2018 Fiscal Year Annual Research 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 / corrosion / chloride penetration / hydration degree / crack / durability |
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| Outline of Annual Research Achievements |
In FY2018, we continued the experimental study of corrosion for hydrophobic mortar, using different immersion-drying cycles in salt water. In addition, to improve the accuracy, passive layers of steel bars were removed before the cycles. The result revealed that the steel bars in the hydrophobic mortar showed almost no corrosion, whereas the bars in normal mortars showed obvious corrosion at surface.
In addition, more detailed study on the strength and hydration degree of the mortar was carried out. Strength was found to decrease as the order of the hydrophobic agent addition ratio 0%, 1%, 3%, and 5%. However, hydration degree obtained from XRD/Rietveld and TG-DTA showed that the hydrophobic agent did not affect the hydration of cement significantly.
According to the whole study in the past three years, it was confirmed that the hydrophobic mortar had a good water tightness and chloride resistance, even if cracks occurred. As a result, corrosion resistance of mortar was significantly improved for protecting steel bars embedded inside from corroding. Therefore, the mortar is promising to be used in practice for improving durability. On the other hand, strength was found to decrease as the addition ratio of the hydrophobic agent increased. It was mainly resulted from the coarsened pore structure instead of the postponed hydration process.
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