• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.285-291
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• 1998

During recent years, the durability of concrete structures has been considered in concret practice and material research. To preserve the brittleness of concrete as well as energy absorption and impact resistance, amount of fiber usage has greatly increased in the field of public works. Ultra fine powder, silica fume, mixed into concrete, it reduce void of concrete structure. Especially, there's a great effect for strength improvement of concrete by initial pozzolanic reactions. For these reasons, if silica fume mixed into concrete, it decrease the total void by microfilter effect . Pozzolan reaction, between cement particle and silica powder, can elaborate the micro structure of matrix. And so, in this paper, we deal SFRC for the purpose of efficiently using of industrial by-products(silica fume). Also we performed the test for durability such as freeze-thaw resistance and accelerated carbonation of SFRC using silica fume.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.339-344
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• 1997

During recent years the durability of concrete structures has attracted considerable interest in concrete practice, material research and long-term deformation. To preserve the brittleness of concrete as well as energy absorption and impact resistance, amount of fiber usage has greatly increased year to year in the field of public works. When fly ash, fine powder, mixed into concrete, it condensed the void of concrete structure. Expecially, there's a great effect for strength improvement of concrete by initial pozzolanic reactions. Pozzolan reaction, between cement particle and fly ash, can elaborate the micro structure of matrix. So it was able to improve the effect of fiber reinforced by increased adhesion between cement paste and steel fiber. And so, in this paper, we dealt SFRC for the purpose of efficiently using of industrial by-products and its economical manufacturing. Also we performed the test for durability such as chemical resistance, freeze-thaw resistance and accelerated carbonation of SFRC using fly ash.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.253-256
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• 2004

Recently, construction works of scale are getting larger with economic growth. Shotcreting is one of major processes in tunnels construction. Accelerator is used in tunnel and underground structures to ensure early strength of shotcrete. Silicate based accelerator and aluminate based accelerator is getting widely in the field. But these accelerators have many problems due to decesase of long-term strength and low quality of the hardened shotcrete. in order to solve these problems, recently developed powder types cement mineral accelerator. In this study, we tested chloride permeability, freezing and thawing and accelerated carbonation of shotcrete. As a result of the test, wet-mixed shotcrete with powder types cement mineral accelerator exhibited durability improvement compared to the conventional shotcrete accelerator.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.589-592
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• 2006

The durability of concrete involves resistance to freeze-thaw action, corrosion, permeation, carbonation, chemical attack and so on. Generally, properties of concrete have been well understood under the separate action of these deterioration mechanisms. However, in practice, the degradation of concrete usually is the result of combined action of physical and chemical attack and can be accelerated by the combined action of several deterioration mechanisms. In the present study, to evaluate the combined deterioration by freeze-thaw action and seawater attack, ground granulated blast-furnace slag or silica fume concrete with water or seawater as mixing water was exposed to 300 cycles of freeze-thaw action. Tests were conducted to determined the relative dynamic modulus of elasticity and compressive strength. Furthermore, The MIP analysis were performed on the deteriorated part of concrete due to freeze-thaw action and seawater attack.

• 한국구조물진단유지관리공학회 논문집
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• 제6권1호
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• pp.205-212
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• 2002

The deterioration rate of concrete structures in urban area is accelerated due to rapid urbanization and environmental pollution. Repair materials and methods newly introduced in Korea should be investigated whether they are appropriate for the urban environment in Korea. The creek concrete structures are exposed in severe environmental condition than others. Based on these background in mind, the study is focused on evaluation of performance on repair materials used to rehabilitate creek concrete structures. To evaluate the performance of repair materials, four kinds of repair materials were selected based on polymer emulsion. This experimental study was conducted on fundamental performance such as setting time, compressive strength, bending strength, bonding strength, thermal expansion coefficient, and durability performance such as chloride diffusion, carbonation, chemical attack, and steel corrosion rate. On the basis of this study, the optimal repair material which is proper to the environment condition can be selected and service life of creek concrete structures can be extended. As a result, the life cycle cost can be reduced and the waste of material resources will be cut down.

• 한국구조물진단유지관리공학회 논문집
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• 제19권6호
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• pp.29-36
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• 2015

본 연구에서는 유황을 폴리머화하여 콘크리트 표면보호재로 활용가능성을 검토하기 위하여 내구성능 및 생물독성 평가를 실시하였다. 평가 결과, 콘크리트 표면보호재의 내화학성능은 산, 알칼리 용액에 대하여 화학저항성이 우수한 것으로 나타났다. 배합조건별 촉진내후성 실험 후 부착강도평가 결과 규사분말 및 플라이애시를 동시에 혼합한 배합에서 가장 우수한 강도특성을 나타내었다. 콘크리트용 표면보호재 시험체의 온냉반복 후에도 모든 배합조건에서 부착강도 1 MPa을 상회하였고, SFS배합에서 가장 높은 부착강도를 나타내었다. 표면보호재를 도포한 콘크리트의 촉진탄산화 및 염소이온침투저항성을 검토한 결과, 규사분말을 채움재로 사용한 표면보호재를 도포한 시험체에서 가장 우수한 내구성능을 나타내었다. 유황폴리머를 콘크리트 표면보호재로 사용시 생물독성 검토를 위해 어독성 실험을 수행한 결과, 유황폴리머는 생물에 미치는 영향은 없는 것으로 나타났다. 표면보호재의 내화학성, 동결융해저항성, 탄산화, 염소이온침투저항성 등을 모두 고려하여 볼 때, 본 연구범위에서는 유황폴리머에 채움재로서 규사분말과 플라이애시를 각각 20%씩 대체하는 것이 적절한 수준인 것으로 판단된다.

• 콘크리트학회논문집
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• 제15권1호
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• pp.117-124
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• 2003

최근 강모래의 고갈로 인하여 해사의 사용이 증대되고 있는 실정에 있다. 그러나 해사는 철저하게 제염처리 하여 사용하지 않으면 철근 콘크리트 구조물의 철근에 막대한 영향을 미칠 수 있다. 본 연구에서는 제염처리하지 않은 해사를 시멘트 콘크리트에 직접 사용하여도 철근의 부식을 억제할 수 있는 방청재료를 개발하기 위한 연구의 일환으로서, 기존의 에폭시 철근과 비교하여 경제적이고 방식 성능면에서 우수한 재료로서 폴리머 시멘트 슬러리를 이용하고자 하였다. 각종 폴리머를 사용하고 여러 가지 부식촉진 실험을 통하여 도장하지 않은 철근과 도장한 철근과의 성능을 비교평가하였다. 연구결과, 폴리머 시멘트 슬러리로 도장한 철근은 도장하지 않은 철근에 비해 염화나트륨 수용액에 대한 침지 및 분무시험과 시멘트 콘크리트 속에서의 부식에 관한 실험에 있어서도 매우 우수한 방식성능을 발휘하였다. 다양한 부식촉진 실험결과, 철근의 부식은 염분, 중성화 및 촉진양생에 의해 크게 영향을 받으며, 복합적인 인자가 작용될 때, 더욱더 심한 부식이 발생하였다. 이러한 부식을 폴리머 시멘트 슬러리에 의한 도장으로 억제할 수 있는데, 폴리머 시멘트 슬러리의 매트릭스에 존재하는 폴리머 필림의 연속된 막에 의해 염화물 이온의 침투가 차단되었기 때문이며, 폴리머 시멘트 슬러리의 완벽한 방식효과는 도장두께로 조절할 수 있을 것이다.

• 한국구조물진단유지관리공학회 논문집
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• 제28권5호
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• pp.54-61
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• 2024

이 연구는 OPC와 FA를 사용한 시멘트 페이스트를 대상으로 촉진탄산화 실험을 수행하고, 탄산화 된 페이스트의 성분분석을 통해 pH 예측방법의 상관성을 도출하였다. TG-DTA를 이용하여 열분해로 인한 중량변화 분석과 XRF를 이용한 성분분석을 수행하였으며, 각각의 실혐결과와 pH 측정결과에 대한 비교검토를 수행하였다. 이 연구에서는 CO₂와 CaO의 성분비, 탄산칼슘과 수산화칼슘의 성분비와 pH간의 상관성 분석방법을 제안하였다. XRF로 측정된 CO₂성분과 pH간의 관계를 분석한 결과, 모든 배합의 상관계수가 모두 0.84 이상으로 높은 상관성을 나타냈다. TG-DTA를 통한 탄산칼슘과 수산화칼슘에 대한 pH의 상관분석결과, 탄산칼슘에 대한 상관계수는 모든 배합에서 0.86 이상으로 나타났다. 다만 수산화칼슘과 pH간의 상관계수가 낮게 나타나 두 성분분석결과의 비율을 이용하여 pH와의 상관관계를 분석하였다.

• Architectural research
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• 제7권1호
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• pp.49-54
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• 2005

Conventional studies have focused on the reduction in the water-cement ratio, the use of various admixtures, etc., to ensure the durability of reinforced concrete structures against such deterioration factors as carbonation and chloride attack. However, improvement in the concrete quality alone is not considered sufficient or realistic for meeting the recent demand for a service life of over 100 years. This study intends to improve the durability of reinforced concrete structures by improvement in the reinforcing steel, which has remained untouched due to cost problems, through subtle adjustment of the steel components to keep the cost low. As a fundamental study on the performance of Cr-bearing rebars in steel reinforced concrete structures exposed to corrosive environments, The test specimens were made by installing 8 types of rebars in concretes with a chloride ion content of 0.3, 0.6, 1.2, 2.4 and $24kg/m^3$. Corrosion accelerated curing were then conducted with them. The corrosion resistance of Cr-bearing rebars was examined by measuring crack widths, half-cell potential, corrosion area and weight loss after 155 cycles of corrosion-accelerating curing. The results of the study showed that the corrosion resistance increased as the Cr content increased regardless of the content of chloride ions, and that the Cr-bearing rebars with a Cr content of 5% and 9% showed high corrosion resistance in concretes with a chloride ion content of 1.2 and $2.4kg/m^3$, respectively.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문발표회
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• pp.77-82
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• 2003

The purpose of this study is development of technique to use cementitious powder as recycle cement produced from deteriorated Concrete waste which has a large quantity of calcium carbonate. Therefore, after having theoretical consideration based on the properties of hish-heated concrete and concerning about neutralization of Concrete, we analysis chemical properties of ingredients of cementitious powder After making origin cement paste, then processing the accelerated carbonation, we consider the properties of hydration and chemical properties of cementitious powder under various temperature conditions As a result of the thermal analysis, the CacO3 content of cementitious powder would affect decision of heat temperature to recover its hydrated ability because CacO3 content is increased when neutraliTation is preBlessed. And as a result of XRD analysis. in case of origin powder of non-neutralized paste, CaO peak is found at $700^{\circ}C$. but, heat temperature to generate CaO would increase when the content of neutralized ingredients is increased. Finally, recycle cement heated at $700^{\circ}C$ shows the best compressive strength when the content of neutralized ingredients in recycle cement is less then 50%. However, it would be quite difficult to manage quality of recycle cement according to recycling points of various concrete waste.