2017 Fiscal Year Research-status Report
A study on water tightness and chloride penetration of hydrophobic concrete
| Project/Area Number |
16K18130
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| Research Institution | Saitama University |
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Principal Investigator |
欒 堯 埼玉大学, 理工学研究科, 助教 (20725288)
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Keywords | bulk hydrophobicity / crack / chloride penetration / corrosion / hydration degree / pore structure / strength |
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| Outline of Annual Research Achievements |
In FY2017, we carried out chloride penetration and corrosion experiments of the hydrophobic mortar under cracked condition. It was found that, compared to normal mortar, the chloride penetrating into the hydrophobic mortar was much less than that into normal mortar. Steel bars embedded into the hydrophobic mortar also had less corrosion than that into normal mortar.
In addition, we tested hydration degree and pore structure of hardened cement paste with different ratios of hydrophobic agent. Similar with the result of mortar performed in FY2016, the hydrophobic agent showed little impact on the hydration degree. On the other hand, when 3% agent was added, the pore structure became slightly denser, whereas 5% agent caused a much coarser structure than that of normal cement paste.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
As written in the research plan, chloride penetration and steel corrosion in cracked specimen should be investigated experimentally. In the work of FY2017, such studies for mortar specimens were carried out. A good resistance to chloride penetration and corrosion for the hydrophobic mortar was found. This provides a good base for the research of FY2018. In addition, hydration degree and pore structure of hardened cement paste have a very close relation to strength. Those properties were also investigated through experiment.
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| Strategy for Future Research Activity |
In FY2018, some work will continue to focus on chloride penetration and corrosion, under more environmental conditions such as different cycles of wetting and drying, and different chloride concentrations. Furthermore, micro-structure of hydrophobic mortar will be observed by microscopy to see the change of morphology caused by hydrophobic agent. In addition, numerical analysis of water transport, chloride penetration and corrosion will be conducted and compared with the experiment.
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| Causes of Carryover |
In FY2017, some more electrodes were planned to be purchased for potentiometric titration test of chloride ion. Eventually, it was found that the existing electrodes in our laboratory were sufficient for performing the current experiment. Therefore, the purchase was not carried out.
In FY2018, more corrosion test will be carried out for different environmental conditions. The test will investigate not only the final corrosion amount of steel bar in hydrophobic mortar but also the corrosion process. Therefore, non-destructive device is needed. A portable corrosion meter will be purchased.
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