Core Tip: After the hole as the material damage, the slurry is prestressed concrete structures prestressed steel last protective barrier. Plastic corrugated pipe is a new pore-forming material, compared with the metal bellows, it has the following advantages: The material damage as a hole, the slurry is prestressed concrete structures prestressed steel last protective barrier. Plastic corrugated pipe is a new pore-forming material, compared with the metal bellows, it has the following advantages:

Plastic corrugated pipe material is HDPE. Its corrosion resistance is far superior to metal, not afraid of acid, alkali corrosion, which itself does not corrode, can effectively protect the tendons from corrosion. Many prestressed structures suffer severely affected the outside world, such as de-icing salt or brine. When the tension members since the collapse of the waterproof layer, micro-cracks and leaking drainage obstruction or failure, tendons will likely to be a corrosive effect. "FIP Construction Guide (1990)" in the grouting tendons noted that no permanent metal pipe corrosion resistance, enough to resist water leakage and reach the slurry and tendons. The corrugated plastic pipe to provide barrier protection that goes far superior to metal bellows as tendons, to prevent contamination of harmful substances through the pipeline, thus ensuring the post-tensioned structure is better durability;

Under the same conditions, SBG (B) plastic wave tube tunnel reserved for significantly less than the friction coefficient of metal bellows reserved channel coefficient of friction, reducing the tension during the prestressing friction loss. In general, the friction coefficient of plastic corrugated pipe is 0.14 and the friction coefficient of metal bellows is 0.25 (0.2-0.25) for Highway Bridges, variation coefficient of 0.0015.;

High-strength plastic corrugated pipes, are not afraid to step on the pressure, it can not easily be vibrated holding demolition, sealing performance and anti-leakage performance than metal bellows, more suitable for vacuum grouting.