Corrosion factors of underground steel considering reaction/transportation of substances and proposal of countermeasure for the corrosion protection

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K04657
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 22010:Civil engineering material, execution and construction management-related
• Research Institution: Shizuoka Institute of Science and Technology (2022); National Institute of Maritime, Port and Aviation Technology (2020-2021)
• Principal Investigator: Nishida Takahiro 静岡理工科大学, 理工学部, 教授 (10345358)
• Co-Investigator(Kenkyū-buntansha): 河合 慶有 愛媛大学, 理工学研究科(工学系), 准教授 (90725631)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 鋼材腐食 / 土中 / 抑制方法 / アノード / カソード / 酸素低減

Outline of Final Research Achievements

In this study, electrochemical parameters such as polarisation resistance and natural potential of steel buried in soil were measured through exposure tests. As a result, it was confirmed that the corrosion rate increased once in the early stage of exposure and then decreased. However, in the case of sand, no significant increase in corrosion rate was observed when the steel was installed at the bottom. These results suggest that the corrosion of steel in soil is strongly influenced by oxygen and that corrosion can be reduced by reducing oxygen. In particular, steel in clay tends to develop macrocell corrosion due to changes in oxygen permeability, and this study investigated techniques to prevent localised corrosion of underground steel and found the use of oxygen reducing agents to be effective.

Free Research Field

社会インフラ材料学

Academic Significance and Societal Importance of the Research Achievements

本研究では，種々のパラメータを勘案し，カソード反応がアノード反応に及ぼす影響を考慮し，酸素や水の土中での移動速度を関連付けて評価した．また，コンクリート中鋼材を対象として，内部の酸素低減による鉄筋腐食の抑制について検討を進めており，工業副産物や微生物に基づいた技術の特許申請をしている．本研究ではこれらの知見を応用し，酸素低減可能な材料を散布することにより土中の酸素量を低減することを試みた．このような検討はこれまで見当たらず，この点が本研究の独創性である．