Recently, the spray UHPC construction technology jointly developed by CCCC Second Navigation Engineering Bureau and Ocean University of China was successfully applied in the wet joint protection construction of bridge piers in the Hangzhou Bay Cross-sea Bridge Concrete Performance Maintenance and Improvement (2023-2024) project. This application was jointly implemented by CCCC Second Navigation Engineering Bureau Technology Center and Building Technology Branch. The use of spray UHPC technology for wet joint protection of bridge piers is the first in the world. The successful implementation of this project has provided new quality productivity for the development of marine structure reinforcement and protection technology.
UHPC spraying applied to wet joints of bridge piers in Hangzhou Bay
The Hangzhou Bay Cross-sea Bridge is located in the Hangzhou Bay, one of the three largest tidal bays in the world. The area has strong winds and waves, high tidal range, rapid currents, and harsh environment. After 15 years of service, the wet joints of bridge piers have developed typical diseases such as cracks and defects. This application aims to repair the existing structure while improving the overall durability. In view of the short window period, strict material performance requirements and difficult construction organization of this project, the project team has upgraded the original technology again and creatively developed a complete set of UHPC spraying construction technology with ultra-long collapse protection, ultra-long-distance pumping, ultra-fast hardening, ultra-high strength and ultra-high impermeability. The collapse protection time of UHPC spraying exceeds 4h, the pumping distance exceeds 50m, the setting time is less than 10min, the 1d compressive strength is greater than 80MPa, and the impermeability grade is above P40.
Picture of the wet joint of the pier after the UHPC spraying protection construction
The development of the complete set of UHPC spraying technology took 4 years, during which it was supported by the "14th Five-Year Plan" Shandong Provincial Key R&D Plan and the CCCC Applied Basic Research Project, forming a series of materials-equipment-construction products and services such as special rheology regulators, setting regulators, premixes, wet spraying machines and spraying construction for UHPC spraying, which have broad application prospects in the fields of existing structure repair and reinforcement, tunnel support, marine structure protection and life extension, structural waterproofing and anti-corrosion.
This project is a typical representative of the Second Civil Aviation Administration's front-end and back-end collaborative innovation and complementary development model. It fully demonstrates the Second Civil Aviation Administration's corporate spirit of "striving for technological leadership and creating first-class management", and facilitates a virtuous cycle of technological innovation in the technology center and industrial innovation in branches and subsidiaries. It is of great significance to promote the construction of the Second Civil Aviation Administration's new quality productivity industrial ecology.
