• 한국구조물진단유지관리공학회 논문집
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• 제1권1호
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• pp.107-112
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• 1997

A series of reinforced concrete beams was tested to evaluate the flexural performance of the repaired RC beams. The key parameters for this study were the size and location of the patch, and the repair materials, including polymer, polymer-cementitious and cementitious materials. The repaired specimens failed by a typical flexural mode with minor interfacial bond failure. Beams repaired with polymer, polymer-cementitious and cementitious materials recover 100%, 91%, and 97% of the flexural strength respectively, while beams with cement mortar lose approximately 30% of the strength. Compared with the pressure injection techniques the specimens repaired with patching techniques show low flexural strength, with significant interfacial bond failure. Location and size of the repaired part do not affect the recovering performance. Interfacial behavior between repair and strengthening materials is the major influencing factor for the composite structures.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.445-448
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• 2004

Recently, bridge deck overlay with latex modified concrete is widely applied in domestic. the capacity of bridge deck overlay depends on bond state on the surface. factors that have an effect on bond state are clean condition on the surface, absence of surface microcracking, absence of laitance, overlay curing. In this study, it is researched that characteristic of bond strength according to moisture condition on the surface and the removal method of concrete. As a result, it shows high bond strength in dry condition when w/c is $31\%$ and in moisture condition when w/c is $38\%$ respectively. characteristic of bond strength according to the removal method of concrete shows high bond strength when using water-jets rather than jackhammers.

• Restorative Dentistry and Endodontics
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• 제46권3호
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• pp.32.1-32.10
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• 2021

Objectives: This study aimed to evaluate the effect of the application method of universal adhesives on the shear bond strength (SBS) of repaired composites, applied with different thicknesses. Materials and Methods: The 84 specimens (Filtek Z350 XT) were prepared, stored in distilled water for a week and thermocycled (5,000 cycles, 5℃ to 55℃). They were roughened using 400-grit sandpapers and etched with phosphoric acid. Then, specimens were equally divided into 2 groups; Single Bond Universal (SU) and Prime&Bond Universal (PB). Each group was subdivided into 3 subgroups according to application methods (n = 14); UC: 1 coat + uncuring, 1C: 1 coat + curing, 3C: 3 coats + curing. After storage of the repaired composite for 24 hours, specimens were subjected to the SBS test and the data were statistically analyzed by 2-way analysis of variance and independent t-tests. Specimens were examined with a stereomicroscope to analyze fracture mode and a scanning electron microscope to observe the interface. Results: Adhesive material was a significant factor (p = 0.001). Bond strengths with SU were higher than PB. The highest strength was obtained from the 1C group with SU. Bonding in multiple layers increased adhesive thicknesses, but there was no significant difference in SBS values (p = 0.255). Failure mode was predominantly cohesive in old composites. Conclusions: The application of an adequate bonding system plays an important role in repairing composite resin. SU showed higher SBS than PB and the additional layers increased the adhesive thickness without affecting SBS.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
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• pp.98-99
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• 2015

In the study, based on analysing bond strength of MPC and existing rapid harding grout according to shape of cross section, early ages shape of cross section is investigated about effect on bond strength to use MPC as an emergency repair material for road defects such as the form of a pot-hole. The result, MPC is about 10% higher than the shear bond strength rapid harding grout, about 20% higher bending bond strength.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.397-400
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• 2006

Most of the civil structures in Korea and abroad have many kinds of damages when they are facing over-loaded traffics, long-term serviceability, and severe environmental conditions. Repair, rehabilitation, and retrofit are important for maintaining the serviceability of structures. In recent year, VES-LMC has been widely used as repair material for bridge deck repair and rehabilitation, because the VES-LMC has a various benefits such as traffic opening after 3 hours of curing, higher durability and bond strength. In case of any structure repaired or rehabilitated with VES-LMC, those were influenced capacity of bond between the base layer of slab and VES-LMC as well as physical properties of each other materials. The capacity of bond depended on purity of interface, micro cracks, curing of VES-LMC and so like. A kind of popular concrete repair technique, High pressure water jetting equipment is extremely efficient at removing damaged concrete. Removing damaged or poor quality concrete from sensitive structures such as bridge, tunnels, multi-story car parking decks and runways, using the high pressure water jetting could remove damaged or poor quality concrete remaining healthy and sound concrete. Accordingly, the purpose of this study is that it was to evaluate effect of hydrodemolition on the bond strength of VES-LMC overlay compared with effects of other method such as breaker, untreated. Also, it was evaluated the effect of surface moisture.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.965-970
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• 2002

The strengthening of concrete structures in situ with externally bonded carbon fiber is increasingly being used for repair and rehabilitation of existing structures. Carbon fiber is attractive for this application due to its good tensile strength, resistances to corrosion, and low weight. Generally bond strength and behavior between concrete and carbon fiber mesh(CFM) is very important, because of the enhanced bond of CFM. Therefore if bond strength is sufficient, it will be expected to enhance reinforcement effect. If insufficient, reinforcement effect can not be enhanced because of bond failure between concrete and CFM. This study is to investigate the bond strength of CFM to the concrete using direct pull-out test and tensile-shear test. The key variables of the experiment are the location of clip, number of clips and thickness of cover mortar. The general results indicate that the clip anchorage technique for increasing bond strength with CFM appear to be effective to maintain the good post-failure behavior.

• 구강회복응용과학지
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• 제34권2호
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• pp.89-96
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• 2018

목적: 본 연구의 목적은 비스 아크릴 복합 레진의 수리 시 지연시간, 표면처리, 수리재료가 미치는 영향을 전단 결합강도 비교를 통해 알아보고, 폴리메틸 메타크릴레이트 레진을 이용한 비스 아크릴 복합 레진 수리의 효용성을 평가하고자 하는 것이다. 연구 재료 및 방법: 총 90개의 비스 아크릴 복합 레진 시편을 제작하였고, 지연시간, 표면처리, 수리재료에 따라 10개씩 9개의 실험군으로 분류하였다. 각각의 시편들은 제작 직후 만능시험기를 사용하여 전단 결합강도를 측정하였고, 통계분석 프로그램(IBM SPSS statistics 20)을 이용하여 분석하였다. 전단 결합강도 측정 후 시편의 파절 단면을 관찰하였다. 결과: 시편 제작 직후, 접착제(bonding agent)를 이용하여 광중합형 유동성 복합 레진을 접착한 실험군에서 가장 높은 전단 결합강도를 보였다($17.54{\pm}3.14MPa$). 결론: 비스 아크릴 복합 레진을 수리할 때 경과시간에 따라 재제작 여부를 고려해야 하며, 효과적인 수리를 위해 사용부위나 목적에 따라 알맞은 재료와 표면처리 방법을 고려하는 것이 바람직할 것이다.

• 한국건축시공학회지
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• 제24권1호
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• pp.23-34
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• 2024

본 연구의 목적은 RC 구조물의 균열 보수용 폴리머 시멘트 복합체의 휨접착성능을 평가하기 위함이다. 시멘트 모르타르에 다양한 크기의 균열을 만들어 PCCs를 충전한 후, 소정의 양생을 거쳐 휨접착강도와 휨강도 개선 정도를 파악하였다. 연구결과, 균열보수용 PCCs의 휨접착강도는 시멘트의 종류, 폴리머 종류 및 폴리머 결합재비에 따라 영향을 받으며 실리카퓸을 혼입한 초조강시멘트를 사용한 경우가 보통시멘트를 사용한 경우에 비해 최대 19.0%의 휨접착강도 개선효과가 나타났다. PCCs로 충전된 시멘트 모르타르의 휨강도 개선 정도는 균열폭의 영향보다는 균열깊이에 따라 큰 차이를 보였으며 균열에 충전된 PCCs가 단순히 보수재료로서 기능뿐만 아니라 어느 정도 휨강도를 개선시키는 보강재료로서도 역할을 하였다. 본 연구결과, 초조강시멘트, 3종류의 폴리머 디스퍼전과 실리카퓸, 60%~80%의 높은 폴리머 결합재비로 제작한 PCCs가 균열을 충전하는 보수재료로서 현장에서 충분히 사용될 수 있을 것이다.

• Restorative Dentistry and Endodontics
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• 제44권3호
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• pp.23.1-23.9
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• 2019

Objectives: The aim of this study was to investigate the microshear bond strength (${\mu}SBS$) of different universal adhesive systems applied to hybrid computer-aided design/computer-aided manufacturing (CAD-CAM) restorative materials repaired with a composite resin. Materials and Methods: Four types of CAD-CAM hybrid block materials-Lava Ultimate (LA), Vita Enamic (VE), CeraSmart (CS), and Shofu Block HC (SH)-were used in this study, in combination with the following four adhesive protocols: 1) control: porcelain primer + total etch adhesive (CO), 2) Single Bond Universal (SB), 3) All Bond Universal (AB), and 4) Clearfil Universal Bond (CU). The ${\mu}SBS$ of the composite resin (Clearfil Majesty Esthetic) was measured and the data were analyzed using two-way analysis of variance and the Tukey test, with the level of significance set at p < 0.05. Results: The CAD-CAM block type and block-adhesive combination had significant effects on the bond strength values (p < 0.05). Significant differences were found between the following pairs of groups: VE/CO and VE/AB, CS/CO and CS/AB, VE/CU and CS/CU, and VE/AB and CS/AB (p < 0.05). Conclusions: The ${\mu}SBS$ values were affected by hybrid block type. All tested universal adhesive treatments can be used as an alternative to the control treatment for repair, except the AB system on VE blocks (the VE/AB group). The ${\mu}SBS$ values showed variation across different adhesive treatments on different hybrid CAD-CAM block types.

• 대한치과기공학회지
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• 제39권3호
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• pp.161-167
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• 2017

Purpose: We compare the bond strength of heat-cured PMMA of Lucitone 199 and QC-20 and Tokuyama Rebase Resin of self-cured resin, which are widely used and well accepted in clinical practice. In order to test the mechanical bonding and chemical bonding, we will compare the bond strength between EstheShot Bright, Smiletone, Repair and Rebase resins. Methods: The denture base resin used in this study was PMMA heat-cured QC-20 and Lucitone 199, polyamide resin EstheShot Bright, Smiletone. And Two types of self-curing Rapid Repair and Tokuyama Rebase were used as resection resins. To measure the bond strength, the denture specimens were fabricated in the size of $10{\times}64{\times}3.5mm$ as instructed by the manufacturer. A surface treatment agent was applied to the cut surfaces of each denture specimen, and the specimens were placed in a preformed silicone mold, and autoclaved excimer resins were prepared. The bending strength of the fabricated specimens was measured using a universal testing machine (STM-5, United Calibration Co., U.S.A.) to measure the three-point bending strength. Results: In both polycarbonate and polyacetal resin, a special resin surface treatment agent showed higher bonding strength than the resin surface treatment agent(p<0.05). Regardless of the type of surface treatment, polycarbonate showed higher bond strength than polyacetal resin(p<0.05). Conclusion: It is considered desirable to use a special surface treating agent for the thermoplastic denture base resin such as polycarbonate and polyacetal resin.