• Magazine of the Korea Concrete Institute
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• v.27 no.1
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• pp.41-44
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• 2015

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.212-218
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• 1995

This study experimentally evaluated the performance of damaged section which was repaired using polymer materials in reinforced flexural flexural members Six different materials, two types of polymer, two types of polymer-cement and two types of cement, were used by means of injection method on prepacked concrete and spray mortar patching method. As results, the repair works could be done easily and surfaces of the repaired section were smooth.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.941-944
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• 2008

Various ductile fiber reinforced cement composite(DFRCC) including large quantities of PVA fiber or steel fiber have been developed recently and studies to find applications in diverse domains are currently conducted actively. Regard to economical efficiency, DFRCC becomes competitive when applied as special elements and repair material with small quantities rather than the casting of large volume for the main body of structures in field. The authors have developed FRP-DFRCC composite slab for bridges and a wet spraying repair technique using DFRCC. In case of the application on FRP-DFRCC composite slab, it was found that there was no problems the structure and durability of it after passed 3 months. And in case of the application on the application of the deteriorated sewage box that passed 20 years, it was found that there was no difference the repair performance between domestic PVA fiber and the Japan. Therefore, DFRCC using PVA fiber, the concrete structures can be increased to performance and secured the economical efficiency.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.30-36
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• 2018

Researches on strengthening and rehabilitation are important since structural capacity is degraded by deterioration or damage of structural members. An effective strengthening scheme such as an externally bonded Carbon Fiber Reinforced Polymers (CFRP) can improve the structural performance of a concrete structure in a cost-effective way. Therefore, many experimental studies on strengthening methods have been widely carried out. In regards to the shear strengthening of a concrete beam, variables of the experimental studies were the amount of CFRP, the angle of the strip, the width of the strip, and the interaction between the materials. However, there are insufficient researches on bi-directional CFRP layout compared to the previous researches. In this study, a total of ten concrete beams were designed and tested to evaluate the shear strengthening effect using CFRP strips. The effectiveness of strengthening was investigated based on the shear contribution of materials, strain distribution of stirrup, and the maximum shear capacity of specimens.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.2
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• pp.10-19
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• 2019

Management plan with repairing is essential for RC structures exposed to chloride attack since durability problems occur with extended service life. Conventionally deterministic method is adopted for evaluation of service life and repair cost, however more reasonable repair cost can be obtained through continuous repair cost from probabilistic maintenance technique. Unlike the previous researches considering only normal distribution of life time, PLTFs (Probabilistic Life Time Function) which can be capable of handling log and normal distributions are attempted for initial and repair service life, and repair cost is evaluated for OPC and GGBFS concrete. PLTF with log distributions in initial service life is more effective to save repair cost since it is more dominant after average than normal distribution. Repair cost in GGBFS concrete decreases to 30% of OPC concrete due to longer initial service life and lower repairing event. The proposed PLTF from the work can handle not only normal distributions but also log distributions for initial and repair service life, so that it can provide more reasonable repair cost evaluation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.1
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• pp.9-20
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• 2023

For highway concrete structures, the deterioration of the structure is accelerated due to the increase in the use of deicing materials, and sectional repair work is being frequently carried out to restore performance. However, after the repair work, re-damage such as cracks, delamination, and poor bond performance is exhibited in the repaired sectional area. In this study, overseas repair material requirements were first analyzed, and present domestic requirements were improved repair material performance through field surveys of common concrete structures, laboratory experiments, and test construction on a disused concrete bridge. In addition, performancebased quality requirements were presented so that all materials that meet the required performance can be applied, and different test methods for each material were unified into concrete test methods for consistent test results analysis. The considered performance requirements were compression strength, bending strength, and bond strength for structural properties, and length change rate, crack resistance, thermal expansion coefficient, and elasticity coefficient were for dimensional behavior. For resistance to chloride penetration resistance and freeze-thaw resistance were presented as durability. The proposed requirements for concrete repair materials are expected to contribute to the improvement of the quality of concrete sectional repair work in Korea.

• Journal of the Korea Institute of Building Construction
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• v.19 no.5
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• pp.411-419
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• 2019

Underground concrete structures are constructed under a geographical environment called underground and exposed to various environments that promote deterioration. Among them, groundwater promotes deterioration of underground concrete structures due to contaminated water from the ground. In this study, the chemical resistance performance test evaluation of five different receptors for a total of 15-type leakage repair materials of five series was conducted to determine the chemical stability of the leakage repair material used in the crack area. The results show a general increase and decrease in most chemical receptors, but the biggest increase and decrease was shown in acrylic systems, which were found in sodium chloride and sodium hydroxide, and epoxy was found in hydrochloric acid. The cement system is showing a lot of increase and decrease in sodium chloride. It is expected that the results of these studies will be used as a basis for chemical stabilization in the development of new materials.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.6
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• pp.179-187
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• 2010

Corrosion of rebar embedded reinforced concrete is the main cause of collapse and degradation of reinforced concrete structure. Degradation occurs in reinforced concrete structures from corrosion caused by the Chloride that the damage other than the severe degradation of the structure in terms of maintenance and construction when the huge expense required and deciding terms is hard. Therefore, early detection of rebar corrosion is important for efficient maintenance and repairing and planning. Meanwhile, how to evaluate the corrosion of the non-destructive measurements have been used a lot. In particular CM-II (corrosion meter) is used to measurement the natural potential, polarization resistance and the resistivity of the concrete, but has some disadvantages. Embedded mini-sensor has been developed in order to overcome these disadvantages. So Measurement corrosion for using the mini-sensor compares with the measured results CM-II (corrosion meter), the developed mini-sensor verify the validity.

• Magazine of the Korea Concrete Institute
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• v.17 no.6 s.89
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• pp.56-61
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• 2005

• Proceedings of the Korea Concrete Institute Conference
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• 1992.10a
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• pp.88-93
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• 1992

근래 들어 철근 콘크리트에 있어서의 철근 부식이 관심의 대상이 되고 있는데 그 이유는 이 현상이 실제 구조물에서 광범위하게 발생함이 확인되었고 이로 이한 보수비용이 급증하였기 때문이다. 철근의 부식이 처음 거론된 것은 해양구조물과 내화학성 구조물에서였고 최근 들어서는 교량상판, 주차공간 등 염기에 노출되어 철근 부식이 우려되는 각 종의 구조물에 광범위하레 그 대책이 연구되기에 이르렀다. 이와 같은 철근부식의 제어방법으로는 첫째로 콘크리트의 수밀화를 들 수 있고 다음으로 콘크리트의 표면을 처리하거나 피복두께를 늘리는 방법이 있다. 마지막으로 철근 자체에 방청성능을 직접 부여하여 철근의 부식을 방지하고자 하는 방법을 들 수 있다. 본 연구는 이러한 대책중에서 가장 적극적인 방법에 속하는 에폭시 도포 철근의 기본적인 방청성능을 고찰하기 위해 수행되었다.