2018 Fiscal Year Final Research Report
Study on Deterioration of Concrete under Weak Sulfuric Acid Environment
| Project/Area Number |
15K06306
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Building structures/Materials
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| Research Institution | Tokai University |
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Principal Investigator |
ITO Korekiyo 東海大学, 九州教養教育センター, 教授 (50380663)
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| Co-Investigator(Kenkyū-buntansha) |
小山 智幸 九州大学, 人間環境学研究院, 准教授 (50215430)
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| Project Period (FY) |
2015-04-01 – 2019-03-31
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| Keywords | Concrete / Sulfuric Acid / Weak Acid Environment / Fly Ash / Blast Furnace Slag / Durability |
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| Outline of Final Research Achievements |
In this study, influence of factors such as water-cement ratio and fly ash content on deterioration process of concrete under weak sulfuric acid environment was investigated. The main conclusions are as follows.
(1) As a result of XRF analysis, it was confirmed that a concentrated layer of sulfur element was formed around the position of neutralization front inside mortar specimens immersed in sulfuric acid solution of pH 4 to 5. And the results were basically the same as those obtained from concrete specimens embedded in weak acid soil for 14 years.
(2) In mortar specimens containing large quantity of fly ash with constant cement content and having a low water-cement ratio, penetration of sulfate ions into mortar specimens was largely avoided. Therefore, in contrast to strong sulfuric acid environment, densifying the concrete matrix is effective as a protective measure for deterioration of concrete under the weak sulfuric acid environment.
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| Free Research Field |
建築構造・材料
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| Academic Significance and Societal Importance of the Research Achievements |
本研究のように、pH4～5の弱酸性領域を対象とし、硫酸による劣化過程を物質の移動や腐食物質生成の視点から実験室実験と暴露実験によって長期的に検討した研究はあまり見あたらない。また、弱酸性の硫酸劣化においては、緻密な硬化体ほど劣化の抑制効果が大きいことを明らかにし、石炭火力発電所から発生する産業副産物であるフライアッシュを所定のセメント量を確保した上で大量混合することは有効であることを示した。よって、本研究の成果は弱酸性環境下におけるコンクリート構造物の硫酸劣化の対策方法や耐久設計法の確立だけでなく、資源の有効利用によるセメント・コンクリート分野の環境負荷低減にも大きく貢献するものと考えられる。
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