The paper presents the experimental investigation of RC beams retrofitted with Textile Reinforced Mortar (TRM), featuring enhanced bond capacity. Anchoring systems, including an extension of retrofitting length and the use of chemical anchors, are newly employed to improve the structural performance of the RC beam retrofitted with TRM. For the experimental investigation, a total of seven shear-critical RC beams, with and without stirrups, were designed and constructed. The structural behaviors of specimens retrofitted with the proposed TRM methods were compared to those of non-retrofitted specimens or specimens strengthened with conventional TRM methods. Crack pattern, force-displacement relationship, and absorbed energy were evaluated for each specimen. The experimental results indicate a significant improvement in the shear capacity of the RC beam with the proposed retrofitting method. Therefore, it is concluded that the application of an extended retrofitting length and chemical anchors to the TRM retrofitting method can effectively enhance the bond capacity of TRM, thereby improving the shear performance of RC beams.

The purpose of this study was to develop a carbon fiber sheet with embedded fiber optic sensor for maintenance and performance improvement of aged concrete bridges. The carbon fiber sheet reinforcement method can separate the concrete and the carbon fiber sheet, so it is necessary to investigate the bond performance level. However, separation of concrete and carbon fiber sheet and investigation of concrete scaling phenomenon are carried out by human, so it is difficult to secure objectivity and accurate investigation. Therefore, in this study, a method to confirm the bond level of carbon fiber sheet by reinforcing with a carbon fiber sheet with a fiber optic sensor was examined. In this study, we investigated the strain of fiber optic sensor embedded in carbon fiber sheet to identify the separate point of carbon fiber sheet. The strain measured by fiber optic sensor was measured by numerical analysis. The strain rate of the carbon fiber sheet was compared with that of the carbon fiber sheet. As a result, it was confirmed that the strain was changed at the point where the carbon fiber sheet was separated, and the strain occurred in the carbon fiber sheet was examined to predict the separate point.

The purpose of this study is to develop a carbon fiber sheet with embedded fiber optic sensor for maintenance and performance improvement of aged concrete bridges. The carbon fiber sheet bonded method has many advantages in terms of member repair and reinforcement, but it is disadvantageous in that it is necessary to directly identify the separate point generated during the bonded of the carbon fiber sheets by an artificial method. In this study, we examined the method of confirming the separate point of the carbon fiber sheets by examining the strain of the fiber optic sensor embedded in the carbon fiber sheets. The strain rate measured by the fiber optic sensor was replaced by the strain of the carbon fiber sheets derived from the FEM analysis.

GFRP(Glass Fiber Reinforced Polymer Plastic) has a superior corrosion resistance, high specific strength/stiffness, etc. Therefore, such properties can be used to mitigate the problems associated with the use of conventional construction materials. In this study, the various rib and pitch distance of hybrid fiber GFRP bars were evaluated by experimental method. From the test result, thirty two types of FRP hybrid bars such as spiral type with the dimension of rib geometry were fabricated. To evaluate the bond properties of them, direct pull-out test was performed. All testing procedures including specimen preparation, set-up of test equipment and measuring devices were made in accordance with the recommendations of ASTM D 7913. From the test results, it was found that cross type hybrid GFRP reinforcing bars showed the highest bond strength than that of the others due to the higher relative rib area.

GFRP(Glass Fiber Reinforced Polymer Plastic) has a superior corrosion resistance, high specific strength/stiffness, etc. Therefore, such properties can be used to mitigate the problems associated with the use of conventional construction materials. In this study, the various rib and pitch distance of hybrid fiber GFRP bars were evaluated by experimental method. From the test result, thirty two types of FRP hybrid bars such as spiral and cross type with the dimension of rib geometry were fabricated. To evaluate the bond properties of them, direct pull-out test was performed. All testing procedures including specimen preparation, set-up of test equipment and measuring devices were made in accordance with the recommendations of ASTM D 7913. From the test results, it was found that cross type hybrid GFRP reinforcing bars showed the highest bond strength than that of the others due to the higher relative rib area.

PURPOSES : This study focuses on the evaluation of interface performance with varying surface texture and tack coat application in an asphalt overlay. METHODS : The evaluation is carried out in two phases: tracking test and interface bond strength test. Using an image processing tool, tracking test is conducted to evaluate the susceptibility of the tack coat material to produce excessive tracking during application. Using the pull-off test method, the bond strength test is performed to determine the ability of the interface layer to resist failure. RESULTS: Results show that the underseal application yields less tracking compared to other applications. However, the bond strength is barely within the minimum acceptable value. On the other hand, RSC-4 produces higher bond strength for all surface types, but the drying time is long, which produces excessive tracking. CONCLUSIONS: While underseal application may be suitable for a trackless condition, the bond strength is less appealing compared to the rest of the tack applications available. RSC-4 demonstrated a high and consistent bond strength performance, but more time is required for drying to avoid excessive tracking. Tack coat application and surface type combination produce varying results. Therefore, these should be considered when selecting suitable future tack coat application options.

Rehabilitation of existing steel structure attached to a steel because cross-section is generally raising. But when the area of reinforcement increases, also increases the weight of steel can cause degradation of the operations. In addition, welding process cause discomfort which due to the interference of other process. To replace the existing method, there are researches and applications for civil steel structures on the outside. In this study, bond performance of FRP and Steel were tested to reinforce steel structures by using AFRP as well as CFRP.

콘크리트 구조물은 시공 후 다양한 원인에 의해 물리적, 화학적 변형을 통해 물리적인 성능이 저하된다. 이러한 콘크리트 구조물의 성능저하는 사용수명을 감소하기 때문에 합리적인 보수보강이 필요하다. 최근 콘크리트 구조물의 효율적인 보수을 위해, 부착성능을 향상시킨 하이브리드 보수재료에 대한 연구가 활발히 수행되어오고 있다. 본 연구에서는 기존콘크리트와의 부착성능 및 수밀성을 향상시키기 위해 초속경 시멘트에 PVA 분말수지, 나일론 섬유, 라텍스를 혼입 한 하이브리드 보수재를 개발하였다. 보수재료의 성능평가를 위해 압축강도, 건조수축, 부착강도 실험을 수행하였다. 또한 미리 손상이 발생한 시험체를 제작한 후 보수 전후의 휨부착 성능평가를 수행하였다. 휨강도 평가결과, 기존의 초속경시멘트만 혼입한 시험체를 제외한 모든 실험체에서 110%~150%정도 휨강도가 크게 나타났고, 휨강도에 의해 발생된 균열패턴은 모든 실험체가 기존 콘크리트와 일체 거동하는 것으로 나타났다.

The purpose of this study was to evaluate the mechanical properties and bond performance of epoxy paint containing graphene materials. Experiment result, it was confirmed that graphene materials are effective to improve the mechanical properties of the epoxy paint, but it is not effective to improve the bond performance.

본 논문은 바탕면의 함수조건에 따른 보수재료로서 MKPC의 인발 부착강도, 전단 부착강도, 계면 부착강도를 폴리머 시멘트 모르 타르, 에폭시 모르타르와 비교 분석하였다. 그 결과 MKPC는 PC 및 MKPC와 비교하여 바탕면 함수조건에 따른 부착성능의 변화가 상대적으 로 작은 것으로 나타났다. 또한 MKPC의 경우 절건 바탕면에서의 부착성능은 무기계 보수재료인 폴리머 시멘트 모르타르와 비교하여 우수한 특성을 지니고 있으며, 습윤 바탕면에서의 부착성능은 폴리머 시멘트 모르타르와 유사한 수준을 보이고 있으나 에폭시 모르타르와 비교하여 우수한 특성을 지니는 것으로 나타났다.

This is A Study on the Bond Performance of Synthetic Polymer Composite Waterproofing and Anticorrosion Method in accordance with PE Fiber Reinforcement. Test results, A Bond Performance of the Test Specimen was confirmed to have increased 37.5%. By PE Fiber Reinforcement.

Authors investigated the fatigue bond performance on the grouted joint connection of wind tower. High strength cementeous grout has 140MPa of a compressive strength was incerted in the gap of small scaled steel tube simulated the wind tower joint. The stress level was 65 and 74% of static strength that is 35MPa, respectevely. From the test, each specimens endured the repeated loads up to 2,000,000 cycles.

이 연구에서는 초고성능 콘크리트 (UHPC)와 보통 콘크리트 (NSC)간 계면부착강도에 관한 연구를 수행하였다. UHPC를 보수⋅보강재 로 활용하기 위한 기존의 부착강도에 관한 연구와 달리, UHPC를 프리캐스트 합성부재로 활용하기 위한 연구에 초점을 맞추었으며, 여기 에 영향을 미칠 수 있는 다양한 요인에 대하여 검토하였다. 기존 연구들을 분석한 결과, UHPC-NSC 계면 부착강도에 영향을 미칠 수 있는 요인으로는 계면의 형상, 합성 전 UHPC의 경화 진행상태, 합성 전 UHPC의 수분 흡수상태, 그리고 합성 후 양생장소와 같이 크게 4가지 로 구분되었다. 계면의 형상을 변수로 한 실험에서는 형상에 따라 각기 다른 파괴모드가 나타났으며, 기존 연구에서 확인되지 않았던 거칠 게 처리한 UHPC 계면 일부가 파괴되는 새로운 파괴모드가 발견되었다. 합성 전 UHPC의 경화진행 상태가 부착강도에 영향을 미치는 것 으로 나타났으며, 이러한 영향은 부착 파괴모드에 따라 다르게 나타났다. 또한, 합성 전 UHPC의 수분상태가 부착강도에 영향을 주었으며, UHPC의 양생방법에 따라 서로 상반되는 결과를 보였다. 마지막으로, 합성한 시편의 양생조건 역시 계면 부착강도에 영향을 미친다는 것 을 확인하였다.

In this study, bond performance of grouted joint with high performance cement grout was verified. The grout which the compressive strength of grout was over 120MPa. was applied for wind turbine tower connections. From the results, the connection joint using high performance grout has sufficient bond strength.

This study presents bond performance of insulated concrete sandwich panel systems considering different type of insulation through two-way acting insulated concret sandwich panel mock-up test under wind pressure.

본 연구에서는 순환 굵은 골재를 사용한 철근콘크리트 (RC) 보의 부착거동을 평가하였다. 총 4개 실험체를 제작하였으며, 실험변수는 굵은 골재의 종류(천연 및 순환골재)와 순환골재의 흡수율로 하였다. 본 실험에서는 흡수율이 3%와 6%인 순환 굵은 골재를 사용하였으며, 실험체는 단순지지 형태로 집중하중을 받도록 계획하였다. 실험체의 부착특성을 효과적으로 평가하기 위하여 Ichinose가 제안한 실험방법을 채택하였다. 본 실험결과, 순환 굵은 골재의 흡수율에 따른 부착 특성의 차이는 발견되지 않았다.

에폭시 모르타르의 적정 배합비를 결정하기 위해서 규사의 입도 조정을 통해 적정 입도비를 알아보고, 규사인 60목과 4호의 배합비를 달리한 공시체를 제작하여 각각의 압축 및 인장 실험을 실시한다. 체의 치수(mm)종류체통과 중량 백분율(%)2.51.20.60.30.15모래80-10050-9025-6010-302-102.2 규사의 입도 조정