| Project/Area Number |
16560396
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Civil engineering materials/Construction/Construction management
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| Research Institution | Kitami Institute of Technology |
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Principal Investigator |
AYUTA Koichi Kitami Institute of Technology, Faculty of Engineering, Professor, 工学部, 教授 (90003186)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 2005: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2004: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Seawater / Freezing-thawing action / Scaling / Mechanism of frost damage / Cooling rate / Moisture / Micro structure / Cement paste / コンクリート / 凍害機構 |
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| Research Abstract |
The results of this study indicates the following :
It is well known that concrete undergoes significant deterioration when exposed to sea water and frost in cold regions. In order to clarify the effects of freezing and thawing actions on the scaling of concrete exposed to sea water, we performed the following tests.
The specimens were immersed in either seawater or freshwater for 28 days so that the specimens had a water-cement ratio of 50%. The specimens were then subjected to freezing and thawing tests using three different cooling rates (0.25℃/min.,0.5℃/min.,0.75℃/min.) At the conclusion of the tests, the scaling ratio, pore water ratio and frozen water ratio were measured and the specimens examined for micro cracks using scanning electron microscope.
The specimens soaked in seawater developed scaling : the slower the cooling rate, the greater the scaling. The specimens that had been cooled at the slower rate (0.25℃/min.) had higher pore water ratio and frozen water ratio. Close experiment of these specimens revealed seawater in the cement paste. Micro cracks were also found. Therefore, scaling was the result of micro cracking.
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