binder ratio of 10% and the content of ultra-rapid-hardening cement of 5% can be recommended for the section jacketing materials. The recommended mortar mixture satisfied the targeted requirements as follows: initial flow of 220 mm, high-early strength gain, 28-day compressive strength of 35MPa, and adhesive strength exceeding 1.2MPa.

• International Journal of Highway Engineering
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• v.4 no.3 s.13
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• pp.15-23
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• 2002

The waterproofing system's performance is known to show a determing by complex interaction of material factors, design details, and the quality of construction, and the waterproofing integrity of waterproofing membranes is determined by the bond to the deck and the amount of damage to the waterproofing membrane. In this research, the basic properties of waterproofing membranes on market and the tensile adhesive chracteristics of waterproofing systems of concrete bridge deck have also been investigated in the view of the damages frequently reported from job site. For the tensile adhesive strength of sheet waterproofing membranes, the results after asphalt concrete paving tends to increase more than before those. The results of the liquid waterproofing membranes are upside-down, and the more concrete has strength, the more strength of tensile adhesive increase. The ambient temperature of asphalt concrete when application of the waterproofing membrane has considerable influence on the performance of waterproofing system. As described above, waterproofing system can be influenced by several factors. If they are not considered under construction, the overlooking will cause the damages of pavement and waterproofing system after traffic opening.