Due to its advantages, prestressed concrete is currently very popular in the construction industry. It guarantees greater cost-benefit and better construction progress.
There are essentially two types of prestressing processes.
- preload
- Post-tensioning
During prestressing, the ties are first tensioned and then the concreting work is carried out. In tensioned construction, as the name suggests, the wires are tensioned after the completion of the concreting work.
The article Bridge Construction to BS 5400 specifies the methods for constructing a prestressed girder.
Let's discuss the advantage of prestressed concrete.
Advantages of prestressed concrete
- Prestressed concrete can be designed to prevent tensile cracks in the concrete. Then the entire section is under pressure and no tensile cracks occur. This increases the durability of the structure.
- The carrying capacity is comparatively higher. Large spans can be supported.
- As high-strength steel wires are used in the construction, the required reinforcement area is reduced.
- Furthermore, material costs are comparatively lower compared to normal reinforced concrete components. The cross-sectional size and the area of steel to be used are smaller.
- With their help, larger gaps can be overcome.
- The deflection of prestressed concrete elements is comparatively less compared to reinforced concrete components of similar type.
- Depending on the position of the fixing profile, the load capacity varies.
- For repetitive production, the use of prestressed components is more economical.
- As the profile has less weight, it can be transported.
- The completion of the concrete work is greater
- The same conveyor can often be used for repetitive jobs. In bridge construction, there are standard beams that only need to be manufactured repeatedly because the same type can be used in all applicable locations.
Disadvantages of prestressed concrete
- Requires skilled workers
- Great attention must be paid to quality control.
- Special techniques are required to apply prestressing forces and anchor the strands.
- This requires high-strength concrete, which is expensive.
- Complicated clamping devices are required.
- The production of formwork is very difficult and to avoid the formation of honeycombs special compaction methods must be used.
- Work must be actively monitored.
- Greater technical knowledge is required.
