2022 Fiscal Year Final Research Report

Development of Vibro-Radar with Electromagnetic Pulse for Deterioration Diagnosis Application of Rebar Vibration Spectroscopy

Research Project

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Project/Area Number	20H02395
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Review Section	Basic Section 25020:Safety engineering-related
Research Institution	Gunma University
Principal Investigator	Takashi Miwa 群馬大学, 大学院理工学府, 教授 (30313414)
Co-Investigator(Kenkyū-buntansha)	鎌田敏郎大阪大学, 大学院工学研究科, 教授 (10224651) 小澤満津雄群馬大学, 大学院理工学府, 教授 (80313906)
Project Period (FY)	2020-04-01 – 2023-03-31
Keywords	非破壊検査 / 電磁パルス / 加振 / コンクリート構造物 / 電磁波レーダ / 鉄筋腐食 / 振動計測
Outline of Final Research Achievements	In this study, an Quadrature Doppler radar displacement measurement system was developed to measure the broadband vibration response of steel inside concrete vibrated by electromagnetic pulses, enabling nondestructive measurement of steel vibration at a depth of approximately 8 cm. As examples of applications to deteriorated concrete, we were able to measure the first-order deflection vibration of the steel material, which is specific to the unfilled case, in the evaluation of grouting of PC sheathing. Furthermore, as a result of the application to the evaluation of rebar corrosion, a pulse-shaped vibration peak was observed in the corroded area by scanning the vibration response just above the rebar, suggesting that the peak value is proportional to the amount of black rust. This research is the first attempt in the world and is considered to be an extremely significant achievement toward the development of a nondestructive quantitative evaluation method for rebar corrosion.
Free Research Field	計測工学
Academic Significance and Societal Importance of the Research Achievements	RC構造物の劣化の主要因はコンクリート自体よりも鉄筋付着力の低下、PC鋼材のグラウト充填不足、鉄筋腐食など、鋼材の劣化に起因するものが多い。これまで、コンクリート構造物内の鋼材自身の機械的な応答は弾性波応答として間接的に計測するのみであったが、本手法の発展により直接これらを計測できれば極めて広範囲の劣化評価に応用できる。特に鉄筋腐食評価においては、腐食量の定量評価が最大の課題となっており、本手法が磁性を有する黒錆が電磁パルスに反応して変形する応答を捉えていると考えており、振動応答のピーク値が黒錆量に比例することが示唆できたことは特筆すべき成果である。