Changsha Evening News, Changsha, April 5 (all media reporter Chen Huanming) In the Xiaoyuan Park, 120 meters long Red Flag canal main canal restoration and reinforcement test section has been completed. The test section uses four different construction methods, the purpose is to find the best "treatment plan" for the restoration and reinforcement of the 8.5km Red Flag Canal main canal. The reporter learned that the ultra-high performance concrete injection method, one of the four test methods, is used by Changsha enterprise Renjian Group after four years of independent research and development of special engineering materials, the material can be widely used in Bridges, tunnels, airport runways and other building bodies and repair construction, filling the domestic technology gap.

The ultra-high performance spray anticorrosive mortar independently developed by Hunan Renjian Group after 4 years has been applied to the repair and reinforcement test section of the main canal of Red Flag Canal. Changsha Evening News reporter Chen Huanming correspondent Fan Dali photo report

Red Flag Canal is one of the two major water systems in Changsha city. It has a history of 40 to 50 years, so it is urgent to repair and strengthen it. The underground depth of the channel is more than 4 meters, if the construction of open excavation method, it will have a great impact on the life and travel of citizens, so the project decided to adopt the trenchless construction.

"With the passage of time, more and more underground culverts, urban Bridges and tunnels need to be repaired and reinforced. We started to conduct technical research in this field as early as 2016, and have invested tens of millions of yuan in R&D funds and gone through thousands of tests." Yang Juan, chairman of Renjian Group, introduced that in view of the special requirements of Bridges, tunnels, airport runways, port terminals, etc., in building repair, the enterprise jointly with Central South University, Changsha University of Science and Technology, etc., independently developed a kind of ultra-high performance spraying anti-corrosion mortar that can be used for structural support spray construction.

"This material is a cement-based anti-corrosion repair material modified by a variety of functional auxiliaries, with good adhesion to the base, waterproof, anti-corrosion, no shrinkage, excellent durability and other characteristics." Fan Dali, deputy general manager of Hunan Renjian Baogu Company, showed a quality inspection report to reporters, which showed that the compressive strength of this new material to 28 days is as high as 110.6 mpa, which is 3 to 5 times the concrete used in general engineering construction.

Workers are spraying construction in the repair and reinforcement test section of the main canal of Red Flag Canal

A few days ago, the reporter saw at the site of the repair and reinforcement test section of the main canal of the Red Flag Canal that a mechanical arm can move freely on the track, and the front spray gun can move with full freedom to spray, and the inner wall of the 4-meter-long main canal can be sprayed in 1 hour. "Under normal circumstances, eight workers can complete the repair and reinforcement of 5 meters of the main canal every day." Fan Dali said that the company has a complete set of core technology system, including concrete materials, on-site construction technology and spray robot arm, and has obtained 5 national invention patents. The new technology has a good application prospect in the main construction of Marine engineering and municipal engineering, as well as the repair and reinforcement of high-speed rail, high-speed, bridge and tunnel.

Renjianbaogu ultra-high performance concrete spraying method has been successfully applied in the repair and reinforcement test section of the main canal of Hongqi Canal

The reporter learned that at present, there are fewer engineering cases for reference and reference for the restoration and reinforcement projects of the same type of underground culverts in China, and there is no mature construction method standards, investment charging standards and technical experience for different construction methods. After the completion of the test section, it will not only provide a solution for the trenchless repair and reinforcement of the main canal of Changsha Hongqi Canal, but also make up for the research gaps at home and abroad, and provide scientific basis and reference for the construction, operation and management of related canals in other Chinese cities and sewage treatment plants.