On Sept. 23, 2022, NHRI organized a comprehensive performance evaluation meeting online and onsite in Nanjing for the project of Research, Development and Industrialization Demonstration of Complete Set of Rapid Repair Technologies for Underwater Concrete Defects, a key special project of Science and Technology Powering Economy 2020 under the national key R&D program. An expert panel composed of technical and financial experts from Hohai University, Southeast University, Port and Shipping Development Center of Jiangsu Provincial Department of Transportation, CCCC Second Harbor Engineering Company ltd., and China Design Group was established for the meeting. The meeting, chaired by GUAN Tiesheng, Director of NHRI Research Management Department, saw more than 30 attendees, including project leaders, technical backbones, and relevant NHRI management staff.
The project team made reports on the project overview, overall implementation, major achievements, industrialization and engineering demonstration, and fund expenditure. The panel carefully reviewed relevant documents and considered, after inquiries and discussions, that the scheduled tasks and performance indicators had been comprehensively achieved, with standard management organization and reasonable fund use. It was unanimously agreed that the project passed the comprehensive performance evaluation.
Focusing on the major strategic needs of the quality and safe operation of underwater engineering in China, and the difficulties of rapid repair of underwater concrete structure defects, the project is led by Nanjing R&D Hi-Tech Co., Ltd. with joint efforts of NHRI Materials and Structural Engineering and Anhui Port and Shipping Construction Investment Group Co. Ltd. A complete set of technologies including underwater defect assessment, key material preparation, construction technology research and development, and repair effect evaluation has been formed, and a series of innovative results achieved as following. 1) The non-destructive diagnosis technology of underwater concrete defects based on a side-scan sonar system and mounted on unmanned ships has been developed, and the image interpretation and quantitative evaluation methods of defects proposed to improve the detection efficiency and recognition accuracy of underwater concrete defects. 2) Underwater fast-hardening non-dispersible cement-based materials, underwater crack grouting materials, underwater elastic rapid plugging phase change materials, and cement-based elastic mortar grouting materials and their construction technologies have been developed to realize the rapid repair of underwater concrete structure defects. 3) A simulation device for underwater repair material performance evaluation based on flow velocity, water pressure and water temperature control has been invented. 4) An enterprise standard of underwater non-dispersive concrete repair materials has been compiled. The results have been successfully applied in the canal lining defect treatment of the Jiaozuo Section of the middle route of the South-to-North Water Diversion Project in Henan Province, the foundation pit seepage interception and reinforcement of the Genglou double-line ship lock project of the Shaying River waterway, and the underwater repair of cast-in-place concrete piles of navigation marks in the Hongze Lake area, with remarkable with remarkable social and economic benefits, and broad application prospects.
