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| With the Swiss prestressed anchor corrosion treatment |
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UpdateTime：[2012/8/17 15:39:28] Hits：[2575] From：TONRY MINING SAFETY SUPPORT TECHNOLOGY CO.,LTD
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With the Swiss prestressed anchor corrosion treatment
Prestressed anchor corrosion mechanism and corrosion solution undertook comprehensive research, but as a result of prestressed anchor under condition of high stress corrosion is more complex, is not mature approach, they usually use the method is based on the formation condition of adopting double-layer maintenance, such as free barrier layer, selection of casing maintenance, anchor root waterproof barrier, mortar pump cement slurry perfusion, electromagnetic flowmeter power protection. But often choose to use or perfusion has certain thickness of cement mortar and the tendon is wrapped outside the PVC plastic pipe, tube and the tendons between filled with preservative oil.
In our country started using prestressed anchor, attached great importance to deal with anti-corrosion. In 1965 Meishan dam using 3200kN prestressed anchor rod construction process, will combine the project construction undertook a lot of discussion and experimental tasks, and rust problems put forward special report. Not only in the construction line experiment is carried out, and during the sealing operation 8 years later, also on the anchor hole anchorage on-site analysis: cement stone soaking solution pH #118alue of 12.5, clearing rate was 13.5%, buried in the dam foundation of wire shiny appearance very well ( maintenance layer thickness 20mm). According to that, when the cement stones with a pH #118alue greater than 12, vacancy rate of less than 14%. Only 20 25mm thick layer of protection, which has satisfactory corrosion resistance ability.
For a long time observation and analysis of Meishan dam, located 7 prestressed anchor observation hole. Bolt all passes 924 insulating glue immersion, bundle and then 2 - 3 layers of asphalt sacks wrapped, forming a complete magnetic separator rust preventive maintenance layer. But the movement 6, after 8 years, there have been 3 holes in the steel rolling machine wire cracking. Anhui Province Hydropower depicting Institute, Meishan hydropower station through in-depth discussion after that, each wire fracture crack with stress corrosion ( both hydrogen embrittlement ) characteristics, due to the surrounding medium ( such as orifice ponding and 924 plastic insulation ) containing harmful substances formed by sulfide. These experimental results of enlightenment, selection of additives, preservatives and other chemical substances, should pay special attention to steel wire products can contain harmful substances.
Cement mortar or grout is a better protective data, has been engineering experience, but should pay attention to guarantee the grouting quality, not only should ensure grouting fullness, should also pay attention to useful maintenance layer thickness satisfaction should also pay attention to describe, using materials and additives and various additive material chemical composition, the content of chloride ions should be less than 0.02%.
Double safeguard of unbonded prestressed anchor, has started in China in the anchorage project application. This type of prestressed anchor data, China has also started mass production. Its main characteristic is in the wire or strand surface spraying anti-corrosion materials, the outer layer added with plastic casing, steel wire or strand anticorrosive oil filling. In order to more effectively protection, in addition to observation anchor and covered the tensioning prestressed anchor, in double maintenance of the prestressed anchor with the hole wall also use cement slurry perfusion, to prevent the plastic casing aging failure or breakage and formation in the construction process of prestressed anchor of rust and corrosion.
The above content by prestressed anchor http://www.kuangshanzhihu.com |
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