Post tensioning is a technique that involves introducing permanent prestressing force into a concrete structure after it has hardened. The Huayongxin Post Tensioning System utilizes high-strength prestressing tendons, positioned correctly and stressed with the aid of a Stressing Jack, to introduce constructive stress into the concrete structure. This process enhances overall productivity and the efficient utilization of construction materials. Huayongxin's Post Tensioning works encompass a wide range of engineering applications, including bridge construction, buildings, and civil projects, both above and underground.

To appreciate the benefits of post tensioning, it is crucial to understand the behavior of concrete. Concrete possesses high compressive strength but is weak in tension. When a load is applied to a conventional concrete beam, it tends to deflect under the weight of the load. This deflection causes the concrete farthest from the load to stretch and elongate, leading to cracks. To counteract this issue, rebar cages are often embedded as passive reinforcement. These rebars do not carry any load until the concrete deflects and cracks, at which point they begin to bear the load and counteract the force of the crack.

In contrast, post tensioning utilizes active reinforcement through prestressed tendons. The prestressed force in the tendons enables the beam to withstand and carry the load. When properly designed and installed, post tensioned beams exhibit minimal deflection and almost no cracking, even under full load conditions.

In modern post tensioning practices, low relaxation 7-wire high tensile steel PC strand is commonly used as prestressing tendons. By utilizing these high tensile steel strands, the need for non-prestressed reinforcement steel can be significantly reduced, often at a ratio of 1:3 or 1:4. This optimized utilization of materials results in improved construction efficiency.

Mechanical anchorage devices, known as "Anchors," are used at the two ends of the tendons to provide the necessary anchorage function after tendon stressing. Post tensioning systems are generally categorized as bonded or unbonded.

In a bonded system, the tendons within ducts are embedded in concrete and grouted after stressing. The grout serves to establish compatibility between the prestressed concrete and the tendons, ensuring homogeneity within the structure. In this bonded configuration, any applied load or strain experienced by the concrete is also transferred to the prestressed tendons, and vice versa.

In an unbonded system, the tendons are anchored only at both ends, deliberately preventing bonding with the concrete along their length. The tendons can either be buried inside or located outside the concrete, but in either case, they are not bonded to the concrete. One example of an unbonded system is the stay cable system used in bridge construction.

Post tensioning introduces deviation forces, anchor forces, and frictional forces into the concrete. These forces are optimally utilized through various tendon profiles, positioning, and carefully planned stressing sequences to control deflections. Effective deflection control is crucial for countering loads and preventing concrete cracking.

The advantages of post tensioning technology in civil construction are numerous:

1. Larger spans, resulting in fewer columns and supports.
2. Cost savings achieved through reduced material usage, including thinner concrete member sizes and less rebar.
3. Reduced dead load, requiring fewer foundations.
4. Faster construction speed, leading to shorter formwork rotation cycles.
5. Improved crack control and water containment in applications requiring water tightness.
6. Lower overall maintenance and lifecycle costs.
7. Enhanced seismic behavior.
8. Reduced carbon footprint.
9. More sustainable construction solution.

Huayongxin's Post Tensioning System adheres to international standards and is widely accepted in many countries. Our reputation is built on reliability and the delivery of high-performance products.