• 한국도로학회논문집
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• 제19권2호
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• pp.7-15
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• 2017

PURPOSES : Infiltration of moisture, polluted material, and deicer into concrete, accompanied by freeze and thaw can cause significant deterioration of concrete pavement. In order to protect concrete from deterioration, it is necessary to prevent the infiltration of these concrete external materials. The moisture-repellent agent, which is a surface treatment and maintenance material added to concrete structures to render them water resistant, has advantages such as prevention of water infiltration and security against air permeation. Nano-coat, which is referred to as silicon hydride, is typically used as a moisture-repellent agent. Therefore, in this study, an attempt is made to use penetration-type Nano-coat as an alternative in order to evaluate its applicability through environmental resistance tests. METHODS : This study aimed to evaluate the applicability of penetration-type Nano-coat, which can provide water repellency to concrete, in concrete pavements, through various environmental resistance tests such as freezing and thawing resistance, chloride ion penetration resistance, and surface scaling resistance tests. The applicability of penetration-type Nano-coat was demonstrated based on the specification of KS F 2711, KS F 2456, and ASTM C 672. RESULTS :In the case of penetration-type Nano-coat applied on sound concrete, an increase in concrete durability was demonstrated by the negligible chloride ion penetrability and the absence of scaling, as revealed by visual observation of the surface, after 50 cycles of scaling resistance test. In addition, test result of the application of penetration-type Nano-coat on deteriorated concrete established that concrete surface pretreated by grinding provided improved durability than non-treated concrete. CONCLUSIONS :This study indicates that penetration-type Nano-coat is applicable as an effective alternative, to increase the durability of concrete structures. In addition, it was known that pretreatment of deteriorated concrete surface, such as grinding, is required to improve the long-term performance of concrete pavement.

• International Journal of Concrete Structures and Materials
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• 제6권2호
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• pp.87-100
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• 2012

The process of selecting a repair material is a typical one of multi-criteria decision-making (MCDM) problems. In this study Analytical Hierarch Process was applied to solve this MCDM problem. Many factors affecting a process to select an optimal repair material can be classified into quantitative and qualitative requirements and this study handled only quantitative items. Quantitative requirements in the optimal selection model for repair material were divided into two parts, namely, the required chemical performance and the required physical performance. The former is composed of alkali-resistance, chloride permeability and electrical resistivity. The latter is composed of compressive strength, tensile strength, adhesive strength, drying shrinkage, elasticity and thermal expansion. The result of the study shows that this method is the useful and rational engineering approach in the problem concerning the selection of one out of many candidate repair materials even if this study was limited to repair material only for chloride-deteriorated concrete.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 가을 학술논문 발표대회
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• pp.109-110
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• 2021

An attempt has been made on a constructive approach to evaluate the performance of snail shell ash (SSA) for its corrosion performance under marine environments. Corrosion performance of steel rebar in chloride contaminated SSA with (0% to 50%) replacement levels of cement extract medium was examined through electrochemical and weight loss techniques. Initially, snail shell powder (SSP) is made by pulverizing and subsequently SSA is by thermal decomposition methods. A critical level of 20 % SSA improved both corrosion resistance properties of cement extracts. SSA is a suitable replacement material for natural limestone in cement productions.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.991-996
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• 2001

The long-term durability characteristics of high-early-strength concrete were assessed. The effect of long-term durability characteristics of high-early-strength concrete were investigated. In experiment, two different types of fiber were adopted for improvement of durability. High-early-strength fiber reinforced concretes using regulated-set cements are compared with high-early-strength concrete without fiber. The durability performance of the laboratory-cured high-early-strength concrete specimens was determined by conducting an accelerated chloride permeability, abrasion resistance, freeze-thaw, surface deicer salt scaling and wet-dry repetition test. The results indicated that incorporation of fibers enhance durability performance.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.537-540
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• 2003

The effects of substituting cement with fly ash(10%, 15%, 20%) and different fiber addition(polypropylene, cellulose, poly vinyl alcohol), on the control of microcrack and enhanced durability performance of face slab concrete in CFRD was studied experimentally It was conducted experiments of plastic shrinkage of mortar and concrete, and drying shrinkage of concrete. Also, durability test were carried out the chloride permeability, abrasion resistance and freeze-thaw repetition. Through the experimental results, it was concluded that ploy vinyl alcohol fiber containing concrete was the most effective mixture in control of cracking and durability.

• 한국산학기술학회논문지
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• 제14권9호
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• pp.4542-4551
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• 2013

최근 해양환경에 노출된 콘크리트의 내구성에 관한 연구와 산업부산물을 재활용 하면서 해양생태계를 보호할 수 있는 친환경 콘크리트 재료에 관한 연구가 주목 받고 있다. 본 연구는 해양설치용 콘크리트 제품의 최적배합비를 적용한 4종류의 콘크리트 공시체(Control, Marine, Porous, New slag)에 대하여 해양환경폭로실험을 통한 해수저항성과 가혹한 열화환경 조건을 고려한 동결융해저항성과 염소이온침투 저항성을 통한 콘크리트의 내구성능을 평가하였다. 본 연구에서는 양생조건을 표준(담수), 해양환경을 고려한 간만대, 침지대 그리고 인공해수로 구분하여 양생하였으며, 소정의 양생일(7/28/56)마다 압축강도를 측정하여 평가한 해수저항성은 표준(담수)양생보다 해양환경폭로 양생 조건에서 압축강도비가 낮게 나타났다. 또한, 해양생태계 보호를 위해 친환경 재료($CO_2$ 저감형 시멘트, 슬래그 골재등)를 사용한 New slag는 상대적으로 압축강도가 작아 조강성 및 강도발현을 위한 추가적인 연구가 요구된다. 그리고 동결융해저항성은 모두 우수하였으며, 다공성을 고려한 Porous와 친환경 재료를 사용한 New slag가 상대적으로 낮게 나타났다. 염소이온침투 저항성은 양생조건(표준(담수), 침지대)에 따른 차이는 나타나지 않았으며, Marine보다 New slag가 상대적으로 우수하다는 것을 확인할 수 있었다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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• pp.7-8
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• 2017

Corrosion of reinforced concrete embedded in concrete is a deterioration phenomenon due to intrusion of embodied or Airborne chloride ions. Corrosion of a embedded steel increases the volume of the rebar and causes damage to the structure such as cracking and peeling of the concrete. This causes penetration of various corrosive factors and accelerates the corrosion of reinforcing bars, which has a serious effect on the durability of the structure. Researches on the corrosion phenomenon of these rebars by electrochemical methods have been carried out for a long time, but it is a lack of research in Korea. Therefore, in this study, one of electrochemical experimental methods, Tafel extrapolation method, was used to evaluate the performance of reinforcing bars according to the amount of NaCl and LiNO₂ added to concrete.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 추계 학술논문 발표대회
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• pp.43-46
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• 2009

The purpose of this study is to enhance durability of concrete structures that uses this surface protecting material by carrying out the performance test of the surface protecting material of concrete, and as s result, we reached out the conclusion as follow. 1. As a result of the test measuring the stability and adhesive power of conductive film against ultraviolet, freezing & thawing, and damage from seawater that deteriorate the surface protecting material, it was turned out to meet the performance criteria specifying in the KS standard enough to gain a good evaluation to use as a surface protecting material. 2. As a result of the test identifying the neutralization-furtherance, it was assessed to be capable of protecting effectively concrete structures from carbonic acid gas by a very low depth of 0.1mm of neutralization. 3. As a result of the test identifying Penetrated Resistance Properties of chloride ion, as it was turned out to have a very low value of 819 Coulombs, it was assessed that even in the environment where the corrosion by chloride such sea environment is very affective, the film can effectively protect the concrete structure. 4. As a result of the test identifying freezing & thawing, as there was no change in reduction of mass after 400 cycle, it was assessed that the film has a good resistance against freezing & thawing. According to the results of study above, it is expected that this technology can extend its durability of concrete structure and be widely used for concrete structure through means (methods) to prevent the neutralization and damage from seawater as original purposes of the surface protecting material.

• 한국구조물진단유지관리공학회 논문집
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• 제19권6호
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• pp.80-87
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• 2015

본 연구에서는 칼슘알루미네이트 시멘트(CAC) 모르타르의 수화생성물, 강도, 흡수율, 표면전기 저항성 및 염소이온 침투저항성을 실험적으로 고찰하였다. CAC 모르타르의 성능은 보통포틀랜드 시멘트(OPC) 모르타르의 성능과 상호 비교되었다. 실험 결과에 따르면, CAC 모르타르의 주요 수화생성물은 $C_2AH_8$ 및 $CAH_{10}$으로 조사되었으며, 압축 및 부착강도는 OPC 모르타르에 비하여 우수하게 나타났다. 뿐만 아니라, 표면전기 저항성 및 염소이온 침투저항성도 대체적으로 좋은 결과를 나타냄으로서, CAC의 우수한 성능도 확인하였다. 그러나, CAC 모르타르의 흡수율은 초기재령부터 OPC 모르타르에 비하여 다소 크게 나타남으로써, CAC 경화체의 표면흡수 성능을 개선하기 위한 연구가 더 필요할 것으로 판단된다. 반면, CAC 및 OPC 혼용배합 모르타르의 역학적 성능은 CAC 모르타르에 비하여 대체적으로 다소 떨어지는 것으로 조사됨으로써, CAC계 경화체 제조시 주의가 요구된다.

• 한국군사과학기술학회지
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• 제24권2호
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• pp.197-203
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• 2021

Mechanical structures of military equipment have been mainly applied with black oxide coating due to the limitation of surface treatment thickness. However, the mechanical structures applied by the black oxide coating treatment is constantly being corroded by calcium chloride and humidity. Since this can cause serious problems in the operation of equipment, a review to improve surface treatment and corrosion resistance is required. Therefore, in this study, surface treatment methods that can enhance corrosion resistance were selected and corrosion resistance performance was verified through experiments describing harsh field conditions. Thus, applying a proven surface treatment method to future military equipment will prevent corrosion.