• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.160-163
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• 2004

In domestic, various repair materials and method systems to keep up with these reinforced concrete deteriorated due to salt damage, carbonation, chemical decay et. developed and applied. However, on-site quality control of various repair materials and method systems isn't achieved desirably because it is depend completely on a men of experience' opinions above all else regardless of various on-site environments. In this background, mock up test with due regard to real on-site environments was performed to secure fundamental data for establishment of desirable on-site quality control. Mock up test using repair mortar analyzed from angles of construction methods, mechanical spraying pressures, W/M. Construction methods were designed manpower method and spraying method, spraying pressures were designed 32, 42, 52 psi, W/M were designed 14.4, 15.4, $16.4\%$. And compressive strength, Chloride ion diffusion coefficient, bond strength, SEM. of mock up test specimens were evaluated. In conclusion, we confirmed excellency of mechanical spraying pressures, fined extremely excellency of condition of spraying pressure 42 ps, W/M $14.4\%$ within this study. therefore the results of this study will be useful to provide fundamental data for establishment of desirable on-site quality control.

• Journal of the Korea Concrete Institute
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• v.19 no.1
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• pp.39-46
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• 2007

In this study, for the establishment of the performance evaluation methods and the quality control standards of durability recovery method, the quantitative exposure data by long term exposure test under the coast and normal atmosphere is accumulated and analyzed. Investigating and evaluating the result of exposure test during 30 months of exposure age under the coastal and normal atmosphere environment, carbonation depth and chloride-ion penetration depth very little penetrated than cover depth. It seems reasonable to conclude that main cause of Corrosion of reinforcing bar are chloride-ion and macro cell from the result of corrosion area and corrosion velocity. Therefore, it is considered to be applied as the fundamental data on the performance evaluation and quality control standards of repair material and method through continuous exposure test in the future.

• Journal of Microbiology and Biotechnology
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• v.31 no.9
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• pp.1311-1322
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• 2021

Microbially induced calcium carbonate precipitation (MICP) has recently become an intelligent and environmentally friendly method for repairing cracks in concrete. To improve on this ability of microbial materials concrete repair, we applied random mutagenesis and optimization of mineralization conditions to improve the quantity and crystal form of microbially precipitated calcium carbonate. Sporosarcina pasteurii ATCC 11859 was used as the starting strain to obtain the mutant with high urease activity by atmospheric and room temperature plasma (ARTP) mutagenesis. Next, we investigated the optimal biomineralization conditions and precipitation crystal form using Plackett-Burman experimental design and response surface methodology (RSM). Biomineralization with 0.73 mol/l calcium chloride, 45 g/l urea, reaction temperature of 45℃, and reaction time of 22 h, significantly increased the amount of precipitated calcium carbonate, which was deposited in the form of calcite crystals. Finally, the repair of concrete using the optimized biomineralization process was evaluated. A comparison of water absorption and adhesion of concrete specimens before and after repairs showed that concrete cracks and surface defects could be efficiently repaired. This study provides a new method to engineer biocementing material for concrete repair.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1417-1424
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• 2010

To provide more safe road and better travelling service for Expressway customer, we minimize settlement of bridge backfill and properly repair the occurred settlement. So, we devide this study to two parts one is construction part and the other is management part, in construction part we remove settlement occuring elements and in management part we grasp proper repair time, and then we produce general settlement management program. In construction part, for the purpose of developing construction method of reducing settlement, we developed construction method models and they are composed of abutment back section alteration and backfill material alteration by literature reviews and site investigation of backfill settlement. And then, we carried out laboratory model test and full size field test of some developed models.

• Journal of the Korea Concrete Institute
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• v.11 no.3
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• pp.35-45
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• 1999

Recently, many strengthening methods are developed to repair damaged structures, especially, steel plate or carbon fiber sheet bonding methods are widely used. For the bonding methods, the strengthening materials are bonded when the original structure is under loading, which causes difference of initial stresses between original member and bonded material. However, current design method or theory, which mostly depends on ultimately strength design, cannot account the difference of initial stresses between members, and it disregards the reduction of nominal strength. In this study, a new strengthening design theory and program which can account the difference of initial stresses are developed, and applied to the case when a structure in service is repaired. In order to verify the validity of the theory and the program, a test result is referred and compared with the results and it is showed that the calculated values are almost same as the referred data and finally proved that the program is reliable. The results showed that the amount of strengthening material depends on the status of damages of structure, and the nominal strength is reduced depending on the degree of damages.

• Structural Engineering and Mechanics
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• v.22 no.5
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• pp.631-645
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• 2006

Buckling capacity of compression members may change due to inadvertent changes in the member section dimensions or material properties. This may be the result of repair, modification of section properties or degradation of the material properties. In some occasions, enhancement of buckling capacity of compression members may be achieved through splicing of plates or utilization of composite materials. It is very important for a designer to predict the buckling resistance of the compression member and the important parameters that affect its buckling strength once changes in section and/or material properties took place. This paper presents an analytical approach for determining the buckling capacity of a compression member whose geometric and/or material properties has been altered resulting in a multi-step non-uniform section. This analytical solution accommodates the changes and modifications to the material and/or section properties of the compression member due to the factors mentioned. The analytical solution provides adequate information and a methodology that is useful during the design stage as well as the repair stage of compression members. Three case studies are presented to show that the proposed analytical solution is an efficient method for predicting the buckling strength of compression members that their section and/or material properties have been altered due to splicing, coping, notching, ducting and corrosion.

• Journal of the Regional Association of Architectural Institute of Korea
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• v.20 no.6
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• pp.55-61
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• 2018

This study improved the water repair materials of the polyacrylic system applied to concrete structures by controlling expansion, strengthening water resistance, and improving cohesiveness. The improved polyacrylate repair materials were evaluated against the existing products to verify their performance and level of improvement, and applied on-site to the concrete structures that are leaking the improved water. The verification method measured the presence of water leaks and the moisture content of concrete inside. Moisture levels were measured for two months before and after material installation, and at least 0.8 - 1.7% of humidity was reduced after installing polyacrylic resin, and no leakage was found.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.147-148
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• 2011

This study applied BIM(Building Information Modeling) technology for Long-life Housing within exterior, interior and building equipment. There has many changes and depression infill material after construction. Therefore to understand establishment of repair and replacement cycle is necessity. In addition, the method of classification is necessary because of construction equipment efficiency. On this study, we will find how can we manage them and establish the repair and repairment cycle by applying BIM technology.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.111-112
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• 2014

This research focuses on the study that micro-crack of concrete is repaired to use self-healing technology. Self-healing concrete is widely studied in domestic and international construction field recently. Micro-crack(less than 0.3mm)of concrete is repaired using a crack repair stick which containing self-healing agents. Therefore, the crack on construction structure will be easily repaired by using a crack repair stick. Also experiment was proceeded because of evaluating the long term durability.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.3
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• pp.322-329
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• 2016

This study is about the method to control the quality of material used to repair leakage and crack of concrete structure and suggests the "Temperature Stability Test Method" as a follow-up study. In the result of performance evaluation for 45 samples of 15 types in 5 series, the temperature stability test showed different material changes including rolling down, volume change, and color change as they are frozen and melt repeatedly in the somewhat extreme conditions at low($-20^{\circ}C$) and high($60^{\circ}C$) temperatures, where 13 samples (approx. 29%) and 32 samples (approx. 71%) showed leakage, respectively, in the permeability test to evaluate leakage. This result shows the enough importance of setting the quality control criteria of leakage repair material currently used to maintain concrete structures considering the temperature conditions, and proves the applicability of the Temperature Stability Test Method as a standard test method to ensure long-term durability of concrete structure.