• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
• /
• pp.479-482
• /
• 2005

The galvanic currents between carbon steel and Cr-bearing rebars have been studied in concrete subjected to carbonation and chloride attack. The results revealed that in case of SD345 contacted with Cr-bearing rebar in concrete under chloride attack environment and carbonation environment, the corrosion acceleration by galvanic corrosion is not generated. Therefore, Cr-bearing rebar can be used together with the carbon steel in the new establishment structure.

• International Journal of Concrete Structures and Materials
• /
• 제18권1E호
• /
• pp.17-22
• /
• 2006

Artificial cracks were made in the cover concrete of specimens embedding ten types of steel rebars of different Cr contents. The research aims for developing Cr-bearing steel rebars resistant to macrocell corrosion environments induced by cracking in cover concrete. The cracks were subjected to intensive penetration of carbon dioxide (carbonation specimens) to form macrocells. The carbonation specimens were then treated with accelerated corrosion curing, during which current macrocell corrosion density was measured. The corrosion area and loss from corrosion were also measured at the end of 105 cycles of this accelerated curing. The results of the study showed that Cr-bearing steel with Cr content of 5% or more suppressed corrosion in a macrocell corrosion environment induced by the differences in the pH values due to carbonation of cracked parts. Cr-bearing steels with Cr content of 7% or more are proven to possess excellent corrosion resistance.

• 한국구조물진단유지관리공학회 논문집
• /
• 제10권4호
• /
• pp.79-86
• /
• 2006

피복 콘크리트의 균열 발생에 기인한 매크로셀 부식 환경하에서의 Cr강방식철근의 방식성을 평가하기 위하여 10종류의 Cr강방식철근을 콘크리트에 매입 후 피복 콘크리트에 모사 균열을 발생시킨 공시체를 제작하였다. 그 후 염수 분무 촉진 양생 105사이클까지의 매크로셀 부식전류밀도의 경시변화와 아노드 캐소드 철근의 자연전위, 부식면적률, 부식감량률을 측정함으로써 Cr강방식철근의 방식성에 대하여 검토하였다. 그 결과, 염화물 이온 농도차 $3kg/m^3$ 이하의 매크로셀 부식 환경에 대하여 Cr함유율 9% 이상의 Cr강재에서 방식성이 확인되었으며 특히, Cr함유율 11% 이상의 Cr강재에서 뛰어난 방식성이 입증되었다.

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

• 한국구조물진단유지관리공학회 논문집
• /
• 제10권3호
• /
• pp.115-122
• /
• 2006

중성화와 염해의 복합 열화 환경하의 콘크리트 내에서의 Cr강방식철근의 방식성을 평가하기 위하여 Cr함유율이 다른 10종류의 철근을 피복 두께 20mm 위치에 매입한 염화물 이온 함유량 0.3, 0.6, 1.2, $2.4kg/{m^3}$의 콘크리트 공시체를 제작하였다. 그 후 촉진 중성화 시험 및 고저온 건습 반복의 부식 촉진 시험 기간 중의 Cr강방식철근의 자연전위, 부식면적률, 부식감량률의 경시변화를 측정함으로써 각 부식 환경에 대한 Cr강방식철근의 방식성에 대하여 검토하였다. 그 결과, 중성화와 염해의 복합 열화 환경의 경우, 염화물 이온 함유량 $1.2kg/m^3$과 $2.4kg/m^3$에 대하여 각각 Cr함유율 7% 이상과 9% 이상의 Cr강방식철근에서 방식성이 확인되었다.