Measurement of combined deterioration resistance of concrete with a compact neutron source

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K04227
• 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: Institute of Physical and Chemical Research
• Principal Investigator: Mizuta Maki 国立研究開発法人理化学研究所, 光量子工学研究センター, 研究員 (00411257)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: コンクリート / 中性子 / 中性子イメージング / 透過画像 / コンパクト中性子源 / 複合劣化 / 水分浸透 / 円柱サンプル

Outline of Final Research Achievements

The aim of this research is to develop nondestructive test method which can visualize water movement in concrete. Neutron imaging is chosen to attain this goal and is conducted at the RIKEN Accelerator-driven compact Neutron Source, RANS.(1)This study was a first trial of neutron imaging for reinforced concrete samples which were extracted from existing RC bridge decks. The RC decks were deteriorated by combined factors and were overlayed by steel fiber reinforced concrete. Water movement in concrete with steel bars and/or fibers was successfully obtained. As a result, existing concrete could be deteriorated more widely and severely than expected by visual observation.(2)Neutron imaging demonstrated that the water penetration rate coefficient could be obtained with a single circular sample. Furthermore, when the sample was a cylinder, it was clarified that the influence of the sample shape on the transmitted images obtained through neutron imaging.

Free Research Field

コンクリート工学

Academic Significance and Societal Importance of the Research Achievements

コンクリート標準示方書【維持管理編】が改訂され、「水の作用」が構造物の全ての劣化に関わる作用として捉えられ、中性化については「水の浸透」を伴う鋼材腐食による劣化進行と性能低下の特徴を考慮した維持管理が示され、劣化機構の一つに「複合劣化」が含められた。構造物の維持管理において、水の影響が強く認識されるようになり、本研究が果たす役割は大きい。
今後、コンクリート構造物の維持管理指標の非破壊計測技術として本研究を発展させる。特殊な技術では、定期的に実施される検査・点検・診断に利用されることは難しいため、理研小型中性子源システムRANSのようなコンパクト中性子源の利用価値の向上にも貢献する。