Prestressed Plastic Corrugated Flat Pipe

Pre stressed plastic corrugated pipe is made of HDPE as the raw material and is mainly used for post tensioned cement structures and hole forming of tension rods. It has the advantages of good sealing, no water leakage or grout leakage, high ring stiffness, low friction parameters, aging resistance, electrical erosion resistance, good flexibility, and is not easily broken by tamping rods. It is also used in new connection methods to make construction connections more convenient. It is mainly used in large-span tensioning engineering construction such as highways, railways, bridges, slopes, and high-rise buildings.
Chinese name: Prestressed plastic corrugated pipe
Advantages: Corrosion resistance
Function: Anti electric erosion, good flexibility and elasticity
Raw material: HDPE

Foreign Name: Pre stressed Plastic Corrugated Pipe

Performance indicators of prestressed plastic corrugated pipe

1. The prestressing perforation system composed of prestressed plastic corrugated pipes and fittings should meet the requirements of post tensioning grouting; In addition to hot welding connections, specialized sealing connection devices can also be provided between pipes; The entire pore forming system is equipped with exhaust, drainage, and grout discharge pipes, which can meet the needs of pressure grouting or vacuum assisted grouting.
2. The prestressed plastic corrugated pipe meets the material properties specified in CJ/T3078.
3. Pre stressed plastic corrugated pipes are generally black in color, and defects such as melt rupture, hard lumps, and severe bubbles are not allowed on the inner and outer walls. In order to achieve a lower friction coefficient and ring stiffness, pre-stressed plastic corrugated pipes should be pipes with spaced circular waveforms.
4. The prestressed plastic corrugated pipe is equipped with a sealing device that can be reliably connected to the prestressed anchor.
5. The inner cross-sectional area of prestressed plastic corrugated pipes should be at least 2.5 to 3 times that of prestressed tendons.
6. The friction coefficient u of prestressed plastic corrugated pipe is 0.10~0.14, and k is taken as 0.0008~0.0015.
7. Pre stressed plastic corrugated pipes have sufficient flexibility and wear resistance to facilitate curved layout and prevent the rupture of tensioning holes. It is recommended that the spacing between the positioning steel bars should not exceed 0.8 meters, and the minimum bending radius should be between 0.9 and 1.5 meters.

Characteristics of prestressed plastic corrugated pipe

1. The prestressed plastic corrugated pipe is made of high-density polyethylene as the main raw material, which is corrosion-resistant, aging resistant, rust free, has good sealing performance, and no water or slurry leakage, which is conducive to protecting the steel strand.
2. Non conductive, can prevent stray current corrosion, and improve the feasibility of electronic monitoring of prestressed steel bars.
3. Good sealing and anti-seepage performance, more suitable for vacuum grouting.
4. High strength, high rigidity, good flexibility, not afraid of stepping and pressure, not easily broken by vibrating rods;
5. Reduce the friction loss of prestress during the tensioning process, with a friction coefficient of only 0.10~0.14.
6. Pre stressed plastic corrugated pipes have better fatigue resistance and can greatly improve the fatigue resistance of components.
7. High flexibility, easy connection, and can greatly improve construction efficiency.

Specification of prestressed plastic corrugated pipe

There are two types of prestressed plastic corrugated pipes: round pipes and flat pipes, each with multiple specifications to meet the matching requirements of different specifications and forms of prestressed steel bars such as steel bars, steel strands, and steel wires.
Prestressed plastic corrugated pipe
Mainly used for post tensioned prestressed concrete structures and component perforation. The ZY plastic produced by our company is made of high-density polyethylene (HDPE) or polypropylene (PP) as raw materials using advanced production technology. It has the advantages of good sealing, no water leakage or slurry leakage, high ring stiffness, low friction coefficient, aging resistance, electrical corrosion resistance, good flexibility, and is not easily chiseled by a tamper. The new connection method makes the construction connection more convenient, solving all the disadvantages of traditional metal corrugated pipes
Common names for prestressed plastic corrugated pipes: bridge prestressed corrugated pipe, prestressed plastic spiral pipe, concrete corrugated pipe, prestressed cast-in-place plastic corrugated pipe, bridge plastic corrugated pipe, steel strand corrugated pipe
As an important component of the prestressing system, corrugated pipes have been used as pore forming materials in prestressed engineering for a long time. In order to overcome the disadvantages of poor sealing, easy damage, corrosion, and high friction of metal corrugated pipes, and to provide an additional anti-corrosion barrier for prestressed reinforcement, it is recommended to use plastic corrugated pipes made of polyethylene or polypropylene as a revolutionary product of bonded post tensioning method to provide the service life of the structure.

technical requirement

Complies with the transportation industry standard JT/T529--2004
The raw material for plastic corrugated pipes should be the original granular material. It is strictly prohibited to use powdered and reconstituted granular raw materials. High density polyethylene (HDPE) should meet the requirements of GB/T11116, and polypropylene (PP) should meet the requirements of GB/T18742.1.
The appearance of plastic corrugated pipes should be smooth, with uniform color, and there should be no separator rupture, bubbles, cracks, hard blocks, or scratches that affect their use on the inner and outer walls.
The stiffness of the plastic corrugated pipe ring shall not be less than 6kN/m2
When plastic corrugated pipes are subjected to lateral local loads, the surface of the pipe should not rupture; After unloading for 5 minutes, the residual deformation of the pipe shall not exceed 10% of the outer diameter of the pipe.
After the plastic corrugated pipe is repeatedly bent five times according to the prescribed bending method, if the special plug gauge can pass smoothly through the plastic corrugated pipe, the flexibility of the plastic corrugated pipe is qualified.
The maximum allowable vacuum impact rate (TIR) for the low-temperature drop hammer impact test of plastic corrugated pipes is 10%.

Connection of plastic corrugated pipe

The extension of plastic corrugated pipes can be welded using a plastic welding machine or mechanically connected. Mechanical connections are made in the form of joints, including three types: connecting pipes for pipe to pipe connections, connecting heads for pipe to anchor pad connections, and exhaust pipe connecting heads for pipe to exhaust pipe connections.
Pre stressed plastic corrugated pipes have good flexibility, high ring stiffness, are not afraid of stepping and pressure, and are not easily broken by pounding rods.
Prestressed plastic corrugated pipe is a single wall corrugated pipe extruded from high-density polyethylene (HDPE) through a plastic extruder, used for post tensioned prestressed concrete structures as a perforated pipe for prestressed reinforcement. The appearance quality, structural dimensions, ring stiffness, local lateral load, flexibility and other technical indicators of the prestressed plastic corrugated pipe products produced by our company meet the technical requirements of the industry standard "Plastic Corrugated Pipes for Prestressed Concrete Bridges" JT/T529-2004 and GB/T9647-2003 * * standards of the Ministry of Transport.

Prestressed plastic corrugated pipe is a new type of perforated material, which has the following advantages compared to prestressed metal corrugated pipe:

1. The prestressed plastic corrugated pipe is produced using advanced production technology with high-density polyethylene (HDPE) as the raw material. Its corrosion resistance is far superior to that of metals, and it is not afraid of acid or alkali corrosion. It does not corrode itself and can effectively protect prestressed tendons from corrosion. Many prestressed structures are subjected to severe external influences, such as de icing salt or saltwater. Prestressed plastic corrugated pipes can provide a much better barrier protection for prestressed tendons than metal corrugated pipes, preventing harmful substances from penetrating the pipeline and contaminating it, thereby ensuring better durability of post tensioned prestressed structures.
Under the same conditions, the friction coefficient of the pre stressing plastic corrugated pipe reserved hole is significantly lower than that of the metal corrugated pipe reserved hole, reducing the friction loss of pre stressing during the tensioning process. The friction coefficient of a typical prestressed plastic corrugated pipe is 0.14, while the friction coefficient of a metal corrugated pipe is 0.25; Pre stressed plastic corrugated pipes have high strength, are not afraid of stepping and pressure, and are not easily chiseled by vibrating rods. Their sealing and anti-seepage properties are higher than those of metal corrugated pipes, making them more suitable for vacuum grouting;
3. Pre stressed plastic corrugated pipes have good flexibility, high ring stiffness, are not afraid of stepping and pressure, and are not easily chiseled by tamping rods.
4. Pre stressed plastic corrugated pipes are non-conductive and can prevent stray current corrosion, while metals are good conductors of electricity;
5. Prestressed plastic corrugated pipes have better fatigue resistance and can greatly improve the fatigue resistance of components.

Use of plastic corrugated pipe products

Compared with traditional metal corrugated pipes, plastic corrugated pipes need to be equipped with various specialized joints for connecting with clamp group anchor pads, connecting pipes for connecting between corrugated pipes, and drainage pipes that can bleed the cement slurry pressed into the corrugated pipes after being connected to the corrugated pipes. During use, vacuum grouting is a new technology in the construction of post tensioned prestressed concrete structures. Its basic principle is to use a vacuum pump to evacuate one end of the duct, creating a vacuum degree of about -0.1MPa. Then, the optimized special cement slurry is injected from the other end of the duct using a grouting pump until the entire duct is filled, and a positive pressure of ≤ 0.7MPa is applied to improve the fullness and compactness of the prestressed duct grouting.
The use of vacuum grouting technology is an effective measure to improve the safety and durability of post tensioned prestressed concrete structures. The new process of using plastic corrugated pipes and vacuum assisted grouting for prestressed steel bundles connected by plastic corrugated pipes can solve the problems of increasingly long prestressed duct forming, insufficient prestressed tension extension, and difficulty in filling the duct grouting. For ultra long bundles, if traditional metal corrugated pipes are used as pore forming pipeline materials, there are many drawbacks such as high friction resistance of pore forming materials, difficulty in construction of pore forming materials, easy leakage of grout during construction, and insufficient compaction of grout, which can easily cause the tension extension to be difficult to meet the requirements. Vacuum assisted grouting uses a vacuum pump to first remove the air in the borehole, so that the borehole reaches a negative pressure state, and then uses a grouting machine to inject cement grout into the prestressed borehole with positive pressure, thereby eliminating bubbles in the borehole and improving the fullness of the grout in the borehole.

What is the friction coefficient of prestressed plastic corrugated pipe?

Under the same conditions, the friction coefficient of the pre stressing plastic corrugated pipe reserved channel is significantly lower than that of the metal corrugated pipe reserved channel, reducing the friction loss of pre stressing during the tensioning process. The friction coefficient of a typical prestressed plastic corrugated pipe is 0.14, while the friction coefficient of a metal corrugated pipe is 0.25; Pre stressed plastic corrugated pipes have high strength, are not afraid of stepping and pressure, and are not easily chiseled by vibrating rods. Their sealing and anti-seepage properties are higher than those of metal corrugated pipes, making them more suitable for vacuum grouting;

What is the appearance of plastic corrugated pipes?

The appearance of plastic corrugated pipes should be smooth, with uniform color, and there should be no separator rupture, bubbles, cracks, hard blocks, or scratches that affect their use on the inner and outer walls. When plastic corrugated pipes are subjected to lateral local loads, the surface of the pipe should not rupture; After unloading for 5 minutes, the residual deformation of the pipe shall not exceed 10% of the outer diameter of the pipe.