• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.458-466
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• 2023

Structures in our surroundings deteriorate over time due to environmental and chemical factors, resulting in a decrease in their performance. The primary causes of degradation in concrete structures are carbonation, salt damage, and freeze-thaw cycles. Various maintenance methods exist to address these degradation issues. However, research and technological development for existing maintenance methods have been ongoing, but the accuracy and effectiveness of repair materials and techniques have not been extensively validated. Therefore, in this study, we conducted a material performance evaluation of various manufacturers' repair materials. Based on this evaluation, we applied corrosion inhibitors and epoxy, which are the methods most closely related to crack repair, to assess the durability performance against carbonation, salt damage, and freeze-thaw cycles. The results show approximately a two-fold performance improvement against carbonation and salt damage, and a 5% enhancement in repair performance against freeze-thaw cycles. Thus, it is considered effective in preventing rebar corrosion when appropriate maintenance is carried out according to environmental and chemical factors during structural repairs.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.13-14
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• 2015

Carbonation is the results of the interaction of carbon dioxide gas in the atmosphere with the alkaline hydroxides in the concrete. in other words, of the hydrates in the cement pastes, the one which reacts with readily is Ca(OH)₂, the product of the reaction being CaCO₃ and which decreases the alkalinity of concrete. Consequently, RC structure is deteriorated due to steel corrosion in concrete. As the importance of maintenance of reinforced concrete structure recently has emerged, the attention of durability of structure has been increasing. There are many studies about durability decline especially due to the carbonation. In order to study carbonation progress after surface repair of carbonated concrete, each carbonation penetration velocity from different repair materials of concrete structure is compared through the experiment of carbonation accelerating CO₂ concentration to 100%. As carbonation infiltration progress is predicted through this study, the counterplan of service life evaluation will be prepared on selection of repair materials of concrete structure.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1267-1272
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• 2007

In the case of the railway bridge, there are following the progress of works after the drainage method of a bridge surface - vibration proof rubber establishment, track gravel construction and rail construction etc. But these works are not enforced consecutively by the execution and economical reason. This is the reason of the long period of exposure after drainage execution. In many case, from the deterioration phenomenon by long term exposure of surface, there are a lot of occasions that do not keep primitive penetration depth waterproof primitive time. It is the most important that select the drainage method that have durability - it is not fallen in long-term exposure of surface. The major objective of this study is to deduce objective analysis result through examination about the Deterioration Restraining Agent method and to master KNOW-HOW of DRA drainage method. Through the study, minimize economical damage by frequent repair and reinforcement and present the reasonable standard of judgement fot drainage method of construction.

• Journal of the Korea Concrete Institute
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• v.13 no.1
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• pp.9-15
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• 2001

The low-durability performance of concrete structure occurs by interactive deterioration factors. In particular, carbonation increased with its time elapse is known as the general manner of deterioration characteristics. Recently, the fundamental researches of the carbonation mechanism, besides method and technique for durability improvement of deteriorated structure are advanced actively. So in this paper, alkali-recovery and maintenance performance when the impregnating alkalization agents are used, are compared and examined quantitively with the basis of past proposed study. As a result, alkali-recovery performance be ensured by impregnating alkalization agent on the carbonated concrete which has low pH by accelerated carbonation test. And alkali maintenance performance was effected by the finishing materials on the alkali recovered concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.6
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• pp.95-102
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• 2007

Recently, an improved capacity for RC bridges is required by their deterioration or necessary to carry traffic increase. Strengthening is known as a better way to improve capacity of bridges than reconstructing in terms of economy. The surface bonded method, which is normally used with FRP material, has some advantages related to conveninent application and time-save among other strengthening methods. FRP material is light and has high tensile strength compared to steel. Therefore, this paper presents how structural capacity strengthed with CFRP sheet and Glass fiber-Steel Plate (GSP) is improved.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.131-136
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• 2013

The purpose of this study is to establish the flexural strengthening method of the concrete members. To accomplish this objective, a total of seven concrete beams were tested. From this study, it is found that the initial flexural stiffness and strength of the beams reinforced with NSM CFRP strips were significantly improved compared to the beam without CFRP strip. Failure of the beam reinforced with NSM strips is initiated by failure of NSM strips, eventually sudden explosive compressive failure in the loaded region. This strengthening method combined with NSM CFRP strips and high performance mortar for concrete cover recovery is evaluated by a good strengthening method for the strength, durability and good appearance of concrete structures.

• Proceedings of the KIEE Conference
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• 2008.04b
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• pp.22-24
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• 2008

다도체 송전선로에서 전선 간격 유지 및 진동을 완화시켜주는 역할을 하는 스페이서댐퍼가 손상 받게 되면 즉시 유지보수 및 교체 작업을 하여야 한다. 그러나 이러한 작업은 송전선로 위에서 이루어지므로 전선의 장력과 작업자의 하중으로 인해 유지보수 및 교체작업이 매우 어렵고, 작업시간이 많이 소요되며, 전선표면손상, 스페이서댐퍼의 위치 변동 및 무리한 작업으로 인한 작업안전성 저하 등의 문제점이 있다. 따라서, 상기한 문제점을 해소하고 작업 효율의 상승을 위하여 작업시 각 전선의 간격을 쉽게 벌리고 좁힐 수 있는 작업용 공구인 스페이서지그(Spacer Jig)와 이를 이용한 송전선로의 스페이서댐퍼 유지보수 및 교체공법을 개발하여 교체작업시간 단축 및 작업안전성을 향상시킨 우수한 기술을 개발하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.145-152
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• 2013

As a typical construction material, concrete has been used in building all kinds of structures since the late $19^{th}$ century. Although it was recognized to secure durability as long as the regulations on design and construction have been reasonably complied, the trends of life-shortening and deterioration have frequently occurred due to all kinds of the external effects that have been experienced during the procedures of using the structures. To make matters even worse, deterioration of the concrete structures according to deterioration can not be controlled any more. Finally, the reality is that repair and maintenance are necessary in the maintenance aspect of the concrete structure. In this study, CRM(Chemical Resistance of Laminating Reinforcement Method), which had been developed to reinforce the surface of concrete and specially improve chemical resistance performance, has been applied to enhance the existing repairing and maintenance method. Therefore, the result has been drawn with comparison and analysis of the specimens applied with the general repairing and maintenance method and CRM through a variety of durability test in this study. With the result of the test, durability of the specimen applied with CRM has been more improved than the existing repairing and maintenance method, which is judged as because of the laminating effect due to reinforcement of epoxy impregnated of alkali-resistance fiber and double layered fiber reinforced seat.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.4
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• pp.79-88
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• 2007

Concrete structures undergo degradation of durability performance and it generally propagates to the structural problems. Recently. a lot of materials for surface protection for concrete are developed, however, performance is not clearly improved due to the difficulties such as repair construction technique and quality of materials for repairing. In this study, liquid inorganic impregnant for concrete structures is developed and durability performance for impregnated concrete specimens is carried out. Furthermore, the performances of the concrete specimens with developed impregnant is also compared with those of the specimens with impregnant conventionally used. Additional CSH gel is formed through the reaction of calcium hydroxide ($Ca(OH)_2$) and impregnant with silicate. As a result of the reaction, impregnated concrete is evaluated to have more denser surface and resistance to deterioration. Finally it is experimentally verified that the concrete specimens with developed impregnant show better durability performance than normal specimens and those with conventional impregnant.

• International Journal of Highway Engineering
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• v.12 no.4
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• pp.101-110
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• 2010

In this paper, it has been studied about the CRCO to maintain or rehabilitate the aged JCP. The CRCO and JCO was constructed at useless section of Seo-Hae-Ahn express highway in South Korea. The performance evaluation was conducted. Especially, it was focused on the roll of longitudinal reinforced steels inserted into the CRCO. On crack survey results from field construction section, the reflection cracks at joint of the existing pavement occurred in CRCO. However, due to the constraints of longitudinal reinforced steels, crack width was small. Total crack length and quantity in the CRCO more than that in the JCO. And crack spacing in the CRCO was narrower than it in the CRCP. Through the bonding strength test results, if the cold milling and cleaning as well as surface treatment is applied, there will be no debonding problem at interlayer in the early age. From analysis of the horizontal behavior at the joint, the longitudinal reinforced steels constrained crack width which became wider than initial state over time. Also, that steel in the CRCO reduced the horizontal movement due to temperature variation(4 times than that in the JCO). But, if interface is debonded, the roll decreased. Vertical VWG data showed that CRCO did not occur debonding problem at steel location, but there was some problem in JCO. It was confirmed by field coring. The tensile strain appeared in the CRCO, But the compressive strain occurred in the JCO in early age. Through the FWD test result, deflection in the CRCO was less than that in the JCO. And K value in the CRCO was greater than it in the JCO.