• 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.

• Composites Research
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• v.36 no.2
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• pp.108-116
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• 2023

In this paper, kinematic design and multi-body dynamics analysis were conducted to develop a small manipulator platform for automating the maintenance of structures made of composite materials. To design manipulator kinematically, the existing composite repair process was considered. The 3D design was conducted after selecting the basic specifications of manipulator and end-effecter in consideration of the patch lamination process for repair. Then, variables necessary for simulation and control were generated in MATLAB through inverse kinematic analysis. To evaluate the structural stability of platform, multibody dynamics analysis was conducted using Altair Inspire and Optistruct. Based on the simulation conducted in Inspire, multibody dynamics analysis was conducted in Optistruct, and structural stability was verified through the results of maximum displacement and Von-Mises stress over time. To verify the design, manufacturing and controlling of platform were conducted and compared with the simulation. It was confirmed that the actual repair process path and the simulation showed a good agreement.

• Journal of the Korea Institute of Building Construction
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• v.24 no.1
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• pp.23-34
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• 2024

This research aims to assess the flexural bonding efficacy of polymer-cement composites(PCCs) in mending cracks within reinforced concrete(RC) structures. The study involved infilling PCCs into cement mortar cracks of varying dimensions, followed by evaluations of enhancements in flexural adhesion and strength. The findings indicate that the flexural bond performance of PCCs in crack repair is influenced by the cement type, polymer dispersion, and the polymer-to-binder ratio. Specifically, the use of ultra-high early strength cement combined with silica fume resulted in an up to 19.0% improvement in flexural bond strength compared to the application of ordinary Portland cement with silica fume. It was observed that the augmentation in flexural strength of cement mortar filled with PCCs was significantly more dependent on the depth of the crack rather than the width. Furthermore, PCCs not only acted as repair agents but also as reinforcement materials, enhancing the flexural strength to a certain extent. Consequently, this study concludes that PCCs formulated with ultra-high early strength cement, various polymer dispersions, silica fume, and a high polymer-to-binder ratio ranging from 60% to 80% are highly effective as maintenance materials for crack filling in practical settings.

• 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.

• The Monthly Technology and Standards
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• s.110
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• pp.48-49
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• 2011

(주)비앤비코리아의 금속용 고내마모성 보수 보강재는 일반적인 냉간용접제(cold welding)로 금속의 부식, 침식, 마모 등에 의해 파손된 곳에 적용할 수 있는 제품이다. 친환경적인 재료로 만들어졌으며, 기계적 강도가 좋고, 보수가 쉽고 빠른 장점이 있다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.4
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• pp.153-159
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• 2006

Recently, the polymer is used as an admixture in the repair mortar, which contains various admixtures and mineral admixtures. In this study, the fresh and mechanical properties of repair mortar influenced by the types of polymers(classified as E.V.A.) and the range of polymer ratio were investigated. It was found that with increasing the ratio of polymer, mechanical properties(compressive strength, flexural strength, adhesive strength) of repair mortar is improved and drying shrinkage is increased.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.36 no.5
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• pp.147-154
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• 2020

Currently, there are no specific repair methods for RC structures damaged by fire, and repair methods are applied when durability deteriorates due to aging. In addition, a number of recent studies have been reported that have conducted fire resistance assessment of the repair materials themselves, assuming exposure to high-temperature environments such as fires. However, researches that evaluate the fire resistance performance of the repair materials by applying existing repair materials to the actual fire damaged reinforced concrete structures are very rare. Therefore, in this study, a number of existing repair materials were applied to fire-damaged concrete column to compare and evaluate the fire resistance performance with the original cover concrete.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.3
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• pp.202-209
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• 2023

In this study, microstructures and mechanical properties of repair materials using calcium sulfoaluminate (CSA) and/or amorphous calcium aluminate (ACA) cements were experimentally investigated. By XRD ansysis, the hydrates formed in repair materials were identified. In addition, the microstructures of repair materials were visually examined through SEM observation. Setting time of mortars made with repair materials were measured. The strength development and ultrasonic velocity of the mortars were also evaluated at the predetermined ages. As a result, it seems that ACA showed a benefit effect with respect to mechanical properties of mortars.

• Magazine of the Korea Concrete Institute
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• v.7 no.6
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• pp.4-4
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• 1995

• Magazine of the Korea Concrete Institute
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• v.7 no.6
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• pp.74-91
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• 1995